NUT 4D6298 - Caterpillar

Corrosion in sea water circuits can result in the following issues: premature deterioration of cooling system components, leaks and possible cooling system contamination. The corrosion may be caused by the lack of zinc rods in the sea water system.Zinc rods are installed in the sea water cooling system to help prevent the corrosive oxidation that is caused by sea water. Electrical current is conducted through the contact of the zinc rods with the cooling system components. The zinc rods oxidize rather than the cooling system components. Rapid deterioration of zinc rods may indicate the presence of uncontrolled electrical currents from improperly installed electrical attachments or improperly grounded electrical attachments.The engineer for the operation must determine the interval for inspecting the zinc rods. The interval for inspecting the zinc rods will depend on the size of the zinc rods and the number of zinc rods that are installed.
Table 1
Locations of the Zinc Rod
Location Quantity
Elbow of the Auxiliary Water Pump 1 Inspect the Zinc Rods
Remove the zinc rod.
Inspect the zinc rod. Ensure that the zinc rod will remain effective until the next scheduled inspection.
If the zinc rod has deteriorated excessively, install a new zinc rod.
Illustration 1 g00481100
Tap the zinc rod lightly with a hammer. If the zinc rod breaks, install a new zinc rod.
If the zinc rod will be reused, scrape the layer of oxidation from the zinc rod before installation. The layer of oxidation reduces the effectiveness of the zinc rod. Replace the Zinc Rods
Use pliers to unscrew the old zinc rod from the plug. If not enough material remains or the zinc rod has broken off, drill the zinc from the plug.
Clean the plug.
Illustration 2 g00748510
(1) Shoulder
(2) Threads
(3) External threads of the plug Note: Do not apply adhesive or sealant to the threads of the zinc rod (2).
Apply 9S-3263 Thread Lock Compound to the shoulder (1) of a new zinc rod. Apply the compound only to the shoulder of the zinc rod. Install the zinc rod onto the plug.
Coat the external threads of the plug (3) with 5P-3413 Pipe Sealant. Install the zinc rod. See Specifications, SENR3130, "Torque Specifications" for the torque for the plug.