R stamp requirements

[fhw]

Hi all,

If the Stainless Steel bolts of a U-stamped Heat exchanger body flange (Channel-tubesheet-shell) are going to be replaced with Carbon Steel bolts, would that need R stamp on the Heat exchanger?

Thanks

 

[metengr]

Yes, because you are affecting the pressure retaining capability of the heat exchanger.

 

[bpv66]

The NBIC Part 3 addresses the replacement of defective bolting in paragraph 3.3.4.2(e), so in my opinion, this would be an "R" Stamp Repair. You can't go to Lowe's and purchase replacement bolts. There are ASME material requirements that need to be met.

Keep in mind if the replacement bolt material has a lower allowable stress than the original bolt material then this activity becomes an R Stamp Alteration (see 3.4.3(g) of the NBIC Part 3).

 

[metengr]

Comeon, this question was asked before...

thread286-398842

 

[r6155]

Why the replacement?
Regards
r6155

 

[Christine74]

I would add that this should probably be considered an NBIC Alteration rather than a Repair. Even if the carbon steel bolts have a higher allowable stress than the stainless steel bolts, a calculation would still need to be performed to ensure that the higher-strength bolts do not cause the body flanges to fail.

-Christine