Evaluation of residual stresses in lock valve elements of petrochemical productions

Irkutsk National Research Technical University, 83, Lermontov Str., Irkutsk, 664074, Russia

^* Corresponding author: nicolaeva-ep@yandex.ru

Abstract

Lock valves of the pipeline is an important and responsible product. It is designed to shut off the flow of liquid or gaseous fluid. During transportation ambient temperature reaches 400°C, and the pressure-over 30 MPa. Leakage of the fluid through the details and components of lock valves is not permitted. The batch of high-pressure valves was withdrawn after some time of its usage at the petrochemical enterprise. Premature wear of input branch pipe saddles was dis-covered. The cause of destruction of the input branch pipe saddles was erosion be-cause of abrasive particles, which are present in the working fluid. Locking node of the high-pressure armature is highly loaded element. The welding depositions are widely used to increase the strength of the valve locking node. It is established that under recommended heat treatment of the valve an ordered microstructure is formed and residual stress in the welding deposition zone is reduced. The article shows the relationship of residual stress with microstructure of the material. The magnitude of residual stresses in high-pressure valve locking node - in the brunch pipe saddle and the adjacent zones -was determined by x-ray method.