WRC Bulletin 107(537) - CAESAR II - Help

CAESAR II Users Guide

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CAESAR II Version
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The Welding Research Council Bulletin 107 (WRC 107) has been used extensively since 1965 to estimate local stresses in vessel/attachment junctions. There are three editions of the WRC 107 bulletin available in the software. You can set the default using Tools > Configure/Setup. For more information about the options available in the editor, see Configuration Editor.

In 2010, WRC Bulletin 537 was released. According to the foreword of WRC Bulletin 537, "WRC 537 provides exactly the same content in a more useful and clear format. It is not an update or a revision of 107." CAESAR II uses the graphs from Bulletin 107. Bulletin 537 simply provides equations in place of the curves found in Bulletin 107.

WRC Bulletin 107 provides an analytical tool to evaluate the vessel stresses in the immediate vicinity of a nozzle. You can use this method to compute the stresses at both the inner and outer surfaces of the vessel wall and report the stresses in the longitudinal and circumferential axes of the vessel/nozzle intersection. The convention adopted by WRC 107 to define the applicable orientations of the applied loads and stresses for both spherical and cylindrical vessels are shown below.

WRC 107 Module Geometry for a Sphere

WRC 107 Axis Convention for a Cylinder

Spherical Shells

Cylindrical Shells

Defining WRC Axes:

P-axis: Along nozzle centerline and positive entering vessel.

M1-axis: Perpendicular to nozzle centerline along convenient global axis.

M2-axis: Cross P-axis into M1 axis and the result is M2-axis.

Defining WRC Axes:

P-axis: Along nozzle centerline and positive entering vessel.

MC-axis: Along vessel centerline and positive to correspond with any parallel global axis.

M2-axis: Cross the P-axis with MC axis and result is ML-axis.

Defining WRC Stress Points:

u: Upper, stress on outside of vessel wall at junction.

l: Lower, stress on inside of vessel at junction.

A: Position on vessel at junction along negative M1 axis.

B: Position on vessel at junction along positive M2 axis.

C: Position on vessel at junction along positive M2 axis.

D: Position on vessel at junction along negative M2 axis.

Defining WRC Stress Points:

u: Upper, stress on outside of vessel wall at junction.

l: Lower, stress on inside of vessel at junction.

A: Position on vessel at junction along negative MC axis.

B: Position on vessel at junction, along positive MC axis.

C: Position on vessel at junction, along positive ML axis.

D: Position on vessel at junction, along negative ML axis.

Shear axis VC is parallel and in the same direction as the bending axis ML. Shear axis VL is parallel and in the opposite direction as the bending axis MC.

The WRC 107/537 convention system has the benefit of being independent of the orientation of the vessel. All loads and moments are defined locally with respect to the vessel and the nozzle.

The following WRC 107 convention system is used for a cylindrical vessel:

P - Radial load
Vc - Circumferential shear load
Vl - Longitudinal shear load
Mc - Circumferential moment
Ml - Longitudinal moment
Mt - Torsional moment


The following WRC 107 convention system is used for a spherical vessel:

P - Radial load
V1 - Shear load from points B to A
V2 - Shear load from points D to C
M1 - Moment from points A to B
M2 - Moment from points D to C
Mt - Torsional moment

WRC 107 is commonly used to conservatively estimate vessel shell stress state at the edge of a reinforcing pad. The stress state in the vessel wall when the nozzle has a reinforcing pad can be estimated by considering a solid plug with an outside diameter equal to the O.D. of the reinforcing pad, subjected to the same nozzle loading.

Before attempting to use WRC 107 to evaluate the stress state of any nozzle-vessel junction, always verify that the geometric restrictions limiting the application of WRC 107 are not exceeded. These vary according to the attachment and vessel types. Refer to the WRC 107 bulletin directory for this information.

Using WRC 107 is not recommended when the nozzle is very light or when the parameters in the WRC 107 data curves are unreasonably exceeded. Output from WRC 107 includes the figure numbers for the curves accessed, the curve abscissa, and the values retrieved. Check these outputs against the actual curve in WRC 107 to become familiar with the accuracy of the stresses calculated. For example, if parameters for a particular problem are always near or past the end of the figures curve data, then the calculated stresses may not be reliable.