The opening and closing part of the soft seal gate valve is the gate plate, the direction of motion of the gate plate is perpendicular to the direction of the fluid, the gate valve can only be fully opened and fully closed, and can not be adjusted and throttled. The two sealing faces of the commonly used mode gate valve form a wedge, and the wedge Angle varies with the valve parameters, usually 50, and 2°52 "when the medium temperature is not high. General gate valves generally exist water leakage, easy to rust and other phenomena. Soft seal gate valve (elastic seat seal gate valve), the material of the gate plate is cast iron lined rubber, which overcomes the shortcomings of the general gate valve such as poor sealing, elastic fatigue, easy rust and so on.

Soft seal gate valve is the replacement of the traditional gate valve, it uses the elastic material of the gate, the use of elastic material generated by the micro deformation compensation, can achieve a good sealing effect. Soft seal gate valve has the advantages of light switch, reliable seal, good elastic memory and long service life. The gate valve of the hard sealing face is cast iron or stainless steel, and the opening and closing resistance is small, and the flow is not blocked, but the sealing performance is poor. The difference between soft seal gate valves is the different form of gate sealing surface.

General requirements for soft seal gate valves

1. Gate valve specifications and categories, should meet the requirements of pipeline design documents.

2.The type of gate valve should indicate the national standard number requirements. If it is the enterprise standard, the relevant description of the model should be indicated.

3.The working pressure of the gate valve, the requirement is ≥ the working pressure of the pipeline, without affecting the price, the working pressure of the valve should be greater than the actual working pressure of the pipeline, and any side of the gate valve closed condition should be able to withstand 1.1 times the valve working pressure value without leakage; When the valve is open, the valve body should be able to withstand the requirements of twice the working pressure of the valve.

Soft seal gate valve material

1.The body material, should be cast iron, cast steel, stainless steel, 316L, and indicate the grade and the actual physical and chemical test data of cast iron.

2.The valve stem material, strive to stainless steel valve stem (2CR13), large diameter valve should also be stainless steel clad valve stem.

3.The nut material, cast aluminum brass or cast aluminum bronze, and the hardness and strength are greater than the valve stem.

4.The valve stem bushing material, its hardness and strength should not be greater than the valve stem, and in the water immersion condition with the valve stem, the valve body does not form electrochemical corrosion.

5. Material of sealing surface

① Gate valve types are different, sealing methods and material requirements are different;
② Ordinary wedge gate valve, copper ring material, fixing method, grinding method should be explained;
③ Physical, chemical and health test data of gate valve and valve plate lining material;

6. Valve shaft packing

① Because the gate valve in the pipe network is usually opened and closed infrequently, the packing is required to be inactive for several years, the packing is not aging, and the sealing effect is maintained for a long time;
② Valve packing should also withstand frequent opening and closing, sealing effect of the best;
③ In view of the above requirements, the valve shaft packing should not be replaced for a lifetime or more than 10 years;

④ If the packing needs to be replaced, the pneumatic valve design should consider the measures that can be replaced under the condition of water pressure.