Can a quick opening vessel be U stamped?

[trevornelson]

Hi all,
The question is:
Many closure manufacturers advertise that they can supply U stamp and u-2A partial data reports. Can you U stamp a QOC as it isn't a pressure retaining part until it is welded into a vessel and cannot be pressure tested until welded in?

In Europe the complete vessel is PED certified post hydrotest. Separate components like valves are PED certified ( they are treated differently) but the whole vessel certification then overrides. PED does not cover QOC as they are classed as pipe fittings.

I am thinking UG-11 also classes QOC as pipe fittings so can you legitimately U stamp a QOC or is the U stamp thing on closures a marketing ploy?

IF it is a ploy how do they do this? is it they have U stamp for whole pig trap barrel fabrication and just stamp the QOC because they have the stamp??

I am confused and cannot find definitive clarification in the standards as it isn't ( unless some king engineer can point to the clause) that says QOC yes or no for stamping. I do not want to procure a closure that isnt stamped if it legitimately requires a stamp, but likewise I would like to be advised on the regs as I want to interperate them correctly.

Thanks


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[gr2vessels]

The QOC doesn't need to be welded anywhere for hydrotest and U-stamping. It can be designed, fabricated, tested and certified/stamped in accordance with ASME VIII code, as a pressure vessel component, not as a piping component (UG-35.2). Refer also to the design of a pig launcher/receiver as a pressure vessel, not as a piping item. I am surprised to your statement that PED is considering QOC's only as pipe fittings. For example, DNV-OS-F101 specifically regulates the design of pig launcher/receivers as pressure vessels, not piping components, including their QOC (refer Table 5-13).
Hope this helps, Cheers,
gr2vessels

 

[trevornelson]

Hi gr2 vessels
Sorry I still find this unclear.

UG35 covers design requirements of QOC, which I understand. I think what I need is which part of the code covers U stamp applicability? I was under the impression that a U stamp covered the pressure vessel, can individual components be individually stamped? and if so is there a list of components that can be stamped. Is there an ASME code that covers just U stamping and what, and what not can be stamped?

In a list I require:
1. Which part of the code lists QOC as a competent that can be U stamped individual to the vessel.
2. What conditions would be required for the U stamp. I guess stamp holder, Design to ASME inc ug35, materials, hydrotest
3. How can you stamp without hydrotest? The only way to test a closure without welding due to BWH is to machine the rear hub as long hub with a blind , pressure test the closure, and cut off the blind and machine down to a weld prep.IS this required every time as I have seen U2A data reports with notes stating not pressure tested. In which case how can they e stamped?
4. Can a closure company that doesn't make vessels or launchers have U stamp accreditation? considering U stamp is a vessel stamp. Is there a lesser stamp for just component suppliers?


I agree on your comments re DNV F101, that however is an offshore code. PED covers on land applications only in which case Closures are treated as pipe fittings and cannot be individually CE marked. Strangely Valves can be CE marked but closures and pressure retaining pipe fittings not. Crazy I know but true.

I apologies if I am missing something here, but I think I am missing something here! I cannot find a ASME tech helpline or equivalent either which could give me an answer direct from ASME.

Thank you for your time , I appreciate it.

Trevor.

 

[gr2vessels]

1. The ASME Boiler and Pressure Vessel Code provides rules for the construction of boilers, pressure vessels, and nuclear components. This includes requirements for materials, design, fabrication, examination, inspection, and stamping. Items constructed in accordance with all of the applicable rules of the Code are identified with the official Code Symbol Stamp described in the governing Section of the Code. That includes UG-35.2. Hence, a fabricator of QOC with U-stamp accreditation can stamp his product accordingly.
2. U-1(e)(3) pressure retaining covers for vessel openings, such as manhole or handhole covers, and bolted covers with their attaching bolting and nuts;
3. Please read UG-11.
4. Each QOC is hydrotested before U-stamp is applied on the name plate. Please contact the manufacturer for details of his hydrotest procedure. Just remember to not rush into making incorrect statements of hydrotest procedures;- the closure can be blinded both ends and hydrotested.
4. You seem a little bit confused about the applicability of the U-stamp. Please refer to entire ASME-VIII Div. 1. Yes, the components can be provided with partial certification in accordance with ASME VIII requirements. That includes the flanged covers you buy from the manufacturer (assuming you don't design and manufacture every single blind you use), prefabricated nozzles, ASME B16 flanges, etc.
5. Please note that the offshore code (DNV) cannot invent new codes, but use the existing ones, as listed in Table 5-13. As far as your statement 'PED covers on land applications only in which case Closures are treated as pipe fittings and cannot be individually CE marked', I could not find any evidence, would you please substantiate the statement?
Cheers,
gr2vessels

 

[LittleEd]

The QOC can be U stamped as a PART, not a complete vessel. When only a PART of a vessel is fabricated, the U-2 or U-2A Mfr's Partial Data Report is completed instead of U-1 or U-1A. Hydrostatic testing would occur when the vessel the QOC PART is welded into is completed. The U-1 or U-1A mfrs data report must include the reference for the U-2 or U-2A partial data report of the QOC incorporated into the completed vessel.

So you can U stamp complete vessels and you can also U stamp PARTs that go into making complete vessels (such as hinged closures, tank heads, rolled & welded shells).