Effect of chloramines on ductile-iron pipe gaskets of various eslastomer compounds

Degradation reported from laboratory testing of elastomer sheet materials subjected to chloramines has not correlated to experience in the field for some applications. The effect of chloramines, or any other chemicals, on elastomers in potable Water systems is both material-and-application specific. The large surface-area-to-mass exposure ratio of, for example, toilet bowl flapper valves, is quite different from the small surface-area-to-mass exposure ratio of ductile-iron pipe gaskets. To investigate this, side-by-side tests of elastomer sheet materials and ductile-iron pipe push-on and mechanical joint gaskets exposed to 110 mg/L total chloramine solution were conducted. The push-on and mechanical joint gaskets were tested in assembled joints. The tests, done over 364 days, revealed that although the majority of the elastomer sheet materials experienced significant visual degradation and large changes in mass, volume, and hardness, the ductile-iron pipe push-on and mechanical joint gaskets showed no visual degradation and only slight detectable chlorine penetration.