Hydrostatic Pressure Tests: What You Need To Know

The Purpose of Hydrostatic Testing

Hydrostatic pressure testing is an important process used to measure the structural integrity of pipelines. It is a test that uses pressure to determine the strength and stability of a pipeline or pressurized vessel, and is often used in the construction and maintenance of pipelines. 

This form of testing is a critical part of pipeline safety. It helps to ensure that a pipeline is strong enough to withstand the different pressures and conditions that it will experience in its lifetime. It also helps to identify any potential hazards or failures that could occur in the future, which could be catastrophic in the event of a pipeline rupture.

How Hydrostatic Pressure Testing Works

Hydrostatic pressure testing involves filling a pipeline with a liquid (usually water) and then pressurizing it to a predetermined level, generally high pressure not above the designed pressure of the piping system. After the pressure has stabilized, it is held for 4-8 hours. 

If the test is for strength and leaks, the pressure during the test can be increased to perform a spike test. This is generally done when corrosion, cracking, and other potential problems are identified while visually inspecting pipelines.

While the pipeline is pressurized, pressure readings should be monitored for drops in pressure. Additionally, if the piping system is aboveground, the pipeline should be visually inspected. If no leaks are identified and any fluctuations in pressure have an explanation, the test was successful. Pressure can be reduced by the testing equipment, and the water used during the test must be disposed of in a way that is not harmful to the environment.

Hydrostatic Pressure Testing Standards

Hydrostatic Pressure Testing is an important component of safety and compliance for a variety of industries, from aerospace and automotive to oil and gas production. As such, there are a number of different standards and regulations that must be followed when hydrostatic tests are conducted.


The two main organizations that set standards and regulations for hydrostatic pressure testing are the American Society of Mechanical Engineers (ASME) and the American Petroleum Institute (API). The ASME sets safety standards and regulations for pressure equipment and systems, while the API sets standards and regulations for oil and gas production.

The ASME has several different codes and standards related to hydrostatic pressure testing, including the Boiler and Pressure Vessel Code (BPVC) and the B31.1 Power Piping Code. The BPVC sets the requirements for the design, fabrication, inspection, and testing of boilers and pressure vessels, while the B31.1 sets the requirements for the design, construction, operation, maintenance, and inspection of power piping systems.

The API also has several different standards related to hydrostatic testing work, such as the API Standard 653, which sets the requirements for the inspection, repair, and alteration of aboveground storage tanks.


The U.S. Department of Transportation’s Pipeline and Hazardous Materials Safety Administration (PHMSA) also regulates and sets the standards for hydrostatic pressure testing of pipelines. The PHMSA’s Minimum Examination and Gauge Accuracy (MEGA) rule is the primary regulation for hydrostatic pressure testing.

The MEGA rule requires that operators of hazardous liquid and gas pipelines must perform an initial hydrostatic pressure test on a pipeline before it is placed in service. This initial test must be conducted with a minimum test pressure of 125% of the maximum operating pressure of the pipeline, and must continue for a period of at least four hours. The MEGA rule also requires that pipelines must be tested at least once every ten years to ensure they can withstand their maximum operating pressure.

In addition to the initial test and periodic tests, the MEGA rule also requires that operators must perform hydrostatic pressure testing whenever there are repairs or alterations to a pipeline that might affect its pressure requirements. This includes repairs caused by corrosion, mechanical damage, or any other kind of damage. Operators must also perform hydrostatic pressure tests whenever the pipeline is exposed to a higher pressure than its maximum operating pressure.

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