How To Choose The Right Gate Valve Size for Your Pipeline

Flanges
ASME B16.5 covers the flange ratings. The flange pressure and temperature limits are tabled in material groups. Group 2.1 includes type 304, group 2.2 includes type 316 and group 2.3 includes 304L & 316L. There are about 46 material groups.

Valves
ASME B16.34 applies to flanged, welded and threaded valves. B16.34 essentially includes the same material groups that apply to flanges. The pressure and temperature limits are not necessarily the same. Material group 2.2 includes standard class and special class tables. At 100 Degrees F the working pressure for Class 150 in table 2.2A the pressure limit is 275 psig. At degrees F Class 150 is limited to 20 psig.

Nukular
As you can see I can't even spell it if you don't say it like President's Bush and Carter. Hi JLseagull,

thanks. The valve is socket weld bellows sealed SS Sch. 40 Nuclear Class 3 Globe valve.

Currently, this valve is installed in a system with the design pressure of P=240 psig and temperature T=200F. On the other hand, I got the valve spec sheet indicating that the max inlet pressure is 225 and max temp is 250F. As you can see, the system pressure is higher than that of the valve. However, I believe the spec sheet is referring to the maximum working pressure and temperature for the valve. The design pressure for pressure boundary integrity should be higher. Is that correct?

Patrick