Calcium Sulphonate Complex Grease in Wet and Marine Environments

Why water resistance is the deciding property

On cranes, winches, deck machinery and dock equipment, grease is exposed to spray, rain and condensation. A grease that washes out leaves the bearing unprotected and the corrosion that follows usually costs more than the lubricant. Water resistance is therefore a primary selection criterion, not a secondary one.

Calcium sulphonate complex greases are built on a thickener system that holds water at the surface rather than absorbing it into the structure. In practice this means the grease stays where it was applied and continues to separate moving surfaces after repeated wetting.

Corrosion protection built into the formulation

Calcium sulphonate thickeners carry inherent anti-corrosion behaviour, which is useful where salt spray is continuous and where reapplication intervals are long. That does not remove the need for correct surface preparation on new assemblies, but it raises the margin against rusting on wire ropes, pins and slow-moving bearings.

For salt-spray or humid chamber testing, ask for the actual test duration and the reported rating rather than a pass or fail statement. Test conditions vary and a short duration does not represent a season on deck.

Load carrying and mechanical stability

Calcium sulphonate complex greases typically show strong extreme pressure behaviour, which suits heavily loaded oscillating bearings, pivot pins and gear teeth on deck equipment. Mechanical stability matters just as much: a grease that softens under shear will migrate out of the bearing and expose the surface.

• Confirm the base oil viscosity suits the slow rotational speeds common on deck machinery.
• Check low-temperature pumpability if the equipment operates in cold climates or in refrigerated cargo areas.
• Verify the grease remains in place on vertical surfaces and inverted bearing positions.

Compatibility and changeover from lithium grease

Many marine and port assets arrive filled with lithium or lithium complex grease. Thickener incompatibility can produce softening, hardening or oil separation when the two products are mixed in a bearing. Where a changeover is planned, clean and repack the bearing, or confirm compatibility in writing with both lubricant suppliers before mixing.

Label every lubrication point after conversion and update the maintenance schedule. A partial changeover with unlabelled points is the most common cause of unexpected grease failure on vessels and terminals.

Relubrication intervals on wet equipment

Water exposure shortens grease life, particularly where the grease is also exposed to heat. On deck machinery, intervals often need to be shorter than the equipment builder's land-based recommendation. Condition-based checks such as grease sampling from large bearing housings give a better basis for adjustment than a fixed calendar alone.