6" Dummy Leg Support on 12 " pipe
6" Dummy Leg Support on 12 " pipe
(OP)
I'm having some trouble in performing a check on a dummy leg support within Caesar II. I have a 12" horizontal run pipe, and a 6" vertical support pipe with no repad. The info that I have seen so far does not impose any SIF's on the connection, and I think that there should be. I have performed a WRC 107 check on the "nozzle", and all stresses are fine, but when I model the connection within Caesar, it fails miserably





RE: 6" Dummy Leg Support on 12 " pipe
use a one size smaller for a dummy support.The recommended size for a 12""run pipe is 8"dummy...and you could even go to a full size but it is better to put a pad.
RE: 6" Dummy Leg Support on 12 " pipe
I am not in favour of oversized trunnions.
Acceptance criterion for trunnion is based on local stresses and Caesar II cannot handle that. MWKellogg's Design of Piping Systems Chaper 3 gives a methodology to calculate local stresses..it is quite straight forward and you can put it into a spreadsheel and off you go!
Most piping engineers have a copy (or a photocopy) of this great reference of the 1960's.
Good luck
RE: 6" Dummy Leg Support on 12 " pipe
By the way, I assume you are in B31.3; just last week, I discovered that welding of attachments (shoes, trunnions, supports, etc.) in B31.4 is now strictly forbidden.
RE: 6" Dummy Leg Support on 12 " pipe
I do agree with you, but I have found it faster to use FE/PIPE.
NimalJayaratne (Mechanical) Also, I have the MWKellogg's Design of Piping Systems sence 1973. RE: Chaper 3. Have check with FE-PIPE.
Leonard Stephen Thill
www.thill.biz
RE: 6" Dummy Leg Support on 12 " pipe
A simple approach that I have used with round or structural attachment is the line load method given within section 7.6 of the Pressure Vessel Design Handbook - Bednar, 2nd. edition.
Good Luck.
RE: 6" Dummy Leg Support on 12 " pipe
I have also referred to a paper published by MWK later on the subject...I'll see whether I can dig it out from my museum...
RE: 6" Dummy Leg Support on 12 " pipe
Use these softwares, to reduce your complicated analysis burden. they make the analysis seem so easy.
Narendra K. Roy
Gramya Research Analysis Institute,
PO box 4016, Vadodara 390015, India
Website: www.gramya.com ; www.charismaglobal.com
RE: 6" Dummy Leg Support on 12 " pipe