Examination of Protective Coatings Utilized on Army DS2 Containers

This report characterizes and evaluates the integrity of protective coatings used on DS2 containers and isolate the origin of the corrosion observed on the containers. Three different size containers were examined. It was determined by optical microscopy and visual examination that the corrosion was initiated from exterior surfaces, particularly in recesses, weld seams, and other areas which trapped moisture. Optical and electron microscopy was performed on cross-sectional specimens of the coating. Inconsistent phosphate coating coverage was revealed on the five-gallon container and the urethane topcoat thickness was below specified requirements. The epoxy primer was thicker than specified. The wash primer, epoxy primer, and topcoat thicknesses of the 14-liter container did not meet the specification. The exterior terne coating on the 1-1/3-quart container exhibited corrosion and blistering in many areas. Several recommendations were made: design flaws conductive to corrosion should be eliminated, alternative materials (e.g. plastics, stainless steels, and aluminum) should be considered, and more stringent quality control of coating application, as well as the handling of coated containers, should be enacted. Finally, if the present coating system and material for the container are not changed, then periodic inspections should be performed to detect corrosion in the early stages.