🕷️ Crawler Inspector

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Raw Queries and Responses

1. Shard Calculation

Query:

Response:

Calculated Shard: 152 (from laksa122)

2. Crawled Status Check

Query:

curl -X POST \
  'http://laksa152.int.ahrefs:8124/' \
  -H 'Content-Type: text/plain' \
  -H 'X-ClickHouse-Database: crawler3' \
  -H 'Authorization: Basic YXBpOg==' \
  -d 'SELECT getAhrefsURLFromUnparsed(src_unparsed) AS found_url, ifNull(toUnixTimestamp(download_stamp), 0) AS crawl_time, ifNull(toUnixTimestamp(props_url_first_seen), 0) AS first_indexed_time, download_http_code AS http_code, src_unparsed AS src_unparsed, src_root_hash AS src_root_hash, history_drop_reason AS history_drop_reason, meta_title AS meta_title, meta_descriptions AS meta_descriptions, attrs_boilerpipe_text AS attrs_boilerpipe_text, attrs_markdown AS attrs_markdown, attrs_readable_markdown AS attrs_readable_markdown, meta_canonical AS meta_canonical FROM crawler3.page_info_local FINAL PREWHERE (src_root_hash, src_unparsed) IN ((getAhrefsRootHashFromUnparsed(getAhrefsUnparsedNoserviceFromURL(\'https://en.wikipedia.org/wiki/Hydrostatic_test\')), getAhrefsUnparsedNoserviceFromURL(\'https://en.wikipedia.org/wiki/Hydrostatic_test\'))) FORMAT JSONEachRow'

Response:

{"found_url":"https:\/\/en.wikipedia.org\/wiki\/Hydrostatic_test","crawl_time":1774134082,"first_indexed_time":1431384594,"http_code":200,"src_unparsed":"org,wikipedia!en,\/wiki\/Hydrostatic_test s443","src_root_hash":"17790707453426894952","history_drop_reason":null,"meta_title":"Hydrostatic test - Wikipedia","meta_descriptions":[],"attrs_boilerpipe_text":"From Wikipedia, the free encyclopedia\nHydrostatic tester\nA\nhydrostatic test\nis a way in which\npressure vessels\nsuch as\npipelines\n,\nplumbing\n,\ngas cylinders\n,\nboilers\nand fuel tanks can be tested for strength and leaks. The test involves filling the vessel or pipe system with a liquid, usually water, which may be dyed to aid in visual\nleak detection\n, and pressurization of the vessel to the specified test pressure. Pressure tightness can be tested by shutting off the supply valve and observing whether there is a pressure loss. The location of a leak can be visually identified more easily if the water contains a colorant. Strength is usually tested by measuring permanent deformation of the container.\nHydrostatic testing is the most common method employed for testing pipes and pressure vessels. Using this test helps maintain safety standards and durability of a vessel over time. Newly manufactured pieces are initially qualified using the hydrostatic test. They are then revalidated at regular intervals according to the relevant standard. In some cases where a hydrostatic test is not practicable a pneumatic pressure test may be an acceptable alternative.\n[\n1\n]\nTesting of pressure vessels for transport and storage of gases is very important because such containers can explode if they fail under pressure.\nHydrostatic tests are conducted under the constraints of either the industry's or the customer's specifications, or may be required by law. The vessel is filled with a nearly incompressible liquid – usually\nwater\nor\noil\n– pressurised to test pressure, and examined for leaks or permanent changes in shape.\nRed\nor\nfluorescent\ndyes\nmay be added to the water to make leaks easier to see. The test pressure is always considerably higher than the operating pressure to give a factor of safety. This factor of safety is typically 166.66%, 143% or 150% of the designed working pressure, depending on the regulations that apply. For example, if a cylinder was rated to DOT-2015 PSI (approximately 139 bar), it would be tested at around 3360 PSI (approximately 232 bar).\nWater\nis commonly used because it is cheap and easily available, and is usually harmless to the system to be tested. Hydraulic fluids and oils may be specified where contamination with water could cause problems. These fluids are nearly incompressible, therefore requiring relatively little work to develop a high pressure, and is therefore also only able to release a small amount of energy in case of a failure - only a small volume will escape under high pressure if the container fails. If\nhigh pressure\ngas\nwere used, then the gas would expand to V=(nRT)\/p  with its compressed volume resulting in an explosion, with the attendant risk of damage or injury.\nWater jacket test\nSmall pressure vessels are normally tested using a water jacket test. The vessel is visually examined for defects and then placed in a container filled with water, and in which the change in volume of the vessel can be measured, usually by monitoring the water level in a calibrated tube. The vessel is then pressurised for a specified period, usually 30 or more seconds, and if specified, the expansion will be measured by reading off the amount of liquid that has been forced into the measuring tube by the volume increase of the pressurised vessel. The  vessel is then depressurised, and the permanent volume increase due to plastic deformation while under pressure (\npermanent set\n) is measured by comparing the final volume in the measuring tube with the volume before pressurisation.\n[\n2\n]\nA leak will give a similar result to permanent set, but will be detectable by holding the volume in the pressurised vessel by closing the inlet valve for a period before depressurising, as the pressure will drop steadily during this period if there is a leak. In most cases a permanent set that exceeds the specified maximum will indicate failure. A leak may also be a failure criterion, but it may be that the leak is due to poor sealing of the test equipment. If the vessel fails, it will normally go through a condemning process marking the cylinder as unsafe.\n[\n2\n]\n[\n3\n]\nThe information needed to specify the test is stamped onto the cylinder. This includes the design standard, serial number, manufacturer, and  manufacture date. After testing, the vessel or its nameplate will usually be stamp marked with the date of the successful test, and the test facility's identification mark.\n[\n3\n]\nA simpler test, that is also considered a hydrostatic test but does not require pressure pumps, is to pressurise the vessel by filling it with water to a hydrostatic head by using a riser pipe connected to the tank and to physically examine the outside for leaks. This type of test is suitable for containers such as boat fuel tanks, which are not pressure vessels but must work under the hydrostatic pressure of the contents. A hydrostatic test head is usually specified as a height above the tank top. The tank is pressurised by filling water to the specified height through a temporary standpipe if necessary. It may be necessary to seal vents and other outlets during the test.\n[\n4\n]\nPortable fire extinguishers are safety tools that are required in most public buildings. Fire extinguishers are also recommended in homes. Over time the conditions in which they are housed, and the manner in which they are handled affect the structural integrity of the extinguisher. A structurally weakened fire extinguisher can malfunction or even burst when it is needed the most. To maintain the quality and safety of this product, hydrostatic testing is utilized. All critical components of the fire extinguisher should be tested to ensure proper function.\nHydrotesting of pipes, pipelines and vessels is performed to expose defective materials that have missed prior detection, ensure that any remaining defects are insignificant enough to allow operation at design pressures, expose possible leaks and serve as a final validation of the integrity of the constructed system. ASME B31.3 requires this testing to ensure tightness and strength.\nBuried high pressure oil and gas pipelines are tested for strength by pressurising them to at least 125% of their\nmaximum allowable working pressure\n(MAWP) at any point along their length. Since many long distance transmission pipelines are designed to have a steel hoop stress of 80% of\nspecified minimum yield strength\n(SMYS) at\nMaximum allowable operating pressure\nMAOP, this means that the steel is stressed to SMYS and above during the testing, and test sections must be selected to ensure that excessive plastic deformation does not occur.\n[\ncitation needed\n]\nFor piping built to ASME B31.3, if the design temperature is greater than the test temperature, then the test pressure must be adjusted for the related allowable stress at the design temperature.  This is done by multiplying 1.5 MAWP by the ratio of the allowable stress at the test temperature to allowable stress at the design temperature per ASME B31.3 Section 345.4.2 Equation 24.  Test pressures need not exceed a value that would produce a stress higher than yield stress at test temperature. ASME B31.3 section 345.4.2 (c)\nOther codes require a more onerous approach.  BS PD 8010-2 requires testing to 150% of the\ndesign\npressure – which should not be less than the MAOP plus surge and other incidental effects that will occur during normal operation.\n[\ncitation needed\n]\nLeak testing is performed by balancing changes in the measured pressure in the test section against the theoretical pressure changes calculated from changes in the measured temperature of the test section.\nAustralian standard AS2885.5 \"Pipelines – Gas and liquid petroleum: Part 5: Field pressure testing\" gives an excellent explanation of the factors involved.\n[\nclarification needed\n]\nIn the aerospace industry, depending on the airline, company or customer, certain codes will need to be followed. For example, Bell Helicopter has a certain specification that will have to be followed for any parts that will be used in their helicopters.\n[\ncitation needed\n]\nMost countries have legislation or pressure vessel codes which requires vessels to be regularly tested, for example every two years (with a visual inspection annually) for high pressure gas cylinders and every five or ten years for lower pressure ones such as used in\nfire extinguishers\n.\n[\n5\n]\n[\nclarification needed\n]\nGas cylinders which fail are normally destroyed as part of the testing protocol to avoid the dangers inherent in them being subsequently used.\n[\n6\n]\nThese common US standard gas cylinders have the following requirements:\n[\n7\n]\nDOT-3AL gas cylinders must be tested every 5 years and have an unlimited life.\nDOT-3HT gas cylinders must be tested every 3 years and have a 24-year life.\nDOT-3AA gas cylinders must be tested every 5 years and have an unlimited life. (Unless stamped with a star (*) in which case the cylinder meets certain specifications and can have a 10-year hydrostatic test life).\nTypically organizations such as DOT\nPHMSA\n,\nISO\n,\nASTM\nand\nASME\nspecify the guidelines for the different types of pressure vessels.\nHydraulic testing is a hazardous process and should be performed with caution by competent personnel. Adhering to prescribed procedures defined in relevant\ntechnical standards\nappropriate to the specific application and jurisdiction will usually reduce these risks to an acceptable level.\nA leak of high pressure liquid can cut or penetrate the skin and inject itself into body tissues. This can cause serious direct injury to the operator, and if the fluid is toxic or contaminated there will be additional adverse effects.\nA pressurised hose that is not securely attached or which fails under pressure may whip around spraying water or oil and could hit someone and cause injuries. A\nwhiplash arrestor\ncan be used to restrain such hoses.\nEnclosing the components to be tested, hazard signage, use of appropriate\npersonal protective equipment\nand providing barriers to access for non-essential personnel are common precautions.\nNondestructive testing\n – Type of analysis technique\nTesting and inspection of diving cylinders\n – Periodical inspection and testing to revalidate fitness for service\n^\n\"Proof-Pressure Test and Leak Detection Test in Metal Expansion Joints\"\n(PDF)\n.\nwww.macoga.com\n. Macoga SA\n. Retrieved\n24 September\n2021\n.\n^\na\nb\nSauta, Tom (1 Oct 2010).\n\"Hydro-Test Water Jacket Cylinder Test System Setup.wmv\"\n. www.hydrotest.com\n. Retrieved\n29 July\n2025\n– via YouTube.\n^\na\nb\nAngel (17 May 2022).\n\"How to Hydro Test a scuba tank\"\n. Scuba Tech Key Largo\n. Retrieved\n29 July\n2025\n– via YouTube.\n^\nKim; An, Tae-Hyun; Lee, Tak-Kee (April 2022).\n\"Preliminary Study on Deformation During Hydrostatic Testing in a Deep Tank }first1=Geun-Gon\"\n.\nJ. Ocean Eng. Technol\n.\n36\n(2):\n115–\n124.\ndoi\n:\n10.26748\/KSOE.2021.075\n.\n^\n\"Federal Register :: Request Access\"\n.\n^\n\"Federal Register :: Request Access\"\n.\n^\n\"Federal Register :: Request Access\"\n.\n\"OSHA\"\n. Retrieved\n2006-10-05\n.","attrs_markdown":"[Jump to content](https:\/\/en.wikipedia.org\/wiki\/Hydrostatic_test#bodyContent)\n\nMain menu\n\nMain menu\n\nmove to sidebar\n\nhide\n\nNavigation\n\n- [Main page](https:\/\/en.wikipedia.org\/wiki\/Main_Page \"Visit the main page [z]\")\n- [Contents](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Contents \"Guides to browsing Wikipedia\")\n- [Current events](https:\/\/en.wikipedia.org\/wiki\/Portal:Current_events \"Articles related to current events\")\n- [Random article](https:\/\/en.wikipedia.org\/wiki\/Special:Random \"Visit a randomly selected article [x]\")\n- [About Wikipedia](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:About \"Learn about Wikipedia and how it works\")\n- [Contact us](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Contact_us \"How to contact Wikipedia\")\n\nContribute\n\n- [Help](https:\/\/en.wikipedia.org\/wiki\/Help:Contents \"Guidance on how to use and edit Wikipedia\")\n- [Learn to edit](https:\/\/en.wikipedia.org\/wiki\/Help:Introduction \"Learn how to edit Wikipedia\")\n- [Community portal](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Community_portal \"The hub for editors\")\n- [Recent changes](https:\/\/en.wikipedia.org\/wiki\/Special:RecentChanges \"A list of recent changes to Wikipedia [r]\")\n- [Upload file](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:File_upload_wizard \"Add images or other media for use on Wikipedia\")\n- [Special pages](https:\/\/en.wikipedia.org\/wiki\/Special:SpecialPages \"A list of all special pages [q]\")\n\n[![](https:\/\/en.wikipedia.org\/static\/images\/icons\/enwiki-25.svg) ![Wikipedia](https:\/\/en.wikipedia.org\/static\/images\/mobile\/copyright\/wikipedia-wordmark-en-25.svg) ![The Free Encyclopedia](https:\/\/en.wikipedia.org\/static\/images\/mobile\/copyright\/wikipedia-tagline-en-25.svg)](https:\/\/en.wikipedia.org\/wiki\/Main_Page)\n\n[Search](https:\/\/en.wikipedia.org\/wiki\/Special:Search \"Search Wikipedia [f]\")\n\nAppearance\n\n- [Donate](https:\/\/donate.wikimedia.org\/?wmf_source=donate&wmf_medium=sidebar&wmf_campaign=en.wikipedia.org&uselang=en)\n- [Create account](https:\/\/en.wikipedia.org\/w\/index.php?title=Special:CreateAccount&returnto=Hydrostatic+test \"You are encouraged to create an account and log in; however, it is not mandatory\")\n- [Log in](https:\/\/en.wikipedia.org\/w\/index.php?title=Special:UserLogin&returnto=Hydrostatic+test \"You're encouraged to log in; however, it's not mandatory. [o]\")\n\nPersonal tools\n\n- [Donate](https:\/\/donate.wikimedia.org\/?wmf_source=donate&wmf_medium=sidebar&wmf_campaign=en.wikipedia.org&uselang=en)\n- [Create account](https:\/\/en.wikipedia.org\/w\/index.php?title=Special:CreateAccount&returnto=Hydrostatic+test \"You are encouraged to create an account and log in; however, it is not mandatory\")\n- [Log in](https:\/\/en.wikipedia.org\/w\/index.php?title=Special:UserLogin&returnto=Hydrostatic+test \"You're encouraged to log in; however, it's not mandatory. [o]\")\n\n## Contents\nmove to sidebar\n\nhide\n\n- [(Top)](https:\/\/en.wikipedia.org\/wiki\/Hydrostatic_test)\n- [1 Testing procedures](https:\/\/en.wikipedia.org\/wiki\/Hydrostatic_test#Testing_procedures)\n- [2 Examples](https:\/\/en.wikipedia.org\/wiki\/Hydrostatic_test#Examples)\n- [3 Pipeline testing](https:\/\/en.wikipedia.org\/wiki\/Hydrostatic_test#Pipeline_testing)\n- [4 Testing frequency](https:\/\/en.wikipedia.org\/wiki\/Hydrostatic_test#Testing_frequency)\n- [5 Safety](https:\/\/en.wikipedia.org\/wiki\/Hydrostatic_test#Safety)\n- [6 See also](https:\/\/en.wikipedia.org\/wiki\/Hydrostatic_test#See_also)\n- [7 References](https:\/\/en.wikipedia.org\/wiki\/Hydrostatic_test#References)\n- [8 External links](https:\/\/en.wikipedia.org\/wiki\/Hydrostatic_test#External_links)\n\nToggle the table of contents\n\n# Hydrostatic test\n6 languages\n\n- [অসমীয়া](https:\/\/as.wikipedia.org\/wiki\/%E0%A6%B9%E0%A6%BE%E0%A6%87%E0%A6%A1%E0%A7%8D%E0%A7%B0%E2%80%99%E0%A6%B7%E0%A7%8D%E0%A6%9F%E0%A7%87%E0%A6%9F%E0%A6%BF%E0%A6%95_%E0%A6%AA%E0%A7%B0%E0%A7%80%E0%A6%95%E0%A7%8D%E0%A6%B7%E0%A6%BE \"হাইড্ৰ’ষ্টেটিক পৰীক্ষা – Assamese\")\n- [Deutsch](https:\/\/de.wikipedia.org\/wiki\/Druckpr%C3%BCfung \"Druckprüfung – German\")\n- [Bahasa Indonesia](https:\/\/id.wikipedia.org\/wiki\/Tes_hidrostatis \"Tes hidrostatis – Indonesian\")\n- [Русский](https:\/\/ru.wikipedia.org\/wiki\/%D0%93%D0%B8%D0%B4%D1%80%D0%B0%D0%B2%D0%BB%D0%B8%D1%87%D0%B5%D1%81%D0%BA%D0%BE%D0%B5_%D0%B8%D1%81%D0%BF%D1%8B%D1%82%D0%B0%D0%BD%D0%B8%D0%B5 \"Гидравлическое испытание – Russian\")\n- [Slovenščina](https:\/\/sl.wikipedia.org\/wiki\/Hidrostati%C4%8Dni_test \"Hidrostatični test – Slovenian\")\n- [Українська](https:\/\/uk.wikipedia.org\/wiki\/%D0%93%D1%96%D0%B4%D1%80%D0%B0%D0%B2%D0%BB%D1%96%D1%87%D0%BD%D1%96_%D0%B2%D0%B8%D0%BF%D1%80%D0%BE%D0%B1%D1%83%D0%B2%D0%B0%D0%BD%D0%BD%D1%8F \"Гідравлічні випробування – Ukrainian\")\n\n[Edit links](https:\/\/www.wikidata.org\/wiki\/Special:EntityPage\/Q1260986#sitelinks-wikipedia \"Edit interlanguage links\")\n\n- [Article](https:\/\/en.wikipedia.org\/wiki\/Hydrostatic_test \"View the content page [c]\")\n- [Talk](https:\/\/en.wikipedia.org\/wiki\/Talk:Hydrostatic_test \"Discuss improvements to the content page [t]\")\n\nEnglish\n\n- [Read](https:\/\/en.wikipedia.org\/wiki\/Hydrostatic_test)\n- [Edit](https:\/\/en.wikipedia.org\/w\/index.php?title=Hydrostatic_test&action=edit \"Edit this page [e]\")\n- [View history](https:\/\/en.wikipedia.org\/w\/index.php?title=Hydrostatic_test&action=history \"Past revisions of this page [h]\")\n\nTools\n\nTools\n\nmove to sidebar\n\nhide\n\nActions\n\n- [Read](https:\/\/en.wikipedia.org\/wiki\/Hydrostatic_test)\n- [Edit](https:\/\/en.wikipedia.org\/w\/index.php?title=Hydrostatic_test&action=edit \"Edit this page [e]\")\n- [View history](https:\/\/en.wikipedia.org\/w\/index.php?title=Hydrostatic_test&action=history)\n\nGeneral\n\n- [What links here](https:\/\/en.wikipedia.org\/wiki\/Special:WhatLinksHere\/Hydrostatic_test \"List of all English Wikipedia pages containing links to this page [j]\")\n- [Related changes](https:\/\/en.wikipedia.org\/wiki\/Special:RecentChangesLinked\/Hydrostatic_test \"Recent changes in pages linked from this page [k]\")\n- [Upload file](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:File_Upload_Wizard \"Upload files [u]\")\n- [Permanent link](https:\/\/en.wikipedia.org\/w\/index.php?title=Hydrostatic_test&oldid=1328520287 \"Permanent link to this revision of this page\")\n- [Page information](https:\/\/en.wikipedia.org\/w\/index.php?title=Hydrostatic_test&action=info \"More information about this page\")\n- [Cite this page](https:\/\/en.wikipedia.org\/w\/index.php?title=Special:CiteThisPage&page=Hydrostatic_test&id=1328520287&wpFormIdentifier=titleform \"Information on how to cite this page\")\n- [Get shortened URL](https:\/\/en.wikipedia.org\/w\/index.php?title=Special:UrlShortener&url=https%3A%2F%2Fen.wikipedia.org%2Fwiki%2FHydrostatic_test)\n\nPrint\/export\n\n- [Download as PDF](https:\/\/en.wikipedia.org\/w\/index.php?title=Special:DownloadAsPdf&page=Hydrostatic_test&action=show-download-screen \"Download this page as a PDF file\")\n- [Printable version](https:\/\/en.wikipedia.org\/w\/index.php?title=Hydrostatic_test&printable=yes \"Printable version of this page [p]\")\n\nIn other projects\n\n- [Wikimedia Commons](https:\/\/commons.wikimedia.org\/wiki\/Category:Hydrostatic_test)\n- [Wikidata item](https:\/\/www.wikidata.org\/wiki\/Special:EntityPage\/Q1260986 \"Structured data on this page hosted by Wikidata [g]\")\n\nAppearance\n\nmove to sidebar\n\nhide\n\nFrom Wikipedia, the free encyclopedia\n\nNon-destructive test of pressure vessels\n\nFor the autopsy procedure, see [lung float test](https:\/\/en.wikipedia.org\/wiki\/Lung_float_test \"Lung float test\").\n\n|   |   |\n|---|---|\n| [![icon](https:\/\/upload.wikimedia.org\/wikipedia\/en\/thumb\/9\/99\/Question_book-new.svg\/60px-Question_book-new.svg.png)](https:\/\/en.wikipedia.org\/wiki\/File:Question_book-new.svg) | This article **needs additional citations for [verification](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Verifiability \"Wikipedia:Verifiability\")**. Please help [improve this article](https:\/\/en.wikipedia.org\/wiki\/Special:EditPage\/Hydrostatic_test \"Special:EditPage\/Hydrostatic test\") by [adding citations to reliable sources](https:\/\/en.wikipedia.org\/wiki\/Help:Referencing_for_beginners \"Help:Referencing for beginners\"). Unsourced material may be challenged and removed. *Find sources:* [\"Hydrostatic test\"](https:\/\/www.google.com\/search?as_eq=wikipedia&q=%22Hydrostatic+test%22) – [news](https:\/\/www.google.com\/search?tbm=nws&q=%22Hydrostatic+test%22+-wikipedia&tbs=ar:1) **·** [newspapers](https:\/\/www.google.com\/search?&q=%22Hydrostatic+test%22&tbs=bkt:s&tbm=bks) **·** [books](https:\/\/www.google.com\/search?tbs=bks:1&q=%22Hydrostatic+test%22+-wikipedia) **·** [scholar](https:\/\/scholar.google.com\/scholar?q=%22Hydrostatic+test%22) **·** [JSTOR](https:\/\/www.jstor.org\/action\/doBasicSearch?Query=%22Hydrostatic+test%22&acc=on&wc=on) *(September 2009)* *([Learn how and when to remove this message](https:\/\/en.wikipedia.org\/wiki\/Help:Maintenance_template_removal \"Help:Maintenance template removal\"))* |\n\n[![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/c\/c5\/Hydrostatic_Tester.jpg\/250px-Hydrostatic_Tester.jpg)](https:\/\/en.wikipedia.org\/wiki\/File:Hydrostatic_Tester.jpg)\n\nHydrostatic tester\n\nA **hydrostatic test** is a way in which [pressure vessels](https:\/\/en.wikipedia.org\/wiki\/Pressure_vessel \"Pressure vessel\") such as [pipelines](https:\/\/en.wikipedia.org\/wiki\/Pipeline_transport \"Pipeline transport\"), [plumbing](https:\/\/en.wikipedia.org\/wiki\/Plumbing \"Plumbing\"), [gas cylinders](https:\/\/en.wikipedia.org\/wiki\/Gas_cylinder \"Gas cylinder\"), [boilers](https:\/\/en.wikipedia.org\/wiki\/Boiler \"Boiler\") and fuel tanks can be tested for strength and leaks. The test involves filling the vessel or pipe system with a liquid, usually water, which may be dyed to aid in visual [leak detection](https:\/\/en.wikipedia.org\/wiki\/Leak_detection \"Leak detection\"), and pressurization of the vessel to the specified test pressure. Pressure tightness can be tested by shutting off the supply valve and observing whether there is a pressure loss. The location of a leak can be visually identified more easily if the water contains a colorant. Strength is usually tested by measuring permanent deformation of the container.\n\nHydrostatic testing is the most common method employed for testing pipes and pressure vessels. Using this test helps maintain safety standards and durability of a vessel over time. Newly manufactured pieces are initially qualified using the hydrostatic test. They are then revalidated at regular intervals according to the relevant standard. In some cases where a hydrostatic test is not practicable a pneumatic pressure test may be an acceptable alternative.[\\[1\\]](https:\/\/en.wikipedia.org\/wiki\/Hydrostatic_test#cite_note-Proof-1)\n\nTesting of pressure vessels for transport and storage of gases is very important because such containers can explode if they fail under pressure.\n\n## Testing procedures\n\\[[edit](https:\/\/en.wikipedia.org\/w\/index.php?title=Hydrostatic_test&action=edit&section=1 \"Edit section: Testing procedures\")\\]\n\nHydrostatic tests are conducted under the constraints of either the industry's or the customer's specifications, or may be required by law. The vessel is filled with a nearly incompressible liquid – usually [water](https:\/\/en.wikipedia.org\/wiki\/Water \"Water\") or [oil](https:\/\/en.wikipedia.org\/wiki\/Oil \"Oil\") – pressurised to test pressure, and examined for leaks or permanent changes in shape. [Red](https:\/\/en.wikipedia.org\/wiki\/Red \"Red\") or [fluorescent](https:\/\/en.wikipedia.org\/wiki\/Fluorescent \"Fluorescent\") [dyes](https:\/\/en.wikipedia.org\/wiki\/Dye \"Dye\") may be added to the water to make leaks easier to see. The test pressure is always considerably higher than the operating pressure to give a factor of safety. This factor of safety is typically 166.66%, 143% or 150% of the designed working pressure, depending on the regulations that apply. For example, if a cylinder was rated to DOT-2015 PSI (approximately 139 bar), it would be tested at around 3360 PSI (approximately 232 bar).\n\n[Water](https:\/\/en.wikipedia.org\/wiki\/Water \"Water\") is commonly used because it is cheap and easily available, and is usually harmless to the system to be tested. Hydraulic fluids and oils may be specified where contamination with water could cause problems. These fluids are nearly incompressible, therefore requiring relatively little work to develop a high pressure, and is therefore also only able to release a small amount of energy in case of a failure - only a small volume will escape under high pressure if the container fails. If [high pressure](https:\/\/en.wikipedia.org\/wiki\/High_pressure \"High pressure\") [gas](https:\/\/en.wikipedia.org\/wiki\/Gas \"Gas\") were used, then the gas would expand to V=(nRT)\/p with its compressed volume resulting in an explosion, with the attendant risk of damage or injury.\n\n[![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/7\/76\/Water_jacket_test_diagram.jpg\/250px-Water_jacket_test_diagram.jpg)](https:\/\/en.wikipedia.org\/wiki\/File:Water_jacket_test_diagram.jpg)\n\nWater jacket test\n\nSmall pressure vessels are normally tested using a water jacket test. The vessel is visually examined for defects and then placed in a container filled with water, and in which the change in volume of the vessel can be measured, usually by monitoring the water level in a calibrated tube. The vessel is then pressurised for a specified period, usually 30 or more seconds, and if specified, the expansion will be measured by reading off the amount of liquid that has been forced into the measuring tube by the volume increase of the pressurised vessel. The vessel is then depressurised, and the permanent volume increase due to plastic deformation while under pressure (permanent set) is measured by comparing the final volume in the measuring tube with the volume before pressurisation.[\\[2\\]](https:\/\/en.wikipedia.org\/wiki\/Hydrostatic_test#cite_note-Sauta_2010-2)\n\nA leak will give a similar result to permanent set, but will be detectable by holding the volume in the pressurised vessel by closing the inlet valve for a period before depressurising, as the pressure will drop steadily during this period if there is a leak. In most cases a permanent set that exceeds the specified maximum will indicate failure. A leak may also be a failure criterion, but it may be that the leak is due to poor sealing of the test equipment. If the vessel fails, it will normally go through a condemning process marking the cylinder as unsafe.[\\[2\\]](https:\/\/en.wikipedia.org\/wiki\/Hydrostatic_test#cite_note-Sauta_2010-2)[\\[3\\]](https:\/\/en.wikipedia.org\/wiki\/Hydrostatic_test#cite_note-Hydro_Key_Largo-3)\n\nThe information needed to specify the test is stamped onto the cylinder. This includes the design standard, serial number, manufacturer, and manufacture date. After testing, the vessel or its nameplate will usually be stamp marked with the date of the successful test, and the test facility's identification mark.[\\[3\\]](https:\/\/en.wikipedia.org\/wiki\/Hydrostatic_test#cite_note-Hydro_Key_Largo-3)\n\nA simpler test, that is also considered a hydrostatic test but does not require pressure pumps, is to pressurise the vessel by filling it with water to a hydrostatic head by using a riser pipe connected to the tank and to physically examine the outside for leaks. This type of test is suitable for containers such as boat fuel tanks, which are not pressure vessels but must work under the hydrostatic pressure of the contents. A hydrostatic test head is usually specified as a height above the tank top. The tank is pressurised by filling water to the specified height through a temporary standpipe if necessary. It may be necessary to seal vents and other outlets during the test.[\\[4\\]](https:\/\/en.wikipedia.org\/wiki\/Hydrostatic_test#cite_note-4)\n\n## Examples\n\\[[edit](https:\/\/en.wikipedia.org\/w\/index.php?title=Hydrostatic_test&action=edit&section=2 \"Edit section: Examples\")\\]\n\nPortable fire extinguishers are safety tools that are required in most public buildings. Fire extinguishers are also recommended in homes. Over time the conditions in which they are housed, and the manner in which they are handled affect the structural integrity of the extinguisher. A structurally weakened fire extinguisher can malfunction or even burst when it is needed the most. To maintain the quality and safety of this product, hydrostatic testing is utilized. All critical components of the fire extinguisher should be tested to ensure proper function.\n\n## Pipeline testing\n\\[[edit](https:\/\/en.wikipedia.org\/w\/index.php?title=Hydrostatic_test&action=edit&section=3 \"Edit section: Pipeline testing\")\\]\n\nHydrotesting of pipes, pipelines and vessels is performed to expose defective materials that have missed prior detection, ensure that any remaining defects are insignificant enough to allow operation at design pressures, expose possible leaks and serve as a final validation of the integrity of the constructed system. ASME B31.3 requires this testing to ensure tightness and strength.\n\nBuried high pressure oil and gas pipelines are tested for strength by pressurising them to at least 125% of their [maximum allowable working pressure](https:\/\/en.wikipedia.org\/wiki\/Maximum_allowable_working_pressure \"Maximum allowable working pressure\") (MAWP) at any point along their length. Since many long distance transmission pipelines are designed to have a steel hoop stress of 80% of [specified minimum yield strength](https:\/\/en.wikipedia.org\/wiki\/Specified_minimum_yield_strength \"Specified minimum yield strength\") (SMYS) at [Maximum allowable operating pressure](https:\/\/en.wikipedia.org\/wiki\/Maximum_allowable_operating_pressure \"Maximum allowable operating pressure\") MAOP, this means that the steel is stressed to SMYS and above during the testing, and test sections must be selected to ensure that excessive plastic deformation does not occur.\\[*[citation needed](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Citation_needed \"Wikipedia:Citation needed\")*\\]\n\nFor piping built to ASME B31.3, if the design temperature is greater than the test temperature, then the test pressure must be adjusted for the related allowable stress at the design temperature. This is done by multiplying 1.5 MAWP by the ratio of the allowable stress at the test temperature to allowable stress at the design temperature per ASME B31.3 Section 345.4.2 Equation 24. Test pressures need not exceed a value that would produce a stress higher than yield stress at test temperature. ASME B31.3 section 345.4.2 (c)\n\nOther codes require a more onerous approach. BS PD 8010-2 requires testing to 150% of the *design* pressure – which should not be less than the MAOP plus surge and other incidental effects that will occur during normal operation.\\[*[citation needed](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Citation_needed \"Wikipedia:Citation needed\")*\\]\n\nLeak testing is performed by balancing changes in the measured pressure in the test section against the theoretical pressure changes calculated from changes in the measured temperature of the test section.\n\nAustralian standard AS2885.5 \"Pipelines – Gas and liquid petroleum: Part 5: Field pressure testing\" gives an excellent explanation of the factors involved.\\[*[clarification needed](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Please_clarify \"Wikipedia:Please clarify\")*\\]\n\nIn the aerospace industry, depending on the airline, company or customer, certain codes will need to be followed. For example, Bell Helicopter has a certain specification that will have to be followed for any parts that will be used in their helicopters.\\[*[citation needed](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Citation_needed \"Wikipedia:Citation needed\")*\\]\n\n## Testing frequency\n\\[[edit](https:\/\/en.wikipedia.org\/w\/index.php?title=Hydrostatic_test&action=edit&section=4 \"Edit section: Testing frequency\")\\]\n\nMost countries have legislation or pressure vessel codes which requires vessels to be regularly tested, for example every two years (with a visual inspection annually) for high pressure gas cylinders and every five or ten years for lower pressure ones such as used in [fire extinguishers](https:\/\/en.wikipedia.org\/wiki\/Fire_extinguisher \"Fire extinguisher\").[\\[5\\]](https:\/\/en.wikipedia.org\/wiki\/Hydrostatic_test#cite_note-5) \\[*[clarification needed](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Please_clarify \"Wikipedia:Please clarify\")*\\] Gas cylinders which fail are normally destroyed as part of the testing protocol to avoid the dangers inherent in them being subsequently used.[\\[6\\]](https:\/\/en.wikipedia.org\/wiki\/Hydrostatic_test#cite_note-6)\n\nThese common US standard gas cylinders have the following requirements:[\\[7\\]](https:\/\/en.wikipedia.org\/wiki\/Hydrostatic_test#cite_note-7)\n\n- DOT-3AL gas cylinders must be tested every 5 years and have an unlimited life.\n- DOT-3HT gas cylinders must be tested every 3 years and have a 24-year life.\n- DOT-3AA gas cylinders must be tested every 5 years and have an unlimited life. (Unless stamped with a star (\\*) in which case the cylinder meets certain specifications and can have a 10-year hydrostatic test life).\n\nTypically organizations such as DOT [PHMSA](https:\/\/en.wikipedia.org\/wiki\/PHMSA \"PHMSA\"), [ISO](https:\/\/en.wikipedia.org\/wiki\/ISO \"ISO\"), [ASTM](https:\/\/en.wikipedia.org\/wiki\/ASTM \"ASTM\") and [ASME](https:\/\/en.wikipedia.org\/wiki\/ASME \"ASME\") specify the guidelines for the different types of pressure vessels.\n\n## Safety\n\\[[edit](https:\/\/en.wikipedia.org\/w\/index.php?title=Hydrostatic_test&action=edit&section=5 \"Edit section: Safety\")\\]\n\nHydraulic testing is a hazardous process and should be performed with caution by competent personnel. Adhering to prescribed procedures defined in relevant [technical standards](https:\/\/en.wikipedia.org\/wiki\/Technical_standards \"Technical standards\") appropriate to the specific application and jurisdiction will usually reduce these risks to an acceptable level.\n\n- A leak of high pressure liquid can cut or penetrate the skin and inject itself into body tissues. This can cause serious direct injury to the operator, and if the fluid is toxic or contaminated there will be additional adverse effects.\n- A pressurised hose that is not securely attached or which fails under pressure may whip around spraying water or oil and could hit someone and cause injuries. A [whiplash arrestor](https:\/\/en.wikipedia.org\/wiki\/Glossary_of_underwater_diving_terminology:_T%E2%80%93Z#whiplash_arrestor \"Glossary of underwater diving terminology: T–Z\") can be used to restrain such hoses.\n- Enclosing the components to be tested, hazard signage, use of appropriate [personal protective equipment](https:\/\/en.wikipedia.org\/wiki\/Personal_protective_equipment \"Personal protective equipment\") and providing barriers to access for non-essential personnel are common precautions.\n\n## See also\n\\[[edit](https:\/\/en.wikipedia.org\/w\/index.php?title=Hydrostatic_test&action=edit&section=6 \"Edit section: See also\")\\]\n\n- [Nondestructive testing](https:\/\/en.wikipedia.org\/wiki\/Nondestructive_testing \"Nondestructive testing\") – Type of analysis technique\n- [Testing and inspection of diving cylinders](https:\/\/en.wikipedia.org\/wiki\/Testing_and_inspection_of_diving_cylinders \"Testing and inspection of diving cylinders\") – Periodical inspection and testing to revalidate fitness for service\n\n## References\n\\[[edit](https:\/\/en.wikipedia.org\/w\/index.php?title=Hydrostatic_test&action=edit&section=7 \"Edit section: References\")\\]\n\n1. **[^](https:\/\/en.wikipedia.org\/wiki\/Hydrostatic_test#cite_ref-Proof_1-0)**\n   [\"Proof-Pressure Test and Leak Detection Test in Metal Expansion Joints\"](https:\/\/www.macoga.com\/documents\/en\/metal-expansion-joints\/proof-pressure-test-leak-detection-test.pdf) (PDF). *www.macoga.com*. Macoga SA. Retrieved 24 September 2021.\n2. ^ [***a***](https:\/\/en.wikipedia.org\/wiki\/Hydrostatic_test#cite_ref-Sauta_2010_2-0) [***b***](https:\/\/en.wikipedia.org\/wiki\/Hydrostatic_test#cite_ref-Sauta_2010_2-1)\n   Sauta, Tom (1 Oct 2010). [\"Hydro-Test Water Jacket Cylinder Test System Setup.wmv\"](https:\/\/www.youtube.com\/watch?v=KLrV0vGBZEk). www.hydrotest.com. Retrieved 29 July 2025 – via YouTube.\n3. ^ [***a***](https:\/\/en.wikipedia.org\/wiki\/Hydrostatic_test#cite_ref-Hydro_Key_Largo_3-0) [***b***](https:\/\/en.wikipedia.org\/wiki\/Hydrostatic_test#cite_ref-Hydro_Key_Largo_3-1)\n   Angel (17 May 2022). [\"How to Hydro Test a scuba tank\"](https:\/\/www.youtube.com\/watch?v=Bwd-GFCtLl8). Scuba Tech Key Largo. Retrieved 29 July 2025 – via YouTube.\n4. **[^](https:\/\/en.wikipedia.org\/wiki\/Hydrostatic_test#cite_ref-4)**\n   Kim; An, Tae-Hyun; Lee, Tak-Kee (April 2022). [\"Preliminary Study on Deformation During Hydrostatic Testing in a Deep Tank }first1=Geun-Gon\"](https:\/\/doi.org\/10.26748%2FKSOE.2021.075). *J. Ocean Eng. Technol*. **36** (2): 115–124\\. [doi](https:\/\/en.wikipedia.org\/wiki\/Doi_\\(identifier\\) \"Doi (identifier)\"):[10\\.26748\/KSOE.2021.075](https:\/\/doi.org\/10.26748%2FKSOE.2021.075).\n5. **[^](https:\/\/en.wikipedia.org\/wiki\/Hydrostatic_test#cite_ref-5)**\n   [\"Federal Register :: Request Access\"](https:\/\/www.ecfr.gov\/current\/title-49\/subtitle-B\/chapter-I\/subchapter-C\/part-180#p-180.209\\(j\\)).\n6. **[^](https:\/\/en.wikipedia.org\/wiki\/Hydrostatic_test#cite_ref-6)**\n   [\"Federal Register :: Request Access\"](https:\/\/www.ecfr.gov\/current\/title-49\/subtitle-B\/chapter-I\/subchapter-C\/part-180#p-180.205\\(i\\)).\n7. **[^](https:\/\/en.wikipedia.org\/wiki\/Hydrostatic_test#cite_ref-7)**\n   [\"Federal Register :: Request Access\"](https:\/\/www.ecfr.gov\/current\/title-49\/section-180.209).\n\n## External links\n\\[[edit](https:\/\/en.wikipedia.org\/w\/index.php?title=Hydrostatic_test&action=edit&section=8 \"Edit section: External links\")\\]\n\n- [\"OSHA\"](https:\/\/www.osha.gov\/SLTC\/etools\/evacuation\/portable_hydro.html). Retrieved 2006-10-05.\n\n| [v](https:\/\/en.wikipedia.org\/wiki\/Template:Plumbing \"Template:Plumbing\") [t](https:\/\/en.wikipedia.org\/wiki\/Template_talk:Plumbing \"Template talk:Plumbing\") [e](https:\/\/en.wikipedia.org\/wiki\/Special:EditPage\/Template:Plumbing \"Special:EditPage\/Template:Plumbing\")[Plumbing](https:\/\/en.wikipedia.org\/wiki\/Plumbing \"Plumbing\") |   |\n|---|---|\n| Fundamental concepts | [Air gap (plumbing)](https:\/\/en.wikipedia.org\/wiki\/Air_gap_\\(plumbing\\) \"Air gap (plumbing)\") [Backflow](https:\/\/en.wikipedia.org\/wiki\/Backflow \"Backflow\") [Compatibility (chemical)](https:\/\/en.wikipedia.org\/wiki\/Compatibility_\\(chemical\\) \"Compatibility (chemical)\") [Corrosion](https:\/\/en.wikipedia.org\/wiki\/Corrosion \"Corrosion\") [Drain (plumbing)](https:\/\/en.wikipedia.org\/wiki\/Drain_\\(plumbing\\) \"Drain (plumbing)\") [Drinking water](https:\/\/en.wikipedia.org\/wiki\/Drinking_water \"Drinking water\") [Fuel gas](https:\/\/en.wikipedia.org\/wiki\/Fuel_gas \"Fuel gas\") [Friction loss](https:\/\/en.wikipedia.org\/wiki\/Friction_loss \"Friction loss\") [Grade (slope)](https:\/\/en.wikipedia.org\/wiki\/Grade_\\(slope\\) \"Grade (slope)\") [Greywater](https:\/\/en.wikipedia.org\/wiki\/Greywater \"Greywater\") [Heat trap](https:\/\/en.wikipedia.org\/wiki\/Heat_trap \"Heat trap\") [Hydrostatic loop](https:\/\/en.wikipedia.org\/wiki\/Hydrostatic_loop \"Hydrostatic loop\") [Leak](https:\/\/en.wikipedia.org\/wiki\/Leak \"Leak\") [Neutral axis](https:\/\/en.wikipedia.org\/wiki\/Neutral_axis \"Neutral axis\") [Onsite sewage facility](https:\/\/en.wikipedia.org\/wiki\/Onsite_sewage_facility \"Onsite sewage facility\") [Pressure](https:\/\/en.wikipedia.org\/wiki\/Pressure \"Pressure\") [Sanitary sewer](https:\/\/en.wikipedia.org\/wiki\/Sanitary_sewer \"Sanitary sewer\") [Sewer gas](https:\/\/en.wikipedia.org\/wiki\/Sewer_gas \"Sewer gas\") [Sewage](https:\/\/en.wikipedia.org\/wiki\/Sewage \"Sewage\") [Sewerage](https:\/\/en.wikipedia.org\/wiki\/Sewerage \"Sewerage\") [Siphon](https:\/\/en.wikipedia.org\/wiki\/Siphon \"Siphon\") [Storm sewer](https:\/\/en.wikipedia.org\/wiki\/Storm_drain \"Storm drain\") [Stormwater](https:\/\/en.wikipedia.org\/wiki\/Stormwater \"Stormwater\") [Surface tension](https:\/\/en.wikipedia.org\/wiki\/Surface_tension \"Surface tension\") [Tap water](https:\/\/en.wikipedia.org\/wiki\/Tap_water \"Tap water\") [Thermal expansion](https:\/\/en.wikipedia.org\/wiki\/Thermal_expansion \"Thermal expansion\") [Thermal insulation](https:\/\/en.wikipedia.org\/wiki\/Thermal_insulation \"Thermal insulation\") [Thermosiphon](https:\/\/en.wikipedia.org\/wiki\/Thermosiphon \"Thermosiphon\") [Trap (plumbing)](https:\/\/en.wikipedia.org\/wiki\/Trap_\\(plumbing\\) \"Trap (plumbing)\") [Venturi effect](https:\/\/en.wikipedia.org\/wiki\/Venturi_effect \"Venturi effect\") [Wastewater](https:\/\/en.wikipedia.org\/wiki\/Wastewater \"Wastewater\") [Water hammer](https:\/\/en.wikipedia.org\/wiki\/Hydraulic_shock \"Hydraulic shock\") [Water supply network](https:\/\/en.wikipedia.org\/wiki\/Water_supply_network \"Water supply network\") [Water table](https:\/\/en.wikipedia.org\/wiki\/Water_table \"Water table\") [Well](https:\/\/en.wikipedia.org\/wiki\/Well \"Well\") |\n| Technology | [Brazing](https:\/\/en.wikipedia.org\/wiki\/Brazing \"Brazing\") [British Standard Pipe](https:\/\/en.wikipedia.org\/wiki\/British_Standard_Pipe \"British Standard Pipe\") (BSP) [Cast iron pipe](https:\/\/en.wikipedia.org\/wiki\/Cast_iron_pipe \"Cast iron pipe\") [Chemical drain cleaners](https:\/\/en.wikipedia.org\/wiki\/Chemical_drain_cleaners \"Chemical drain cleaners\") [Compression fitting](https:\/\/en.wikipedia.org\/wiki\/Compression_fitting \"Compression fitting\") [Copper tubing](https:\/\/en.wikipedia.org\/wiki\/Copper_tubing \"Copper tubing\") [Crimp (joining)](https:\/\/en.wikipedia.org\/wiki\/Crimp_\\(joining\\) \"Crimp (joining)\") [Drain-waste-vent system](https:\/\/en.wikipedia.org\/wiki\/Drain-waste-vent_system \"Drain-waste-vent system\") [Ductile iron pipe](https:\/\/en.wikipedia.org\/wiki\/Ductile_iron_pipe \"Ductile iron pipe\") [Flare fitting](https:\/\/en.wikipedia.org\/wiki\/Flare_fitting \"Flare fitting\") [Garden Hose Thread](https:\/\/en.wikipedia.org\/wiki\/Garden_hose_thread \"Garden hose thread\") (GHT) [Gasket](https:\/\/en.wikipedia.org\/wiki\/Gasket \"Gasket\") [Hydronics](https:\/\/en.wikipedia.org\/wiki\/Hydronics \"Hydronics\") [Leak detection](https:\/\/en.wikipedia.org\/wiki\/Leak_detection \"Leak detection\") [National pipe thread](https:\/\/en.wikipedia.org\/wiki\/National_pipe_thread \"National pipe thread\") (NPT) [Nominal Pipe Size](https:\/\/en.wikipedia.org\/wiki\/Nominal_Pipe_Size \"Nominal Pipe Size\") (NPS) [O-ring](https:\/\/en.wikipedia.org\/wiki\/O-ring \"O-ring\") [Oakum](https:\/\/en.wikipedia.org\/wiki\/Oakum \"Oakum\") [Pipe (fluid conveyance)](https:\/\/en.wikipedia.org\/wiki\/Pipe_\\(fluid_conveyance\\) \"Pipe (fluid conveyance)\") [Pipe dope](https:\/\/en.wikipedia.org\/wiki\/Pipe_dope \"Pipe dope\") [Pipe support](https:\/\/en.wikipedia.org\/wiki\/Pipe_support \"Pipe support\") [Plastic pipework](https:\/\/en.wikipedia.org\/wiki\/Plastic_pipework \"Plastic pipework\") [Push-to-pull compression fittings](https:\/\/en.wikipedia.org\/wiki\/Push-to-pull_compression_fittings \"Push-to-pull compression fittings\") [Putty](https:\/\/en.wikipedia.org\/wiki\/Putty \"Putty\") [Sealant](https:\/\/en.wikipedia.org\/wiki\/Sealant \"Sealant\") [Sewage pumping](https:\/\/en.wikipedia.org\/wiki\/Sewage_pumping \"Sewage pumping\") [Soldering](https:\/\/en.wikipedia.org\/wiki\/Soldering \"Soldering\") [Solvent welding](https:\/\/en.wikipedia.org\/wiki\/Solvent_welding \"Solvent welding\") [Swaging](https:\/\/en.wikipedia.org\/wiki\/Swaging \"Swaging\") [Thread seal tape](https:\/\/en.wikipedia.org\/wiki\/Thread_seal_tape \"Thread seal tape\") [Threaded pipe](https:\/\/en.wikipedia.org\/wiki\/Threaded_pipe \"Threaded pipe\") [Tube bending](https:\/\/en.wikipedia.org\/wiki\/Tube_bending \"Tube bending\") [Water heat recycling](https:\/\/en.wikipedia.org\/wiki\/Water_heat_recycling \"Water heat recycling\") |\n| Components | [Atmospheric vacuum breaker](https:\/\/en.wikipedia.org\/wiki\/Atmospheric_vacuum_breaker \"Atmospheric vacuum breaker\") [Automatic bleeding valve](https:\/\/en.wikipedia.org\/wiki\/Automatic_bleeding_valve \"Automatic bleeding valve\") [Automatic faucet](https:\/\/en.wikipedia.org\/wiki\/Automatic_faucet \"Automatic faucet\") [Backflow prevention device](https:\/\/en.wikipedia.org\/wiki\/Backflow_prevention_device \"Backflow prevention device\") [Ball valve](https:\/\/en.wikipedia.org\/wiki\/Ball_valve \"Ball valve\") [Bleed screw](https:\/\/en.wikipedia.org\/wiki\/Bleed_screw \"Bleed screw\") [Booster pump](https:\/\/en.wikipedia.org\/wiki\/Booster_pump \"Booster pump\") [Butterfly valve](https:\/\/en.wikipedia.org\/wiki\/Butterfly_valve \"Butterfly valve\") [Check valve](https:\/\/en.wikipedia.org\/wiki\/Check_valve \"Check valve\") [Chemigation valve](https:\/\/en.wikipedia.org\/wiki\/Chemigation_valve \"Chemigation valve\") [Chopper pump](https:\/\/en.wikipedia.org\/wiki\/Chopper_pump \"Chopper pump\") [Circulator pump](https:\/\/en.wikipedia.org\/wiki\/Circulator_pump \"Circulator pump\") [Cistern](https:\/\/en.wikipedia.org\/wiki\/Cistern \"Cistern\") [Closet flange](https:\/\/en.wikipedia.org\/wiki\/Closet_flange \"Closet flange\") [Concentric reducer](https:\/\/en.wikipedia.org\/wiki\/Concentric_reducer \"Concentric reducer\") [Condensate pump](https:\/\/en.wikipedia.org\/wiki\/Condensate_pump \"Condensate pump\") [Coupling (piping)](https:\/\/en.wikipedia.org\/wiki\/Coupling_\\(piping\\) \"Coupling (piping)\") [Diaphragm valve](https:\/\/en.wikipedia.org\/wiki\/Diaphragm_valve \"Diaphragm valve\") [Dielectric union](https:\/\/en.wikipedia.org\/wiki\/Dielectric_union \"Dielectric union\") [Double check valve](https:\/\/en.wikipedia.org\/wiki\/Double_check_valve \"Double check valve\") [Eccentric reducer](https:\/\/en.wikipedia.org\/wiki\/Eccentric_reducer \"Eccentric reducer\") [Expansion tank](https:\/\/en.wikipedia.org\/wiki\/Expansion_tank \"Expansion tank\") [Faucet aerator](https:\/\/en.wikipedia.org\/wiki\/Faucet_aerator \"Faucet aerator\") [Float switch](https:\/\/en.wikipedia.org\/wiki\/Float_switch \"Float switch\") [Float valve](https:\/\/en.wikipedia.org\/wiki\/Ballcock \"Ballcock\") [Floor drain](https:\/\/en.wikipedia.org\/wiki\/Floor_drain \"Floor drain\") [Flow limiter](https:\/\/en.wikipedia.org\/wiki\/Flow_limiter \"Flow limiter\") [Flushing trough](https:\/\/en.wikipedia.org\/wiki\/Flushing_trough \"Flushing trough\") [Flushometer](https:\/\/en.wikipedia.org\/wiki\/Flushometer \"Flushometer\") [Gate valve](https:\/\/en.wikipedia.org\/wiki\/Gate_valve \"Gate valve\") [Globe valve](https:\/\/en.wikipedia.org\/wiki\/Globe_valve \"Globe valve\") [Grease trap](https:\/\/en.wikipedia.org\/wiki\/Grease_trap \"Grease trap\") [Grinder pump](https:\/\/en.wikipedia.org\/wiki\/Grinder_pump \"Grinder pump\") [Hose coupling](https:\/\/en.wikipedia.org\/wiki\/Hose_coupling \"Hose coupling\") [Manifold](https:\/\/en.wikipedia.org\/wiki\/Manifold_\\(fluid_mechanics\\) \"Manifold (fluid mechanics)\") [Needle valve](https:\/\/en.wikipedia.org\/wiki\/Needle_valve \"Needle valve\") [Nipple (plumbing)](https:\/\/en.wikipedia.org\/wiki\/Nipple_\\(plumbing\\) \"Nipple (plumbing)\") [Pinch valve](https:\/\/en.wikipedia.org\/wiki\/Pinch_valve \"Pinch valve\") [Piping and plumbing fitting](https:\/\/en.wikipedia.org\/wiki\/Piping_and_plumbing_fitting \"Piping and plumbing fitting\") [Plug (sanitation)](https:\/\/en.wikipedia.org\/wiki\/Plug_\\(sanitation\\) \"Plug (sanitation)\") [Pressure regulator](https:\/\/en.wikipedia.org\/wiki\/Pressure_regulator \"Pressure regulator\") [Pressure vacuum breaker](https:\/\/en.wikipedia.org\/wiki\/Pressure_vacuum_breaker \"Pressure vacuum breaker\") [Pressure-balanced valve](https:\/\/en.wikipedia.org\/wiki\/Pressure-balanced_valve \"Pressure-balanced valve\") [Pump](https:\/\/en.wikipedia.org\/wiki\/Pump \"Pump\") [Radiator (heating)](https:\/\/en.wikipedia.org\/wiki\/Radiator_\\(heating\\) \"Radiator (heating)\") [Reduced pressure zone device](https:\/\/en.wikipedia.org\/wiki\/Reduced_pressure_zone_device \"Reduced pressure zone device\") [Reducer](https:\/\/en.wikipedia.org\/wiki\/Reducer \"Reducer\") [Relief valve](https:\/\/en.wikipedia.org\/wiki\/Relief_valve \"Relief valve\") [Riser clamp](https:\/\/en.wikipedia.org\/wiki\/Riser_clamp \"Riser clamp\") [Rooftop water tower](https:\/\/en.wikipedia.org\/wiki\/Rooftop_water_tower \"Rooftop water tower\") [Safety valve](https:\/\/en.wikipedia.org\/wiki\/Safety_valve \"Safety valve\") [sewage pumping](https:\/\/en.wikipedia.org\/wiki\/Sewage_pumping \"Sewage pumping\") [Street elbow](https:\/\/en.wikipedia.org\/wiki\/Street_elbow \"Street elbow\") [Submersible pump](https:\/\/en.wikipedia.org\/wiki\/Submersible_pump \"Submersible pump\") [Tap (valve)](https:\/\/en.wikipedia.org\/wiki\/Tap_\\(valve\\) \"Tap (valve)\") [Thermostatic mixing valve](https:\/\/en.wikipedia.org\/wiki\/Thermostatic_mixing_valve \"Thermostatic mixing valve\") [Trench drain](https:\/\/en.wikipedia.org\/wiki\/Trench_drain \"Trench drain\") [Vacuum breaker](https:\/\/en.wikipedia.org\/wiki\/Vacuum_breaker \"Vacuum breaker\") [Vacuum ejector](https:\/\/en.wikipedia.org\/wiki\/Vacuum_ejector \"Vacuum ejector\") [Valve](https:\/\/en.wikipedia.org\/wiki\/Valve \"Valve\") [Water tank](https:\/\/en.wikipedia.org\/wiki\/Water_tank \"Water tank\") [Zone valve](https:\/\/en.wikipedia.org\/wiki\/Zone_valve \"Zone valve\") |\n| [Plumbing fixtures](https:\/\/en.wikipedia.org\/wiki\/Plumbing_fixture \"Plumbing fixture\") | [Accessible bathtub](https:\/\/en.wikipedia.org\/wiki\/Accessible_bathtub \"Accessible bathtub\") [Bathtub](https:\/\/en.wikipedia.org\/wiki\/Bathtub \"Bathtub\") [Bidet](https:\/\/en.wikipedia.org\/wiki\/Bidet \"Bidet\") [Dehumidifier](https:\/\/en.wikipedia.org\/wiki\/Dehumidifier \"Dehumidifier\") [Dishwasher](https:\/\/en.wikipedia.org\/wiki\/Dishwasher \"Dishwasher\") [Drinking fountain](https:\/\/en.wikipedia.org\/wiki\/Drinking_fountain \"Drinking fountain\") [Electric water boiler](https:\/\/en.wikipedia.org\/wiki\/Electric_water_boiler \"Electric water boiler\") [Evaporative cooler](https:\/\/en.wikipedia.org\/wiki\/Evaporative_cooler \"Evaporative cooler\") [Flush toilet](https:\/\/en.wikipedia.org\/wiki\/Flush_toilet \"Flush toilet\") [Garbage disposal unit](https:\/\/en.wikipedia.org\/wiki\/Garbage_disposal_unit \"Garbage disposal unit\") [Hot water storage tank](https:\/\/en.wikipedia.org\/wiki\/Hot_water_storage_tank \"Hot water storage tank\") 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By using this site, you agree to the [Terms of Use](https:\/\/foundation.wikimedia.org\/wiki\/Special:MyLanguage\/Policy:Terms_of_Use \"foundation:Special:MyLanguage\/Policy:Terms of Use\") and [Privacy Policy](https:\/\/foundation.wikimedia.org\/wiki\/Special:MyLanguage\/Policy:Privacy_policy \"foundation:Special:MyLanguage\/Policy:Privacy policy\"). Wikipedia® is a registered trademark of the [Wikimedia Foundation, Inc.](https:\/\/wikimediafoundation.org\/), a non-profit organization.\n\n- [Privacy policy](https:\/\/foundation.wikimedia.org\/wiki\/Special:MyLanguage\/Policy:Privacy_policy)\n- [About Wikipedia](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:About)\n- [Disclaimers](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:General_disclaimer)\n- [Contact Wikipedia](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Contact_us)\n- [Legal & safety contacts](https:\/\/foundation.wikimedia.org\/wiki\/Special:MyLanguage\/Legal:Wikimedia_Foundation_Legal_and_Safety_Contact_Information)\n- [Code of Conduct](https:\/\/foundation.wikimedia.org\/wiki\/Special:MyLanguage\/Policy:Universal_Code_of_Conduct)\n- [Developers](https:\/\/developer.wikimedia.org\/)\n- [Statistics](https:\/\/stats.wikimedia.org\/#\/en.wikipedia.org)\n- [Cookie statement](https:\/\/foundation.wikimedia.org\/wiki\/Special:MyLanguage\/Policy:Cookie_statement)\n- [Mobile view](https:\/\/en.wikipedia.org\/w\/index.php?title=Hydrostatic_test&mobileaction=toggle_view_mobile)\n\n- [![Wikimedia Foundation](https:\/\/en.wikipedia.org\/static\/images\/footer\/wikimedia.svg)](https:\/\/www.wikimedia.org\/)\n- [![Powered by MediaWiki](https:\/\/en.wikipedia.org\/w\/resources\/assets\/mediawiki_compact.svg)](https:\/\/www.mediawiki.org\/)\n\nSearch\n\nToggle the table of contents\n\nHydrostatic test\n\n6 languages\n\n[Add topic](https:\/\/en.wikipedia.org\/wiki\/Hydrostatic_test)","attrs_readable_markdown":"From Wikipedia, the free encyclopedia\n\n[![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/c\/c5\/Hydrostatic_Tester.jpg\/250px-Hydrostatic_Tester.jpg)](https:\/\/en.wikipedia.org\/wiki\/File:Hydrostatic_Tester.jpg)\n\nHydrostatic tester\n\nA **hydrostatic test** is a way in which [pressure vessels](https:\/\/en.wikipedia.org\/wiki\/Pressure_vessel \"Pressure vessel\") such as [pipelines](https:\/\/en.wikipedia.org\/wiki\/Pipeline_transport \"Pipeline transport\"), [plumbing](https:\/\/en.wikipedia.org\/wiki\/Plumbing \"Plumbing\"), [gas cylinders](https:\/\/en.wikipedia.org\/wiki\/Gas_cylinder \"Gas cylinder\"), [boilers](https:\/\/en.wikipedia.org\/wiki\/Boiler \"Boiler\") and fuel tanks can be tested for strength and leaks. The test involves filling the vessel or pipe system with a liquid, usually water, which may be dyed to aid in visual [leak detection](https:\/\/en.wikipedia.org\/wiki\/Leak_detection \"Leak detection\"), and pressurization of the vessel to the specified test pressure. Pressure tightness can be tested by shutting off the supply valve and observing whether there is a pressure loss. The location of a leak can be visually identified more easily if the water contains a colorant. Strength is usually tested by measuring permanent deformation of the container.\n\nHydrostatic testing is the most common method employed for testing pipes and pressure vessels. Using this test helps maintain safety standards and durability of a vessel over time. Newly manufactured pieces are initially qualified using the hydrostatic test. They are then revalidated at regular intervals according to the relevant standard. In some cases where a hydrostatic test is not practicable a pneumatic pressure test may be an acceptable alternative.[\\[1\\]](https:\/\/en.wikipedia.org\/wiki\/Hydrostatic_test#cite_note-Proof-1)\n\nTesting of pressure vessels for transport and storage of gases is very important because such containers can explode if they fail under pressure.\n\nHydrostatic tests are conducted under the constraints of either the industry's or the customer's specifications, or may be required by law. The vessel is filled with a nearly incompressible liquid – usually [water](https:\/\/en.wikipedia.org\/wiki\/Water \"Water\") or [oil](https:\/\/en.wikipedia.org\/wiki\/Oil \"Oil\") – pressurised to test pressure, and examined for leaks or permanent changes in shape. [Red](https:\/\/en.wikipedia.org\/wiki\/Red \"Red\") or [fluorescent](https:\/\/en.wikipedia.org\/wiki\/Fluorescent \"Fluorescent\") [dyes](https:\/\/en.wikipedia.org\/wiki\/Dye \"Dye\") may be added to the water to make leaks easier to see. The test pressure is always considerably higher than the operating pressure to give a factor of safety. This factor of safety is typically 166.66%, 143% or 150% of the designed working pressure, depending on the regulations that apply. For example, if a cylinder was rated to DOT-2015 PSI (approximately 139 bar), it would be tested at around 3360 PSI (approximately 232 bar).\n\n[Water](https:\/\/en.wikipedia.org\/wiki\/Water \"Water\") is commonly used because it is cheap and easily available, and is usually harmless to the system to be tested. Hydraulic fluids and oils may be specified where contamination with water could cause problems. These fluids are nearly incompressible, therefore requiring relatively little work to develop a high pressure, and is therefore also only able to release a small amount of energy in case of a failure - only a small volume will escape under high pressure if the container fails. If [high pressure](https:\/\/en.wikipedia.org\/wiki\/High_pressure \"High pressure\") [gas](https:\/\/en.wikipedia.org\/wiki\/Gas \"Gas\") were used, then the gas would expand to V=(nRT)\/p with its compressed volume resulting in an explosion, with the attendant risk of damage or injury.\n\n[![](https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/7\/76\/Water_jacket_test_diagram.jpg\/250px-Water_jacket_test_diagram.jpg)](https:\/\/en.wikipedia.org\/wiki\/File:Water_jacket_test_diagram.jpg)\n\nWater jacket test\n\nSmall pressure vessels are normally tested using a water jacket test. The vessel is visually examined for defects and then placed in a container filled with water, and in which the change in volume of the vessel can be measured, usually by monitoring the water level in a calibrated tube. The vessel is then pressurised for a specified period, usually 30 or more seconds, and if specified, the expansion will be measured by reading off the amount of liquid that has been forced into the measuring tube by the volume increase of the pressurised vessel. The vessel is then depressurised, and the permanent volume increase due to plastic deformation while under pressure (permanent set) is measured by comparing the final volume in the measuring tube with the volume before pressurisation.[\\[2\\]](https:\/\/en.wikipedia.org\/wiki\/Hydrostatic_test#cite_note-Sauta_2010-2)\n\nA leak will give a similar result to permanent set, but will be detectable by holding the volume in the pressurised vessel by closing the inlet valve for a period before depressurising, as the pressure will drop steadily during this period if there is a leak. In most cases a permanent set that exceeds the specified maximum will indicate failure. A leak may also be a failure criterion, but it may be that the leak is due to poor sealing of the test equipment. If the vessel fails, it will normally go through a condemning process marking the cylinder as unsafe.[\\[2\\]](https:\/\/en.wikipedia.org\/wiki\/Hydrostatic_test#cite_note-Sauta_2010-2)[\\[3\\]](https:\/\/en.wikipedia.org\/wiki\/Hydrostatic_test#cite_note-Hydro_Key_Largo-3)\n\nThe information needed to specify the test is stamped onto the cylinder. This includes the design standard, serial number, manufacturer, and manufacture date. After testing, the vessel or its nameplate will usually be stamp marked with the date of the successful test, and the test facility's identification mark.[\\[3\\]](https:\/\/en.wikipedia.org\/wiki\/Hydrostatic_test#cite_note-Hydro_Key_Largo-3)\n\nA simpler test, that is also considered a hydrostatic test but does not require pressure pumps, is to pressurise the vessel by filling it with water to a hydrostatic head by using a riser pipe connected to the tank and to physically examine the outside for leaks. This type of test is suitable for containers such as boat fuel tanks, which are not pressure vessels but must work under the hydrostatic pressure of the contents. A hydrostatic test head is usually specified as a height above the tank top. The tank is pressurised by filling water to the specified height through a temporary standpipe if necessary. It may be necessary to seal vents and other outlets during the test.[\\[4\\]](https:\/\/en.wikipedia.org\/wiki\/Hydrostatic_test#cite_note-4)\n\nPortable fire extinguishers are safety tools that are required in most public buildings. Fire extinguishers are also recommended in homes. Over time the conditions in which they are housed, and the manner in which they are handled affect the structural integrity of the extinguisher. A structurally weakened fire extinguisher can malfunction or even burst when it is needed the most. To maintain the quality and safety of this product, hydrostatic testing is utilized. All critical components of the fire extinguisher should be tested to ensure proper function.\n\nHydrotesting of pipes, pipelines and vessels is performed to expose defective materials that have missed prior detection, ensure that any remaining defects are insignificant enough to allow operation at design pressures, expose possible leaks and serve as a final validation of the integrity of the constructed system. ASME B31.3 requires this testing to ensure tightness and strength.\n\nBuried high pressure oil and gas pipelines are tested for strength by pressurising them to at least 125% of their [maximum allowable working pressure](https:\/\/en.wikipedia.org\/wiki\/Maximum_allowable_working_pressure \"Maximum allowable working pressure\") (MAWP) at any point along their length. Since many long distance transmission pipelines are designed to have a steel hoop stress of 80% of [specified minimum yield strength](https:\/\/en.wikipedia.org\/wiki\/Specified_minimum_yield_strength \"Specified minimum yield strength\") (SMYS) at [Maximum allowable operating pressure](https:\/\/en.wikipedia.org\/wiki\/Maximum_allowable_operating_pressure \"Maximum allowable operating pressure\") MAOP, this means that the steel is stressed to SMYS and above during the testing, and test sections must be selected to ensure that excessive plastic deformation does not occur.\\[*[citation needed](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Citation_needed \"Wikipedia:Citation needed\")*\\]\n\nFor piping built to ASME B31.3, if the design temperature is greater than the test temperature, then the test pressure must be adjusted for the related allowable stress at the design temperature. This is done by multiplying 1.5 MAWP by the ratio of the allowable stress at the test temperature to allowable stress at the design temperature per ASME B31.3 Section 345.4.2 Equation 24. Test pressures need not exceed a value that would produce a stress higher than yield stress at test temperature. ASME B31.3 section 345.4.2 (c)\n\nOther codes require a more onerous approach. BS PD 8010-2 requires testing to 150% of the *design* pressure – which should not be less than the MAOP plus surge and other incidental effects that will occur during normal operation.\\[*[citation needed](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Citation_needed \"Wikipedia:Citation needed\")*\\]\n\nLeak testing is performed by balancing changes in the measured pressure in the test section against the theoretical pressure changes calculated from changes in the measured temperature of the test section.\n\nAustralian standard AS2885.5 \"Pipelines – Gas and liquid petroleum: Part 5: Field pressure testing\" gives an excellent explanation of the factors involved.\\[*[clarification needed](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Please_clarify \"Wikipedia:Please clarify\")*\\]\n\nIn the aerospace industry, depending on the airline, company or customer, certain codes will need to be followed. For example, Bell Helicopter has a certain specification that will have to be followed for any parts that will be used in their helicopters.\\[*[citation needed](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Citation_needed \"Wikipedia:Citation needed\")*\\]\n\nMost countries have legislation or pressure vessel codes which requires vessels to be regularly tested, for example every two years (with a visual inspection annually) for high pressure gas cylinders and every five or ten years for lower pressure ones such as used in [fire extinguishers](https:\/\/en.wikipedia.org\/wiki\/Fire_extinguisher \"Fire extinguisher\").[\\[5\\]](https:\/\/en.wikipedia.org\/wiki\/Hydrostatic_test#cite_note-5) \\[*[clarification needed](https:\/\/en.wikipedia.org\/wiki\/Wikipedia:Please_clarify \"Wikipedia:Please clarify\")*\\] Gas cylinders which fail are normally destroyed as part of the testing protocol to avoid the dangers inherent in them being subsequently used.[\\[6\\]](https:\/\/en.wikipedia.org\/wiki\/Hydrostatic_test#cite_note-6)\n\nThese common US standard gas cylinders have the following requirements:[\\[7\\]](https:\/\/en.wikipedia.org\/wiki\/Hydrostatic_test#cite_note-7)\n\n- DOT-3AL gas cylinders must be tested every 5 years and have an unlimited life.\n- DOT-3HT gas cylinders must be tested every 3 years and have a 24-year life.\n- DOT-3AA gas cylinders must be tested every 5 years and have an unlimited life. (Unless stamped with a star (\\*) in which case the cylinder meets certain specifications and can have a 10-year hydrostatic test life).\n\nTypically organizations such as DOT [PHMSA](https:\/\/en.wikipedia.org\/wiki\/PHMSA \"PHMSA\"), [ISO](https:\/\/en.wikipedia.org\/wiki\/ISO \"ISO\"), [ASTM](https:\/\/en.wikipedia.org\/wiki\/ASTM \"ASTM\") and [ASME](https:\/\/en.wikipedia.org\/wiki\/ASME \"ASME\") specify the guidelines for the different types of pressure vessels.\n\nHydraulic testing is a hazardous process and should be performed with caution by competent personnel. Adhering to prescribed procedures defined in relevant [technical standards](https:\/\/en.wikipedia.org\/wiki\/Technical_standards \"Technical standards\") appropriate to the specific application and jurisdiction will usually reduce these risks to an acceptable level.\n\n- A leak of high pressure liquid can cut or penetrate the skin and inject itself into body tissues. This can cause serious direct injury to the operator, and if the fluid is toxic or contaminated there will be additional adverse effects.\n- A pressurised hose that is not securely attached or which fails under pressure may whip around spraying water or oil and could hit someone and cause injuries. A [whiplash arrestor](https:\/\/en.wikipedia.org\/wiki\/Glossary_of_underwater_diving_terminology:_T%E2%80%93Z#whiplash_arrestor \"Glossary of underwater diving terminology: T–Z\") can be used to restrain such hoses.\n- Enclosing the components to be tested, hazard signage, use of appropriate [personal protective equipment](https:\/\/en.wikipedia.org\/wiki\/Personal_protective_equipment \"Personal protective equipment\") and providing barriers to access for non-essential personnel are common precautions.\n\n- [Nondestructive testing](https:\/\/en.wikipedia.org\/wiki\/Nondestructive_testing \"Nondestructive testing\") – Type of analysis technique\n- [Testing and inspection of diving cylinders](https:\/\/en.wikipedia.org\/wiki\/Testing_and_inspection_of_diving_cylinders \"Testing and inspection of diving cylinders\") – Periodical inspection and testing to revalidate fitness for service\n\n1. **[^](https:\/\/en.wikipedia.org\/wiki\/Hydrostatic_test#cite_ref-Proof_1-0)**\n   [\"Proof-Pressure Test and Leak Detection Test in Metal Expansion Joints\"](https:\/\/www.macoga.com\/documents\/en\/metal-expansion-joints\/proof-pressure-test-leak-detection-test.pdf) (PDF). *www.macoga.com*. Macoga SA. Retrieved 24 September 2021.\n2. ^ [***a***](https:\/\/en.wikipedia.org\/wiki\/Hydrostatic_test#cite_ref-Sauta_2010_2-0) [***b***](https:\/\/en.wikipedia.org\/wiki\/Hydrostatic_test#cite_ref-Sauta_2010_2-1)\n   Sauta, Tom (1 Oct 2010). [\"Hydro-Test Water Jacket Cylinder Test System Setup.wmv\"](https:\/\/www.youtube.com\/watch?v=KLrV0vGBZEk). www.hydrotest.com. Retrieved 29 July 2025 – via YouTube.\n3. ^ [***a***](https:\/\/en.wikipedia.org\/wiki\/Hydrostatic_test#cite_ref-Hydro_Key_Largo_3-0) [***b***](https:\/\/en.wikipedia.org\/wiki\/Hydrostatic_test#cite_ref-Hydro_Key_Largo_3-1)\n   Angel (17 May 2022). [\"How to Hydro Test a scuba tank\"](https:\/\/www.youtube.com\/watch?v=Bwd-GFCtLl8). Scuba Tech Key Largo. Retrieved 29 July 2025 – via YouTube.\n4. **[^](https:\/\/en.wikipedia.org\/wiki\/Hydrostatic_test#cite_ref-4)**\n   Kim; An, Tae-Hyun; Lee, Tak-Kee (April 2022). [\"Preliminary Study on Deformation During Hydrostatic Testing in a Deep Tank }first1=Geun-Gon\"](https:\/\/doi.org\/10.26748%2FKSOE.2021.075). *J. Ocean Eng. Technol*. **36** (2): 115–124\\. [doi](https:\/\/en.wikipedia.org\/wiki\/Doi_\\(identifier\\) \"Doi (identifier)\"):[10\\.26748\/KSOE.2021.075](https:\/\/doi.org\/10.26748%2FKSOE.2021.075).\n5. **[^](https:\/\/en.wikipedia.org\/wiki\/Hydrostatic_test#cite_ref-5)**\n   [\"Federal Register :: Request Access\"](https:\/\/www.ecfr.gov\/current\/title-49\/subtitle-B\/chapter-I\/subchapter-C\/part-180#p-180.209\\(j\\)).\n6. **[^](https:\/\/en.wikipedia.org\/wiki\/Hydrostatic_test#cite_ref-6)**\n   [\"Federal Register :: Request Access\"](https:\/\/www.ecfr.gov\/current\/title-49\/subtitle-B\/chapter-I\/subchapter-C\/part-180#p-180.205\\(i\\)).\n7. **[^](https:\/\/en.wikipedia.org\/wiki\/Hydrostatic_test#cite_ref-7)**\n   [\"Federal Register :: Request Access\"](https:\/\/www.ecfr.gov\/current\/title-49\/section-180.209).\n\n- [\"OSHA\"](https:\/\/www.osha.gov\/SLTC\/etools\/evacuation\/portable_hydro.html). Retrieved 2006-10-05.","meta_canonical":null}

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Boilerpipe Text	From Wikipedia, the free encyclopedia Hydrostatic tester A hydrostatic test is a way in which pressure vessels such as pipelines , plumbing , gas cylinders , boilers and fuel tanks can be tested for strength and leaks. The test involves filling the vessel or pipe system with a liquid, usually water, which may be dyed to aid in visual leak detection , and pressurization of the vessel to the specified test pressure. Pressure tightness can be tested by shutting off the supply valve and observing whether there is a pressure loss. The location of a leak can be visually identified more easily if the water contains a colorant. Strength is usually tested by measuring permanent deformation of the container. Hydrostatic testing is the most common method employed for testing pipes and pressure vessels. Using this test helps maintain safety standards and durability of a vessel over time. Newly manufactured pieces are initially qualified using the hydrostatic test. They are then revalidated at regular intervals according to the relevant standard. In some cases where a hydrostatic test is not practicable a pneumatic pressure test may be an acceptable alternative. [ 1 ] Testing of pressure vessels for transport and storage of gases is very important because such containers can explode if they fail under pressure. Hydrostatic tests are conducted under the constraints of either the industry's or the customer's specifications, or may be required by law. The vessel is filled with a nearly incompressible liquid – usually water or oil – pressurised to test pressure, and examined for leaks or permanent changes in shape. Red or fluorescent dyes may be added to the water to make leaks easier to see. The test pressure is always considerably higher than the operating pressure to give a factor of safety. This factor of safety is typically 166.66%, 143% or 150% of the designed working pressure, depending on the regulations that apply. For example, if a cylinder was rated to DOT-2015 PSI (approximately 139 bar), it would be tested at around 3360 PSI (approximately 232 bar). Water is commonly used because it is cheap and easily available, and is usually harmless to the system to be tested. Hydraulic fluids and oils may be specified where contamination with water could cause problems. These fluids are nearly incompressible, therefore requiring relatively little work to develop a high pressure, and is therefore also only able to release a small amount of energy in case of a failure - only a small volume will escape under high pressure if the container fails. If high pressure gas were used, then the gas would expand to V=(nRT)/p with its compressed volume resulting in an explosion, with the attendant risk of damage or injury. Water jacket test Small pressure vessels are normally tested using a water jacket test. The vessel is visually examined for defects and then placed in a container filled with water, and in which the change in volume of the vessel can be measured, usually by monitoring the water level in a calibrated tube. The vessel is then pressurised for a specified period, usually 30 or more seconds, and if specified, the expansion will be measured by reading off the amount of liquid that has been forced into the measuring tube by the volume increase of the pressurised vessel. The vessel is then depressurised, and the permanent volume increase due to plastic deformation while under pressure ( permanent set ) is measured by comparing the final volume in the measuring tube with the volume before pressurisation. [ 2 ] A leak will give a similar result to permanent set, but will be detectable by holding the volume in the pressurised vessel by closing the inlet valve for a period before depressurising, as the pressure will drop steadily during this period if there is a leak. In most cases a permanent set that exceeds the specified maximum will indicate failure. A leak may also be a failure criterion, but it may be that the leak is due to poor sealing of the test equipment. If the vessel fails, it will normally go through a condemning process marking the cylinder as unsafe. [ 2 ] [ 3 ] The information needed to specify the test is stamped onto the cylinder. This includes the design standard, serial number, manufacturer, and manufacture date. After testing, the vessel or its nameplate will usually be stamp marked with the date of the successful test, and the test facility's identification mark. [ 3 ] A simpler test, that is also considered a hydrostatic test but does not require pressure pumps, is to pressurise the vessel by filling it with water to a hydrostatic head by using a riser pipe connected to the tank and to physically examine the outside for leaks. This type of test is suitable for containers such as boat fuel tanks, which are not pressure vessels but must work under the hydrostatic pressure of the contents. A hydrostatic test head is usually specified as a height above the tank top. The tank is pressurised by filling water to the specified height through a temporary standpipe if necessary. It may be necessary to seal vents and other outlets during the test. [ 4 ] Portable fire extinguishers are safety tools that are required in most public buildings. Fire extinguishers are also recommended in homes. Over time the conditions in which they are housed, and the manner in which they are handled affect the structural integrity of the extinguisher. A structurally weakened fire extinguisher can malfunction or even burst when it is needed the most. To maintain the quality and safety of this product, hydrostatic testing is utilized. All critical components of the fire extinguisher should be tested to ensure proper function. Hydrotesting of pipes, pipelines and vessels is performed to expose defective materials that have missed prior detection, ensure that any remaining defects are insignificant enough to allow operation at design pressures, expose possible leaks and serve as a final validation of the integrity of the constructed system. ASME B31.3 requires this testing to ensure tightness and strength. Buried high pressure oil and gas pipelines are tested for strength by pressurising them to at least 125% of their maximum allowable working pressure (MAWP) at any point along their length. Since many long distance transmission pipelines are designed to have a steel hoop stress of 80% of specified minimum yield strength (SMYS) at Maximum allowable operating pressure MAOP, this means that the steel is stressed to SMYS and above during the testing, and test sections must be selected to ensure that excessive plastic deformation does not occur. [ citation needed ] For piping built to ASME B31.3, if the design temperature is greater than the test temperature, then the test pressure must be adjusted for the related allowable stress at the design temperature. This is done by multiplying 1.5 MAWP by the ratio of the allowable stress at the test temperature to allowable stress at the design temperature per ASME B31.3 Section 345.4.2 Equation 24. Test pressures need not exceed a value that would produce a stress higher than yield stress at test temperature. ASME B31.3 section 345.4.2 (c) Other codes require a more onerous approach. BS PD 8010-2 requires testing to 150% of the design pressure – which should not be less than the MAOP plus surge and other incidental effects that will occur during normal operation. [ citation needed ] Leak testing is performed by balancing changes in the measured pressure in the test section against the theoretical pressure changes calculated from changes in the measured temperature of the test section. Australian standard AS2885.5 "Pipelines – Gas and liquid petroleum: Part 5: Field pressure testing" gives an excellent explanation of the factors involved. [ clarification needed ] In the aerospace industry, depending on the airline, company or customer, certain codes will need to be followed. For example, Bell Helicopter has a certain specification that will have to be followed for any parts that will be used in their helicopters. [ citation needed ] Most countries have legislation or pressure vessel codes which requires vessels to be regularly tested, for example every two years (with a visual inspection annually) for high pressure gas cylinders and every five or ten years for lower pressure ones such as used in fire extinguishers . [ 5 ] [ clarification needed ] Gas cylinders which fail are normally destroyed as part of the testing protocol to avoid the dangers inherent in them being subsequently used. [ 6 ] These common US standard gas cylinders have the following requirements: [ 7 ] DOT-3AL gas cylinders must be tested every 5 years and have an unlimited life. DOT-3HT gas cylinders must be tested every 3 years and have a 24-year life. DOT-3AA gas cylinders must be tested every 5 years and have an unlimited life. (Unless stamped with a star (*) in which case the cylinder meets certain specifications and can have a 10-year hydrostatic test life). Typically organizations such as DOT PHMSA , ISO , ASTM and ASME specify the guidelines for the different types of pressure vessels. Hydraulic testing is a hazardous process and should be performed with caution by competent personnel. Adhering to prescribed procedures defined in relevant technical standards appropriate to the specific application and jurisdiction will usually reduce these risks to an acceptable level. A leak of high pressure liquid can cut or penetrate the skin and inject itself into body tissues. This can cause serious direct injury to the operator, and if the fluid is toxic or contaminated there will be additional adverse effects. A pressurised hose that is not securely attached or which fails under pressure may whip around spraying water or oil and could hit someone and cause injuries. A whiplash arrestor can be used to restrain such hoses. Enclosing the components to be tested, hazard signage, use of appropriate personal protective equipment and providing barriers to access for non-essential personnel are common precautions. Nondestructive testing – Type of analysis technique Testing and inspection of diving cylinders – Periodical inspection and testing to revalidate fitness for service ^ "Proof-Pressure Test and Leak Detection Test in Metal Expansion Joints" (PDF) . www.macoga.com . Macoga SA . Retrieved 24 September 2021 . ^ a b Sauta, Tom (1 Oct 2010). "Hydro-Test Water Jacket Cylinder Test System Setup.wmv" . www.hydrotest.com . Retrieved 29 July 2025 – via YouTube. ^ a b Angel (17 May 2022). "How to Hydro Test a scuba tank" . Scuba Tech Key Largo . Retrieved 29 July 2025 – via YouTube. ^ Kim; An, Tae-Hyun; Lee, Tak-Kee (April 2022). "Preliminary Study on Deformation During Hydrostatic Testing in a Deep Tank }first1=Geun-Gon" . J. Ocean Eng. Technol . 36 (2): 115– 124. doi : 10.26748/KSOE.2021.075 . ^ "Federal Register :: Request Access" . ^ "Federal Register :: Request Access" . ^ "Federal Register :: Request Access" . "OSHA" . Retrieved 2006-10-05 .
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[o]") ## Contents move to sidebar hide - [(Top)](https://en.wikipedia.org/wiki/Hydrostatic_test) - [1 Testing procedures](https://en.wikipedia.org/wiki/Hydrostatic_test#Testing_procedures) - [2 Examples](https://en.wikipedia.org/wiki/Hydrostatic_test#Examples) - [3 Pipeline testing](https://en.wikipedia.org/wiki/Hydrostatic_test#Pipeline_testing) - [4 Testing frequency](https://en.wikipedia.org/wiki/Hydrostatic_test#Testing_frequency) - [5 Safety](https://en.wikipedia.org/wiki/Hydrostatic_test#Safety) - [6 See also](https://en.wikipedia.org/wiki/Hydrostatic_test#See_also) - [7 References](https://en.wikipedia.org/wiki/Hydrostatic_test#References) - [8 External links](https://en.wikipedia.org/wiki/Hydrostatic_test#External_links) Toggle the table of contents # Hydrostatic test 6 languages - [অসমীয়া](https://as.wikipedia.org/wiki/%E0%A6%B9%E0%A6%BE%E0%A6%87%E0%A6%A1%E0%A7%8D%E0%A7%B0%E2%80%99%E0%A6%B7%E0%A7%8D%E0%A6%9F%E0%A7%87%E0%A6%9F%E0%A6%BF%E0%A6%95_%E0%A6%AA%E0%A7%B0%E0%A7%80%E0%A6%95%E0%A7%8D%E0%A6%B7%E0%A6%BE "হাইড্ৰ’ষ্টেটিক পৰীক্ষা – Assamese") - [Deutsch](https://de.wikipedia.org/wiki/Druckpr%C3%BCfung "Druckprüfung – German") - [Bahasa Indonesia](https://id.wikipedia.org/wiki/Tes_hidrostatis "Tes hidrostatis – Indonesian") - [Русский](https://ru.wikipedia.org/wiki/%D0%93%D0%B8%D0%B4%D1%80%D0%B0%D0%B2%D0%BB%D0%B8%D1%87%D0%B5%D1%81%D0%BA%D0%BE%D0%B5_%D0%B8%D1%81%D0%BF%D1%8B%D1%82%D0%B0%D0%BD%D0%B8%D0%B5 "Гидравлическое испытание – Russian") - [Slovenščina](https://sl.wikipedia.org/wiki/Hidrostati%C4%8Dni_test "Hidrostatični test – Slovenian") - [Українська](https://uk.wikipedia.org/wiki/%D0%93%D1%96%D0%B4%D1%80%D0%B0%D0%B2%D0%BB%D1%96%D1%87%D0%BD%D1%96_%D0%B2%D0%B8%D0%BF%D1%80%D0%BE%D0%B1%D1%83%D0%B2%D0%B0%D0%BD%D0%BD%D1%8F "Гідравлічні випробування – Ukrainian") [Edit links](https://www.wikidata.org/wiki/Special:EntityPage/Q1260986#sitelinks-wikipedia "Edit interlanguage links") - [Article](https://en.wikipedia.org/wiki/Hydrostatic_test "View the content page [c]") - [Talk](https://en.wikipedia.org/wiki/Talk:Hydrostatic_test "Discuss improvements to the content page [t]") English - [Read](https://en.wikipedia.org/wiki/Hydrostatic_test) - [Edit](https://en.wikipedia.org/w/index.php?title=Hydrostatic_test&action=edit "Edit this page [e]") - [View history](https://en.wikipedia.org/w/index.php?title=Hydrostatic_test&action=history "Past revisions of this page [h]") Tools Tools move to sidebar hide Actions - [Read](https://en.wikipedia.org/wiki/Hydrostatic_test) - [Edit](https://en.wikipedia.org/w/index.php?title=Hydrostatic_test&action=edit "Edit this page [e]") - [View history](https://en.wikipedia.org/w/index.php?title=Hydrostatic_test&action=history) General - [What links here](https://en.wikipedia.org/wiki/Special:WhatLinksHere/Hydrostatic_test "List of all English Wikipedia pages containing links to this page [j]") - [Related changes](https://en.wikipedia.org/wiki/Special:RecentChangesLinked/Hydrostatic_test "Recent changes in pages linked from this page [k]") - [Upload file](https://en.wikipedia.org/wiki/Wikipedia:File_Upload_Wizard "Upload files [u]") - [Permanent link](https://en.wikipedia.org/w/index.php?title=Hydrostatic_test&oldid=1328520287 "Permanent link to this revision of this page") - [Page information](https://en.wikipedia.org/w/index.php?title=Hydrostatic_test&action=info "More information about this page") - [Cite this page](https://en.wikipedia.org/w/index.php?title=Special:CiteThisPage&page=Hydrostatic_test&id=1328520287&wpFormIdentifier=titleform "Information on how to cite this page") - [Get shortened URL](https://en.wikipedia.org/w/index.php?title=Special:UrlShortener&url=https%3A%2F%2Fen.wikipedia.org%2Fwiki%2FHydrostatic_test) Print/export - [Download as PDF](https://en.wikipedia.org/w/index.php?title=Special:DownloadAsPdf&page=Hydrostatic_test&action=show-download-screen "Download this page as a PDF file") - [Printable version](https://en.wikipedia.org/w/index.php?title=Hydrostatic_test&printable=yes "Printable version of this page [p]") In other projects - [Wikimedia Commons](https://commons.wikimedia.org/wiki/Category:Hydrostatic_test) - [Wikidata item](https://www.wikidata.org/wiki/Special:EntityPage/Q1260986 "Structured data on this page hosted by Wikidata [g]") Appearance move to sidebar hide From Wikipedia, the free encyclopedia Non-destructive test of pressure vessels For the autopsy procedure, see [lung float test](https://en.wikipedia.org/wiki/Lung_float_test "Lung float test"). \| \| \| \|---\|---\| \| [![icon](https://upload.wikimedia.org/wikipedia/en/thumb/9/99/Question_book-new.svg/60px-Question_book-new.svg.png)](https://en.wikipedia.org/wiki/File:Question_book-new.svg) \| This article needs additional citations for [verification](https://en.wikipedia.org/wiki/Wikipedia:Verifiability "Wikipedia:Verifiability"). 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Find sources: ["Hydrostatic test"](https://www.google.com/search?as_eq=wikipedia&q=%22Hydrostatic+test%22) – [news](https://www.google.com/search?tbm=nws&q=%22Hydrostatic+test%22+-wikipedia&tbs=ar:1) · [newspapers](https://www.google.com/search?&q=%22Hydrostatic+test%22&tbs=bkt:s&tbm=bks) · [books](https://www.google.com/search?tbs=bks:1&q=%22Hydrostatic+test%22+-wikipedia) · [scholar](https://scholar.google.com/scholar?q=%22Hydrostatic+test%22) · [JSTOR](https://www.jstor.org/action/doBasicSearch?Query=%22Hydrostatic+test%22&acc=on&wc=on) (September 2009) ([Learn how and when to remove this message](https://en.wikipedia.org/wiki/Help:Maintenance_template_removal "Help:Maintenance template removal")) \| [![](https://upload.wikimedia.org/wikipedia/commons/thumb/c/c5/Hydrostatic_Tester.jpg/250px-Hydrostatic_Tester.jpg)](https://en.wikipedia.org/wiki/File:Hydrostatic_Tester.jpg) Hydrostatic tester A hydrostatic test is a way in which [pressure vessels](https://en.wikipedia.org/wiki/Pressure_vessel "Pressure vessel") such as [pipelines](https://en.wikipedia.org/wiki/Pipeline_transport "Pipeline transport"), [plumbing](https://en.wikipedia.org/wiki/Plumbing "Plumbing"), [gas cylinders](https://en.wikipedia.org/wiki/Gas_cylinder "Gas cylinder"), [boilers](https://en.wikipedia.org/wiki/Boiler "Boiler") and fuel tanks can be tested for strength and leaks. The test involves filling the vessel or pipe system with a liquid, usually water, which may be dyed to aid in visual [leak detection](https://en.wikipedia.org/wiki/Leak_detection "Leak detection"), and pressurization of the vessel to the specified test pressure. Pressure tightness can be tested by shutting off the supply valve and observing whether there is a pressure loss. The location of a leak can be visually identified more easily if the water contains a colorant. Strength is usually tested by measuring permanent deformation of the container. Hydrostatic testing is the most common method employed for testing pipes and pressure vessels. Using this test helps maintain safety standards and durability of a vessel over time. Newly manufactured pieces are initially qualified using the hydrostatic test. They are then revalidated at regular intervals according to the relevant standard. In some cases where a hydrostatic test is not practicable a pneumatic pressure test may be an acceptable alternative.[\[1\]](https://en.wikipedia.org/wiki/Hydrostatic_test#cite_note-Proof-1) Testing of pressure vessels for transport and storage of gases is very important because such containers can explode if they fail under pressure. ## Testing procedures \[[edit](https://en.wikipedia.org/w/index.php?title=Hydrostatic_test&action=edit&section=1 "Edit section: Testing procedures")\] Hydrostatic tests are conducted under the constraints of either the industry's or the customer's specifications, or may be required by law. The vessel is filled with a nearly incompressible liquid – usually [water](https://en.wikipedia.org/wiki/Water "Water") or [oil](https://en.wikipedia.org/wiki/Oil "Oil") – pressurised to test pressure, and examined for leaks or permanent changes in shape. [Red](https://en.wikipedia.org/wiki/Red "Red") or [fluorescent](https://en.wikipedia.org/wiki/Fluorescent "Fluorescent") [dyes](https://en.wikipedia.org/wiki/Dye "Dye") may be added to the water to make leaks easier to see. The test pressure is always considerably higher than the operating pressure to give a factor of safety. This factor of safety is typically 166.66%, 143% or 150% of the designed working pressure, depending on the regulations that apply. For example, if a cylinder was rated to DOT-2015 PSI (approximately 139 bar), it would be tested at around 3360 PSI (approximately 232 bar). [Water](https://en.wikipedia.org/wiki/Water "Water") is commonly used because it is cheap and easily available, and is usually harmless to the system to be tested. Hydraulic fluids and oils may be specified where contamination with water could cause problems. These fluids are nearly incompressible, therefore requiring relatively little work to develop a high pressure, and is therefore also only able to release a small amount of energy in case of a failure - only a small volume will escape under high pressure if the container fails. If [high pressure](https://en.wikipedia.org/wiki/High_pressure "High pressure") [gas](https://en.wikipedia.org/wiki/Gas "Gas") were used, then the gas would expand to V=(nRT)/p with its compressed volume resulting in an explosion, with the attendant risk of damage or injury. [![](https://upload.wikimedia.org/wikipedia/commons/thumb/7/76/Water_jacket_test_diagram.jpg/250px-Water_jacket_test_diagram.jpg)](https://en.wikipedia.org/wiki/File:Water_jacket_test_diagram.jpg) Water jacket test Small pressure vessels are normally tested using a water jacket test. The vessel is visually examined for defects and then placed in a container filled with water, and in which the change in volume of the vessel can be measured, usually by monitoring the water level in a calibrated tube. The vessel is then pressurised for a specified period, usually 30 or more seconds, and if specified, the expansion will be measured by reading off the amount of liquid that has been forced into the measuring tube by the volume increase of the pressurised vessel. The vessel is then depressurised, and the permanent volume increase due to plastic deformation while under pressure (permanent set) is measured by comparing the final volume in the measuring tube with the volume before pressurisation.[\[2\]](https://en.wikipedia.org/wiki/Hydrostatic_test#cite_note-Sauta_2010-2) A leak will give a similar result to permanent set, but will be detectable by holding the volume in the pressurised vessel by closing the inlet valve for a period before depressurising, as the pressure will drop steadily during this period if there is a leak. In most cases a permanent set that exceeds the specified maximum will indicate failure. A leak may also be a failure criterion, but it may be that the leak is due to poor sealing of the test equipment. If the vessel fails, it will normally go through a condemning process marking the cylinder as unsafe.[\[2\]](https://en.wikipedia.org/wiki/Hydrostatic_test#cite_note-Sauta_2010-2)[\[3\]](https://en.wikipedia.org/wiki/Hydrostatic_test#cite_note-Hydro_Key_Largo-3) The information needed to specify the test is stamped onto the cylinder. This includes the design standard, serial number, manufacturer, and manufacture date. After testing, the vessel or its nameplate will usually be stamp marked with the date of the successful test, and the test facility's identification mark.[\[3\]](https://en.wikipedia.org/wiki/Hydrostatic_test#cite_note-Hydro_Key_Largo-3) A simpler test, that is also considered a hydrostatic test but does not require pressure pumps, is to pressurise the vessel by filling it with water to a hydrostatic head by using a riser pipe connected to the tank and to physically examine the outside for leaks. This type of test is suitable for containers such as boat fuel tanks, which are not pressure vessels but must work under the hydrostatic pressure of the contents. A hydrostatic test head is usually specified as a height above the tank top. The tank is pressurised by filling water to the specified height through a temporary standpipe if necessary. It may be necessary to seal vents and other outlets during the test.[\[4\]](https://en.wikipedia.org/wiki/Hydrostatic_test#cite_note-4) ## Examples \[[edit](https://en.wikipedia.org/w/index.php?title=Hydrostatic_test&action=edit&section=2 "Edit section: Examples")\] Portable fire extinguishers are safety tools that are required in most public buildings. Fire extinguishers are also recommended in homes. Over time the conditions in which they are housed, and the manner in which they are handled affect the structural integrity of the extinguisher. A structurally weakened fire extinguisher can malfunction or even burst when it is needed the most. To maintain the quality and safety of this product, hydrostatic testing is utilized. All critical components of the fire extinguisher should be tested to ensure proper function. ## Pipeline testing \[[edit](https://en.wikipedia.org/w/index.php?title=Hydrostatic_test&action=edit&section=3 "Edit section: Pipeline testing")\] Hydrotesting of pipes, pipelines and vessels is performed to expose defective materials that have missed prior detection, ensure that any remaining defects are insignificant enough to allow operation at design pressures, expose possible leaks and serve as a final validation of the integrity of the constructed system. ASME B31.3 requires this testing to ensure tightness and strength. Buried high pressure oil and gas pipelines are tested for strength by pressurising them to at least 125% of their [maximum allowable working pressure](https://en.wikipedia.org/wiki/Maximum_allowable_working_pressure "Maximum allowable working pressure") (MAWP) at any point along their length. Since many long distance transmission pipelines are designed to have a steel hoop stress of 80% of [specified minimum yield strength](https://en.wikipedia.org/wiki/Specified_minimum_yield_strength "Specified minimum yield strength") (SMYS) at [Maximum allowable operating pressure](https://en.wikipedia.org/wiki/Maximum_allowable_operating_pressure "Maximum allowable operating pressure") MAOP, this means that the steel is stressed to SMYS and above during the testing, and test sections must be selected to ensure that excessive plastic deformation does not occur.\[[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed "Wikipedia:Citation needed")\] For piping built to ASME B31.3, if the design temperature is greater than the test temperature, then the test pressure must be adjusted for the related allowable stress at the design temperature. This is done by multiplying 1.5 MAWP by the ratio of the allowable stress at the test temperature to allowable stress at the design temperature per ASME B31.3 Section 345.4.2 Equation 24. Test pressures need not exceed a value that would produce a stress higher than yield stress at test temperature. ASME B31.3 section 345.4.2 (c) Other codes require a more onerous approach. BS PD 8010-2 requires testing to 150% of the design pressure – which should not be less than the MAOP plus surge and other incidental effects that will occur during normal operation.\[[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed "Wikipedia:Citation needed")\] Leak testing is performed by balancing changes in the measured pressure in the test section against the theoretical pressure changes calculated from changes in the measured temperature of the test section. Australian standard AS2885.5 "Pipelines – Gas and liquid petroleum: Part 5: Field pressure testing" gives an excellent explanation of the factors involved.\[[clarification needed](https://en.wikipedia.org/wiki/Wikipedia:Please_clarify "Wikipedia:Please clarify")\] In the aerospace industry, depending on the airline, company or customer, certain codes will need to be followed. For example, Bell Helicopter has a certain specification that will have to be followed for any parts that will be used in their helicopters.\[[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed "Wikipedia:Citation needed")\] ## Testing frequency \[[edit](https://en.wikipedia.org/w/index.php?title=Hydrostatic_test&action=edit&section=4 "Edit section: Testing frequency")\] Most countries have legislation or pressure vessel codes which requires vessels to be regularly tested, for example every two years (with a visual inspection annually) for high pressure gas cylinders and every five or ten years for lower pressure ones such as used in [fire extinguishers](https://en.wikipedia.org/wiki/Fire_extinguisher "Fire extinguisher").[\[5\]](https://en.wikipedia.org/wiki/Hydrostatic_test#cite_note-5) \[[clarification needed](https://en.wikipedia.org/wiki/Wikipedia:Please_clarify "Wikipedia:Please clarify")\] Gas cylinders which fail are normally destroyed as part of the testing protocol to avoid the dangers inherent in them being subsequently used.[\[6\]](https://en.wikipedia.org/wiki/Hydrostatic_test#cite_note-6) These common US standard gas cylinders have the following requirements:[\[7\]](https://en.wikipedia.org/wiki/Hydrostatic_test#cite_note-7) - DOT-3AL gas cylinders must be tested every 5 years and have an unlimited life. - DOT-3HT gas cylinders must be tested every 3 years and have a 24-year life. - DOT-3AA gas cylinders must be tested every 5 years and have an unlimited life. (Unless stamped with a star (\) in which case the cylinder meets certain specifications and can have a 10-year hydrostatic test life). Typically organizations such as DOT [PHMSA](https://en.wikipedia.org/wiki/PHMSA "PHMSA"), [ISO](https://en.wikipedia.org/wiki/ISO "ISO"), [ASTM](https://en.wikipedia.org/wiki/ASTM "ASTM") and [ASME](https://en.wikipedia.org/wiki/ASME "ASME") specify the guidelines for the different types of pressure vessels. ## Safety \[[edit](https://en.wikipedia.org/w/index.php?title=Hydrostatic_test&action=edit&section=5 "Edit section: Safety")\] Hydraulic testing is a hazardous process and should be performed with caution by competent personnel. Adhering to prescribed procedures defined in relevant [technical standards](https://en.wikipedia.org/wiki/Technical_standards "Technical standards") appropriate to the specific application and jurisdiction will usually reduce these risks to an acceptable level. - A leak of high pressure liquid can cut or penetrate the skin and inject itself into body tissues. This can cause serious direct injury to the operator, and if the fluid is toxic or contaminated there will be additional adverse effects. - A pressurised hose that is not securely attached or which fails under pressure may whip around spraying water or oil and could hit someone and cause injuries. A [whiplash arrestor](https://en.wikipedia.org/wiki/Glossary_of_underwater_diving_terminology:_T%E2%80%93Z#whiplash_arrestor "Glossary of underwater diving terminology: T–Z") can be used to restrain such hoses. - Enclosing the components to be tested, hazard signage, use of appropriate [personal protective equipment](https://en.wikipedia.org/wiki/Personal_protective_equipment "Personal protective equipment") and providing barriers to access for non-essential personnel are common precautions. ## See also \[[edit](https://en.wikipedia.org/w/index.php?title=Hydrostatic_test&action=edit&section=6 "Edit section: See also")\] - [Nondestructive testing](https://en.wikipedia.org/wiki/Nondestructive_testing "Nondestructive testing") – Type of analysis technique - [Testing and inspection of diving cylinders](https://en.wikipedia.org/wiki/Testing_and_inspection_of_diving_cylinders "Testing and inspection of diving cylinders") – Periodical inspection and testing to revalidate fitness for service ## References \[[edit](https://en.wikipedia.org/w/index.php?title=Hydrostatic_test&action=edit&section=7 "Edit section: References")\] 1. [^](https://en.wikipedia.org/wiki/Hydrostatic_test#cite_ref-Proof_1-0)* ["Proof-Pressure Test and Leak Detection Test in Metal Expansion Joints"](https://www.macoga.com/documents/en/metal-expansion-joints/proof-pressure-test-leak-detection-test.pdf) (PDF). www.macoga.com. Macoga SA. Retrieved 24 September 2021. 2. ^ [*a](https://en.wikipedia.org/wiki/Hydrostatic_test#cite_ref-Sauta_2010_2-0) [b](https://en.wikipedia.org/wiki/Hydrostatic_test#cite_ref-Sauta_2010_2-1) Sauta, Tom (1 Oct 2010). ["Hydro-Test Water Jacket Cylinder Test System Setup.wmv"](https://www.youtube.com/watch?v=KLrV0vGBZEk). www.hydrotest.com. Retrieved 29 July 2025 – via YouTube. 3. ^ [a](https://en.wikipedia.org/wiki/Hydrostatic_test#cite_ref-Hydro_Key_Largo_3-0) [b](https://en.wikipedia.org/wiki/Hydrostatic_test#cite_ref-Hydro_Key_Largo_3-1) Angel (17 May 2022). ["How to Hydro Test a scuba tank"](https://www.youtube.com/watch?v=Bwd-GFCtLl8). Scuba Tech Key Largo. Retrieved 29 July 2025 – via YouTube. 4. [^](https://en.wikipedia.org/wiki/Hydrostatic_test#cite_ref-4)* Kim; An, Tae-Hyun; Lee, Tak-Kee (April 2022). ["Preliminary Study on Deformation During Hydrostatic Testing in a Deep Tank }first1=Geun-Gon"](https://doi.org/10.26748%2FKSOE.2021.075). J. Ocean Eng. Technol. 36 (2): 115–124\. [doi](https://en.wikipedia.org/wiki/Doi_\(identifier\) "Doi (identifier)"):[10\.26748/KSOE.2021.075](https://doi.org/10.26748%2FKSOE.2021.075). 5. [^](https://en.wikipedia.org/wiki/Hydrostatic_test#cite_ref-5) ["Federal Register :: Request Access"](https://www.ecfr.gov/current/title-49/subtitle-B/chapter-I/subchapter-C/part-180#p-180.209\(j\)). 6. [^](https://en.wikipedia.org/wiki/Hydrostatic_test#cite_ref-6) ["Federal Register :: Request Access"](https://www.ecfr.gov/current/title-49/subtitle-B/chapter-I/subchapter-C/part-180#p-180.205\(i\)). 7. [^](https://en.wikipedia.org/wiki/Hydrostatic_test#cite_ref-7) ["Federal Register :: Request Access"](https://www.ecfr.gov/current/title-49/section-180.209). ## External links \[[edit](https://en.wikipedia.org/w/index.php?title=Hydrostatic_test&action=edit&section=8 "Edit section: External links")\] - ["OSHA"](https://www.osha.gov/SLTC/etools/evacuation/portable_hydro.html). 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Readable Markdown	From Wikipedia, the free encyclopedia [![](https://upload.wikimedia.org/wikipedia/commons/thumb/c/c5/Hydrostatic_Tester.jpg/250px-Hydrostatic_Tester.jpg)](https://en.wikipedia.org/wiki/File:Hydrostatic_Tester.jpg) Hydrostatic tester A hydrostatic test is a way in which [pressure vessels](https://en.wikipedia.org/wiki/Pressure_vessel "Pressure vessel") such as [pipelines](https://en.wikipedia.org/wiki/Pipeline_transport "Pipeline transport"), [plumbing](https://en.wikipedia.org/wiki/Plumbing "Plumbing"), [gas cylinders](https://en.wikipedia.org/wiki/Gas_cylinder "Gas cylinder"), [boilers](https://en.wikipedia.org/wiki/Boiler "Boiler") and fuel tanks can be tested for strength and leaks. The test involves filling the vessel or pipe system with a liquid, usually water, which may be dyed to aid in visual [leak detection](https://en.wikipedia.org/wiki/Leak_detection "Leak detection"), and pressurization of the vessel to the specified test pressure. Pressure tightness can be tested by shutting off the supply valve and observing whether there is a pressure loss. The location of a leak can be visually identified more easily if the water contains a colorant. Strength is usually tested by measuring permanent deformation of the container. Hydrostatic testing is the most common method employed for testing pipes and pressure vessels. Using this test helps maintain safety standards and durability of a vessel over time. Newly manufactured pieces are initially qualified using the hydrostatic test. They are then revalidated at regular intervals according to the relevant standard. In some cases where a hydrostatic test is not practicable a pneumatic pressure test may be an acceptable alternative.[\[1\]](https://en.wikipedia.org/wiki/Hydrostatic_test#cite_note-Proof-1) Testing of pressure vessels for transport and storage of gases is very important because such containers can explode if they fail under pressure. Hydrostatic tests are conducted under the constraints of either the industry's or the customer's specifications, or may be required by law. The vessel is filled with a nearly incompressible liquid – usually [water](https://en.wikipedia.org/wiki/Water "Water") or [oil](https://en.wikipedia.org/wiki/Oil "Oil") – pressurised to test pressure, and examined for leaks or permanent changes in shape. [Red](https://en.wikipedia.org/wiki/Red "Red") or [fluorescent](https://en.wikipedia.org/wiki/Fluorescent "Fluorescent") [dyes](https://en.wikipedia.org/wiki/Dye "Dye") may be added to the water to make leaks easier to see. The test pressure is always considerably higher than the operating pressure to give a factor of safety. This factor of safety is typically 166.66%, 143% or 150% of the designed working pressure, depending on the regulations that apply. For example, if a cylinder was rated to DOT-2015 PSI (approximately 139 bar), it would be tested at around 3360 PSI (approximately 232 bar). [Water](https://en.wikipedia.org/wiki/Water "Water") is commonly used because it is cheap and easily available, and is usually harmless to the system to be tested. Hydraulic fluids and oils may be specified where contamination with water could cause problems. These fluids are nearly incompressible, therefore requiring relatively little work to develop a high pressure, and is therefore also only able to release a small amount of energy in case of a failure - only a small volume will escape under high pressure if the container fails. If [high pressure](https://en.wikipedia.org/wiki/High_pressure "High pressure") [gas](https://en.wikipedia.org/wiki/Gas "Gas") were used, then the gas would expand to V=(nRT)/p with its compressed volume resulting in an explosion, with the attendant risk of damage or injury. [![](https://upload.wikimedia.org/wikipedia/commons/thumb/7/76/Water_jacket_test_diagram.jpg/250px-Water_jacket_test_diagram.jpg)](https://en.wikipedia.org/wiki/File:Water_jacket_test_diagram.jpg) Water jacket test Small pressure vessels are normally tested using a water jacket test. The vessel is visually examined for defects and then placed in a container filled with water, and in which the change in volume of the vessel can be measured, usually by monitoring the water level in a calibrated tube. The vessel is then pressurised for a specified period, usually 30 or more seconds, and if specified, the expansion will be measured by reading off the amount of liquid that has been forced into the measuring tube by the volume increase of the pressurised vessel. The vessel is then depressurised, and the permanent volume increase due to plastic deformation while under pressure (permanent set) is measured by comparing the final volume in the measuring tube with the volume before pressurisation.[\[2\]](https://en.wikipedia.org/wiki/Hydrostatic_test#cite_note-Sauta_2010-2) A leak will give a similar result to permanent set, but will be detectable by holding the volume in the pressurised vessel by closing the inlet valve for a period before depressurising, as the pressure will drop steadily during this period if there is a leak. In most cases a permanent set that exceeds the specified maximum will indicate failure. A leak may also be a failure criterion, but it may be that the leak is due to poor sealing of the test equipment. If the vessel fails, it will normally go through a condemning process marking the cylinder as unsafe.[\[2\]](https://en.wikipedia.org/wiki/Hydrostatic_test#cite_note-Sauta_2010-2)[\[3\]](https://en.wikipedia.org/wiki/Hydrostatic_test#cite_note-Hydro_Key_Largo-3) The information needed to specify the test is stamped onto the cylinder. This includes the design standard, serial number, manufacturer, and manufacture date. After testing, the vessel or its nameplate will usually be stamp marked with the date of the successful test, and the test facility's identification mark.[\[3\]](https://en.wikipedia.org/wiki/Hydrostatic_test#cite_note-Hydro_Key_Largo-3) A simpler test, that is also considered a hydrostatic test but does not require pressure pumps, is to pressurise the vessel by filling it with water to a hydrostatic head by using a riser pipe connected to the tank and to physically examine the outside for leaks. This type of test is suitable for containers such as boat fuel tanks, which are not pressure vessels but must work under the hydrostatic pressure of the contents. A hydrostatic test head is usually specified as a height above the tank top. The tank is pressurised by filling water to the specified height through a temporary standpipe if necessary. It may be necessary to seal vents and other outlets during the test.[\[4\]](https://en.wikipedia.org/wiki/Hydrostatic_test#cite_note-4) Portable fire extinguishers are safety tools that are required in most public buildings. Fire extinguishers are also recommended in homes. Over time the conditions in which they are housed, and the manner in which they are handled affect the structural integrity of the extinguisher. A structurally weakened fire extinguisher can malfunction or even burst when it is needed the most. To maintain the quality and safety of this product, hydrostatic testing is utilized. All critical components of the fire extinguisher should be tested to ensure proper function. Hydrotesting of pipes, pipelines and vessels is performed to expose defective materials that have missed prior detection, ensure that any remaining defects are insignificant enough to allow operation at design pressures, expose possible leaks and serve as a final validation of the integrity of the constructed system. ASME B31.3 requires this testing to ensure tightness and strength. Buried high pressure oil and gas pipelines are tested for strength by pressurising them to at least 125% of their [maximum allowable working pressure](https://en.wikipedia.org/wiki/Maximum_allowable_working_pressure "Maximum allowable working pressure") (MAWP) at any point along their length. Since many long distance transmission pipelines are designed to have a steel hoop stress of 80% of [specified minimum yield strength](https://en.wikipedia.org/wiki/Specified_minimum_yield_strength "Specified minimum yield strength") (SMYS) at [Maximum allowable operating pressure](https://en.wikipedia.org/wiki/Maximum_allowable_operating_pressure "Maximum allowable operating pressure") MAOP, this means that the steel is stressed to SMYS and above during the testing, and test sections must be selected to ensure that excessive plastic deformation does not occur.\[[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed "Wikipedia:Citation needed")\] For piping built to ASME B31.3, if the design temperature is greater than the test temperature, then the test pressure must be adjusted for the related allowable stress at the design temperature. This is done by multiplying 1.5 MAWP by the ratio of the allowable stress at the test temperature to allowable stress at the design temperature per ASME B31.3 Section 345.4.2 Equation 24. Test pressures need not exceed a value that would produce a stress higher than yield stress at test temperature. ASME B31.3 section 345.4.2 (c) Other codes require a more onerous approach. BS PD 8010-2 requires testing to 150% of the design pressure – which should not be less than the MAOP plus surge and other incidental effects that will occur during normal operation.\[[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed "Wikipedia:Citation needed")\] Leak testing is performed by balancing changes in the measured pressure in the test section against the theoretical pressure changes calculated from changes in the measured temperature of the test section. Australian standard AS2885.5 "Pipelines – Gas and liquid petroleum: Part 5: Field pressure testing" gives an excellent explanation of the factors involved.\[[clarification needed](https://en.wikipedia.org/wiki/Wikipedia:Please_clarify "Wikipedia:Please clarify")\] In the aerospace industry, depending on the airline, company or customer, certain codes will need to be followed. For example, Bell Helicopter has a certain specification that will have to be followed for any parts that will be used in their helicopters.\[[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed "Wikipedia:Citation needed")\] Most countries have legislation or pressure vessel codes which requires vessels to be regularly tested, for example every two years (with a visual inspection annually) for high pressure gas cylinders and every five or ten years for lower pressure ones such as used in [fire extinguishers](https://en.wikipedia.org/wiki/Fire_extinguisher "Fire extinguisher").[\[5\]](https://en.wikipedia.org/wiki/Hydrostatic_test#cite_note-5) \[[clarification needed](https://en.wikipedia.org/wiki/Wikipedia:Please_clarify "Wikipedia:Please clarify")\] Gas cylinders which fail are normally destroyed as part of the testing protocol to avoid the dangers inherent in them being subsequently used.[\[6\]](https://en.wikipedia.org/wiki/Hydrostatic_test#cite_note-6) These common US standard gas cylinders have the following requirements:[\[7\]](https://en.wikipedia.org/wiki/Hydrostatic_test#cite_note-7) - DOT-3AL gas cylinders must be tested every 5 years and have an unlimited life. - DOT-3HT gas cylinders must be tested every 3 years and have a 24-year life. - DOT-3AA gas cylinders must be tested every 5 years and have an unlimited life. (Unless stamped with a star (\) in which case the cylinder meets certain specifications and can have a 10-year hydrostatic test life). Typically organizations such as DOT [PHMSA](https://en.wikipedia.org/wiki/PHMSA "PHMSA"), [ISO](https://en.wikipedia.org/wiki/ISO "ISO"), [ASTM](https://en.wikipedia.org/wiki/ASTM "ASTM") and [ASME](https://en.wikipedia.org/wiki/ASME "ASME") specify the guidelines for the different types of pressure vessels. Hydraulic testing is a hazardous process and should be performed with caution by competent personnel. Adhering to prescribed procedures defined in relevant [technical standards](https://en.wikipedia.org/wiki/Technical_standards "Technical standards") appropriate to the specific application and jurisdiction will usually reduce these risks to an acceptable level. - A leak of high pressure liquid can cut or penetrate the skin and inject itself into body tissues. This can cause serious direct injury to the operator, and if the fluid is toxic or contaminated there will be additional adverse effects. - A pressurised hose that is not securely attached or which fails under pressure may whip around spraying water or oil and could hit someone and cause injuries. A [whiplash arrestor](https://en.wikipedia.org/wiki/Glossary_of_underwater_diving_terminology:_T%E2%80%93Z#whiplash_arrestor "Glossary of underwater diving terminology: T–Z") can be used to restrain such hoses. - Enclosing the components to be tested, hazard signage, use of appropriate [personal protective equipment](https://en.wikipedia.org/wiki/Personal_protective_equipment "Personal protective equipment") and providing barriers to access for non-essential personnel are common precautions. - [Nondestructive testing](https://en.wikipedia.org/wiki/Nondestructive_testing "Nondestructive testing") – Type of analysis technique - [Testing and inspection of diving cylinders](https://en.wikipedia.org/wiki/Testing_and_inspection_of_diving_cylinders "Testing and inspection of diving cylinders") – Periodical inspection and testing to revalidate fitness for service 1. [^](https://en.wikipedia.org/wiki/Hydrostatic_test#cite_ref-Proof_1-0)* ["Proof-Pressure Test and Leak Detection Test in Metal Expansion Joints"](https://www.macoga.com/documents/en/metal-expansion-joints/proof-pressure-test-leak-detection-test.pdf) (PDF). www.macoga.com. Macoga SA. Retrieved 24 September 2021. 2. ^ [*a](https://en.wikipedia.org/wiki/Hydrostatic_test#cite_ref-Sauta_2010_2-0) [b](https://en.wikipedia.org/wiki/Hydrostatic_test#cite_ref-Sauta_2010_2-1) Sauta, Tom (1 Oct 2010). ["Hydro-Test Water Jacket Cylinder Test System Setup.wmv"](https://www.youtube.com/watch?v=KLrV0vGBZEk). www.hydrotest.com. Retrieved 29 July 2025 – via YouTube. 3. ^ [a](https://en.wikipedia.org/wiki/Hydrostatic_test#cite_ref-Hydro_Key_Largo_3-0) [b](https://en.wikipedia.org/wiki/Hydrostatic_test#cite_ref-Hydro_Key_Largo_3-1) Angel (17 May 2022). ["How to Hydro Test a scuba tank"](https://www.youtube.com/watch?v=Bwd-GFCtLl8). Scuba Tech Key Largo. Retrieved 29 July 2025 – via YouTube. 4. [^](https://en.wikipedia.org/wiki/Hydrostatic_test#cite_ref-4)* Kim; An, Tae-Hyun; Lee, Tak-Kee (April 2022). ["Preliminary Study on Deformation During Hydrostatic Testing in a Deep Tank }first1=Geun-Gon"](https://doi.org/10.26748%2FKSOE.2021.075). J. Ocean Eng. Technol. 36 (2): 115–124\. [doi](https://en.wikipedia.org/wiki/Doi_\(identifier\) "Doi (identifier)"):[10\.26748/KSOE.2021.075](https://doi.org/10.26748%2FKSOE.2021.075). 5. [^](https://en.wikipedia.org/wiki/Hydrostatic_test#cite_ref-5) ["Federal Register :: Request Access"](https://www.ecfr.gov/current/title-49/subtitle-B/chapter-I/subchapter-C/part-180#p-180.209\(j\)). 6. [^](https://en.wikipedia.org/wiki/Hydrostatic_test#cite_ref-6) ["Federal Register :: Request Access"](https://www.ecfr.gov/current/title-49/subtitle-B/chapter-I/subchapter-C/part-180#p-180.205\(i\)). 7. [^](https://en.wikipedia.org/wiki/Hydrostatic_test#cite_ref-7) ["Federal Register :: Request Access"](https://www.ecfr.gov/current/title-49/section-180.209). - ["OSHA"](https://www.osha.gov/SLTC/etools/evacuation/portable_hydro.html). Retrieved 2006-10-05.
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