Materials for sealing surfaces The sealing surface is the most critical working surface for the valve. The quality of the sealing surface is related to the service life of the valve. Usually, the sealing surface's material should consider factors such as corrosion resistance, scratch resistance, erosion resistance, and oxidation resistance, which are divided into the following two categories: Soft sealed materials Rubber including nitrile rubber and fluorine rubber...

This standard adopts the national standard GB/T13927 Pressure Tests of Industrial Valves. 1. Subject content and scope of application This standard specifies the requirements, methods and evaluation indicators for pressure tests of general valves. This standard applies to the pressure test of gate valves, globe valves, check valves, plug valves, ball valves, butterfly valves, diaphragm valves, etc. 2. Terminology 2.1 Test pressure The gauge pressure born by the inner cavity...

The generation of static electricity Static electricity is a common physical phenomenon, which is closely related to our life. Our bodies and clothes will also generate a lot of static electricity, especially in winter. Any two objects of different materials come into contact with each other and then separate; the contact is accompanied by friction, and static electricity will be generated. There are two main key reasons for static electricity: one is the different...

1. Overview A flange is the most commonly used connection in fluid pipelines, which is convenient for installation, maintenance, and replacement of the pipeline. Flanges are generally used for gate valves, globe valves, check valves, ball valves and plug valves under medium and low pressure. The valve body connected by flanges generally has three parts, two flange ends and one middle flange. For small-diameter valves (DN50...

3.6 Stems and packing The threaded part of the valve stem should not be in contact with the conveying fluid, except for the special requirement, and the valve stem and stem nut assembly should be self-locking. The valve stem and packing should be resistant to various corrosion. The packing should meet the requirements of Q/BU.J1502-93. The packing shall be ring shaped packing made of graphite and expanded graphite. 3.7 Hard alloy surfacing Try to avoid surfacing cobalt-based cemented...

(2) C2 valves The body of the C2 valve can be made of forged steel and cast steel. When the welding seam on the pressure-bearing boundary can be inspected by radiography, the forged welding structure can also be used. The connection between the valve body and valve bonnet of valves with different pressure adopts pressure self-sealing and sealed bolt connection. For the pressure of 5.0MPa and above, concave-convex mating surfaces and fully embedded gaskets are used. Concave-convex gaskets,...

Abstract: The design methods of main parts of gate valves, globe valves, check valves and ball valves for nuclear power plants are introduced and the general requirements for nuclear power valves are discussed in this article. 1. Overview Nuclear power valves refer to valves used in nuclear islands (N1), conventional islands (CI) and auxiliary facilities (BOP) systems of power plants in nuclear power plants. According to the safety level,...

1. Hot cracks Hot cracks are generated at high temperatures in the welding process of valves, which have characteristics of cracking along the original austenite grain boundary. Different welding metals such as low-alloy high-impact steel, stainless steel, cast iron aluminum alloys and special metals can make forms, temperatures and the main causes of hot cracks different. Hot cracks are divided into crystal...

The assembly of the valve is a process that combines all the parts of a valve, which is the last manufacturing process of a valve. The process of assembling several parts to form a new part is the assembly of a part, while assemble several parts to a whole valve is the general assembly. The assembly greatly influences the quality of the valve. If the valve is assembled not well, the specific requirements can't be met even though there are accurate design and qualified parts. Leakages...

Alumina (AL2O3) Alumina (AL2O3) has good hardness and is widely used, which is usually used to grind workpieces made from cast iron, copper, steel and stainless steel. Silicon Carbide (SiC) Silicon carbide has two colors, that is, green and black, and its hardness is higher than that of alumina. Green silicon carbide is suitable for grinding hard alloys, while black silicon carbide is used for grinding brittle and soft materials, such as cast iron and brass. ...

After a valve is used for a long time, the sealing surface of the valve disc and valve seat will be worn and the sealing will be weakened. Repairing the sealing surface is a very important task with a lot of workloads. The main method of repair is grinding. For the severely worn sealing surface, the surfacing is firstly conducted and then grounding after turning. The grinding of the valve includes the cleaning and inspection process, grinding...

1. The structural characteristics of the double cut-off plug valve The double cut-off plug valve (Figure 1) is designed for special applications with strict sealing and cut-off requirements. The valve design is very compact; it is light and takes up small space. Also, the advantage of this valve design is that it is shorter than the conventional two shut-off valve and discharge valve. In most cases, the structural length of the double cut-off valve is the same as a common...