covered with cement. When ready to apply, the dried cement is "tackified" 

 with solvent, and the sheet is hand rolled onto the surface. The hand 

 rolling is needed to ensure adhesion. After rolling, the edges of each 

 piece are trimmed to give a fairly uniform coating. The material together 

 with its application is several times costlier than paint. However, where 

 a longer-lived antifouling coating is required, such as in warm water inlet 

 ports, this antifouling sheeting is recommended. 



System and Material Identification Interrelationships 



Warm Water System . The 26° C (79° F) seawater flowing through the warm 

 water pipe at 1.2 m/s (4 ft/s) will create an environment conducive to 

 fouling."-* The concrete platform surfaces and all the metal surfaces in 

 contact with the warm water inlet and outlet and which are amenable to 

 periodic refurbishment will require a good antifouling coating, such as a 

 heavily loaded organotin rubber sheeting. The trash grating protecting 

 the inlet opening will also benefit from an antifouling coating. The 

 grating and the inlet and outlet surfaces should be mechanically cleaned 

 on a fixed maintenance schedule. In other areas, the choice of paint or 

 sheeting will depend on the shape and force of water flow. The pump, 

 valves, and pipes on the inlet and outlet sides of the heat exchanger will 

 require organotin coatings, except in areas where water velocities in 

 excess of 10 knots are encountered during operation, A second antifouling 

 system, such as chlorine, will be required when these units are shut down. 



Cold Water System . The cold water system will have 80° C (46° F) seawater 

 flowing through at 1.2 m/s (4 ft/s). Because of the low temperature and 

 very low depth source, the fouling character of this water will be weak, 

 and the constant darkness in the cold water pipe will further inhibit 

 growth. In addition, since refurbishment of any antifouling system can 

 only occur when the whole power plant is dry-docked, it is recommended that 

 no section of the cold water intake system need use antifouling coatings. 

 For the cold water oulet all the recommendations for the warm water outlet 

 will apply. 



36 



