3 replies to this topic

[Viru]

I am working on flare line piping arrangements. Line size 24".My query --> Is Piping thermal expansion loops with 45 degree elbows is advantageous over exp. loop with 90 degree elbows??

[fallah]

Viru,

 

It isn't a normal practice to do so, but appears using 45 degree elbows would create more room for pipe expansion provided that for such size there would be standard 45 degree elbow in the market...but stress analysis can specify if it is advantageous...

Edited by fallah, 20 March 2014 - 01:12 PM.

[Art Montemayor]

Viru:

 

As Fallah mentions, I have found that using 45^o elbows has given not only more expansion, but the distribution of expansion stress has been much less severe and more evenly distributed.  I’ve used it in pipe sizes up to 4”.

 

If we consider that an “omega” loop is universally used to ideally and evenly distribute expansion forces in piping, then we can understand that elbow angles less than 90^o are a means to achieve something similar.  However, bear in mind that like in all engineering solutions there is a tradeoff: you will wind up with more pipe welds and more expensive components (the hard-to-find 45^o elbows).  On the other hand, this is “big bore” piping and there may be favorable factors here to help you:

• Since this is flare piping, the design process pressure is relatively low;
• Since this is big bore piping, this facilitates the use of mitered elbows.  This means that you might be justified in locally fabricating the mitered elbows.

Nevertheless, if you find that you can locally fab the elbows and justify their use, always apply Fallah’s excellent recommendation: never go forth with such an installation without doing serious and documented piping stress analysis and careful welding procedures and inspections.

Good luck.

[Viru]

Thanks for guidance. That was my first post on this website. Happy to see your reply.