Radiography requirement of nozzles
Radiography requirement of nozzles
(OP)
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!
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!





RE: Radiography requirement of nozzles
I have never run into this as we fix it without even thinking about it
RE: Radiography requirement of nozzles
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.
RE: Radiography requirement of nozzles
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.
RE: Radiography requirement of nozzles
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).
RE: Radiography requirement of nozzles
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.
RE: Radiography requirement of nozzles
Also see ASME VIII Div. 1 UW-35 and UW-38
"Defects" are not allowed in all codes in the world.
Regards
r6155
RE: Radiography requirement of nozzles
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.
RE: Radiography requirement of nozzles
Hence these requirements shall be done is welds are radiographed or not.
Regards
r6155
RE: Radiography requirement of nozzles
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
RE: Radiography requirement of nozzles