A: shell start;

B: shell end;

Axis X: shell transverse axis;

Axis Y: shell transverse axis;

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

Axis Z: shell longitudinal axis.

Axis Z is located in horizontal plane.

Axis X and Y can be vertical according to the shell options:

For strength analysis (fig. 3.29):

Point A.

When calculating allowable loads, stiffnesses and stress intensification factors for a nozzle (fig. 3.30):

Points A, B.

Inner overpressure.

Outer pressure.

Hydrostatic pressure.

Thermal strains.

Concentrated loads to free end (B) for strength analysis (fig. 3.31):

Allowable loads for runhead pipe (fig. 3.32).

Stiffness and flexibility factors for runhead pipe (fig. 3.32).

Stress intensification factors (fig. 3.32).

The base element allows to add cylindrical segments at the start and end.

If the cylindrical segment length $l_{g1}$ ($l_{g2}$) is set to a negative or zero value (default), then the corresponding segment will not be added.

If the remaining values are set to negative values, they will be accepted as for the main part.

When is added the segment, the restriction on the distance from this edge to the fitting decreases by $\sqrt{0.3 D s}$.