To PWHT or Not PWHT, that is the question

[bmoorthy]

ASME Sec VIII Div 1.
U Stamped
Contains lethal Fluid
Vessel contains Body Flange
Material of construction of Shell, Nozzles, Dish heads Austenitic Stainless Steel.
Material of construction of Body Flange (That gets welded to Shell) and companion Flange (gets welded to the skirt (Straight face )of the Dish Head) : Carbon Steel with 3 mm Weld Overlay
Fusion Weld Joint between Shell and Body flange is done using Inconel Filler metal.

Question:
1) Does the above vessel require PWHT?
If Yes: Which clause of ASME Sec VIII Div 1 does one find the requirement (UW or UCL does not directly address the above).

2) Are there code cases
3) Any Interpretations?

3) If PWHT is not requied for the above vessel, do we have to perform PWHT , for the following vessel:
(another vessel with same service, this configuration is occured dure to material shortage and due to requirements for dimensional tolerance)

Top Dish Head Austenitic SS,
Dish End to Overlayed Flange Inconel Weld,
overlayed Body Flange (Companion flange) to overlayed Shell piece(CS + Austenitic SS ) weld using CS Wled + SS overlay. That is, First, Butt weld between Body flange and CS Shell done using CS and then overlayed (Body flange and Shell and then machined the Body Flange).
Overlayed Shell to Cladded shell (another Shell piece is Explosion bonded plate) welded using CS Weld and clad Restored
CS Clad shell to Another Clad Shell using Inconel Weld.
Clad Shell to Austenitic Dish Head (Bottom Dish head) Using Inconel Weld.

 

[metengr]

Review UW-2 "Service Restrictions" of ASME Section VIII, Div 1. All of the answers to your questions can be found in this location.

 

[bmoorthy]

UW2 Says Carbon Steel vessels need to be PWHTed. UW2 does not indicate requirement for Cladded vessel or SS vessel with Overlayed flange, hence the question.

 

[metengr]

bmoorthy;
PWHT for austenitic stainless steels follows the requirements in book section UHA of ASME Section VIII, Div 1. Since PWHT is neither required or prohibited, this means PWHT is not necessary for lethal service.

Regarding CS, this is self explanatory from UW-2 (a), any fabrication welding requires PWHT.