Module B6
According to AD B6 Section 7.1.2, a pipe bend cannot
be considered as a stiffener.
This also applies analogously to expansion joints.
Underground cylindrical apparatus (PDF 400K)
From: Dietrich Gleich, Richard Weyl, Apparateelemente, Praxis der sicheren Auslegung, Springer Verlag Berlin Heidelberg 2006 (pp. 85 - 89).
Area moment of inertia calculation (external link)
To do this, select the option 'Calculation of cylindrical shells with expansion joints' when starting the module. See picture.
Non-closed internal support rings on columns as well as guide spirals on the outside of vessels as stiffeners in case of external overpressure
Non-closed internal support rings (e.g. on columns) must not be considered as stiffeners against external pressure / vacuum. A calculation method for non-closed support rings is provided by EN 13445-3.
Closed internal support rings can be taken into account if they meet the requirements of AD 2000-Merkblatt B6. However, this must be noted on the main drawing so that they are not removed during rebuilding.
Guide spirals on the outside of a vessel can be used as stiffeners - with a pitch angle less than or equal to 20° - in the calculation if they meet the requirements of AD 2000-Merkblatt B6. The bulge length l corresponds to the axial length of 2 turns of the guide spiral.
In TGL 32 903/22 it is specified that guide spirals can be considered as stiffening rings if the pitch ts (l2) of the guide spiral is not greater than 0.3 x Di. This specification can be adopted.
Stiffening by half pipe coils (PDF 500K)
From: Eberhard Wegener, Festigkeitsberechnung Verfahrenstechnischer Apparate, Wiley-VCH, Weinheim 2002