ASME B16.34 - Off spec valve classes

[anning]

I've been working on specifying a wye pattern globe valve and I've noticed that it seems quite common in valve catalogs to specify these valves as class 1690 and class 2680. Are these classes related in any way to the ASME 16.34 valve classes? I cannot find a spec anywhere that uses these numbers yet the manufacturers tend to refer to ASME B16.34. Can anyone explain this to me? Thanks.

Grant

 

[bcd]

Yes they are related to ASME B16.34 Limited Pressure Class. Do a google search for "Class 1690 Pressure rating" and you will find numerous valve manufacturers offering product with these ratings. You should also look at B16.34 section for limited class to understand the differences with the standard class ratings and the specific rules. For example, limited class is restricted to NPS 2-1/2 and smaller, weld and thread end only. Only specific body shapes are allowed. Limited class uses a different equation to establish the pressur/temperature rating for group 1 and 2 materials, which can yield a higher rating than standard class. The benefit is that you can get a less expensive valve with sufficient pressure rating and conformaning to the required code without using the next higher standard class. For example, if your system operating pressure is 1,500 psi, and class 600 max. pressure is 1480 psi, you must either go to class 900 or use the limited option.

 

[hsbcn]

The ASME Limited Pressure Class was introduced in 2009, covering welded and threaded end valves only on 3 pressures: 800,. 1690 and 2680.

My focus is on valve stockists in the us and us who supply duplex and super duplex valves, and inconel and hastelloy valves, plus titanium, alloy 20 and 904L valves.