Planning:

• Ensure you have sufficient time, manpower, and all necessary tools, spares, and the manufacturer's manuals.
• Organize the workspace, ensuring all safety measures are in place.

With the engine shut down, lubricating oil pump stopped, start air locked off, turning gear engaged, Risk assessment and a permit to work obtained, proceed as follows for checking the condition of the bottom end bearing surface of a large slow speed engine.

• Open the crankcase door at the relevant cylinder and ventilate, as the crankcase is an enclosed space (Follow the enclosed space entry procedure).
• Turn the relevant cylinder to BDC and check the bearing clearance. This is because, after squaring up, the clearance should be the same.

To remove the Bottom end bearing (bottom-side)

• Now turn the cylinder to TDC. Mount eyebolts on each side of the crankpin bearing cap and suspend two tackles from the lifting brackets in the athwartship direction.
• Using shackles and wire ropes, hook on the tackles and haul tight.
• Loosen the crankpin bearing studs using hydraulic jacks. Remove the palm nuts.
• Lower the bearing cap while carefully ensuring that the studs do not damage the crankpin journal. Land the bearing cap on a couple of planks placed in the crankpit.
• Using another tackle mounted on top of the crankcase door, carefully lift the bearing cap out of the crankcase and place it on wooden planks.

To remove the Bottom end bearing (top side)

• Fit four guide shoe retaining blocks into the crosshead guides. This will prevent the crosshead and conrod from moving down when the engine is turned.
• Wrap a strop around the bottom of the conrod and attach it to a chain block mounted on the side of the engine.
• Turn the engine while pulling the lower part of the conrod with the lifting tackle so that the crankpin turns out of the top half of the bearing. Ensure that the crankpin does not foul on the top edge of the bearing.
• The crankshaft can be turned to the bottom dead centre, and the top half of the bearing examined/ removed.

Inspect the bearing surface for any signs of scoring, pitting, wiping, ovality, cracks, or corrosive attack. Take photographs of the bearing and make relevant paperwork. The clearance of the bearing should be recorded before opening and after square up. Square up the bearing in the reverse order of dismantling.

• Inspect the condition of all lifting gear, including eyebolts, shackles, and chain blocks, before use. Ensure their load capacity is suitable for the weight being lifted.
• Inspect the hydraulic jack and its hoses for leaks and proper functionality.
  
• Ensure the work area is clean, especially if there are no oil spills on the platform to prevent accidents or contamination.
  
• Ensure all personnel wear proper personal protective equipment (PPE), including safety belts when working inside the crankcase.
  
• Strictly follow engine isolation procedures (lockout/tagout), ensuring the engine cannot be started accidentally.
  
• Ensure no personnel are inside the crankcase during engine turning the engine using turning gear
• Precautions to be taken while lowering and taking out the bearing so that threads, bearing shell, and crankpin are not damaged
• Protect the crankshaft journal and bearing surfaces from dirt and damage during removal and inspection.
  
• Apply the correct hydraulic pressure when loosening and tightening nuts.
  

(c) Possible Defects & Remedies:

• Fretting: Insufficient tightness of the hydraulic nut can cause fretting.
  Ensure proper tightening torque is applied.
• Scoring: Foreign particles in the lube oil can cause scoring.
  Clean the oil system and replace filters.
• Pitting/Corrosion: Acidic attack in the lube oil can cause pitting or corrosion.
  Replace the contaminated lube oil and investigate the source of acidity.
• Wiped Out Bearing: Breakdown of the lube oil film due to overloading or overheating can lead to a wiped-out bearing.
  Replace the bearing and investigate the cause of overloading or overheating.
• Fatigue Cracks: Lack of lubrication can cause fatigue cracks.
  Replace the bearing and investigate the cause of lubrication failure.
• Hot Spots: Lack of lubrication can cause hot spots.
  Replace the bearing and investigate the cause of lubrication failure.
• Ovality: Varying loads can cause ovality.
  Replace the bearing and ensure proper load distribution.

Remedies for defects:

• Slight Marks/Corrosion: Can be polished and removed.
• Deep Cracks/Excessive Wear: Require replacement of the bearing.

(d) Tests Carried Out on Completion of Survey and Reassembly:

• Measure the bearing clearance to ensure it is within limits as specified in the maker's manual
• Check the crankshaft deflection to confirm proper alignment and that there are no undue stresses.
  
• Start the lube oil pumps and check for proper oil flow to the bearings
  
• Turn the engine on the turning gear and monitor amperage to detect any obstruction.
  
• Test run the engine on air, followed by a load test. During operation, monitor the bearing temperature closely to detect any abnormalities.
  
• After stopping the engine, inspect for any white metal fragments, which could indicate wear or damage.
  
• Check for hot spots that could signify improper lubrication or bearing fitment issues.