Examples - PV Elite - Help - Hexagon

Examples illustrating these principles are located in the CodeCalc\Examples directory.

Figure F - Vessel and Nozzle Direction Cosines

After confirming that the geometry guidelines according to WRC 107 are met, the actual preparation of the WRC 107 calculation input can now begin. One of the most important steps in the WRC 107 procedure is to identify the correlation between the stress output global coordinates and the WRC 107 local axes. The software performs this conversion automatically. You will, however, have to identify the vectors defining the vessel as well as the nozzle centerline. The following figure illustrates the definition of the direction vectors of the vessel and the nozzle:

Figure G - Converting Forces/Moments in CAESAR II Global Coordinates to WRC 107 Local Axes

In order to define a vessel direction vector, you must first designate the output data points (A to D) as defined by the WRC 107 bulletin. The line between data points B and A defines the vessel centerline, except for nozzles on heads, where the vessel centerline will have to be defined along a direction which is perpendicular to that of the nozzle. In the vessel/nozzle configuration shown, because point A is assigned to the bottom of the nozzle, the vessel direction vector can be written as (0.0, -1.0, 0.0), while the nozzle direction vector is (1.0, 0.0, 0.0). The nozzle direction vector is always defined as the vector pointing from the vessel nozzle connection to the centerline of vessel.

For different load cases (SUS, EXP, OCC), the restraint loads (forces and moments) can be obtained from typical piping stress analysis program like CAESAR II. These loads reflect the action of the piping on the vessel. The following data would then be entered into the WRC 107 program. You can use either the WRC-107 or global convention. The program will supply a pass/fail status at the end of the report. While on the input screen you can also toggle from one convention to another and the program will transform the loads automatically between the two conventions.