Photo Gallery B6:  Weathering

Of the various forms of corrosion common to any building property, external pipe corrosion caused by weathering, cooling tower overspray, and outdoor environmental conditions is the easiest to avoid.  For uninsulated steel pipe, corrosion is immediately apparent beginning with the first blemish, and can usually be stopped long before it develops into a larger problem.  Virtually all such conditions are entirely due to a lack of maintenance over a very extended period of time.

Common problem areas are at pipe supports and hangers where water collects, and at the flanges of vertical pipe sections where water will pool.  Insulated pipe is far more likely to conceal a corrosion problem than prevent one.  Ironically, insulating the pipe to protect it from external corrosion often produces the opposite effect given that it allows a severe corrosion condition to develop hidden from view.  An active 24 in. condenser water system operating 24/7 will never freeze under most winter conditions.  Once insulated, however, the external corrosion threat is presumed to have been eliminated, when in fact insulating the pipe has only guaranteed a future problem.

Most outdoor insulation is inadequate for its purpose, too thin, and almost never waterproof sealed at the seams.  Installation is often questionable.  Thin galvanized steel coverings are vulnerable to the chemicals in the cooling water which will begin producing pinholes after about 10 years.  Vinyl coverings may not deteriorate due to overspray, are more vulnerable to physical damage.  Over time, most insulation is unavoidably trampled from normal maintenance activity; producing endless sources for moisture and water to enter and remain.

Most importantly, since the insulation is expected to provide all the corrosion protection necessary, the bare pipe is never painted – the most simple and cost-effective first step that would save most systems.