Corrosion under hot and cold thermal insulation can be a serious problem in chemical plants. Not only has corrosion under insulation caused staggering maintenance costs in the millions of dollars but also has led to lost production time as well as affected plant safety. Many of the chemical plants have experienced a variety of problems and some of the specific experiences will be described in this symposium.
As a result, Exxon Chemical Company and many other chemical companies have embarked on a major effort to address the problem. In a companion paper, Exxon Chemicals at Baton Rouge will describe identifiable factors that cause the problem. This paper will review the important steps that Exxon Chemical has taken to control carbon steel corrosion under insulation. Specifically, the review will include (1) organizing and scheduling more rigorous programs of inspection including typical examples, (2) preparation of improved insulation specifications that address each of the factors affecting corrosion, and (3) action programs required to assure that improved insulation specifications are implemented.
An important aspect of controlling corrosion under insulation is through an appropriate inspection program. Unfortunately under normal circumstances, inspection requires the removal of the insulation during downtime, which is both costly and extremely difficult particularly on large towers and complex piping systems. There is an urgent need to develop a nondestructive onstream examination (NDE) method to detect corrosion without removal of insulation. In this connection, the Materials Technology Institute for the Chemical Process Industries is investigating some of the NDE methods. A brief synopsis will be made of the NDE methods employed. However, these methods have had only limited success, and a breakthrough inspection method is still needed. This need for breakthrough represents an important challenge to the international scientific community.