Examinations to be carried out when a crosshead bearing is opened for survey:

1. Examination of Bearing Shells

• Inspect the white metal surface for signs of wiping or squeezing, indicating breakdown of the lubricating oil film.
• Pay special attention to the lower shell, as it carries the maximum load.
• Check for fatigue cracks such as spider-web or mosaic patterns, especially at the centre of the lower shell.
• Look for spark erosion, identified by small black pits, which may indicate poor shaft earthing.
• Examine for cavitation damage, usually seen as localized pitting near oil grooves or oil entry points.
• Carry out a sounding (hammer) test to confirm proper bonding of white metal to the steel backing; a hollow sound indicates de-bonding.

2. Inspection of Crosshead Pin

• Ensure the pin surface is smooth and mirror-finished.
• Check for scoring, scratches, ridges, or polishing marks that indicate lubrication problems.
• Inspect for corrosion or pitting, including standstill corrosion during long idle periods.
• Conduct non-destructive testing (DPT/MPI) to detect micro-cracks, especially around oil holes and stressed areas.

3. Measurement of Clearances and Geometry

• Measure bearing clearances using feeler gauges and compare with maker’s limits.
• Check crosshead pin for ovality and taper using precision instruments.
• Verify alignment (K-value) to ensure uniform load distribution across the bearing surface.

4. Inspection of Associated Components

• Examine telescopic lubricating oil pipes for condition, tightness, and sealing (O-rings).
• Ensure oil grooves in bearing shells are clean and free from blockage or sharp edges.
• Inspect crosshead guides and guide shoes for wear, scoring, excessive clearance, and fretting marks.

5. Lubrication System Checks

• Verify proper functioning of the crosshead lubrication/booster pump and ensure correct oil pressure is maintained.
• Take oil samples from the system and check for contamination such as water or metallic particles (Fe, Sn, Cu).