Helium Leak Detection
The Use of Helium for Pipeline Leak Detection
The first use of pipelines for general purposes can be traced to the US during the 1830s. Later, with the opening of the country’s first commercial oil well in 1859, pipes were used to transport oil from the drill sites to storage tanks and refineries. Since then, their use has become ubiquitous throughout a diverse range of industries. Having evolved from relatively short wooden or iron structures to tough plastic, steel, or concrete tubes, modern pipelines often operate under high pressures. This has required the development of technologies such as helium leak detection in order to keep a check on their structural integrity and, ultimately, to ensure their safety.
Pipelines can be thousands of kilometres long and cross entire continents but they are made up of relatively small sections that are either bolted or welded together. At the time of their construction and at regular intervals throughout their active lifespan, it is necessary to check that they are thoroughly sealed and that their contents cannot escape into the surrounding environment. For this purpose, helium leak-detection equipment is widely used.
Every precaution is taken during the assembly and installation stage and welds may even be examined with special X-ray machines to ensure their integrity. Nevertheless, it is only when the pipeline comes under pressure that its integrity will be truly tested. One way to achieve this is to pump the line full of water under pressure and inspect its length for any sign that it may be escaping. However, the method relies heavily on human observational skills. By contrast, when using helium leak detection, not only are any minute traces of escaping gas readily picked up by the sensitive chemical detectors used but, because of its small molecular size, the gas is able to reveal even the tiniest leaks that would not permit the much larger molecules of water to escape.
As part of the commissioning process, each breach identified will then be repaired and the process of testing repeated. Because the gaseous element helium is inert, there is no risk that a spark could lead to a fire or an explosion during the leak-detection process. Furthermore, because fire can be a hazard in petroleum pipelines, for example, a second inert gas, in this case, nitrogen, is often used to purge the pipeline of all inflammable liquid and vapour prior to testing it for leaks.
As a more efficient alternative, nitrogen gas can be introduced into the pipeline under pressure in combination with trace amounts of helium. When the two gases are combined in this manner, the purging and testing processes can be reduced to a single operation. Not only does this save time but the presence of nitrogen also prevents the formation of moisture in the pipes during the helium leak-detection process.
This is an exacting operation and one that depends upon skill and experience, in addition to the specialised equipment required to carry out this crucial testing procedure. Some of South Africa’s largest and most prestigious companies, including Sasol, Anglo American, Engen, and Total rely on Oleum Process & Pipeline Services for helium leak detection, inspection, cleaning, drying, and other pipeline-related services.
