This paper introduces the fitness-for-service corrosion assessment occurred in Zhanjiang Dongxing Petroleum Enterprise.

Comments: When using diaphragm valves or any valve with a soft seat material in a service where corrosion products can be produced, it is very important to take precautions to prevent those reactions.

Service-lifetime and reliability is estimated considering two models of uniform corrosion with effect of cracks and local corrosion on the theoretic of system simulation and reliability.