EL – Owner’s Manual – Rev.00 – September 2021 35
APPENDIX
Appendix I. Hydrogen Leak Testing
As part of a hydrogen device, it is of vital importance to check every connection made for leaks. For
more information on this matter, please refer to the appendix of ASME B31.12.
There are three main ways recommended to check for leaks:
1. Surface hydrogen detection
2. Soap bubble testing
3. Pressure drops testing
Surface hydrogen testing
Using a calibrated hydrogen sniffer, slowly check for leaks around each connection.
• Precise, it can pinpoint even small
leakages
• Can grade leakages according to
leakage rates
• Does not work when there are elevated
levels of hydrogen in the atmosphere
Soap bubble testing
Using a mixture of soap and water (please ensure the soap used is compatible with the device and the
materials used), the solution is dropped on individual connections using a small pipette. If the
connection bubbles, a leak is present.
• Can be fast for larger leaks on small
parts when testing multiple at one time
• Low-cost
• Best method for detecting exact leak
location detection
• Accurate, it works even with elevated
background H
2
levels
• Cannot detect tiny leakages
• No leak rate or test result information
• Slow: Detecting small bubbles on
typical parts can take much longer than
other methods.
• Risky: An extremely operator
dependent technique with a high
possibility of passing actual failures.
Pressure drop testing
This test is performed by isolating individual sections of a pipe while monitoring the pressure
contained within over time and should be performed at the maximum operating pressure of the
device. If a drop in pressure is observed, which cannot be attributed to changes in temperature, a leak
exists.
• Useful for final verification during
device commissioning
• Can verify several connections at the
same time
• Cannot detect exact leakage source
• Cannot grade leakage rates accurately
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