Material for insulation support ring and lifting lug at low temperature service

[jtseng123]

Dear all,

For operating temperature at (-)230 degF with SS construction, is it acceptable to use CS (SA-516-70)for the insulation support ring which is bolted to SS support clip ? Insulation is 9" thick.

Is it also ok to use CS lifting lug which is welded to SS pad ? We may not cut the lug after erection.

 

[mk3223]

It sounds a cheap work to have CS support ring bolted to the SS clip. my comment is that it's okay to use it to save some cost, and hope it won't fail as the material reaches (-)230F.

 

[TGS4]

For both situations, have you adequately considered the thermal stresses resulting from the different coefficients of thermal expansion?

 

[JAS]

Check the Client specification. Normally, any attachments welded directly to the Vessel shall be of the same material. In this case (at -230F), especially for LG&SR, it shall be of SS. Thermal stresses may be too high for the material and chances of weld cracking.
Thanks,
Jay,

 

[jtseng123]

Thanks for the input.
The support ring will have slot holes bolted to SS support clip such that thermal contraction is not an issue. My concern is: will the CS material too brittle at that temperature such that it can not even take 20 psi bending stress ?

As for CS lifting lug, it is welded to SS poison pad, and I am expecting the weld between lug and pad may crack due to thermal contraction in operation. Is it a concern ?

 

[TGS4]

So long as the stresses are less than 0.3S, per UCS-66, you should be fine with CS.