Derated Flange
Derated Flange
(OP)
Hi,
What is a derated flange, what are its applications.
Tried googling the topic, but did not get satisfactory results.
Have gone through ASME 16.5, but couldn't find the answer.
Thanks for your help.
What is a derated flange, what are its applications.
Tried googling the topic, but did not get satisfactory results.
Have gone through ASME 16.5, but couldn't find the answer.
Thanks for your help.





RE: Derated Flange
The only thing I can think of is that some flanges are dual rated at low sizes (2" and less) as they are dimensionally the same and hence vendors sell #900 flanges as #600, but may be stamped #900.
Is that what you mean?
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: Derated Flange
"Whom the gods would destroy, they first make mad "
RE: Derated Flange
One common, but unfortunately not so well known example is drilling and tapping hubless blind flanges to make threaded reducing flanges. B16.5 Table 6 lists the flange size and reduced outlet size combinations that can be made without lowering the flange rating. Exceed those limits and you de-rate the flange.
Another example is machining a conventional B16.5 raised face flange to make an o-ring seal flange. If the o-ring groove encroaches on the minimum flange thickness, then the flange must be derated. (one way to get around this is to start with an ungrooved RTJ (ring type joint) flange.
In either case, calculations would be required to determine the resultant (de-rated) flange rating.
donf
RE: Derated Flange
RE: Derated Flange
The question arose, after one of the instrumentation guy came to us (Piping) with a specification in which vendor was providing derated flanges with the package instead of standard flanges.
Thanks for your valuable Feedback.