Valve material

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

Stem material

Strive to use stainless steel stem (20Cr13), large-diameter valves should also use stainless steel embedded stem.

Nut material

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

Material of stem bushing

The hardness and strength of the valve stem bushing should not be greater than that of the valve stem, and there should be no electrochemical corrosion with the valve stem and valve body under water immersion.

Material of sealing surface:

  1. Different valve types, different sealing methods and material requirements
  2. For ordinary wedge gate valves, the material, fixing method and grinding method of the copper ring should be explained.
  3. Soft sealing gate valve, physicochemical and hygienic testing data of valve plate rubber lining material
  4. The butterfly valve should 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 testing data, especially the hygienic requirements of rubber, anti-aging performance, and wear resistance; usually NBR and EPDM rubber, etc. are used, and reclaimed rubber is strictly prohibited.

Material of valve shaft

  1. Since the valves in the pipe network are usually opened and closed infrequently, the packing is required to be inactive for several years, and the packing will not age, so that the sealing effect can be maintained for a long time;
  2. The valve shaft packing should also keep the good sealing effect when it is subjected to frequent opening and closing.
  3. In view of the above requirements, the valve shaft packing strives not to be replaced for life or more than ten years;
  4. If the packing needs to be replaced, the valve design should consider measures to be replaced under the condition of water pressure