Formation of Cones by Petal Constrction.

[DK44]

Dears,
Request clarifications

For ASME SEC VIII Div 1, is it permissible to form CS & LAS Cones from Plate by Petal Construction.

1. Normally I understand that the Cones are rolled in segments (without thinning) and joined together with staggered L-Seams.

2. The term Petal constriction will imply that the segments are either Cold Pressed or Hot Pressed without impairing the mechanical properties of the material.

2.1 Only Larger size Dished Heads segments are formed in Crown & Petal Construction involving Cold / Hot Pressing without impairing the mechanical properties of the materials. Hence Petal constriction does not apply to Cone formation.

3. I understand Code provisions of UCS-79 / UG-79

 

[SnTMan]

DK44, my experience with cones is limited to shell & tube heat exchangers of moderate size, mostly eccentric cones, but some concentric as well:

Cones are ordinarly formed from two sections made by multiple small bends formed on a press brake. The long seams are normally on the 90-180 planes. As there is no appreciable thinning post-forming heat treat is not required. Larger or longer cones may of course be formed of as many sections as needed with multiple long seams and circ seams, depends on the forming entity's capabilities. I did have one design where the cone diameter and thickness was such that the vendor made it from four sections, four long seams.

I suppose cones can and are formed by rolling but have no experience with these. It seems unecessarily difficult but with modern equipment, maybe not. I suppose post forming heat treat requirement of the Code would apply.

I have no experience with heads formed from petals, no comment on this.

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[SnTMan]

So, having second thoughts here,

First, I should have said 90-270 (horizontal) plane.
Second, strain not thinning is the correct term.
Third, "As there is no appreciable thinning post-forming heat treat is not required." I am not sure this is true.
Fourth, my experience is with supply by an outside vendor, I really don't know if the vendor post-form heat treated, but I doubt it.

Other than that, I stand by everyting I said

I suppose one should treat a cone as a cylinder under UG-79, it would seem the snall end would govern.



The problem with sloppy work is that the supply FAR EXCEEDS the demand