European Program on Evaluation of Safety Valve Stability
EuroValve „European Program on Evaluation of Safety Valve Stability“ is a research project of the CSE institute for the investigation of valve stability under typical industrial installation conditions. The characteristics of a safety valve depend decisively on the installation situation of the valve with regard to inlet and outlet pipes.
Measurements in 2017 on different types of safety valves of the sizes DN25x40 and DN50x80 from German manufacturers have shown:
- Valves can be excited to oscillate by an upstream inlet line compared to installations without an inlet line.
- Type examinations (VD TÜV100) do not represent the operating conditions in a plant.
- Valve flutter may cause static pressure fluctuations in the inlet line between 25 % up to 175 % of the set pressure.
- the maximum permissible pressure of 110 % of the set pressure can be significantly exceeded for a short period of time.
- The excitation frequency for the same valve varies with the length of the inlet line. As a result, a valve may behave unstable at 30 cm inlet line length, while measurements at 55 cm showed no abnormalities.
- Shorter inlet lines do not necessarily guarantee a more reliable function than longer ones.
- Valves from different manufacturers with different designs have different stability characteristics at the same inlet line geometry (e.g. valve A is stable, while valve B starts to flutter).
- In practice, a replacement of a valve may need special consideration on valve stability.
The long-term objective of the EuroValve project is a better understanding of the causes for safety valve instabilities. Until the end of the project, a comprehensive data base of measurements, a detailed literature review and suggestions for a new design criteria as well as modifications of old systems will be given.