Top entry trunnion ball valve for safe in-line maintenance and method to facilitate such maintenance

摘要

A top entry trunnion mounted rotary ball valve defining a main valve body having an upstream and a downstream ball seat assembly, the ball seat assemblies further including a soft insert seal, a ball seat, a seat retainer and a plurality of compression springs in between the ball seat and the seat retainer. A guiding groove on a cylindrical surface of each of the ball seats, having a first end and a second end at an axial distance equal to or more than a measure of retraction required so as to get a mechanical clearance to remove or assemble the ball member. Each ball seat is retracted in a recess against a force Fc of the compression springs and the mechanical clearance is created between the ball member and the soft insert seal, to remove or assemble the ball member and or any component from inside the valve body.