Laboratory Studies on Pipeline Coating Materials under Accelerated Weathering Condition

Laboratory test has been carried out to assess the rate of degradation of dielectric strength of different pipeline coating materials viz coal tar enamel, hot applied coal tar tape, cold applied polyolefin tape, coal tar epoxy, high build epoxy, polyurethane & 3LPE coating after accelerated weathering in QUV using 313 UVB lamp maintaining a cycle of 4 hour UV and 4 hrs. condensation and after 500 hours salt spray as per ASTM B117. This test is important since the corrosion control systems of most pipelines consist of the combination of coating and cathodic protections. It is desirable that the dielectric properties of the coating deteriorate at the minimum rate possible. Deteriorations of coating with time would lead to a constant requirement of additional cathodic protection current which would be both a technical & economic burden on the pipeline operator. This paper highlights to establish the suitability of proper coating material with respect to cathodic protection.