This study will focus on the galling of studs and what impact that has on the overall performance of a Bolted Flange Joint Assembly. Galling or “cold welding” occurs more so with softer metals. While tightening the nut on to the stud the contact metal will “pull” away from itself and the two surfaces will essentially become one. Once this happens the nut cannot be tightened or loosened and often cutting the stud is the only form of removal.

We’ll be studying how this affects the performance (tightness) of a bolted flange joint assembly. Does the assembly loosen over time or does it remain at the proper tightness? Data will be captured using load cells to accurately represent the amount of force being generated by test studs. There will be a standard test ran with no galling. All other tests with galled studs will be measured and compared against the standard test. One test with only one stud galled, the next with two studs galled, the next with three studs galled, and so on. It may be expected to see some load loss on the load cells with the galled studs. The integrity of the studs, once galled, becomes less than ideal.

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