Great care should be exercised when installing compression couplings, as installation errors can cause pipe failure resulting in expensive property claims. To process water damage claims accurately while identifying subrogration opportunities, adjusters need to know the basics of why fittings can fail.
Figure 1 to the upper left is a view of a typical plumbing compression fitting used to splice plumbing pipes. In some installations with long pipes and limited access, replacement of a section of pipe is accomplished with two compression couplings at each end of the replacement pipe.
The arrow in Figure 2 shows the pipe that had parted from the compression fitting.
Figure 3 depicts the parted pipe and the outline of the compressed rubber seal of the compression fitting. The compression fitting worked its way off the end of the pipe, allowing water to pour down several floors of the building.
Figure 5 illustrates the failure scenario. Figure 5A shows the system with the coupling in place, shortly after the plumbers had left the job site.
Figure 5B shows that the vertical load-carrying capacity of the pipe has been significantly reduced with the usage of the compression fitting. Because of the limited axial-force capacity of the vertical pipe when using compression fittings, the deteriorated hangars failed, shifting the load to the vertical pipe and couplings. The couplings could not support the load, and then slipped and parted.