Development of a new safety criterion for safety valves.
The aim of the “EuroValve” project is to develop effective protection against the phenomenon of “chatter” in safety valves. This is currently done by limiting the inlet line length. However, new measurements show that the current calculation method for the inlet line length does not really guarantee stability. Therefore, in the “EuroValve” project, a new model is to be developed to ensure the stability of the safety valve in the design phase.
Project goals continue to include the development of a quick-fix solution for the large number of safety valves already in use in chemical plants, but would not meet the new criterion.
Valve chatter must be reliably avoided to prevent risks to the valves and resulting events – whether through a new calculation model or through changes to the valves themselves.
Figure: Phenomena during the opening of a safety valve.
Review of existing models
New stability criterion
Evaluation of the impact of the outlet line
Investigation of quick-fix solutions
Inlet and valve modeling
Measurement of the permissible inlet line lengths
New criterion for valve stability
Quick fix solutions for existing installations
Chatter in safety valves reduces mass flow and increases pressure upstream of the valve, creating hazardous operating conditions. The phenomenon depends on both the valve and the piping system, so careful design is required.
Although European and American standards already specify a method for determining the stability of safety relief valves, recent measurements have shown that this method is not completely conservative. There are also other models for predicting valve stability, but both the assumptions and the results of these models differ greatly.
Today, a large number of safety valves are in use in chemical plants all over the world. Any change in the stability calculation would mean that many of these valves would not meet the new criteria. Consequently, pipes would have to be rebuilt or valves completely replaced. A potentially more cost-effective solution would be to explore quick-fix solutions to retrofit existing plants.
Keszthelyi, G., Schmidt, J., Denecke, J., 2021. Evaluation and comparison of safety valve chatter prediction models, in: 2021 DIERS Spring Meeting, Online.
Keszthelyi, G., Schmidt, J., Denecke, J., 2022. Effects of Valve Characteristics and Fluid Force on Valve Stability”, Proc. Conference on Modelling Fluid Flow (CMFF’22), Budapest, Hungary, pp. 1–8.