SS Nozzle through CS Blind 1

[bluedieselblack]

We have an original design with an 8" XX Heavy 304 SS pipe through a A-105 CS, 1500# blind, 7.25" thick. Operating at 600 F. The weld is not full penetration each ends has 1.5" groove and 7/8" fillet. What would be a good way to evaluate the stress in the pipe between the welds due to the differnece in thermal expansion?
Thanks

 

[MJCronin]

blue....

Engage a consultant to perform a detailed finite element analysis ????

-MJC

 

[wjp123]

Hi Blue,
My advice is talk to a very experienced welding engineer.
He will asked all the rigth questions and will give you an answer.
Cheers.

 

[bluedieselblack]

Thanks Guys,
I went back to my mechanics of materials to get a first guess. The expansion length, LE=L*Coef. of Exp* Delta T.
The force to compress a column, LE=P*L/(A*E). Set these two equal and solve for P/A. Compare to ASME Allowable. The required weld is based off P.

 

[racookpe1978]

8" XX Heavy 304 SS pipe through a A-105 CS, 1500# blind, 7.25" thick.

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I read this as the difference in thermal expansion between a 7.25" CS tube and 7.25" 304 SS plate over a delta T of (600 - 75).

That difference (in length between the two constrained pieces of steel) would be less than the proposed stress from welding the second end, woouldn't it? While welding the second end, the very hot steel tube (a very hefty piece of metal itself) is equally constrained around the weld joint by the cooler plate as the tube cools down from 2500+ degrees.