Common assembly methods of valves

The whole machine is the most basic unit of valve assembly, and several parts make up the valve parts (such as valve bonnet, valve disc, etc.). The assembly process of several parts is called component assembly, and the assembly process of several parts and components is called total assembly. Assembly work has a great impact on product quality. Even if the design is accurate and the parts are qualified, if the assembly is improper, the valve will not meet the requirements of the regulations, and even lead to seal leakage.


There are three common methods for valve assembly, namely, complete interchange method, limited interchange method, repairing method.

Complete interchange method

When the valve is assembled by complete interchange method, each part of the valve can be assembled without any repair and selection, and the product can meet the specified technical requirements after assembly. At this time, the valve parts should be processed in full accordance with the design requirements to meet the requirements of dimensional accuracy and geometric tolerance. The advantages of the complete exchange method are: the assembly work is simple and economical, the labor does not need a high degree of skill, the production efficiency of the assembly process is high, and it is easy to organize the assembly line and professional production. However, absolutely speaking, when complete replacement assembly is adopted, the machining accuracy of parts is required to be higher. It is suitable for globe valve, check valve, ball valve and other valves with simple structure and small and medium diameter.

Limited interchange method

The valve is assembled by limited interchange method, and the whole machine can be processed according to the economic precision. When assembling, a certain size with adjustment and compensation effect can be selected to achieve the specified assembly precision. The principle of the selection method is the same as that of the repair method, but the way of changing the size of the compensation ring is different. The former is to change the size of compensation ring by selecting accessories, while the latter is to change the size of compensation ring by trimming accessories. For example: the top core and adjusting gasket of the control valve type double ram wedge gate valve, the adjusting gasket between the two bodies of the split ball valve, etc., is to choose the special parts as compensation parts in the dimension chain related to the assembly accuracy, and achieve the required assembly accuracy by adjusting the thickness of the gasket. In order to ensure that the fixed compensation parts can be selected in different situations, it is necessary to manufacture a set of washer and shaft sleeve compensation parts with different thickness and size in advance for hydraulic control valve model selection during assembly.

Repairing method

The valve is assembled by repairing method, the parts can be processed according to the economic precision, and then a certain size with adjustment and compensation effect can be repaired during assembly, so as to achieve the specified assembly goal. For example, the gate and valve body of wedge gate valve, because of the high processing cost of realizing the exchange requirements, most manufacturers adopt the repair process. That is to say, in the final grinding of the gate sealing surface to control the opening size, the plate should be matched according to the opening size of the valve body sealing surface, so as to achieve the ultimate sealing requirements. This method increases the plate matching process, but greatly simplifies the dimensional accuracy requirements of the previous processing process. The skilled operation of the plate matching process by special personnel will not affect the production efficiency on the whole. Valve assembly process: the valves are individually assembled in a fixed site. The assembly of parts and components and the general assembly of the valves are carried out in the assembly workshop, and all the necessary parts and components are transported to the assembly site. Usually, how many groups of workers are responsible for the assembly of parts and the General Assembly at the same time, which not only shortens the assembly cycle, but also facilitates the application of special assembly tools, and has low requirements for the technical level of workers.

Post time: Jun-11-2021