Hydrostatic Pressure Testing

Hydrostatic pressure testing verifies the structural integrity and leak-tightness of completed pipelines before commissioning.
The test involves filling the pipeline with water and pressurising it to a level above the normal operating pressure.
Stored energy in a pressurised pipeline is significant — a joint or fitting failure releases water with explosive force.
An exclusion zone must be established around the pipeline and all test equipment before pressure is applied.
The test pressure, hold duration, and allowable pressure drop are defined in the pipeline specification and must be followed exactly.
Pressure gauges and recording equipment must be calibrated and certified to ensure accurate and reliable test results.
All air must be vented from the pipeline before pressurising — trapped air compresses and stores dangerous energy.
End caps, blank flanges, and thrust restraints must be designed to withstand the test pressure without displacement.
The competent person supervising the test must monitor pressure continuously and control the pressurisation rate.
Test water disposal must be managed in accordance with environmental regulations — discharge permits may be required.

Explosive failure	A pipeline joint failing under test pressure releases water with enough force to cause fatal injuries — exclusion zones save lives.
Stored energy	Pressurised water in a pipeline stores enormous energy — even a small leak can produce a dangerous high-pressure jet.
Accurate results	Uncalibrated gauges give false results that accept defective joints — calibrated instruments protect the integrity of the installed pipeline.

Do

Don't

Establish an exclusion zone around the pipeline and test equipment before pressurising.
Follow the specified test pressure, duration, and allowable pressure drop exactly.
Use calibrated, certified pressure gauges and recording instruments for every test.
Vent all trapped air from the pipeline completely before applying test pressure.
Verify end caps, flanges, and thrust restraints are designed for the test pressure.
Monitor pressure continuously throughout the test with a competent person present.
Control the pressurisation rate gradually — do not apply full pressure suddenly.
Record all test data including pressures, times, and temperatures for the project records.
Manage test water disposal in compliance with environmental discharge regulations.
Brief all nearby workers on the exclusion zone and test schedule before starting.

DON'T pressurise any pipeline without an exclusion zone established and maintained.
DON'T deviate from the specified test pressure or hold duration in the specification.
DON'T use uncalibrated pressure gauges — they give unreliable and potentially unsafe results.
DON'T pressurise the pipeline until all air has been completely vented from the system.
DON'T rely on temporary end caps not designed for the test pressure being applied.
DON'T leave the pipeline unmonitored during any phase of the pressure test.
DON'T apply full test pressure in one step — increase gradually and observe for leaks.
DON'T accept the test without complete, accurate records of all parameters.
DON'T discharge test water to drains or watercourses without environmental approval.
DON'T enter the exclusion zone while the pipeline is under test pressure.

See also: Pipeline Safety Awareness | HDPE and PE Pipe Butt Fusion

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