“历史地看待”法兰刚度系数ASME VIII-1-2021版中明确了，下图所示的3种的“凸形盖”，即标准的图1-6 (b) (c) (d) ，不必遵循标准的法兰刚度要求。“凸形盖”为CACI版译名，GB/T 150.3称为“带法兰的凸形封头”。标准原文如下：（最后一句为2021版新增）1-6 DISHED COVERS (BOLTED HEADS)(a) Dished heads with bolting flanges, bothconcave and convex to the pressure and conforming to the several typesillustrated in Figure 1-6, shall be designed in accordancewith the equations which follow.Flanges designed to Figure 1-6, sketches (b), (c), and (d)do not needto comply with the rulesin2-14.但图1-6 (a)所示的“凸形盖”不在免除之列。
