Extruded opening in vessel shell

[rww88]

Is the extruded opening shown in the attached drawing practically feasible, either through hot or cold forming? If so, what would be a sensible size (diameter) for the pre-hole? The material is low-allow carbon steel.

 

[TGS4]

What is your Code of Construction? 5/8" thickness must have some decent pressure...

 

[JStephen]

I wouldn't doubt there're shops that could do it, but not ours. Anything we do is either going to be a commercially available fitting or built up by welding from plate, pipe, and flanges.
What is the motivation for doing it like that?
Depending on the thickness, that detail might require additional reinforcing.

 

[rww88]

TGS4 and JStephen, to answer your questions: It is totally a hypothetical, literally extracted from my anatomy. The thickness is derived from 300 psig (internal) and 36 inch diameter ASME flanged and dished head plus corrosion allowance. I was encouraged to seek advice in this forum because days of research attempting to find meaningful technical information regarding the recommended methods of forming extruded flued openings in pressure vessels (ASME Section VIII Division 1 UG-38) shells has proven fruitless. (Figure UG-38 shows an elliptical opening formed in a relatively thin section.) I could not uncover any information or guidance regarding pre-hole size relative to the final extruded inside diameter, nor whether hot versus cold forming would be indicated.

 

[EdStainless]

I know of some HX guys that do this all of the time, they are tooled for specific sizes.
Though these usual go outward, in 36" it shouldn't be too hard.
They just pull a well lubricated tool steel ball through the hole.
You can estimate by the wall height that you want to end up with.
You need some extra so that you can machine the end off square, and then do a true butt weld to it.

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P.E. Metallurgy, Plymouth Tube

 

[rww88]

Thanks for the information EdStainless. A rough calculation based on the dimensions shown in my drawing indicates that the maximum pre-hole diameter could not exceed something on the order of: d = 8.75-[5.89+2(3-1.875)]= 5/8 inch. Does this seem ridiculously small or am I just missing something here? I mean, would the process be one of progressively pulling incrementally larger, well lubricated tool steel balls through the hole, until the desired final opening diameter is achieved?

 

[rb1957]

though I'd expect to lose some thickness, where the shell gets drawn.

another day in paradise, or is paradise one day closer ?

 

[EdStainless]

I have never seen one quite this large done, but they are usually done in one pass.
I would guess that the starting hole is more like 3"-4".
At this size it wouldn't actually be a ball, probably more of a bullet shape.
They are pulled through, that way to are pushing against the backing support.
You will need some backing support, like a thick ring with 10" ID and the 1.25" corner radius.
The wall will get thinner as you draw it.

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P.E. Metallurgy, Plymouth Tube

 

[rww88]

Thanks Ed for your comments. I find it interesting that the ASME Code broaches this topic as important, because apparently this particular opening configuration must not be typically widely employed. As JStephen previously outlined, there exists probably easier and certainly more economical means to accomplish virtually the same end-result. I will continue my quest for knowledge on this particular subject, and contribute anything I find educational to this thread.