Photo Gallery D1:  Corrosion Under Insulation (CUI)

As we have well documented in endless investigations, the failure to protect steel pipe from sweating and corroding at its outside surface produces some of the most widespread as well as expensive forms of pipe failure.  The extensive branch like layout of any chill water or dual temperature piping system behind finished walls means not only millions of dollars to replace, but also massive disruption to building owners and tenants.  When they fail, typically at the smaller diameter threaded risers and take-off lines, water damage alone can easily reach 4 to 8 floors below and the multi-million dollar mark.

In the majority of cases, the first failure leading to its discovery reveals that the pipe has been almost totally destroyed, and that no corrective measures are available other than full pipe replacement.  Neither internal coatings nor external coatings will provide any benefit since almost no pipe wall remains in areas, and simply re-insulating the pipe without first stopping the corrosive attack is utterly worthless.

Rehabilitating the pipe by removing all insulation, removing the rust product, coating the pipe with a “rust reverter” followed by a water proof paint overcoat, and then re-insulating to a higher standard bay be justifiable for much larger mains, but never for smaller lines.  And that is assuming that rehabilitation is even feasible.

An independent critical evaluation at any example of “insulation failure” will often reveal that other factors are involved – such as the installation of insulation which is too thin, inappropriate for the demand, improperly installed, or missing entirely in areas.  Many other factors exist.  The widely mistaken belief propagated by manufacturers and those in the insulation industry that the paper foil tape sealing the seams of standard fiberglass insulation provides an effective moisture barrier remains the No. 1 explanation to most insulation related piping failures.

With insulation failures a long term vulnerability typically requiring over 25 years to develop, no one can be held responsible once it is uncovered.  Recognizing that the insulation installed at chill water and dual temperature piping systems hidden behind sheet rock walls was never expected to see the light of day for the next 40 years helps to explain its condition as well as the poor quality of service it has provided.