更新時(shí)間：2018.07.20

Currently, API and ASME standards are more popular in American standard valves, not the ASTM as mentioned in "hundred trim". ASTM is the material standard, not the standard of the valve itself. American standard valves: valves designed, manufactured, manufactured and tested in accordance with American standards are called American standard valves. 1. The nominal diameter unit of the national standard valve is mm, and the nominal diameter unit of the American standard valve is in(inch). 2. The standard American standard of flange is different from the national standard. 3. The structure length is different. 4. The inspection requirements are different, and the inspection requirements of American standard valves are higher than the national standard.