It is recommended to use gray cast iron valves for transmission and distribution pipelines below medium pressure class B (12MPa). Its greatest advantage is good corrosion resistance and low price, which is very suitable for underground pipeline construction.
Below high pressure B (18MPa), or even below medium pressure A (014MPa), it is recommended to choose ductile iron valve or steel ductile iron valve, especially ductile iron valve. For example: spherical ink.
Compared with cast steel, the mechanical properties of cast iron are not lower than cast steel, but its corrosion resistance and casting process are better than cast steel, and the price is also lower than cast steel (usually about 70% of cast steel). Therefore, the overall performance and price of ductile iron valves are better than those of cast steel valves. In the above-mentioned pipeline solenoid valve pressure range, ductile iron valves should be used as much as possible, but special attention should be paid to the quality monitoring of ductile iron materials.
For valves of category A (116MPa) or higher pressure ratings, it is recommended to choose cast steel valves for explosion-proof solenoid valves; for valves with production pressure ratings below 4MPa, it is recommended to choose cast steel valves;
In recent years, gas companies around the country have begun to use PE pipes, and the current pressure rating of PE pipes is below 014MPa. Polyethylene ball valves have also been launched. This series of ball valves can be buried directly and has good sealing performance. But at present, the price of PE type ball valve is relatively high, especially for ball valves with a diameter greater than 100mm.