ASME Section III Div 2

[parrs]

Need your technical expertise on welding for ASME Section III Div 2 and here is the situation:

There are two plates with different thicknesses, 38 mm and 6 mm. They will be welded together by FCAW. The selected WPS preheat temperature (min): 10C(t>25.4mm:95C). Ambient temperature is normal.
1. Do we need to conduct preheating?
2. Does the definition of thickness follows CC-4552.2.3 of ASME Section III Div 2?
3. If preheating is required, should the thicker plate takes the preheating requirement? What code of practice is applicable for this?

 

[EnergyMix]

Here is what Section III says:

NC-4611 When Preheat Is Necessary
The need for and temperature of preheat are dependent on a number of factors, such as the chemical analysis, degree of restraint of the parts being joined, elevated temperature, physical properties, and material thicknesses. Some practices used for preheating are given in Appendix D as a general guide for the materials listed by P-Number of Section IX. It is cautioned that the preheating suggested in Appendix D does not necessarily ensure satisfactory completion of the welded joint and that the preheating requirements for individual materials within the P-Number listing may be more or less restrictive. The welding procedure specification for the material being welded shall specify the minimum preheating requirements under the welding procedure qualification requirements of Section IX.

Since you are doing nuclear work, I presume you have Appendix D and so can look up the P-Number for the materials you are using.

You might consider doing some practice welds to determine whether pre-heating is necessary or not.

 

[parrs]

Thank you EnergyMix.
Another thing that I want to clarify is for two base metals with different thicknesses but with the same P No., if preheating is required, which thickness will govern the preheating requirement? Is it the thicker material?

 

[EnergyMix]

What does the Code say? You would need to read Appendix D and Section IX.

 

[parrs]

Thanks for the big help EnergyMix.

I'm sorry I overlook your point.