Answer
A crosshead bearing survey is a critical, heavy-engineering task. Proper preparation focuses heavily on safety isolation and tool readiness.
Administrative & Safety Actions
Execute a formal Risk Assessment and hold a comprehensive Tool Box Meeting with the engine team.
Issue an Enclosed Space Entry Permit for the crankcase.
Implement full Lockout/Tagout (LOTO) procedures: Engage the turning gear and lock it out; isolate the main starting air valve and vent the line; open indicator cocks; isolate the engine control system and cushion air supply.
Immobilisation permission from port authority if if within port limits.
Crankcase & Site Preparation
Keep the main LO pump running for a short duration after stopping the engine to ensure uniform cooling, preventing thermal stress or distortion.
Once cooled, stop the pump and let the oil drain completely into the sump.
Ventilate the crankcase thoroughly. Measure the atmosphere parameters manually (O2 greater than 21%, LEL 0%, toxic gases 0 ppm) before allowing anyone inside.
Erect clean, secure, non-slip wooden boards or specialized platforms inside the crankcase over the oil pan. Ensure all pocket tools are secured with lanyards.
Tools & Equipment Readiness
Calibrated telescopic feeler gauges, standard feeler gauges, and outside micrometers.
Hydraulic jacks, high-pressure pumps, and high-pressure hoses configured for the crosshead nuts.
Eye bolts, chain blocks, guide studs, and specialized crosshead hanging gear.
Intrinsically safe, low-voltage explosion-proof lighting or pneumatic lighting.
Systematic Inspection Procedure
The inspection should follow a structured, methodical approach:
A. External Inspection (Prior to Dismantling):
Measure and record bearing clearances using a feeler gauge (at the top of the bearing shell) to compare against baseline data.
Inspect the crankcase for debris, metallic particles, or white metal fragments.
Check the oil distribution and lubricating ducts for any signs of blockage or charring.
B. Internal Inspection (During/After Opening):
Condition of White Metal: Look for signs of "wiping," pitting, scoring, or discoloration (suggesting overheating). Check for edge damage, which is often the first indicator of bearing failure.
Bolt and Stud Integrity: Inspect connecting rod bolts and crosshead studs for signs of stretching, fretting, or thread damage.
Journal Surface: Check the crosshead pin surface for smoothness. Any ridges or deep scratches must be evaluated, and potentially polished, according to manufacturer limits.
Lubrication System: Verify the cleanliness of the lubricating oil supply holes and the integrity of the hydraulic piping (if applicable).
Post-Inspection and Reporting
Documentation: Record all clearances, findings, and measurements in the engine room logbook and the vessel's technical record.
Surveyor Verification: If the survey is for class credit, ensure the surveyor is satisfied with the visual inspection and measurements before closing the crankcase.
Post-Assembly: After reassembly, verify the torque values for all bolts and ensure all locking devices (split pins, tab washers, or wire locks) are correctly fitted.
Operational Test: Perform a functional test of the crosshead lubrication system and conduct a slow-turning trial of the engine with indicator cocks open to ensure everything is correct before full-power operation.