Asset Preservation: Mothballing and Lay-Up

Infrastructure associated with power plant generation equipment is complex and expensive. Protecting this infrastructure from destructive corrosion during system lay-up and mothballing is a critical concern for future startup. Preserved infrastructure is also more valuable in the event of sale of the asset. Of principal concern are mechanical, electrical, water handling systems and the combination of materials associated with these systems all of which require a concise approach to corrosion control. Corrosion of these components occurs for a number of reasons within an idle plant. In an idle condition, plants and associated equipment are subject to temperature fluctuations, water condensation and other conditions that cause corrosion to occur. Under certain combinations of conditions, corrosion can be very rapid. Without adequate control, corrosion can cause of number of problems. The bottom line is that the plant cannot be started up until these components are repaired or replaced. Water that is left in cooling systems can cause corrosion from microbiological activity, oxygen availability corrosion related activity and galvanic corrosion from dissimilar materials. Water forms within electrical control panels and systems causing corrosion of the various metals utilized on computer boards and connections. Some of these conditions provide for more aggressive corrosion conditions than when the system is in full operation. There are concern for tanks, piping and electronic components comprising the fuel storage and delivery system. Corrosion of these components is unacceptable from both an operation and environmental standpoint. This paper presents available technologies available for lay-up and mothballing in the power generation industry. Advantages and disadvantages would be presented and discussed.