Helium Leak Testing by TCR Arabia in Saudi Arabia
Leak Testing is a form of non-destructive testing used for detection and location of leaks and for the measurement of leakage in either pressurized or evacuated Vessel / Heat Exchanger.
Leak for various reasons is a undesirable feature in a component or systems. Still leaks do occur in practice. Hence ,it is essential that leaks are effectively detected and remedial measures to plug the leaks are taken well in advance.
There are various measures of leak testing. Leak Test methods such as Ultrasonic, Bubble, Air Soap Solution etc have sensitivity upto 10 ( - 3 ) std cc / sec range. Helium Leak Testing method has many advantages in terms of sensitivity and reliabilty.
When leak test is carried out, it is necessary to remember that leak rate measured plays a important role.Helium Leak Detector detects leak of the order of 10 ( - 6 ) std cc / sec or better, depending on test method used to detect the leak.
Helium is used as a tracer gas for the following reasons:
- Helium gas is very rare in atmosphere (around 5 ppm). Thus background is very low.
- This gas is non toxic and inert, so does not react with materials and presents no health hazard to operator.
- It has high diffusivity penetrating leaks.
Prior to start of leak test, Helium Mass Spectrometer Leak Detector is calibrated using Standard Calibrated Leak. Vessel or Heat Exchanger is filled with Helium gas. After specified time, potential leak areas like welds, flanged joints,tube to tubeshet joints etc are sniffed with sniffer probe.This is semiquantitative leak test method .
In case of Heat Exchangers,Vessel / Shell is pressurised with Helium at specified pressure and tube to tubesheet weld joints are tested by moving Sniffer Probe around joints to be tested OR Tubes are pressurised with Helium at test pressure and plug joints are leak tested by moving Sniffer Probe around plug Joints.