Pre-heat/PWHT question

[ctgcwiqc]

Material type: SA-516-70
Material thickness: 1.75"
Code of Construction: ASME SEC VIII DIV 1 2004 ED/ADD

We are performing a repair of a tube sheet. The repair is due to a .020" deep steam cut on the gasket surface roughly .5" long. UCS-56 only addresses "welded joints". I have no welded joint, only an addition of metal to the tube-sheet.

1) Am I looking in the wrong location in the code book?
2) Would the thickness be governed by the weld depth, or the actual thickness of the base metal?
2) If the thickness is the actual base metal (tubesheet), is preheat in lieu of PWHT an option without going the route of one of the NBIC alt. methods?

Thanks in advance.

 

[metengr]

This would be a weld repair, and based on your question would be applicable to an in-service item and not under the code of construction (ASME). Look at UW-40 (f) for guidance related to PWHT requirements and nominal thickness. All the answers to your questions can be found in UW-40(f). By the way, the NBIC provides guidance for weld repairs to in-service items, I would suggest you follow it. You might be able to use Welding Method 1.

 

[ctgcwiqc]

Similar question. People always refer to NBIC, which refers you to the original code of construction. That's why I was looking in Sec VIII.

SA-337-5 CL. 2 Tube sheet
4.375" thick
Code of Construction: ASME SEC VIII D1 1986/1885 ADD

Small repair to gasket sealing surface. .125" in depth. Where would the requirement to PWHT be listed in regards to weld repair? This is neither shell, nor channel, nor head. It is the tube sheet, and is not listed as PWHT. It is not a welded joint. Jurisdiction is pointing back at me to answer my own question. AI shrugs his shoulders and say preheat in lieu of. NBIC says no to preheat in lieu of PWHT for P5B materials. I can't believe this small issue would be so difficult to resolve in this day of severe oversight. Would this fall into the realm of AI approval makes everything Kosher? I am split on the issue and could sure use some guidance. I am off to search through the interpretations again. Thanks in advance.

 

[metengr]

The NBIC refers back to the original code of construction for technical details IF they are applicable to the repair or alteration. I don't understand what is so difficult about this repair. It is considered a weld repair, you follow the preheat requirements in the code of construction. You look at the deposit thickness (not the tubesheet thickness) of the repair weld and if the original code of construction exempts you from PWHT based on nominal thickness for the base material P-No, so be it. If the original code of construction does not address it you look at one of the weld repair methods in Alterative Weld Repair Methods in the NBIC. This is very straight forward.