ANSI Code piping Horizontal and Vertical allowable motions 3

[Zoltan Racz]

Gents,
is there any general rule in ANSI Code where the piping Horizontal and Vertical allowable motions are defined/limited as a range?
I am asking about the radial and axial displacements or elongations or deflections in a very crowded pipe rack arrangement piping avoid clash of pipes meanwhile thermal expansion.
Thank you
Zoltan

 

[Snickster]

I don't recall any mention in B31.3 about allowable movements of pipes in a rack but you might want to check. Piping moves alot due to thermal expansion at high tempertures. This movement has to be allowed for in the flexibility and support of the piping as determined by a stress analysis so that connected piping and attached equipment is not overstressed or have loading over the limit in case of equipment at nozzle connections. Depending on the temperature piping may expand axially or laterally many inches or more. This has to be allowed for in the piping design.

On the other hand vertical deflection where the piping lifts off the supporting pipe support is not a good thing. It has been a while but I recall that if you did a stress analysis and determined that the piping was lifting off of the supports during thermal expansion then you would need to correct so no lift off occurs, or run the calculation without supports for the sustained case (pressure plus weight only) and it was ok only if stress passed under the the sustained case without those supports there, but you need to check code requirements on this by reading the applicable ASME Code. One way to corrct lifting off of supports is to use spring hangers/cans.

 

[KevinNZ]

Simple rule, Under thermal expansion pipes (and insulation) are not allow to clash. That includes when one is cold and the other hot. The piping designer has to work out thermal movement and deal with it.

 

[1503-44]

There are no code defined dimensional movement limits.


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