Boiler Tube Bends
Boiler Tube Bends
(OP)
Does anyone know what the maximum thinning of the outer radius of a boiler tube bend is? I seem to remember the thickness after bending had to be within 10% of the original nominal thickness. But I can't find this anywhere in the ASME Codes or the NBIC.
Thanks





RE: Boiler Tube Bends
I have heard people use 5% or 10% variations, but I have never been able to locate any specific requirements in the ASME B&PV Code. Therefore, I revert back to SA 450 and treat tube bends using the permissible ovality and wall thickness variations listed in Table 2.
RE: Boiler Tube Bends
rmw
RE: Boiler Tube Bends
European codes specifically allow the thinnning, because the toroidal equations demonstrate that the use of 2 radii of curvature enhances the strength and allows the use of a thinner wall to restrain membrane stresses, without taking credit for work hardening. See EN 12952-2:2001 par A.4.2
RE: Boiler Tube Bends
The star is for knowing about EN 12952 of which there are 15 parts.
The formula that you refer to comes from TRD the German boiler code who are the secretariat for EN 12952. This probably explains why they look so much like DIN/TRD's. This is especially true for part 15.
regards
athomas236