A Strategy for Preventing Corrosion Under Insulation on Pipeline in the Petrochemical Industry

Abstract

The application of the systems approach and the use of organic coatings have been successful in mitigating corrosion under thermal insulation (CUI) on piping systems, particularly a concern in the petrochemical industry. However, even these organic coatings have a finite protective life and it can be difficult and expensive to determine when the piping system needs maintenance (painting). This article reviews a CUI prevention strategy that provides long-term and reliable prevention of CUI, thus eliminating the problem of identifying the need for maintenance. The authors contend that this strategy reduces safety, health, and environmental risks, while moving towards an inspection-free, maintenance-free operating mode that can significantly reduce the need for and cost of piping maintenance. The authors first review the evolution of the understanding of CUI and its correction, then discuss the cost considerations, current prevention methods (including insulation design and installation to exclude water, application of an organic coating, periodic stripping, and on-going nondestructive on-stream examination, or NDE, inspections), and new CUI prevention measures, including thermal spray aluminum (TSA), stainless steel for small diameter piping, personnel protection cages, Al-foil wrapping of stainless steel pipe, and organic coatings for carbon steel. An additional section considers the cost of deploying CUI prevention measures. The authors conclude that a CUI prevention strategy such as TSA, Al, stainless, or a protective coating system that provides long-term and reliable prevention of CUI can reduce maintenance and inspection costs while maintaining low rates of piping failures from leaks.