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[process.eng88]

Pg. 16-17 of the attached document "Piping Stress Analysis Seminar - Part-II by G. Palani" states the following:

 

Expansion Loops

...........................
 

Generally, if the total expansion in any direction on the pipeway is less than 10 inches, the loop could be avoided by locating the anchor in the middle of the run.

 

The total expansion between the loop anchors should not exceed 12 inches.

 

 

 

 

I would be extremely grateful if someone can quote me a reference from some engineering standard/best design practice document for these guidelines concerning Expansion Loop Requirements.

 

 

Regards 

Attached Files

•  Stress Analysis Seminar - Part 2.pdf   1.18MB   31 downloads

[MTumack]

The guideline looks to me like an experience based rule of thumb.

 

ASME sets out allowable piping stress. When you have two supports far apart and a pipe expands, if the supports are rigid (and supply satisfactory friction) then you havea scenario in which your supports are exerting a compressing force causing bending / buckling in the pipe. Expansion joints are used to eliminate this extra stress. If multiple supports aren't required, then you don't introduce that stress.

 

That being said, I'd say that the number itself seems fairly useless; assuming you have steel pipe (α=6.7E-6 in / in°F)and a temp difference of say... 100°F.

 

Expansion = L * Linear expansion coefficient (α)* DeltaT

 

Solving for L @ 10" of expansion.

 

L = 10" / (6.7E-4in/in°F * 100°F)

L= 14925.4 inch = 1244 feet.

 

Thats a loooong pipe. Or you need like 500-600°F temp swings which are... kind of unrealistic in most scenarios.