1. General requirements:
1.1 The specifications and categories of valves should meet the requirements of pipeline design documents.
1.2 The model of the valve should be indicated according to the national standard number requirements, if it is an enterprise standard, the relevant description of the model should be indicated.
1.3 The working pressure of the valve should be greater than or equal to the working pressure of the pipeline, and any side should be able to withstand 1.1 times the working pressure of the valve without leakage in the closed state;
1.4 The manufacturing standard of the valve should indicate the national standard number based on it, if it is an enterprise standard, the procurement contract should be attached to the enterprise documents.
2. Valve material:
2.1 Since gray cast iron pipes are gradually not recommended, the valve body material should be mainly ductile iron, and the grade and the actual physical and chemical test data of the casting should be indicated.
2.2 The stem material should strive to be stainless steel (such as 2CR13), and the large-diameter valve should also be a stainless steel embedded stem.
2.3 The nut material is cast aluminum brass or cast aluminum bronze, and the hardness and strength are greater than the valve stem.
2.4 The hardness and strength of the stem bushing material should not be greater than the valve stem, and there should be no electrochemical corrosion with the valve stem and valve body under water immersion.
3. Sealing surface material:
3.1 According to different types of valves, the sealing methods and material requirements are also different.
3.2 The material, fixing method and grinding method of the copper ring of the ordinary wedge gate valve should be explained.
3.3 Physical, chemical and hygienic testing data of the valve plate lining material of the soft seal gate valve.
3.4 The butterfly valve shall be marked with the sealing surface material on the valve body and the sealing surface material on the butterfly plate; Their physicochemical test data, especially the hygienic requirements, anti-aging properties, and wear resistance of rubber.
4. Transmission box:
4.1 Since the valves in the pipeline network are usually opened and closed infrequently, the packing is required to be inactive for several years and maintain the sealing effect for a long time.
4.2 If the packing needs to be replaced, the valve design should consider the measures that can be replaced under the condition of water pressure.
5. Technical requirements for cryogenic valves:
For cryogenic valves, in addition to the above general requirements, specific technical conditions need to be met, such as structural type, technical requirements, test methods, etc., to ensure long-term stable operation in a low-temperature environment.
These technical requirements ensure that the valves can operate safely and reliably under a wide range of operating conditions and meet the needs of different industrial applications
