full pen weld 2

[Lutfi]

Some questions:

I have tube steel that needs to be jointed at a splice point that requires full pen welding. I must develop the joint.

AWS does not provide a pre-qualified full pen joint. I am asking that the welder must be a 6GR qualified/certified. Do I need also have qualified for new joint? If so, what is the right verbiage to put on the plans?

What is the best NDT method for this joint? I am speaking of the full pen tube butt weld.

I already posted these under the welding forum.

Regards,


Lutfi

http://www.cdeco.com

 

[Ron]

Lutfi...I'll check my code tomorrow, but I'm fairly sure that your joint is pre-qualified if you specify backing. I would suggest a single V groove weld with backing. Backing is not that difficult to do with HSS.

I agree with the 6GR requirement and you need to specify the joint designation in AWS and require submittal of all procedure specifications and current welder qualifications. As for testing, if the wall thickness is greater than 5/16, then you can use ultrasonic method, otherwise, use radiographic.

 

[Ron]

Lutfi...I confirmed in AWS D1.1 (Section 3.13.3) that your joint can be prequalified if you use backing. Check with some of the welding products suppliers. There might be a pre-fabricated backing bar for your tube size.

 

[SperlingPE]

I have specified a butt welded field splice with backing for a tube. The backing was welded in the shop. No testing done as it was a pre-qual weld.

 

[Lutfi]

Ron,

Thanks for your input. I read 3.13.3 (I still use 2000 edition) last night before I posted and I misread it (must been tiered). At the time I read it as could not do it if welding can be done with backing bar from one side.

Now, with fresh cup of coffee in my hand, and with your input, I do read it as a pre-qualified joint with backing bar no whether welding is can be done from one side or both sided.

I will still require the welder to be 6GR qualified since this is a critical joint.

Regards,



Lutfi

http://www.cdeco.com

 

[Ron]

Lutfi...thanks.

SperlingPE...I'm curious as to why you would not specify testing just because the joint is prequalified. The joint qualification has nothing to do with the quality of the weld placed to join the materials. CJP welds should be tested, either by ultrasonic or radiographic methods.

 

[Lutfi]

Ron,

I agree with you. I am doing 100% visual testing and Magnetic Particle testing due to the 0.25-inch wall thickness.

In my opinion “pre-qualified” does not mean no testing. I have seen many welders who done bad job with simple fillet welds. We all know that they are pre-qualified.

From QC standpoint, I am insisting on testing visually and NDT.

Regards,


Lutfi

http://www.cdeco.com

 

[Ron]

Lutfi..you are right. Testing must be done. For critical welds, if you can't do either ultrasonic or radiographic, have them do visual and mag particle of EACH PASS. Otherwise, you will only get inspection of the completed weld as mag particle is a surface indication method and doesn't show anything below the surface (except an occasional "fuzzy" indication if you have inclusions just below the surface).