Vessel and Pipe Pad Reinforced Lug Load tests

2/14/2013 (R0)

The accuracy of WRC 107 and FEA stress results have been questioned for pad reinforced clips and lugs where the pad and surface of the run pipe or vessel are modeled as a single integral plate or as a single shell whose thickness is equal to the pad thickness.   Both conservative and non-conservative errors of two or more are thought to exist depending on the geometry.  To support improved models of these constructions using finite element analysis Paulin Research Group (PRG) funded and conducted the test shown in Figure 1 below. 

In the new release we are going to be able to take this test into account!!


Figure 1 – Paulin Research Group Pad Reinforced Lug Load Test

The Phase 1 static, elastic load test showed that the concern was warranted and provided direction for further testing that is currently underway.    NozzlePRO model options have been added to PRG software to simulate the different methods commonly used for welding lug type geometries.  Three commonly used lug geometries are shown below.

test2test3Type 1 Lug


test4test5Type 2 Lug


test6test7Type 3 Lug



Figure 2 – Stress in Lug Type 1.  NozzlePRO – Separate Pad and Parent Shell Model



Figure 3 – Stress in Lug Type 2/3. NozzlePRO – Integral Pad and Parent Shell Model