Addressing Gusset Problems: Pipe Cracking Part 1

A key to any piping evaluation program is to understand where problems can occur. Vibrating piping can propagate a crack relatively quickly. Have you ever installed gussets to stabilize a vibrating pipe situation only to find, shortly thereafter, that the gussets have cracked the pipe? If so, you've got lots of company.

The fundamental problem is that gussets, such as shown in Figure 1, are stiffeners, not strengtheners. It is possible to concentrate the stresses, which were distributed over a broad area in the pipe wall, into a small area at each end of a respective gusset plate. A typical condition at a plate end is shown in Figure 2. Here the plate is welded along each side, but the end is left unwelded. The highest vibration stress load is carried by only a small portion of the ends of these welds.