I've a circular vessel with helicoidal rectangular limpet coil to calculate.

How can I calculate this limpet coil under ASME ????? Section 1, Section 2 or ?????????

Thanks for your answers or guidances.

My suggestion is FEA for Division 2. For Division 1 use U-2(g) and FEA or App. 13 and UG-34 or App. 9 or ... . It depends on your design which rules can be applied.
Michael

Dear Frohnert, many thancks for your answer.

Main capacity, is a cylindrical "standard" vessel with a positive pressure (0,80 MPa) (Ø OD # 1500 mm - height # 2000 mm - material SA 516 Grade 60). Externally, is welded a rectangular channel with an helicoidal pitch. Inside this channel, we can find hot water (80°C) with 0,30 MPa of positive pressure. This channel is build like an U profile rolled with pitch.

Like we've pressure inside main shell, pressure inside channel, I thinck that FEA we'll be the best way to confirm thicknesses ???????