Corrosion is the largest single cause of plant and equipment breakdown in process industries. For most applications it is possible to select materials of construction that are completely resistant to attack by the process fluids, but the cost of such an approach is often prohibitive. In practice it is usual to select materials that corrode slowly at a known rate and to make an allowance for this in specifying the material thickness. However, a significant proportion of corrosion failures occur due to some form of localized corrosion, which results in failure in a much shorter time than would be expected from uniform wastage. Additionally, it is important to take into account that external atmospheric corrosion leads to many instances of loss of containment and tends to be a greater problem than internal corrosion. All these aspects of corrosive behavior need to be addressed both at plant design time and during the life of the plant. (reference)
The operator should demonstrate that procedures are in place to ensure that corrosion and the selection of the correct materials of construction are considered at the process design stage. Additionally the operator should demonstrate that it has appropriate inspection and maintenance programs in place in order to prevent corrosion causing loss of containment from its process operations.