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Welding procedure 2

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fatcobra

Materials
Nov 2, 2006
15
I need to qualify a welding procedure for P1 to P4. The Material grades are as follows; SA 335 P11 to SA 106 Grade B. I am thinking the filler metas should be ER80S2 root&hotpass & E8018B2 remainder. Is this the best filler metal for this weld, and are there any negatives.
 
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These choices are fine. You can also use ER70 and E7018.
 
I have always been told to go with the higer grade material, but someone else said that E70S would work also. Are there any negatives using E70S, and does the preheat need to be equivlant to the to the P4 or P1 material.
 
fatcobra;
Preheat requirements are typically determined by base metal chemical composition and thickness. For your application, it would be the higher alloy P-No 4 that would dictate preheat requirements for the weld joint.

Regarding choice of filler metal, this really comes down to design philosophy. Remember, the strength of the weld joint is based on the weaker of the two materials being joined, if the materials are of different chemical composition. Since the weaker base material is P-No 1, the filler metal has to be as strong as the P-No 1 base material, which is the reason why I mentioned that ER70 and E7018 would be acceptable.
 
metengr,

I have one more question about welding procedures. If I have a welder whom is qualified to a maximum thickness deposited of 1/2", once he reaches that amount of deposition, if another qualified welder continues for 1/2", can the original welder finish the weld if the remainder is less than 1/2"? If so is that stated in Section IX and if so where? Thanks
 
Yes, provided the welder is qualified to weld with backing.
 
As usual metengr made it extremely difficult to top his answer up. Fully agree with metengr either weld material: matching P1 or P4 can be used. Three small comments.
1. Careful with material thickness. Due to its strength the P4 material requires less wall thickness. Ensure the joint: both P1 and weld metal meet the strength requirments.
2. PWHT (if required) can be tricky for this base metal combination. The P4 range can be too high for P1 and may destroy the properties (UTS).
3. Always keep in mind not just the qualification but also the application. You should select the weld metal that meets the application/service requirements (eg impact).
Good luck.

Putting Human Factor Back in Engineering
 
a reminder,,
weld without backing also qualifies to weld with or without!!!
 
Fatcobra -
There is some good advice here. You mentioned Procedures and also talked about welder quals. Be sure you understand the Code difference between T and t when it comes to your WPS. T is the material thickness and t is the deposited metal - see also QW-451.1.

As long as your welder has deposited 1/2" during their WPQ with at least 3 passes they can weld unlimited thickess (per the max of the WPS).

Hope this helps some,
 
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