Reduction of Standard equal tees (ASME B16.9) by removing 10 mm from "Run length" 5

[ASDcunha]

On a particular job , because of space constraint, it was required to cut exiting 6" equal tee by 10mm on the "run length" of 143mm . Therefore this dimension was reduced from 143mm to 133 mm at site. This was for 150# rating line.
1) Is cutting of standard fittings(ASME B16.9) allowed?
2) how do you prove to Client that this design is acceptable?
3) what is maximum length that can be cut for a such standard fittings to be acceptable.

Refer attached

 

[mrfailure]

This asks for trouble too as you are planning to modify a Code-approved tee design for expediency. You have to look at how this might affect service stresses on both the tee and the pipes joined to it during service, and you would require review and signoff at minimum by a licensed design engineer. Have you considered instead using a shorter pipe to weld to the tee?

 

I agree that truncating a fitting of standard dimensions could be problematic Code-wise. Here in Canada I suspect you would be required to re-register it as 'new' fitting.

It might also complicate welding, since the OD (for sure) and the ID (possibly) get larger, creating a mismatch with adjacent piping.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[LittleInch]

This is one of those issues where there is an "official" answer and a practical answer.

The official one is as above - there is no allowance with the ASME B 16.9 spec to change dimensions and hence you have an "unofficial" fitting.

In practice, removing 10mm from the straight section of the tee should cause no issues so long as the 10mm bit did not change in OD or ID from the end, i.e. not in the swept part of the tee.

how do you prove it acceptable? Well you could start with seeing if the straight part of the tee is still there after the 10mm has been removed. Then argue that there is no difference between having the pipe and a weld or 10 more mm and then a pipe and a weld.

Official maximum length - 0mm
Practical maximum length - length to where the OD changes / start of the swept portion then add 10mm. but this is then not an ASME B 16.9 fitting and you will need to get a deviation from the owner.

All IMHO.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[XL83NL]

Agree with LI for 100%.
Same holds for your other topic on LWN’s.

Huub
- You never get what you expect, you only get what you inspect.