Thickness of cylidrcal shell under external pressure 1

[vinothsvk]

Dear all,
I am vinoth. I have one doubt. In ASME SEC VIII DIV I UG-28(C), some procedure is given for calculating the required minimum thickness of cylindrical shell (or) tube under external pressure,either seamless (or) with longitudinal butt joints.

If the cylindrical shell have circumferential joint, can we apply the same procedure (UG-28(C)) for calculate the minimum required thickness under external pressure?

For example: Consider a horizontal vessel. Seam to seam length is 10000 mm. Vessel is fabricated by welding the shell course together.(shell course length is 2500 mm). In that case, the distance between the shell course, can we taken as total length(line support)?

Thanking you.have a nice day

 

[JStephen]

If the shell courses are all the same thickness, then yes, you treat it all as one shell with the appropriate total length.

 

[r6155]

it don't matter the quantity of circunferential welds.

Regards
r6155

 

[JG MechEng]

When calculation thickness for external pressure, the only length that matters is the calculated effective shell length. This is the max allowable unsupported shell can length; this value may be longer than the individual shell can lengths. No credit or penalty is taken for circ seams. This is how you determine where to put stiffening rings. Heads are considered to contribute to the shell stiffness so this would be a termination point.