ANSI 150 LB

[TurbineBlade]

Hi,

Where can I find the design pressure and temperature of a Stainless Steel ASME Nuclear Class 3 150 lb 1/2" Globe valve? I am looking from the pressure boundary prespective.

thanks

turbineblade

 

[JLSeagull]

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 1000 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.

 

[TurbineBlade]

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

 

[JimCasey]

>>>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?<<<

Hydro test pressure is 50% higher than the working pressure rating. Ususally hydro is done cold, so you would use the 100F rating from the tables multiplied by 1.5.

You are still not allowed to operate the valve in excess of the ASME pressure/temperature limits. N-plants are designed so conservatively I am surprised that someone used a class 150 valve here. Typically if it's even remotely close to a code limit the designers will specify a class stronger, or a Class 300 in this case.

You <may> find that you can exploit the "special" classes. These are limited to welded valves and radiological verification of weld integrity (x-ray) is required. Special class limits are a little higher than standard class limits.

Before you do ANYTHING else, get a copy of B16.34 and B31.1 and STUDY them.