Trip & Throttle Valve Reliability

Trip & Throttle (or Stop) valves are used in ethylene plants to isolate the energy to steam turbines when required. They are critical Safety Protection components with a high impact on a plant’s reliability; however, they operate under tough conditions like:High pressure & temperature

• Very infrequent operation
• And specifically in an Ethylene plant, very limited opportunities to test or maintain

During 2009/2010, a European Ethylene Producers Committee (EEPC) Issue Group was established to collect and share practical experience and knowledge about the performance of these valves and best practices for testing and maintenance. The effort was concentrated on “special purpose critical turbines”.

This paper summarizes the information compiled and analyzed by the Issue Group from 131 units in 28 European Ethylene plants, including information like:

• Valve manufacturer and type
• Maintenance criteria
• Relationship with Safety protection (SIL), testing
• Failure data