Openings made from plate per Section VIII-Div 1. 1

[4glennb]

An Authorized Inspection Agency is telling me that when welding openings manufactured from plate (in this case SA516-70 manway into an LPG storage tank) directly to the vessel shell or head per Figure UW-16.1(i) that act as a integrally reinforced opening that is calculated as an optional type flange per Appendix 2 must also meet the requirements of UW-13(f) (1) and (2) for material testing. I am arguing that the nozzle is not a Hub type flange as described in UW-13(f) and that it is not used for tubesheet applications as described in appendix 20 therefore does not require test specimen per Fig UW-13.3. Has anyone encountered this problem before??

 

[TomBarsh]

I got lost at "...act as a integrally reinforced opening that is calculated as an optional type flange per Appendix 2".

I assume in this case the SA-516-70 plate is rolled to a ring, welded the seam, then this cylinder forms the neck of the manway. Sounds like integral reinforcement as long as the weld to shell meets those rules. But where does the Appendix 2 flange issue come in?

What is attached to the end of the nozzle neck?

 

[4glennb]

The manway is cut from 2.5" plate x 16" ID x 21" OD SA516-70 and is welded to a 109"OD tank, in the center of the head. There is not welded seam because it is cut ID/OD in the plate. The ring is welded in the head and forms a category D joint. So the nozzle is the plate and a bolt pattern and gasket is machined in the plate. A flat cover is bolted to the welded ring.

Sorry for the confusion.

 

[waskillywabbit]

So you are saying that you have a hole cut in the top of the center of the head and then you are welding on a plate flange w/ a cover bolted on? No nozzle neck? I've never seen that. Interesting if that is the case...

Brian
Pressure Vessels and Autoclave Systems

http://www.mcabeeconstruction.com

The above comments/opinions are solely my own and not those of McAbee Construction.

 

[TomBarsh]

Thanks for clarifying. This sounds like what's known as a studding outlet. In this case, I am tempted to agree with the AIA even though the words of the Code (that I can find) don't seem to require it.

Appendix 2, para 2-2(d) addresses *hubbed* flanges, not, say, slip-on flanges and doesn't allow us just to cookie cutter them out of plate. But on the other hand, the loads acting on your flange are different from those acting on an App 2 flange (well, I guess a reverse flange is similar).

So, I can't point to a Code paragraph to support what the AI says. Sounds good though. ;-)

 

[prex]

gbuck,
you are likely referring to fig UW-16(p), or possibly your flange is inserted into a hole with the same diameter as the OD of the ring (can't find a figure directly applicable to this, possibly your ref.to UW-16(i) is correct, though this doesn't exactly represent your case IMO).
Now can't see where's the hub, so don't understand the position of your AIA. The wording of UW-13(f) is very clear, you must have a machined hub for it be applicable (whilst the fact that a tubesheet or flat head is referenced is less important).
The worryings behind UW-13(f)(2) are clearly two:
1) when the hub is machined from plate, the resistance of the hub to tearing may be impaired by defects in the lamination
2) point 1 is important only if the pressure load passes, at least partly, through the hub (but of course the hub is normally there only for that).
Neither of these two points is applicable to your flange, if my understanding of your geometry is correct.

prex

http://www.xcalcs.com

Online tools for structural design

 

[4glennb]

Thanks prex for the comment. I refered to Fig UW-16.1(i) because this is how the nozzle is welded into the head. The OD of the flange is welded into the head. This is a common practice in the LPG industry. I think that you are correct in your assessment and this is what I explained to the AI. I am trying to fond an interpretation that would confirm what you described.

Many thanks.

 

[deanc]

IMO: See UG-93(d)(3)

 

[4glennb]

Thanks for the post. The flange is inspected in accordance with UG-93(d)(3).