Tube to Tubesheet Weld RT

[teokal]

Hi to all,

We are experimenting on Tube to Tubesheet strength welding, and we are buffled by RT, which in any case it is pretty difficult to make it, but we managed to do it, anyway.
The thing is that it produces a round indication exactly on the "root" area of the orbital weld (ORBITIG - not manual), which seems to be incomplete penetration, or fusion, or just the gap between the tube and the tubesheet... But according to the geometry and design of weld, I believe it is normal to have this "shadow".
RT Technique:
Isotope inside tube, film layed down on tube-to-tubesheet weld, on tube-to-tubesheet test coupon. I attach a photo of what I am talking about, if anyone can understand from the photo quality...
My question is, can anyone provide a RT of an acceptable orbital tube to tubesheet weld, to understand if I am hunting dragons, or not?
Thanks, guys...

Only best result in absolutely necessary time

 

[metengr]

I had not seen an RT of a tube to tubesheet weld nor would I accept it as an owner/client.

 

[r6155]

What is the sense of your experimenting?

Regards
r6155

 

[EdStainless]

Cut it up and examine the cross sections.


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P.E. Metallurgy, Plymouth Tube

 

[teokal]

Gentlemen, thank you for your replies;
metengr, just curious, you wouldn't accept ANY RT, or this one due to indications?
r6155, the experimenting is just trying to achieve the most efficient parameters to produce a good strength tube to tubesheet weld. Positioning of wire, depth of penetration, weld appearance, weld strength, etc.
EdStainless, yes of course, will do so.

Only best result in absolutely necessary time

 

[metengr]

My very simple answer is this weld joint configuration does not lend itself to adequate interpretation with RT.

 

[EdStainless]

Unless you have the sectioned samples to show what the x-ray means I wouldn't accept it.
There is no standard way to read that x-ray because of the angles involved.

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P.E. Metallurgy, Plymouth Tube

 

[JR97]

teokal,

Lacking any other information, I would interpret the radiograph as lack of penetration at the root. If you look at the image,near the 6:00 position the indication gets wider and darker. On the right side it is not continuous but intermittent. That is typical of a lack of penetration in the root area. The gap between the tube and tubesheet would not be in the plane of the radiation so would not show on the film. If it did it would appear as a wide light grey area, not a sharp black line. I echo the other responders to section some mock-up welds. I believe what you will find is the weld did not melt tubesheet/tube at the intersection resulting in a lack of penetration; similar to what you might see on a fillet weld.

JR97

 

[r6155]

Discard RT for your experiment.

Regards
r6155

 

[teokal]

r6155, great idea, but cannot do...
metengr, we do not really agree, RT image - when you know the joint configuration - is enough for interpretation and I would really like to find some excuse not to use it, but it's not my style and it is requested as contractual obligation...
JR97, totally agree, we are repeating our experiment...
EdStainless, the sectioned samples also show incomplete penetration, and we verify what we see on the films.
What I understand, is that RT can be done, pretty easily, the "shadow" I was talking about in my opening thread is really an incomplete penetration, and we have to work more to achieve a full penetration tube to tubesheet weld...
I think that a RP or Spec for tube to tubesheet welds RT could be issued, in order to standartize this test.
Thank you all, guys

Only best result in absolutely necessary time

 

[SJmetallurgist]

Happy to see this matter being discussed here. I work as client and being the QC incharge here, it is very usual for us to get RT examination done on TTS welds as advised by EEMUA doc no. 143. But this RT our vendors conduct for mock up procedure qualification purposes. As such, in my company we have not yet asked any vendor to perform RT examination of production welds. However, I remember a dedicated discussion on this matter with a BASF QC Dept head where he took pride in telling me that their company has very dedicatedly worked with some other companied to devise methods of examining TTS welds for RT.
I am happy to share with you the open source paper written jointly on this subject. And must also re-affirm that your technique is correct. Hope the attached literature re-affirms your technique to you.

The defect shows looks like lack of penetration, which can be ascertained physically by sectioning the tube and i undertand from yr above replies that you have already done that. RT is usual to be done on TTS weld mock up qualification but quite unusual to be asked to be examined on TTS production welds.

Cheers!!!
Shashank