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What is Hydrostating Testing?

Traditionally speaking, a hydrostatic test, also known as a “hydro test” or “pressure integrity test” is a leak test performed to verify the integrity of a pipe, storage tank, pressure vessel, control components or connections (welded, fused or mechanical) of a vessel that will facilitate or store pressure while in service.  These tests can be performed on anything from a section of pipe, to the flanges on a valve, or even on the valve itself prior to being put into service.  The purpose of these tests is to provide traceable and verifiable pressure data which is then used to monitor and, in some cases, improve safety on new and/or existing pressure systems.  Hydrostatic tests are performed at every phase during the life of the vessel, from its point of fabrication, before installation, after installation and then routinely thereafter while in active service.

Common Applications in which Pressure Tests are required

  • Installation and maintenance of transmission and distribution pipelines

  • Installation of fire water systems (plants, refineries or other)

  • Residential gas service installations

  • City gate monitoring of incoming pressure

  • Installation of new piping systems (oil, gas, water, sewer)

  • Well-heads

  • Fabrication of pipe or storage tanks/vessels

  • Compressors

  • Sprinkler systems

  • Pigging, hot tapping or stopple work

  • HDPE pipe replacement

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Why are identifying leaks important?

Identifying potential leaks is of the upmost importance to ensure the safety and integrity of a pressure vessel or pipeline before and during service.  Leakages of any kind can lead to catastrophic incidents involving environmental chemical hazards, injury and in some cases death.  These critical tests document the initial integrity of the pressure vessel. Results are then reviewed and signed off on by a third -inspector, clearing the unit under test for service.  Hydrostatic tests are also performed regularly once a vessel is put into service as part of The Mega Rule (2020), a federally mandated standard designed to ensure that the integrity of the system does not deteriorate over time.  Deterioration caused by rust, corrosion, vibration, tectonic plate movement, overpressure, or other environmental factors can lead to weaknesses in the vessel or vessel’s connections which can cause system failure and injury if not properly monitored and maintained.

How are hydrostatic tests performed?

There are several different applications for performing hydrostatic tests, however traditionally speaking, these tests are performed by isolating the vessel under test, sealing it off completely, and pressurizing it with water (hydrostatic integrity test) or air/nitrogen (pneumatic integrity test) to 1.5x the rated operating pressure of the vessel.  Once pressurized to the appropriate rating as defined by standards and codes laid out by DOT, ANSI, ASME and the state governing bodies, it must maintain that pressure for a predetermined period of time as defined by the applicable standard in use without any significant loss of pressure. The duration of the test as well as the allowable pressure fluctuations can vary greatly by application and are defined within the test operator’s procedures in accordance with the standard being used. Testing requirements such as pressure and duration can also vary depending on the vessel’s material, size, length and environmental factors so it’s important to consult the regulatory guidelines for your application prior to performing any pressure test to ensure compliance.  While the vessel is under test, the pressure/temperature can be monitored by using traditional mechanical equipment such as a chart recorder; however, digital hydrostatic testing equipment:

  • Reduces equipment and annual maintenance costs

  • Increases efficiency without sacrificing stringent requirements needed for third party approval

  • Increases reliability and integrity of test results

  • Improves documentation retention and traceability

  • Simplifies the delivery and storage of test reports via electronic transmission

  • Is more robust and easier to transport

  • Can record multiple variables simultaneously

Mechanical versus Digital Testing Methods

A mechanical hydrostatic test typically requires five standard pieces of test equipment whereas a digital hydrostatic test may only require one to produce traceable results.  This switch alone can lead to very fast return on investment (ROI) in asset maintenance costs alone.

View our online ROI Calculator and see how much you can save by switching to digital today!

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