American standard valve pressure test standard: it is 1.5 times the nominal pressure, the test time is 5min, the valve body does not rupture or deform during the test, the valve does not leak water, and the pressure gauge does not drop, it is qualified. After the strength test is qualified, the tightness test is carried out. The tightness test pressure is equal to the nominal pressure, the valve has no leakage during the test, and the pressure gauge does not drop to qualify.
American standard flanges can refer to ASME B16.5 standards for flanges.
The American standard valve type code is Z-gate valve, P-drain valve, Q-ball valve, D-butterfly valve, J-stop valve, etc.; the national standard pressure corresponding to the American standard pressure of the valve: for 300LB. To use 188.8.131.52. 150LB needs 1.6, 2.0.400LB corresponds to 6.3mpa. 600LB corresponds to 10.0mpa. Because the nominal pressure and the pound-level temperature reference are not the same. There is no strict correspondence between the two.
Five main differences between American standard valves and national standard valves:
1. The unit of the nominal diameter of the national standard valve is mm, and the unit of the nominal diameter of the American standard valve is in (inch).
2. The unit of national standard valve grade is MPa, and the unit of American standard valve pressure grade is LB.
3. The standard American standard and the national standard of the flange are also different.
4. The length of the structure is different.
5. The inspection requirements are different. The inspection requirements of American standard valves are higher than those of the national standard.