Abstract: The advantages and characteristics of pipe in pipe type thermal insulation are described. In China, there were corrosion problems arised by this type therma1 inSu-lation for lack of well matched coating application techniques and quality control system. Based on the field examinations, the influence of corrosive environment upon the effectiveness of protective coatings and cathodic protection are discussed. Hence, the emergency measures are necessary to resolve the corrosion problems.