Photo Gallery A3:  Thread Leaks

The first and most common indicator to a corrosion issue, an impending failure, or pipe weakness problem is a leak at the threads.  With approximately 50% of its wall thickness cut away during installation, this area of pipe will always fail first, and with most threaded systems constructed of schedule 40 pipe – a remaining wall thickness of less than 0.085 in. at the thread cut is common.

Various factors influence the severity of a failure such as the use of galvanized steel connected to a brass valve, age, operating pressure, physical impact, and pipe schedule.  Our finding of advanced failures of threaded thin wall schedule 10 and even ultra thin wall schedule 7 pipe for threaded branch lines at fire systems, while still a shock to many building owners, should have been expected.

A typical corrosion scenario for threaded pipe is for a small leak to develop and then seal itself due to rust and other internal particulates filling the void.  As the water and dissolved solids slowly migrate through the leak, the water evaporates to leave an encrustation of rust and scale that is seemingly growing along its outside surface.  Interpreted properly as a tell-tale warning to an impending failure, the pipe can be replaced.  Ignored, as is the more common response observed, and a far greater failure typically occurs.

The most catastrophic failures we encounter are usually the result of a total pipe separation at the threads of a 1 in. or greater pressurized line.  Even with the quickest response, most total pipe thread separations impact multiple floors, interrupt services, and produce damages in the $$$ million dollar realm.