ASME IX ( Preheat of 5 Cr-1/2 Mo 6'' tube)

[mafla jones]

Hi All,

Kindly need your assistance on this one we have a 5 Cr-½ Mo 6'' heater tube that was weld repaired, however preheat of 175 degrees Celsius was not done prior to welding is this acceptable? we have moved straight to Post Weld Heat Treatment.

Regards,
Edward.A

 

[DekDee]

Edward,
Of course it is not acceptable.
Someone needs to raise an NCR immediately
If you were responsible for the decision to move to PWHT then you better hope your boss doesn't find out or you will be looking for a new job.

 

Beside the obvious, unremediable Code violation, implicit in your proposed solution of immediate PWHT is the fallacy that PWHT can fix whatever thermal errors occurred during welding.
.
DekDee,
If the boss accepts this then the integrity of the entire quality system is in question.


"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[mafla jones]

Thanks guys for your comments

 

[r6155]

The preheating temperatures do not necessarily insure satisfactory completion of the welded joint .
Please, can you tell us more information?,..thickness of weld, extension of repair......

Regards
r6155

 

r6155,
Remove the weld 100%.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[r6155]

I prefer, if possible with same tube and thickness, a mock-up:

1)Weld the test coupon similar as actual repair weld without preheat
2)RT
3)PWHT
4)Bend test + tension test (like a WPQT ASME IX)
5)If tests are OK do a PWHT of actual repairs.

Regards
r6155

 

[weldstan]

We experienced weld cracking in this material when inadequate torch preheating was done. Resulted in leaks during startup.