Helium Leak Detection
Why Helium Leak Detection is Important Before the Start-up of Plant Operations
High-integrity helium leak detection is a scientifically proven method for the detection of small leaks in vessels, plants, and pipelines. Detection is especially important before starting up a plant, as some areas can be difficult to repair and cause hazardous substances to escape – or lead to plant failure if problems are not detected and repaired before start-up. Plants where high-integrity detection is especially useful include, but are not limited to ethylene, LNG, hydrogen, and cryogenic plants vacuum systems, as well as heat exchangers. The technology has a proven track record of over 40 years and was originally developed for detection of leaks in offshore oil and gas plants, typically Topsides. Because of the effectiveness of the process, it has, in the meantime, been widely adapted as the standard method used at hazardous-process plants where the need to ensure perfectly tight seals for start-up operations is essential.
It is an inert and non-toxic gas and, because of these properties, completely harmless. It is also non-flammable and does not condensate. As He2 is almost non-existent in the atmosphere, any gas found can be assumed to be from a leak. Because it has an exceptionally small atomic profile, it can easily pass through even the smallest of spaces; in fact, hydrogen is the only gas with an even smaller molecule. As it is not widely available and is usually expensive, helium is used as a trace gas mixed with Nitrogen at 3-5%. High-integrity helium leak detection has been shown as the most accurate and effective method for detecting small leaks in plants before start-up.
How the Process Works
As any plant or process equipment has a myriad of potential leak points, the process starts with detailed planning, which is best completed by experienced engineers. The leak detection engineer develops the plan by reviewing the drawings of the plant or equipment, identifies all the potential leak points, and then creates a tag register. Each valve flange etc. is taped off to capture the escaped helium in that annulus to be analysed and recorded. The inspected unit is pressurised with helium nitrogen gas. Any gas that escapes is then sampled by piercing the tape with a vacuum probe, after which it is pumped into the mass spectrometer and analysed to determine how much has escaped and, therefore, the size and rate of the leak. Leaks can be quantified to 1 cubic foot per year. After the leak rate is determined, a decision to repair is made and the point of the leak is marked for repair if needed. Not all leaks that are found need repair.
How the Spectrometer Works
The helium molecules entering the spectrometer are ionised. The ionised molecules enter an ion trap. The next step entails the analysis of the ion current to detect therate at which the gas is escaping. The background reading is the reference point. This is just a basic description of the process and, for a comprehensive explanation, we recommend speaking to the experts in our team.
Type of Method Used
As every plant or process is unique, the method is dependent on several factors, best discussed with our professional team.
Avoid the safety risk and cost of expensive repairs later on because of an undetected leak at your plant. Get in touch for more information on our cost-effective helium leak detection services.