Radiography requirement of nozzles 2

[jgibbs22]

Hi:

Got a two part question for everyone. In a non-lethal, 10,000 psi pressure vessel, would a 1/2" grayloc hub being used as a nozzle on a hemispherical hub be required to have radiography performed on the weld? I did not think so due to the size and not using table UW-12 values in the design but wanted to confirm.

Secondly, if RT was performe even if not required and incomplete penetration was discovered, would it still be considered Code rejectaboel and need to be repaired even if the RT was not required in the first place?

Thanks!

 

[vesselfab]

If you find a rejectable weld, you are morally obligated to fix it. Whether code requires it or not.

I have never run into this as we fix it without even thinking about it

 

[Mr168]

While I don't necessarily disagree with vesselfab, no, something is not code rejectable if you have failed NDE that was not code required. This situation comes up a LOT, and often ends up in litigation with large sums of money at stake.

In my experiences, engineering usually says "fix it", and the rest is left up to the procurement and legal teams to take care of going after the backcharges. I don't necessarily feel morally obligated to fix something that wasn't by definition "broken" in the first place, unless there is a definite safety or performance concern, or negligence was the apparent cause.

 

[Duwe6]

Mr158, I have to respectfully disagree. Or perhaps it is a semantics problem.

Defects [ASME calls them 'indications'] are allowed under all Codes -- nothing is required to be perfect.

Rejectable Defects are 'indications' that are of a sufficient nature to cause the product/vessel to fail to meet the required specification / Code. Even if a Rejectable Defect is found by accident, it is still Rejectable and repair or 'scrap & replace' is mandatory.

Example: Full RT per ASME Sect VIII has limits on porosity, and if exceeded, repairs are required. 'Spot' RT under Sect VIII ignors porosity. With the decreased joint efficiency caused by "Spot", porosity is not a Rejectable Defect.

Thus, if you found porosity in a nozzle weld [does not require RT], it is an 'irrelevant indication', or a non-Rejectable defect. If you found Lack-of-Fusion or Incomplete Penetration, those are considered Rejectable under any circumstances. It is a very fine line you are required to draw.

 

[puigi]

Answering this question is not possible without knowing the specific configuration and material of the vessel and fitting, perhaps you should consult your AI on this.
I do not understand your statement about not using the joint efficiencies values listed in table UW-12 in the design.
RT exempttions are listed in UW-11. For specific exemptions based on the material of construction consult the applicable code sections listed in UW-11(2).

 

[bernoullies123]

Response to question 1:
No idea, as I don't have a copy of the code on my wife's computer, nor is there enough info to respond. UT can be used in lieu of RT, RT can be used on full pene, but not on the junction of the nozzle etc. etc.

Response to question 2:
No, simple as that. Your query is about the requirements of the code. Aside from the code, would it be ethical or not... well that is up to you.

 

[r6155]

Please, see ASME V Article 30 "Terminology for Nondestructive Examinations Standard - SE-1316" and search defect, indication, imperfection.

Also see ASME VIII Div. 1 UW-35 and UW-38

"Defects" are not allowed in all codes in the world.

Regards

r6155

 

[EuroWeld]

We had a almost equal situation in the past. By accident we photographed parts of some set in branch welds while examining other welds. The film showed some indications in the branch weld that were not acceptable according to the applied code. But acceptance criteria is not made for this application and becuase these welds were not rt in the beginning this means that these welds are less relevant than CW and LW. Also because misallignement of the source the indications were enlarged on film. We were feeling morally obligated to fix and started milling and hoping to find the indication; nothing could be found. After re-welding and rt afterwile indications were still present, but now less.

According to the code there welds should have only be Penetrant tested. So does these apparatus meet the requirement of the design code? I think, yes. But is it safe, that's another question!

We discussed this matter with our AI and enlarged the hydrostatic test pressure and both apparatus passed the test.
Reason not be go on with repairing is that material is Titanium Grade 2 and we were afraid of grain growth and damage. So apparatus were delivered knowing indications are present. Now almost 10 years later devices are still in service.

In general my opinion is to examine the risks before starting the repairs knowing that in some situations you do more damage than leaving it untouched. All pressure equipment that you fabricate and deliver must be safe for service, taking this as your starting point. Every situation is different and must be studied serarate.

 

[r6155]

Please see "UW-35 a) Butt welded joints shall have complete penetration and full fusion"
Hence these requirements shall be done is welds are radiographed or not.

Regards

r6155

 

[WBH]

jgibbs22,


Question 2:

YES, Even if it was not a code requirement to RT, and you have discovered a condition that exceeds the applicable fabrication code, it is to be repaired to that code.

Why was the weld in question radiographed to be begin with?

Let me ask you another question:
If you accepted, the above item based upon the fact "code did not require RT". Is the condition still present and rejectable by the fabrication code?


WBH

 

[stanweld]

Please review U-1(d). It would appear that your basis for design may well be in error.