Hydrostatic Pressure Testing Determines if it Can Take the Pressure

Hydrostatic Pressure Testing is a nondestructive (NDT) method of finding leaks or verifying performance and durability in pressure vessels such as pipe, tubing, and coils. Although this is considered a nondestructive test and failures are rare, they can occur when the test piece does not meet performance or durability specifications and may render the piece unusable.

Set up of coil for hydrostatic pressure testing This type of testing usually entails filling the test piece with liquid, bleeding out air, pressurizing the piece, then examining it for leaks or permanent changes in shape. A nearly incompressible (compressible only by weight, not air pressure) liquid, usually water or oil, is used because it will only expand by a very small amount should the test piece fail and not pose a danger to the technician. The test also can be performed with pressurized air, but is generally done with the vessel under water for safety reasons.

Hydrostatic pressure testing copper tubing The pressure used in testing is always considerably more than the operating pressure to give the customer a margin for safety. Typically the test is performed at 150 percent of the design or working pressure. For example, if a pipe was rated to a working pressure of 2000 PSI, it would be tested at 3000 PSI.

Inspections at LTI

At LTI, we are equipped to do hydrostatic testing with water, oil, or air under water. Water is our most commonly used test medium because it is less expensive than oil and an easier set up than air, so the cost to our customers is lower. Our technicians can test tubing, pipe and coils to pressures up to 10,000 PSI, in many cases. All testing is performed according to customer requirements and/or industry specifications.

This article is the last in a series for LabNews on the array of services offered by our NDT Department. In the past few issues, we covered X-ray Inspection, Ultrasonic Testing, Liquid Penetrant Inspection and Magnetic Particle Inspection. We also provide SNT-TC-1A certified Visual Inspection, but felt that an article was not warranted. If you missed any past articles on nondestructive testing services, issues from the last few years are available on our website at www.labtesting.com/news-labnews.php.