Valve Knowledge: Valve Assembly Methods Commonly Used

Valve assembly methods commonly used can be three kinds, namely, complete interchangeable method, selection method, and repair method.

(1) Completely interchangeable method

Valve assembly using the completely interchangeable method, each part of the valve does not have to go through any trimming and selection can be assembled, assembled products that can meet the specified technical requirements. At this time, the valve parts should be completely in accordance with the design requirements of processing to meet the requirements of dimensional accuracy and form tolerance.

A completely interchangeable method has the advantage of assembly work being simple and economical, workers do not need a high level of technology, the assembly process of highly productive, easy to organize assembly line and organization of specialized production, but relatively speaking, the use of complete interchangeable assembly, for the parts of the machining accuracy requirements are higher. Suitable for globe valves, check valves, and other relatively simple structures of the valve class as well as medium and small diameter valves.

(2) Selection method

In valve assembly using the selection method, the parts can be processed according to the economic accuracy, assembly, and then a regulation, compensation function of the size of the mating, in order to achieve the required assembly accuracy. The principle of the selection method is the same as the repair method, only the method of changing the size of the compensation ring is different. The former is the method of selecting fittings to change the compensation ring size, and the latter is the method of trimming fittings to change the compensation ring size.

For example: double gate wedge gate valve top core and adjusting gaskets, adjusting gaskets between the two bodies of the folio ball valve, etc., are in the dimensional chain related to assembly accuracy to select special parts as compensation, by adjusting the thickness of the gasket size, to achieve the required assembly accuracy. In order to ensure that in different cases can be fixed compensation parts for selection, it is necessary to pre-produce a set of different thickness dimensions of the gaskets, and bushings compensation parts, for assembly selection.

(3) Repair method

Valve assembly using the repair method, parts can be processed according to the economic accuracy, assembly, and then a regulation, compensation function of the size of the repair, in order to achieve the specified assembly purpose. Such as the gate and valve body of the gate valve, due to the realization that the interchangeable requirements of the processing cost are too high, most manufacturers are using the repair method process. That is, in the final grinding of the gate sealing surface control the open size and the valve body sealing surface of the open size to match the method of “matching board” to achieve the final sealing requirements.

Although this method increases the “match plate” process and greatly simplifies the dimensional accuracy requirements of the previous processing procedures, the “match plate” process of skilled operation of specialists, in general, does not affect production efficiency.