Minimun required thicknes in hot bending elbow

[lganga]

Dear All
We have a vendor that provided induction bending spools for all the plant
.
We found thta the etradoshas a wall thicknes less than the specified.
We wanti to select those elbows able to support the design pressure and a minimun required thickness.
Ansi 31.3 defines a wal thicknes by internal hoop tension.
If that information enough for selecting or we have to preform the stress analisis in order to have all the tension involved?

REgards
Luis

 

[XL83NL]

The formula in ASME B31.3 (not ansi 31.3) is for internal pressure, hoop, (3c). It is one of the Code requirements. Hoop is a primary stress, as are the loads indcued by gravity.
Adding gravity in the equation by means of doing a PSA (Pipe Stress Analysis) is one way of verifying the stresses in a line. Not sure what you mean by internal hoop tension.

If this is a calculation for setting up a pipe spec then Id just check what the MAWP is with the incorrect wall thickness and djust accrdingly.

 

[LittleInch]

If it is induction bent I would have called them bends rather than elbows...

Have a look at this thread and its links

http://www.eng-tips.com/viewthread.cfm?qid=391676

If the wt is less than specified I would just reject them and let the vendor come back with a technical reasoning as to why they comply.

If the bends are subjected to bending stress and axial stress I would check the stress analysis. If you get excessive stress, you often need to have thicker bends to withstand the combined stress.

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