What Does Leak Testing Mean?
Leak testing is the process of checking a system for leaks (a defect). Leak testing can be achieved using various leak detection methods and is employed to test for defects in products and to ensure the proper function and maintenance of industrial systems and pipelines. The choice of the detection method depends on which method is most appropriate for the system at hand.
When systems include a metallic containment, leaks may occur as a result of the encasing material becoming corroded. Consequently, leak testing may also result in the detection of a corrosion problem.
Corrosionpedia Explains Leak Testing
Because the size of a leak is difficult to measure, the leakage rate is the important factor to determine the severity of the leakage.
The leak rate (Q) is expressed as either a volume per unit time or the change in pressure (p) times volume (V) per change in time (t):
Q = (Δp x V) / Δt
Leak testing methods each have their own sensitivity, expressed as the lowest leak rate the method can detect. Highly sensitive methods are required to test highly leak prone systems such as vacuum systems. Other considerations for choosing a leak detection system (LDS) include the size of the system, the type of material contained in the system, the rigidity of the container, the accessibility to the internal environment, the temperature, and the presence of any coatings on the surfaces. In detection methods that use chemicals, usually inert chemicals are chosen, but when chemical inertness is not a requirement, methods using dyes or radioisotopes may be advantageous. Also, some LDSs do not determine the exact location of the leak, which may be disadvantageous for certain systems.
Specific detection methods include:
- Dye penetration
- Radioisotope detection
- Bubble testing
- Helium leak detection
- Halogen leak detection
- Pressure monitoring
- Flow monitoring
- Spark testing
- Biological leak testing
Some leak testing methods, such as thermography, also test for corrosion. As leak testing and corrosion are related, these methods may be convenient in industrial settings.