Pipeline Services
Leak Testing (Nitrogen and Helium)

With the ever increasing demands of aging processing plants, the handling of highly flammable fluids and toxic gas at high pressures requires the need for stringent safety standards. To comply with these standards, all leaks need to be located and remedial actions to be taken.


In order to detect even the smallest leaks, the most effective method is to use helium as a traceable gas as it is mono-atomic. The fact that it is totally inert makes helium ideal for leak detection purposes. Its use for this application is widespread and there are a number of different instruments capable of detecting small concentrations of helium gas. The most sensitive instrument is the mass spectrometer, which combines a high sensitivity with precision selectivity and is therefore not affected by the presence of other gas and contaminants.


As the use of pure helium for leak detection purposes would lead to a huge consumption of this rather expensive gas, a mixture of 1% helium and 99% nitrogen is usually used to enable a reliable detection of leaks down to 0.05 Nm3/year.


The entire operation is carefully planned and carried out in a safe and efficient manner. In preparation for the test, the flange connections are taped in order to encapsulate the space between the flanges, thus capturing any escaping gas resulting from a leak in the encapsulated space. The nitrogen/helium mixture is injected into the system or installation until the required working pressure is achieved. The test probe, which is connected to the Mass Spectrometer via a small bore vacuum hose, is inserted through the tape. Any gas present in the encapsulated space are transported to the Mass Spectrometer and analyzed for traces of helium.


If helium traces are detected, an accurate equivalent leak rate is determined so as to assess any remedial actions to be taken. The results of the test are tabulated and issued in a report, identifying number of leaks detected, location and leak rate per year.


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