General Requirements 1.1 Valve specifications and categories shall comply with the requirements of the pipeline design documents. 1.2 The model of the valve shall be indicated with the national standard number requirements. If it is a corporate standard, the relevant description of the model should be indicated. 1.3 The working pressure of the valve is required to 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; Any side of the valve under closed condition shall be able to withstand 1.1 times the valve working pressure without leakage; When the valve is open, the valve body should be able to withstand twice the valve working pressure. 1.4 The valve manufacturing standard should specify the national standard number on which it is based. If it is a corporate standard, the procurement contract should be accompanied by corporate documents.

2. Valve Standard Material 2.1 The valve body material shall be mainly nodular cast iron, and the brand and actual physical and chemical testing data of the cast iron shall be indicated. 2.2 The material of valve rod shall be stainless steel valve rod (2CR13), and large-diameter valves shall also be stainless steel inlaid valve rod. The nut material shall be cast aluminum brass or cast aluminum bronze, and its hardness and strength shall be greater than that of the valve rod. 2.4 The material of the valve rod bushing shall have a hardness and strength not greater than that of the valve rod, and shall not form electrochemical corrosion with the valve rod and valve body under water immersion conditions. 2.5 Material of sealing surface

① Valve types vary, and sealing methods and material requirements vary;

② For ordinary wedge gate valves, the material, fixing method, and grinding method of the copper ring should be described;

③ Physical, chemical, and hygiene testing data of rubber lining materials for soft seal gate valves and valve plates;

④ Butterfly valves shall be marked with the material of the sealing surface on the valve body and the material of the sealing surface on the butterfly plate; Their physical and chemical test data, especially the sanitary requirements, anti-aging performance and wear resistance of rubber; Generally, NBR and EPDM are used, and it is strictly prohibited to mix recycled rubber.

2.6 Valve Shaft Packing

① Due to the infrequent opening and closing of valves in the pipe network, it is required that the packing should not be active for several years, and the packing should not age, maintaining the sealing effect for a long time;

② The valve shaft packing should also withstand frequent opening and closing, with good sealing effect;

③ In view of the above requirements, the valve shaft packing shall not be replaced for a lifetime or more than ten years;

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