Which thickness (shell/ nozzle neck thickness or higher one) will have to be considered for welding procedure qualification for a shell to nozzle corner joint (for set-in and/ or set-on type construction).

As per IX-80-67
For set-in type construction, only shell thickness is to be considered and for set-on construction, nozzle neck thickness is a consideration.

As per IX-98-20
As per interpretation, higher thickness of joining elements of dissimilar thickness is to be considered for qualification.

Even though the joint configurations indicated in the interpretation IX-98-20 are not exactly for shell-nozzle joints, do we need to consider this interpretation for shell-nozzle corner joints as well. Is interpretation IX-80-67 still in use or obsolete.
If for shell-nozzle corner joint, interpretation IX-98-20 is not applicable, what may be the reason for different interpretations/ requirements for almost similar joint types?

Regards
SS

Sorry, I do not agree with any of the two: In both cases both min (presumably nozzle pipe) and max (presumably shell) thk. shall be considered.
Mauro

Mauro,

Its not a matter of agreement or disagreement, there are two interpretations from ASME and appears to be contradicting on logical ground so the questions are;

1. Whether IX-80-67 is still in use or obsolete?
2. Whether IX-98-20 is applicable for corner joint of shell-nozzle welding?
3. If IX-98-20 is not applicable for shell-nozzle corner joint, what may be the reason for different interpretation for almost similar joint configurations?

or to make it simple, if I have a shell (18 mm thk) - nozzle (nozzle neck - 75 mm thk) corner joint (set-in type), which thickness will govern for qualifying welding procedure?

Regards

Hi SS,

I agree with Mauro.

However, I think we don’t need a interpretation, it is time to read the code.
Important for the answer is the joint. Unfortunately this fact is not mentioned in you question. Therefore, I assume the joint is a groove joint.

The common used processes GTAW, SMAW, GMAW and SAW guide you in the tables QW-253 through QW-256 for the qualified base metal thickness to QW-403.8 und for the qualified deposited weld metal to QW-404.30. Both paragraphs give the reference to the well-known and confusing table QW-451.
In this table you find two columns for the qualified thicknesses of a joint. One column for “Range of Thickness T of Base Metal, Qualified” and one column “Maximum Thickness t of Deposited Weld Metal, Qualified”. That means you have to consider both the base metal thickness (capital letter T) and the weld metal thickness (lower case letter t).
In this table are more notes than content. And unfortunately one of these beautiful notes is the key to your question.


The applicable referenced paragraph for your case is QW-202.4.

That means if the thickness of both members of a groove joint are different you have to consider base metal thickness T1, base metal thickness T2 and the thickness of the weld metal t.

Please note in addition Interpretation IX-80-67 is not obsolete, but was revised:

_________________
Kind regards,
Juergen Fleischfresser

Hi Juergen,

Thanks for your detailed explanation. Yes your assumption was correct for groove joint to figure UG 40- d or e.

If I understood it correctly, for shell - nozzle corner joint to fig UG 40 (d/ e) (shell = 20 mm, nozzle neck = 75 mm) , I am required to qualify a welding procedure using at least 38 mm coupon (considering SMAW/ SAW/ GMAW/ GTAW processes).

Thanks for highlighing revision in IX-80-67 but isn't it like abolishing the interpretation which used to allow qualification based on shell thickness (actual weld deposit thickness)

Any idea about the logic for using higher thickness for welding qualification when the actual weld deposit thickness is much less.

Regards
Sanjeev

Quote:
Any idea about the logic for using higher thickness for welding qualification when the actual weld deposit thickness is much less.

Regards
Sanjeev[/quote]

Weld metal and base metal thk. are two different issues and they influence the metallurgy of the weld in two different ways. e.g.
Base metal thk. as increases adds the capacity of the base metal to draw heat
Weld metal thk as increases adds heat
General consideration about different Interpretation: They are just interpretion, not Code, they may have been issued by different persons and may be different, answers depend very much on how the question has been formulated.
Mauro