A: shell start;

B: shell end;

C: center of bending axial curve;

Leg #1: end of cylindrical part at point A;

Leg #2: end of cylindrical part at point B.

Axis X and Y set bend plane;

angle θ of nozzle insertion is taken from this axis toward axis X;

Axis Z: shell longitudinal axis.

The positive bend angle α rotates point A toward point B around axis Z.

Used to set external loads on the ends or legs of the element:

Axis X: is directed to the axial arc center (coincides with the normal to the axial arc).

Axis Y: is directed along the normal to the elbow plane (coincides with the elbow Z local axis).

Axis Z: is directed along the tangent line to the axial elbow arc.

Designated as "CS leg #1" and "CS leg #2", that is computed at points A and B accordingly.

For point A, an inverted CS is used so that Z axis is directed towards leg #1.

All axis can be horizontal and vertical according to the shell options:

When the "Invert shell direction" option is selected the LCS is rotated around its Z axis by 180°.

If a negative bend angle is given (α < 0), then the LCS is rotated around its X axis by 180°.

For strength analysis (fig. 3.44):

Point A or leg #1.

When calculating allowable loads, stiffnesses and stress intensification factors for a nozzle (fig. 3.45):

Points A, B (legs #1 and #2).

Inner overpressure.

Outer pressure.

Hydrostatic pressure.

Thermal strains.

Concentrated loads to free end (B) or leg #2 for strength analysis (fig. 3.46):

Allowable loads for end B (fig. 3.47).

Stiffness and flexibility factors for end B (fig. 3.47).

Stress intensification factors (fig. 3.47).

The base element also allows to specify cylindrical legs #1 and #2.

If a negative value of the leg length is specified, then it is calculated as follows:

If negative values of the leg thickness and the weld size are given, then they are accepted as for the base element.