Localized PWHT for internal Dishhead

[ting123]

Case :- Multi-chamber Column, two chambers are manufactured and PWHT done separately due to constraint of accommodating this 69 mts long column in the furnace. Now Localized PWHT is being performed on the Joint connecting these two chambers. There is a internal dish head at this junction. As per the vendor(copperheat)they need to heat this internal dish head to near about 400 deg C. My query is, this dish head had been through one PWHT cycle. Now if we heat to 400 deg C (less than PWHT temp 600-640 as per asme code) will the material have a change in the properties. Secondly, The material had been already qualified for three simulated PWHT cycle out of which one is already used and as per project spec remaining two cycles are required for future repair. Will heating to this temperature mean that we are consuming one more cycle.

 

[metengr]

ting123;
For the internal dished head presuming it is carbon steel and exposed to 400 deg C from PWHT being performed nearby, you are not going to appreciably alter the mechanical properties.

 

[metengr]

and forgot to add, would not be counted as another thermal cycle for PWHT because PWHT is not being performed on the internal dished head.

 

[TGS4]

Also, ensure that the local PWHT follows the recommendations in WRC 452.