Fabricated Flanged Pipe Elbows B16.5 or B16.9

[MechPipe13]

Hello All,

I have a quick question about Fabricated Flanged Elbow Fittings.

I have a case where a special angle elbow must be fabricated. The current design as an example would be a B16.9 60 degree elbow with FF weldneck flanges on both ends.

In reviewing the code, I saw two items that seems to cover this area: B16.5 (6.2.5 - Special Degree Elbows) & B16.9 (6.2.4 - Segmental Elbows).

By doing a quick look at the center-to-Contact dimensions for each case, the dimensions are a little different.

My question is that which of the code would essentially govern the fabrication of flanged elbow fittings as I described above? The existing design in our system shows a center-to-contact dimension that match the B16.9 dimension calculation, but I want to make sure that it is the correct way of doing it.

I have a hunch that the dimension might not even be a code issue since this essentially is a fabricated spool piece, but I want to see other people's opinion.

 

[JStephen]

Sounds to me like it would depend on whether the ell was segmented or not?

 

[uaepiping]

Odd type fittings with end flanges can be made. But the applicable code will not be ASME B16.9 or B16.5. It would be ASME Section VIII.
Check it.

 

[LittleInch]

I'll confess I've never ordered a one piece flanged fitting myself, but looking through the codes, a single item flanged elbow can be made to B16.5, noting that section 8.2.1 requires each flanged fitting to be subject to a hydrotest of its own. B 16.9 only covers the single elements of what you describe, i.e. flanges and elbows made as wrought single fittings.

Other than avoiding two welds, I can't personally see why you would want a one piece flanged 60 degree elbow as opposed to a 60 degree elbow and two WN flanges??

If by segmental you mean mitre bend, then I would always go with a smooth elbow, but otherwise varying angles of elbow appear to be permitted by either code - normally they just make a 90 and cut it and dress it to suit. Making a special one piece forged flanged 60 degree elbow would probably cost you a fortune unless you're buying hundreds.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way