ASME section II part A 1

[Arkaprava Ghosh]

Hi all, I have a query regarding thickness tolerance on SA-312 and SA-358 welded pipes.
For SA-312 welded pipes, the under tolerance on thickness is 12.5% of nominal wall thickness and for SA-358 welded pipes the under tolerance thickness is 0.3mm.
Now, as I understand the raw material is the same i.e SA 240, so why are the tolerances on thickness different for the same raw material being used?

 

[metengr]

Different fabrication methods - roll formed from SA 240 and fusion welded (SA 358) versus seamless or long seam welded with no filler metal added (SA 312).

 

[Arkaprava Ghosh]

Thanks metengr, but still, welding processes should have no effect on the thickness tolerances.

 

[XL83NL]

Manufacturing method does, just like metengr explained. Take his word; its the best advice youll get here.