Two-piece trunnion ball valve and manufacturing method thereof

Abstract

The invention discloses a two-part fixed ball valve capable of effectively reducing the coaxiality deviation between the left valve seat hole and the right valve seat hole after the valve body is assembled, and a method for manufacturing the two-part fixed ball valve. The two-piece fixed ball valve sets the inner wall surface at the right end of the connecting hole as a tapered guiding and positioning surface, and sets the outer wall surface at the left end of the connecting ring as a positioning matching surface that matches the guiding and positioning surface. During the body assembly process, the guide positioning surface and the positioning matching surface can be attached to each other for positioning, which avoids the deviation of the verticality of the hole, the shaft clearance and the first assembly end surface and the second assembly end surface in the valve body assembly process. The influence of the cumulative error of the coaxiality between the right valve seat hole and the right valve seat hole effectively reduces the coaxiality deviation between the left valve seat hole and the right valve seat hole after the valve body is assembled, so that the two-piece trunnion ball valve has a good DBB function .

Description

technical field [0001] The invention belongs to the technical field of valves, and in particular relates to a two-body fixed ball valve and a manufacturing method thereof. Background technique [0002] The ball valve is a valve that uses a ball with a circular channel as the opening and closing part. The ball rotates 90 degrees around the axis of the valve stem with the rotation of the valve stem to achieve the purpose of opening and closing; the two-piece fixed ball valve is a common form of ball valves. For two-piece trunnion ball valves used in oil and gas pipelines, it is very important to have good DBB (Double Block and Bleed) function. The popular explanation of the DBB function is: when the valve is in the closed position, pressure is applied to both ends of the valve at the same time, and the sealing performance of the left and right valve seats of the valve is good. When performing the DBB function test of the valve, open the drain hole or vent hole in the middle c...

AI Technical Summary

Problems solved by technology

[0005] In the existing two-piece trunnion ball valve, the left valve body and the right valve body are holes and shaft clearance fit, and the first assembly end surface and the second assembly end surface are pressed and fitted by connecting parts such as bolts; although for small-sized valve bodies In other words, it is easier to ensure the coaxiality of the left valve seat hole and the connecting ring, and it is also relatively easy to ensure the coaxiality of the right valve seat hole and the connecting ring, so as to ensure the seat hole and the right valve seat in the left valve body after assembly. The purpose of the coaxiality between the inner valve seat holes; but this structure still has the following disadvantages: 1) There is a gap between the connecting part hole and the shaft, and the larger the valve, the larger the gap; 2) The second part of the left valve body The second assembly end surface and the first assembly end surface of the right valve body must be perpendicular to the hole and the shaft respectively, but the larger the valve, the more difficult it is to ensure the verticality of the assembly end surface

In production practice, the DBB function test is carried out on the same batch of valves with the same specifications. Some valves have good DBB functions, and some have poor DBB functions.

Even if the same valve is disassembled and reassembled, its DBB function will be deteriorated

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