NITROGEN/HELIUM LEAK DETECTION USED ON NORTH RANKIN 'A' PLATFORM

Abstract

In the past, leaks were found by pressuring the process systems first with water and then with hydrocarbons. This low cost but hazardous method of leak detection used gas detectors and soapy water to detect gas leaks. The disadvantage of this method is that large leaks contaminate the environment, risk a possible explosion and fire, and can result in a considerable loss of product.

In the last few years, NOWSCO Well Service Ltd has developed a leak test process utilizing nitrogen mixed with helium as a tracer gas. With this innovative technology the industry is now able to eliminate the use of hydrocarbons during leak testing, and detect leakage rates as small as 0.1 cubic foot per year. This nitrogen/helium leak testing method was used on North Rankin 'A' platform.

Some 559 leaks were found and rectified, of which 178 occurred in systems that had been previously leak tested with water. This highlights the inadequacy of water leak testing for gas handling systems.

In May of 1984 an essentially leak-free start-up of the process equipment was accomplished on North Rankin 'A' Platform, which is attributed to the helium leak detection method used in the commissioning programme.