Re: Trunnion on an Elbow

I have to disagree with comments made by Zope and Sachin. Trunnion is pretty much an industry accepted pipe support. As pointed out, even the guys at Kellogs ( avery long time ago) have done quite a detailed study on this very subject and recommend its use. The last book that ive read published by CASTI even has a an equation that deals specifically with its proper design. There are over a thousand of this type of pipe support installed in power plant, refinery and petrochem that to date is still around.

And forget about the effect of the SIF, it rarely affect the result of your flexibility analysis. Instead focus on the details - welding, inspection and fitup if your designing one. If anyone is interested, i could post the equation for its design.

• In PipingDesign@yahoogroups.com, "Tushar, Zope" <zope_tushar@f...> wrote:
  > Hello Friends,
  >
  > Use of trunion on elbow is generally accepted practice. Some
  companies do not allow at all and some companies do allow on conditional basis.
  >
  > You can use it for temp. below 150 deg C (No problem at all.)
  > But it's not good to use it above 150 deg C. The reason is simple
  that we can take advantage of flexibility associated with the elbow in stress analysis.
  > Also I would suggest to avoid it above 60 deg C for Stainless Steel
  and Alloy Steel lines.
  >
  > Better go for a support at the pipe (horizontal or vertical as
  well).
  >
  > Thanks and regards.
  >
  > Tushar Zope
  > Piping Engineer
  > Foster Wheeler Eastern Pte. Ltd, Singapore
  > Ph: 6890 0837 Fax: 6223 2989
  >
  > Disclaimer
  > 'The information contained in this email and the files transmitted
  with it are
  > confidential and intended only for the use of the individual or
  entity to whom
  > they are addressed. If you have received this message in error,
  please
  > immediately notify the sender and delete the mail. The views or
  opinions
  > presented in this email are those of the author and do not
  necessarily represent
  > those of the company. The recipient should check this email and any
  attachments
  > for the presence of viruses. Foster Wheeler Eastern Pte Ltd accepts
  no liability
  > for any damage caused by any virus transmitted by this email.'
  >
  >
  >
  > ____________________Reply Separator____________________
  > Subject: Re: [PipingDesign] Trunnion on an Elbow
  > Author: Sachin_Bapat@r...
  > Date: 9/7/02 8:46 AM
  >
  >
  >
  >
  > If you go through piping design books you will find that
  > trunnion on elbow
  > reduces the flexiblity of trunnion & also it modifies the
  value
  > of sif &
  > flexibility factor . piping design book (M W kellogg)
  chapter 4
  > -local
  > components expilicitly derives relation for the same, thats
  > why most of
  > design companies dont prefer trunnion on elbows & use of pads
  > for trunnion
  > on elbow is highly discarded as all these reduce flexibility
  of
  > trunnion ,
  > which may be of concern in rigid layouts
  > hope this answers your query.
  > regards
  > sachin
  >
  >
  >
  >
  >
  > Yahoo! Groups Sponsor
  > ADVERTISEMENT
  >
  >
  <<a href="http://rd.yahoo.com/M=229441.2336363.3766536.2225242/D=egroupw">http://rd.yahoo.com/M=229441.2336363.3766536.2225242/D=egroupw</a>
  >
  eb/S=1705083319:HM/A=1189560/R=0/*<a href="http://www.bmgmusic.com/acq/e">http://www.bmgmusic.com/acq/e</a>
  > e/q6/enroll/mhn/10/>
  >
  > Texas Flange - a good source for information on industrial
  > flanges, all they ask is for referrals for designs they help
  > with.
  > 877-610-8924.
  > www.texasflange.com
  > =====================================================
  > unsubscribe: <a href="/group/PipingDesign/post?postID=Wg5btGC2IyHb2eKYVpThhfd5xzCkxa_ZfarkRc0Rc_lNaMRiBRt2bvzrpMIyiW9X0Ekpwe52UDEROAKbTflvYtK_aloQYjVZQieoR5-zG4o">PipingDesign-unsubscribe@yahoogroups.com</a>
  >
  > Your use of Yahoo! Groups is subject to the Yahoo! Terms of
  > Service <http://docs.yahoo.com/info/terms/>.