European Program on Evaluation of Safety Valve Stability

Abstract

Safety valve instability can lead to incidents with serious danger to human health and the environment. Plant downtime as a result of damage to property causes loss of revenue. To avoid such incidents the approval of safety valves and the construction of inlet and outlet lines are determined by national standards. However, recent findings from a comprehensive test program with API valves disproved the current sizing criteria according to standards like API 520 Part II. Due to these findings new sizing criteria are to be developed. The question that arises is whether these new sizing criteria also have to be applied as is to the installations in Europe. In fact, European safety valves are generally different in geometry and design. Therefore, the European Program on Evaluation of Safety Valve Stability (EuroValve) was started to investigate the stability of safety valves experimentally and to determine appropriate stability criteria especially for European safety valve designs. The focus will be on evaluating and quantifying the influencing parameters on the safety valve stability regarding to the individual valve design and the process and test conditions respectively in a great depth. For the development of these “EuroValve sizing criteria” the physical phenomena causing valve instability must be understood. There is a large number of related parameters which influence valve stability. The present paper outlines a number of these parameters regarding valve design, piping and testing procedures. Different kind of current test rigs are discussed and requirements for practically orientated test conditions are defined. Further, the differences between European and API valves are analyzed regarding valve stability. Finally the key data of the EuroValve program are presented.