API and ASME standards (ASTM, ASTM is the material standard of its production, not the standard of the valve itself) are the most popular American standard ball valves. American standard flanged ball valves are valves designed, manufactured, produced and tested in accordance with American standards. The national standard valves are manufactured according to domestic standards.

The main differences between the American standard flanged ball valve and the national standard are as follows:

     1. According to the production needs of various countries, the nominal diameter of the national standard flanged ball valve is mm, while the nominal diameter of the American standard flanged ball valve is in (inches).

     2. The size of the American standard is also different from the flange designed under the national standard. For example, the national standard flange is 5mm smaller than the American standard flanged ball valve, and the size of the American standard gate valve and globe valve is also different from the national standard.

3. The structural lengths of American standard and national standard flanged ball valves are also different.

4. The product inspection requirements are different. In theory, the inspection requirements of the American standard flanged ball valve are much higher than the national standard.

5. At present, many American standards have become world standards. Valves include ASTM material standards, ASME pressure planning and manufacturing standards, API valve manufacturing, planning, production and testing standards, mainly used in the petrochemical industry; MSS general valve series standards; ANSI American national standards; ISO world standards and domestic standards are now mostly limited to my country.