Corrosion issues in the complex world of the process industries can be daunting if they are not managed effectively. According to the latest information from the National Association of Corrosion Engineers (NACE), the total annual cost of corrosion in the United States is around $1.4 billion in the Oil and Gas Exploration and Production industry, $3.7 billion in the Petroleum Refining industry, $1.7 million in the Petrochemical industry, and $6 billion in the Pulp and Paper industry. This gives a fair estimate of corrosion mitigation opportunities across the globe. Out of the various types of corrosion mechanisms, uniform, general corrosion is the most common form and one of the major contributors to corrosion costs. The good news, however, is it is the most manageable type of corrosion if properly understood, typically much more so than localized corrosion and cracking.
A robust mechanical integrity program that is properly designed to monitor corrosion and indicate when issues increase to a level requiring review or maintenance is key to mitigating and managing corrosion. This integrity program should be universally accepted and consistently applied across the organization to ensure corrosion is managed holistically. In creating this program, there are seven key questions that an organization needs to answer, which are summarized below.
1. Are Thickness Monitoring Locations (TMLs) identified for all our assets?
The answer to this does not necessarily need to be an astounding ‘Yes’. The inclusion of an asset in the thickness monitoring program depends on its susceptibility to thinning corrosion. It is possible to get to this level of understanding only by doing a systematic ‘Corrosion Study’ which identifies corrosion loops. Corrosion loops are process circuits with similar operating conditions, metallurgy, and damage mechanisms. A professionally developed corrosion report gives insight into the damage mechanisms, expected corrosion rates, and integrity operating windows that need to be monitored and controlled for each corrosion circuit. This can then be used as a starting point to identify assets with thinning corrosion mechanisms to be included in the thickness monitoring program thereby identifying the TMLs.