General requirements for soft seal gate valves

1. The specifications and categories of gate valves should comply with the requirements of the pipeline design documents.

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

3. The working pressure of the gate valve should be ≥ the working pressure of the pipeline. Without affecting the price, the working pressure that the valve can withstand should be greater than the actual working pressure of the pipeline. When the gate valve is closed, either side should be able to withstand 1.1 times the working pressure value of the valve without leakage; When the valve is open, the valve body should be able to withstand twice the working pressure of the valve.

Standard quality of soft seal gate valve

1. The valve body material should mainly be cast iron, cast steel, stainless steel, 316L, and indicate the brand and actual physical and chemical testing data of the cast iron.

2. The valve stem material should strive for stainless steel stem (2CR13), and large-diameter valves should also have stainless steel embedded stem.

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

4. The material of the valve stem liner should have a hardness and strength not greater than that of the valve stem, and should not form electrochemical corrosion with the valve stem and valve body when immersed in water.

5. Material of sealing surface

① The types of gate valves vary, and the sealing methods and material requirements also differ;

② The material, fixing method, and grinding method of the copper ring for ordinary wedge gate valves should be specified;

③ Physical, chemical, and hygiene testing data for gate valves and valve plate lining materials;

6. Valve shaft packing

① Due to the infrequent opening and closing of gate valves in the pipeline network, it is required that the packing should remain inactive for several years, and the packing should not age to maintain a long-term sealing effect;

② The valve packing should also have excellent sealing performance when subjected to frequent opening and closing;

③ In view of the above requirements, the valve shaft packing should be kept unchanged for life or more than ten years;

④ If the packing needs to be replaced, the design of the pneumatic valve should consider measures to replace it under water pressure conditions.