UW-12(d) interpretation

[muld0020]

How should UW-12(d) be interpreted for an ASME CODE heat exchanger that has a seamless tube side (cup forging) with a bolted cover and welded nozzles (welded shell side)? (The cup forging is an integral tubesheet/shell/flange on the tube side, with a shell welded to the shell side of the tubesheet).

It would be my understanding that the effeciency (E from UG-27) would be = 1 (for the tube side only), since there is no welding on the cric. and long. "seams" (no welding of a head), thus the seamless vessel section does not need to meet the UW-12(d) requirements. (The shell side circ. seam would meet the applicable UW effeciency.)

My concerns would be if anyone could interpret this any other way, or if there would be any exceptions.

 

[InspectorByDay]

muld0020,

I'm not entirely sure I understand the design you describe, but for seamless tubing which does not contain the welds described in UW-11(a)(5)(b) the requirements for spot radiography in UW-12(d) would not apply and would allow E = 1 for you circumferential stress calcs.

Regards.

 

[muld0020]

Here is a quickie sketch of the situation.

 

[LSThill]

muld0020 (Mechanical)

Question: is your exchanger TEMA Type DEU heat exchanger one pas shell side, two presses tube side

TUVE SIDE: PRESSURE?

 

[muld0020]

I don't see where the pressure or TEMA type come into play here. I'm concerned that if I have a seamless section of material on the tube side (no welds other than nozzles), should my efficiency "E" be equal to 1 or 0.85 (ref. UW-12(d)) for the shell thickness calculation (ref. UG-27). I would say per UW-1 my tube side is not welded therefore specifically UW-12(d) does not apply, the calculation in UG-27 should use E = 1. The tube side can't be RT'd since it is one piece which is where the "E" comes into play anyway.

This is a hypothetical situation so you can assume the following:

Tube side = 3000 psig
Shell side = less than tube side
Sec. VIII Div 1
Material of Tube Side (Tubesheet/Channel Barrel) = SA350 LF2 Cl.1
Material of Shell Side (Shell) = SA516 Gr70

I just want to cover my bases and be certain that choosing E = 1 correct and justifiable.

 

[SnTMan]

muld0020, UW-12 assigns joint efficiencies, based on RT, for various details. You are correct in using E = 1.0 for seamless components. You will see from Type (7) that the concept of joint efficiency for corner joints, such as nozzle attachments, is not applicable.

Regards,

Mike

 

[InspectorJim]

I think since there is no head to shell weld seam you are correct in using 1.0 for your efficiency for UG-27 calc.

 

[InspectorByDay]

If there are no welds then there are no weld categories or joint types. If there are no weld categories or joint types, UW-12(d) would not apply since you having nothing which puts you into UW-11(a)(5)(b).

E = 1 for the channel shell.

The tube sheet ligament efficiency will be per Part UHX for tubesheets integral to channel and shell.

If the shell side is seamless (or welded pipe) with a headed attached with a Type 7 joint, as it appears it is welded to the tubesheet by a corner joint as well, then E would also be 1 regardless of SRT to UW-11(a)(5)(b).

Regards.