Advancement of Lining Inspection Technology Inside Seawater Piping

Abstract

Seawater piping employed for cooling of emergency diesel generator and various components at Nuclear power plant, are internally lined for protection against seawater corrosion. (Fig. 1) However, the lining materials such as rubber or polyethylene tend to incur peel-off or crack due to aged deterioration occurred by the operation, resulting in corrosion of the piping. (Fig. 2) Internal piping integrity of seawater piping is usually performed by periodic visual inspection. But, for the 4B to 20B pipes it has been a challenge to detect the initial degradation because the inspector cannot get into the pipes. Pinhole detection technology that enables detection of microscopic damages and cracks is available to use as means to detect its initial state of degradation, which seems effective as preventive maintenance of the lining. Such being the case, we are developing Seawater Piping Inside Inspection Equipment applicable to the 4B to 20B sizes of pipes by evolving the conventional pinhole detection technology.