Korbbogenboden (DIN28013) ASME Code Section VIII, Division 1

A Korbbogenboden according to DIN 28013 has a crown radius of 0,8 and a knuckle radius of 0,154 x D₀ of its cylindrical skirt. Against the background of the tolerances listed in Section VIII, Division 1, UG-81(a), a 2:1 elliptical head would meet both these requirements and is thus sometimes considered as equivalent. However, as the design formulas for these two types of heads are different, they also result in different required thicknesses. The required thickness of a Korbbogenboden according to ASME Code is slightly greater than that of a 2:1 elliptical head. Is the head specified as “Korbbogenboden”, using the wrong formula would therefore lead to a smaller than required wall thickness.

When performing a UG-37 reinforcement calculation for a nozzle which is completely located in the crown (incl. its reinforcement area), the “Korbbogenboden” is more favourable. The reason being that for reinforcement calculations the crown of a 2:1 elliptical head is determined with 0,9 D₀ instead of 0,8 D₀. Thus there is less reinforcement area available for the compensation of the opening.

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