Minimum wall thickness in bends Minimum wall thickness in bends finiteinjustice123 (Mechanical) (OP) 12 Jun 15 08:05 If during procurement of fired heater 180 Deg Return bends 2 min. wall thickness are specified for e.g. "Return Bend 180 SR 168.3 OD * 22.5 MW * 13.0 MW WP 22" What does it mean. Which min. thk shall be considered for acceptance of the procured material Thanks in Advance "j" "jmd" RE: Minimum wall thickness in bends metengr (Materials) 13 Jun 15 00:20 The minimum wall thickness for 180 degree return bends is the minimum thickness based on design pressure at temperature conditions for straight tube material. RE: Minimum wall thickness in bends bellowsmfg (Aerospace) 16 Jun 15 17:29 metengr is correct. Depending on how the elbow/180 degree bend is formed, there are thinning calculations to determined the final wall thickness of the bend. However, the wall thickness's of available pipe are standard so you usually have some fat in the selection (be is schedule 10, 40, 80 and so on). Calculate for the minimum thickness for the straight pipe and take it from there. Bellows Manufacturing and Research, Inc. https://bellowsmfg.com RE: Minimum wall thickness in bends weldstan (Materials) 28 Jun 15 16:48 Also understand that calcs can be made on ID or OD dimensions.