Great care should be exercised when installing compression couplings, as installation errors can cause pipe failure resulting in expensive property claims.
Figure 1 to the right 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.
They removed a section of the pipe and replaced it along with two compression couplings, one at each end. The plumbers finished the work and left. Approximately three days later, one of the compression fittings parted, causing a significant water loss.
The arrow in Figure 2 (to the left below) shows the pipe that had parted from the compression fitting, while 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 to the right illustrates the failure scenario.
Figure 5A shows the system with the coupling in place, shortly after the plumbers had left the job site.