Leak Testing (LT)


Hi-Tech Testing offers bubble leak and pressure change testing techniques of leak detection. These methods work by pressurizing or pulling a vacuum in a closed system while relying on visual detection or pressure monitoring to detect leaks.

Vacuum Box Bubble Leak testing (VBLT) is commonly used in the testing of welded storage tank floors and sometimes roofs. It works by applying a leak test film solution to the test area then creating a partial vacuum over the area to be examined using a vacuum box designed for the purpose. Leaks are detected by the bubbles formed as the air passes through the leak path in the tank floor.

Direct pressure is the standard technique when testing threaded piping, tubing, welded reinforcing pads, flanged connections and valves. This method works by pressurizing the piece of equipment to be tested and applying the leak test film solution to the areas of concern. The constant formation of bubbles indicates the presence of a leak as well as its location.

The immersion technique is applied when small parts can be immersed in the testing fluid or when the subject can be covered with the test fluid such as a ball valve. This process works by tightly sealing off and pressuring the part being tested, and then immersing it in water. If there is a leak, the pressurized part will emit a steady stream of bubbles out of the leak.

Pressure Change Testing (PCT) consists of pressurizing the piece of equipment to be tested and measuring the change in pressure and temperature after a prescribe amount of time. Loss of pressure not due to temperature fluctuation is indicative of a leak.

Although certification is not a requirement in some of the applicable codes for bubble leak testing, our personnel are qualified and certified in accordance with our written practice which meets, or exceeds, the recommended guidelines of SNT-TC-1A.

Hi-Tech has an ASNT certified Level III in Leak Testing which places us among the few companies offering this service. Consulting and training in bubble leak testing as well as other leak testing methods, e.g. halogen diode, absolute pressure change, helium mass spectrometer, may be provided upon request.

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