A few years ago several CPVC fire sprinkler pipe failures were blamed on contact with spray polyurethane foam (SPUF) insulation. The manufacturers of SPUF formed an alliance and worked together to conduct a study to determine if SPUF was incompatible with CPVC pipe. Their main concern in the study was potential incompatibility of phosphate ester fire retardant chemicals present in the SPUF. The results of the study concluded that, if the foam is applied properly, the integrity of the CPVC pipe is not affected by the SPUF. However, in spite of these findings, we continue to see ESC failures of CPVC pipe contacted by SPUF insulation. Analysis of the fracture surfaces of the pipe reveal the presence of both the phosphate ester fire retardant used in the SPUF as well as the amine catalyst used to cure the foam. Amines are well known to be highly incompatible with CPVC pipe and the amine catlyst are highly migratory so one would certainly predict that SPUF would not be compatible with CPVC pipe. It certainly makes one wonder if the results of a chemical compatibility study of SPUF with CPVC pipe would turn out differently if an independent laboratory performed the testing rather than members of the SPUF alliance.