Sir,

I have a 48 inch pipe ( crude srvice, 427 defg F and 226 psig design conditions, ASTM A335 Gr. P5 material, applicable to ASME B31.3) in a horizonal plane. This pipe is supported, at a 90 deg elbow, by a 24 inch trunnion support.
How can I know if a reinforcement pad is required at this connection or not? If yes, what width of pad is required? and is there any formula,general practice or standard to be followed?

Thanks,

There are two options:

1) Go in for a Finite element analysis

2) Use the well known Kellog formula.

I don't think you will go in for option 1.

So far option 2 is concerned, if you have the M.W, Kellog book you can use the same. Else go in for www.engg-tips.com where in "search" you need to type the word "trunnion". You will find no. of answers where this expression taken from M.W, Kellog is used, with a note as to how to add stresses.

So far addition of stresses is concerned, use your own judmenet as the M.W. Kellod formula does not suggest anything on that. You can use the recommendations given in ASME Sec VIII Div 2 Appendix 4 for the stress summation part,by judiciously categorising the stresses.

Anindya Bhattacharya

Further to my previous rely, I would like to add two points.

1) For pad with the 1.65sqrt( Rm*T) is well known industry practice.

2) It is difficult to weld pad at elbow. You can consider using an elbow whose wall thickness is higher than connected pipe.

Anindya Bhattacharya