tolerance for flange joint

[farzam]

Dear All,

Please let me know what is the tolerance ( misalignment ) for two flanges joint together by stud bolts as per any standard.

Thanks in advance

 

[TGS4]

You should refer to PCC-1. I believe that there is an angular misalignment tolerance in there.

 

[rneill]

You might also want to look at Appendix F in the Process Piping Guide (Engineering Standards Manual) for Los Alamos National Laboratory available online with the following link. They have extensive information on piping system fabrication and installation and provide information on their acceptance criteria for flange alignment.

http://engstandards.lanl.gov/esm/pressure_safety/process_piping_guide_R2.pdf

I'm sure you could also find something somewhere in API or perhaps in documents published by the Pipe Fabrication Institute (PFI) but offhand I'm not sure which or where.

 

[TGS4]

I was right that there is guidance in PCC-1 - Appendix E. However, in that location, they refer to ASME B31.3, paragraph 335.1.1(c).

 

[rneill]

The referenced clause in B31.3 says ...

Flange faces shall be aligned within 1 mm in 200 mm measured across any diameter; flange bolt holes shall be aligned within 3 mm maximum offset.

I think this is pretty much what is in the Los Alamos guideline but they have some pictures which are helpful.