LEAKLAB · TESTING AND ENGINEERING
Valve-seat leakage is assessed separately from external leakage of the body, joints and stem seal.
Define the tested boundary
For closed-seat leakage, agree the leakage class, medium, flow direction, pressure and hold time. For external vacuum tightness, helium spray, sniffer or chamber methods may be considered separately. The test sequence is coordinated with the valve documentation and applicable procedure.
A seat class is not an external helium limit
A valve-seat tightness class cannot automatically serve as an allowable external helium leak rate. The numerical criterion belongs to the particular valve and test conditions. The Russian source uses GOST 9544-2015 and discusses test procedures with GOST 33257-2015; the agreed programme identifies the applicable editions.
Volume, line conductance, tracer concentration, temperature and background influence the system’s ability to detect leakage. Quantitative reports state throughput units and the measurement conditions.
Preparing and verifying the test
- Review the drawing, materials, internal volumes, test boundary and required result.
- Agree the document edition, allowable pressure difference, vacuum and temperature, acceptance criterion and required system sensitivity.
- Clean and dry the object, prepare fixtures and exclude leakage from the test connections.
- Check instrument metrological status and the working characteristics of the complete arrangement; use an appropriate reference response for the selected method.
- Perform the agreed scan or measurement cycle and record the actual conditions. Confirm suspected leaks by repeat tracer-gas exposure where applicable.
- Check system stability after the test and report the result against the agreed criterion.
What the customer receives
The agreed scope can include a test programme, operating or inspection instructions, measured results, a map of located leaks and a technical conclusion. The report identifies the object and tested regions, applicable programme, instruments and metrological status, pressure and temperature, response checks, observations and limitations.
Define your task
Send a drawing or sketch, material, dimensions and volume, working pressure, allowable vacuum and temperature, leak-tightness requirement, number of items, site and schedule. These inputs determine the method, fixture, equipment and reporting scope.
Discuss a test programme