What Are The Main Points Of Valve Selection?

1) Lifting horizontal flap check valve can only be installed horizontally, with the flap vertically upward. Lifting vertical flap check valve can only be installed vertically, and the flow direction of the medium must be upward.

When the swing check valve is installed on a vertical pipeline, the flow direction of the medium must be upward.

2) Pressure reducing valves and traps should be installed on horizontal pipelines: safety valves must be installed vertically upwards.

3) Gas pipeline valves are required to have good air tightness, rapid switching, flexible action, convenient maintenance and good corrosion resistance. Valves with copper sealing rings should not be used; to prevent corrosion of sulfide impurities in the gas. Special oil-sealed plug valves for gas pipelines, special oil-sealed gate valves, sealed butterfly valves, etc. can be used.

4) The oxygen pipeline can use a stop valve or a ball valve, and a special valve for oxygen should be used. It is strictly forbidden to use gate valves for oxygen pipelines with working pressure p>0.1MPa. When P<1.6MPa, malleable cast iron, ductile iron or steel valve can be used; 1.6≤P≤3.0MPa, all stainless steel, all copper alloy or combination of stainless steel and copper-based alloy should be used. It is strictly forbidden to use oily or combustible materials in the corner of the valve with oxygen. Valves should be inspected and processed according to relevant construction and acceptance specifications before installation.

5) Gate valves are strictly prohibited for hydrogen pipelines with working pressure p>0.1MPa, and plug valves, ball valves, and stop valves should be used. For hydrogen pipelines with P≤1.6MPa, cast steel valve bodies can be used; when P<0.1MPa, ductile iron can also be used. When the electrolytic hydrogen contains alkali, the valve with copper or copper alloy cannot be used.

6) For acetylene pipes, malleable cast iron, ductile iron or steel valves can be used; gate valves are forbidden for DN>50mm pipes. The relationship between valve nominal pressure and pipe diameter is as follows: DN≤20mm, PN≥1.0MPa; DN≤50mm, PN≥1.6MPa; 50mm<DN≤80mm, PN≥2.5MPa.