PWHT and SR

[dungun]

Is it mandatory to have PWHT or SR if the medium vessel is ethane?. Based on the thickness,fibre elongation the PWHT and SR is not required. I dont see any requirement in ASME VII div I. Plate SA516 gr 70N c/w impact tested.

 

[metengr]

dungun;
Are you sure you calculated the extreme fiber elongation as indicated in UCS-79? By the nature of your questions, I have serious concerns about your experience with PV Codes and design. I would suggest you seek outside help in this matter.

The designer of the vessel should have noted if the vessel falls under UW-2, and apply all necessary service restrictions including those in UCS-75 and UCS-79.

 

[dungun]

Metengr,
Yes, my vessel already appraise by ASME U-Stamp, in the PWHT and SR column is NO. However the client question why PWHT and SR not require. The vessel thk 20mm and the Diameter 1.2m ID.

 

[metengr]

If the vessel falls under UW-2 Service Restrictions, for P-No 1 material, PWHT is required for thickness in excess of 16mm at welded joints.

 

[GenB]

Just imagining Ethane at 2500# pressure means PWHT to me. I would not bargain with it. extra USD$300 to 500 in the US means nothing compared with the risks of explossion.
also RT-1 girts and long seams shall be required
GenB

 

[codeeng]

If you have formed heads, ellipsoidal or shallower, chances are that PWHT will be required. Check the knuckle radius per UCS-79 (double curvature).

 

[stanweld]

codeeng,
Often the heads are stress relieved or normalized and tempered after forming, thus negating the requirements for PWHT.

 

[codeeng]

stanweld
Sorry, I should have said SR not PWHT, however its also often the case where the required SR is done on completion of the vessel (PWHT).