Valve Other Connection Methods

clip connection

The connection form in which the valve and the two pipes are directly clipped together with bolts.

Butt welding connection

A connection method that is welded directly to the pipe.

threaded connection

This is an easy connection method and is often used for small valves. There are two cases:

1. Direct sealing: The inner and outer threads directly play a sealing role. In order to ensure that the connection does not leak, it is often filled with lead oil, thread hemp and PTFE raw material tape; among which PTFE raw material tape is widely used; this material has good corrosion resistance and excellent sealing effect. It is easy to use and store. When disassembling, it can be completely removed because it is a non-sticky film, which is much better than lead oil and thread hemp.

2. Indirect sealing: the force of thread tightening is transmitted to the washer between the two planes, so that the washer acts as a seal.

ferrule connection

The ferrule connection, its connection and sealing principle is that when the nut is tightened, the ferrule is subjected to pressure, so that the edge of the ferrule bites into the outer wall of the pipe, and the outer cone surface of the ferrule is in close contact with the inner cone surface of the joint under pressure, so Leakage can be reliably prevented.

The advantages of this form of connection are:

1. Small size, light weight, simple structure, easy disassembly and assembly;

2. Strong connection force, wide range of use, can withstand high pressure (1000 kg/cm 2 ), high temperature (650 ° C) and shock and vibration

3. Various materials can be selected, suitable for anti-corrosion;

4. The processing accuracy is not high; it is convenient for high-altitude installation.

The ferrule connection form has been adopted in some small-diameter valve products in China.

Clamp connection

This is a quick connect method that requires only two bolts and is suitable for low pressure valves that are frequently disassembled.

Internal self-tightening connection

All of the above connection forms use external force to offset the pressure of the medium to achieve sealing. The following describes the self-tightening connection form using medium pressure. Its sealing ring is installed at the inner cone and forms a certain angle with the side facing the medium. The pressure of the medium is transmitted to the inner cone and then to the sealing ring. On the cone surface of a certain angle, two component forces are generated, one with The center line of the valve body is parallel to the outside, and the other is pressed against the inner wall of the valve body. The latter force is the self-tightening force. The greater the medium pressure, the greater the self-tightening force. Therefore, this connection form is suitable for high pressure valves. Compared with flange connection, it saves a lot of material and manpower, but it also requires a certain preload, so that it can be used reliably when the pressure in the valve is not high. Valves made using the principle of self-tightening sealing are generally high-pressure valves.

There are many forms of valve connection, for example, some small valves that do not need to be removed are welded with the pipe; some non-metallic valves are connected by socket and socket, and so on. Valve users should be treated according to the specific situation.