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The correct selection of the valve
May 10, 2018

The correct selection of valves is a prerequisite for ensuring the normal operation of equipment, installations and pipe conveying systems without maintenance or replacement of valves. This is very important. The failure rate of the valve itself can often determine the service life and no accident rate of the equipment, the device and the whole system. Therefore, valve selection is the key link in piping system design.

At present, there are more than ten kinds of general valves in China, and the largest ones are gate valve, globe valve, check valve, butterfly valve, ball valve, cock valve, diaphragm valve and so on. Seven kinds of valves are used.

In order to correctly select the valves used, we must have a detailed understanding of the characteristics of various valves. There are two characteristics of the valve in general:

(1) the use characteristics determine the main performance and application scope of the valve. The types of valves are: valve categories (closed valve, regulating valve, safety valve, etc.); type of product (gate valve, cut-off valve, butterfly valve, ball valve, etc.); material for main valve parts (valve body, valve cover, valve disc, seal face); valve transmission mode, etc.

(2) structural characteristics determine the structural features of valve installation, repair and maintenance. Structural characteristics: the structure length and overall height of the valve; connection with the pipe (flange connection, threaded connection clamp connection, external thread connection, welding end connection, etc.); seal face form inlay, thread ring, surfacing, spray welding, body itself processed); valve stem structure form (rotary bar, lift rod) and so on. It is worth noting that in some structural forms, their usage characteristics and structural characteristics are interrelated and can not be completely separated.