SPRING 9D6093 - Caterpillar

3600 Family Of Marine EnginesCorrosion in raw (sea) water circuits can result in premature deterioration of system components, leaks, and possible cooling system contamination. The cause for the accelerated corrosion may be the lack of sacrificial zinc anodes (rods) in the raw water system. When a Caterpillar raw water pump and accessory module-mounted heat exchanger are used, a sufficient number of zinc rods are supplied to protect the portion of the raw water system that is supplied by Caterpillar. Additional zinc rods should be installed to protect the remaining portion of the raw water system. The zinc rods should be installed throughout the raw water flow passages at locations where two dissimilar metals are used and submerged in sea water. It is recommended that the zinc rods be installed in the more valuable of the two components where the dissimilar metals are used. See Illustration 1.
If a Caterpillar raw water pump and/or heat exchanger are not used, zinc rods may not be supplied. However, sufficient zinc rods should be installed to protect the complete raw water system.
In order to maintain protection, inspect the zinc rods at regular intervals (see Note) and replace when deteriorated. When threading the zinc rod into the brass plug, it is important that NO ADHESIVE OR PIPE SEALANT BE APPLIED TO THREADS (2) OF ZINC ROD (1). However, the shoulder of the zinc rod that contacts the brass plug can be coated with 9S3263 Thread Lock. This will help hold the rod in place in the brass plug. Apply 5P3413 Pipe Sealant Compound to external threads (4) of the drain plug. See Illustration 2.
The zinc rods should be inspected within 24 hours of filling the piping with sea water. If no significant corrosion is noted, they should be inspected again after seven days of sea water submersion. If no significant deterioration is noted, reinspect in 60 to 90 days. Thereafter, inspect annually and replace if necessary.
Illustration 1. Right side view of auxiliary sea (raw) water lines group. Typical location of zinc rod (large arrow).
Illustration 2. Location of parts and materials required to prevent excessive corrosion in sea (raw) water circuits. (1) 6L2288 Rod. (2) External threads of zinc rod. (3) 5B9169 Drain Plug. (4) External (1/2"-14 NPTF) threads of drain plug.