| 초록 |
Many of the facilities used in oil refineries and petrochemical plants were constructed over 30 years ago, and are now beginning to show their age. There has been a growing number of leakage incidents at these facilities, caused by deterioration of aging pipes and equipment. Statistics indicate that many of these incidents are caused by corrosion under insulation (CUI) occurring on the pipe surface underneath the insulation. Corrosion-under-insulation (CUI) refers to the external corrosion of piping and vessels fabricated from carbon-manganese, low-alloy and austenitic stainless steels that occurs underneath externally clad or jacketed insulation owing to the penetration of water. By its very nature, CUI tends to remain undetected until the insulation and cladding or jacketing are removed to allow inspection or when leaks to atmosphere occur. For these reasons, CUI management guideline was established on the basis of activities conducted in Committee for the Study of Diagnostic Technologies for Corrosion under Insulation established in The Engineering Advancement Association of Japan (ENAA). In addition, a survey of oil-related businesses and academic societies, such as the Japan Petroleum Institute (JPI) and the Society of Chemical Engineers, Japan, was conducted with the collaboration of the Petroleum Association of Japan and the Japan Petrochemical Industry. In this paper, objectives and application scope of the CUI Guideline were indicated. And also, corrosion risk assessment, case studies of priority assessment and screening test were described on the basis of evaluating the mechanism of CUI. The basic procedures of the CUI testing described in this paper consist of the following three key steps: (i) priority ranking assessment, (ii) screening test and (iii) identification of removal areas. While business operators are to comply with these three basic procedures when using this guideline, they can refer to their existing internal standards that reflect the characteristics of each plant and their many years of experience and expertise, and make necessary changes to the procedures provided. |
