Condition assessment of large diameter seawater Concrete Pipes

Concrete-lined steel pipes, such as Prestressed Concrete Cylinder Pipes (PCCP) are vital infrastructure for refineries and power plants. They have generally large diameters (>1.5m) and are used to convey seawater for cooling systems and heat exchangers. Seawater concrete pipes suffer from a variety of problems such as concrete deterioration and corrosion of the steel inner core and the prestressing wires. These problems affect the structural integrity of the pipes and may lead to their catastrophic failure and the costly shutdown of the refinery. The assessment of the actual conditions of seawater concrete pipes is essential for refinery managers and engineers to plan maintenance work and thus assure continuous functioning of their plants. This paper presents the development of a new nondestructive testing method for the inspection of PCCP. The method uses circumferential guided waves to detect distress in the concrete pipe at the tested location. The obtained results show a method of high potential that if automated, can rapidly scan seawater concrete pipes for structural distress without taking the pipes out of service.