General technical requirements and component materials for valves

General requirements:

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

2. The model of the 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 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; Either side of the valve should be able to withstand 1.1 times the working pressure of the valve without leakage when it is closed; When the valve is open, the valve body should be able to withstand twice the working pressure of the valve.

4. The valve manufacturing standard should specify the national standard number it is based on. If it is an enterprise standard, the procurement contract should be accompanied by the enterprise document.

Valve component material:

1. Valve material, as gray cast iron pipes are gradually not recommended, the valve body material should be mainly ductile iron, and the brand and actual physical and chemical testing data of the casting should be indicated.

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.

3、 Material of sealing surface:

1. The types of valves vary, and the requirements for sealing methods and materials are also different.

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 soft sealed gate valves and valve plate lining materials.

4. Butterfly valves should indicate the sealing surface material on the valve body and the sealing surface material on the butterfly plate; Their physical and chemical test data, especially the sanitary requirements, anti-aging performance and wear resistance of rubber, are usually made of butadiene rubber and EPDM rubber, and recycled rubber is strictly prohibited.