Paul Bowers <pbowers@pipingdesign.com> wrote: If a fitting is modified (say, by set-in welding of a half coupling on a FOB reducer for a drain connection) is the reducer fitting still "certified"? If not, then what about elbolets?
http://pipingdesign.com/images/reducer_drain.jpg http://pipingdesign.com/images/ecc_red_bottom_flat_drain.jpg
Paul
First a short discussion.... The B31.3 and other codes have a chapter called Standards for piping components. Piping component's manufactured to one of the standards found in the chapter are called "Listed" Components.
These listed components all carry Pressure / Temperature ratings. So if you assemble a piping system of pipe and these listed components you will have a pressure and temperature rating for the final system.
What you have described might be called as modification of a listed component's. We had something similar to this in an inquiry a while back... and we found at that time that even touching up the end of a listed component for fit up with a grinding wheel would make it an unlisted component. (Since then we have revised the code to allow for minor fit-up grinding)
So does this mean you cannot use an unlisted component in a code piping system???? No unlisted components are allowed but there are some criteria that assures they will be adequate for the Design Pressure and Temperature see Para. 304.7.2.
Would a drain welded onto a reducer be a modification of a listed component thereby making it an unlisted component???
An inquiry to the Committee might be answered as... yes and then point the inquirer to how B31.3 deals with unlisted components.
But are you asking just what the B31.3 code says, or its intent may be, or whats "right".
A small flat or half coupling on a large diameter reducer should not adversely affect the pressure strength of the reducer. How small a branch vs large size???? That's a bit messier depends on D/t ratios materials etc. so no specifics can be stated.
However one could design the intersection of the bottom of the reducer and the drain outlet itself based on the current branch rules in the code.
Elbolets designed manufactured to a listed standard may be used however make sure that they are welded adequately with the proper size welds. When I look at the WFI and Bonney Forge web sites I see that the 90 degree branch fittings comply with MSS-SP97 but not elbolets despite the fact that everyone uses them! I would contact the vendor and get something in writing that the use of an elbolet would not compromise the P/T rating of the elbow.
Then the final question would these affect the SIF of an Elbow or a reducer.... B31.3 says its up to the designer to figure that out by whatever justifiable means they come up with.
Murky enough???
Have a Happy Holiday...
__
Best Regards,
John C. Luf
Cleveland Ohio U.S.A when I'm not in Austria
Member B31.3, Piping Engineer - Stress Analysis, Pipe Supports, Component Design, and Surge Analysis... according to my daughters master of unimportant trivia
[Non-text portions of this message have been removed] Received on Fri Dec 22 22:45:00 2006
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