How will u remove propeller shaft

Answer

Propeller shaft / tailshaft removal procedure

Preparation
- Vessel to be in dry dock and properly supported on blocks.
- Obtain company approval and inform Class/Surveyor as shaft withdrawal is part of a statutory/class survey or repair.
- Prepare risk assessment, toolbox talk, lifting plan and permits.
- Study shafting drawing, coupling arrangement, bearing positions, shaft weight and centre of gravity.
- Arrange suitable chain blocks/jacks, shaft trolley/rollers, hydraulic equipment and lifting points.
Before dismantling
- Take and record:
  - tailshaft bearing clearances,
  - shaft wear-down readings,
  - propeller position/reference marks,
  - coupling alignment/reference marks.
- Check shaft alignment condition before disturbing the system, where required.
Remove propeller
- Remove rope guard and propeller cone/cap.
- Remove locking arrangement and propeller nut.
- For a keyed or keyless propeller, use the approved hydraulic/oil injection arrangement or propeller withdrawal gear.
- Support the propeller by crane/chain blocks before releasing it.
- Withdraw and land the propeller safely.
- CPP arrangement additionally requires disconnection of hydraulic/control connections as per maker's procedure.
Disconnect shafting inside engine room
- Open intermediate shaft/tailshaft coupling bolts or flange connection.
- Match-mark coupling components before dismantling.
- Support the shaft adequately so that no load is transferred abnormally to bearings or stern tube.
Remove stern tube sealing arrangements
- Drain stern tube lubricating oil as necessary.
- Disconnect oil pipes, header tank connections and monitoring lines.
- Remove aft seal housing/components as required.
- Remove forward seal/gland components if they obstruct shaft withdrawal.
- Protect seal liners and machined surfaces.
Withdraw the tailshaft
- Fit shaft trolley/rollers and suitable supporting arrangements.
- Carefully move the shaft aftwards, normally through the stern tube.
- Continuously support the shaft while withdrawing so that:
  - stern tube bearings are not damaged,
  - shaft journals do not strike the bearing,
  - seal liners and shaft surfaces are protected.
- Use crane support at the aft end as the shaft emerges.
- Land the shaft on properly prepared wooden/rubber-lined supports.

After withdrawal — important examination points

Clean the shaft and carry out:

Visual examination for cracks, scoring, corrosion and fretting.
Check propeller taper and keyway, especially keyway ends.
Examine coupling flange and bolt holes.
Measure shaft diameter and wear.
Check shaft straightness/run-out.
Examine bearing journals.
Conduct NDT, normally MPI/DPI as appropriate, particularly at stress-concentration areas.
Inspect stern tube bearings and measure wear/clearance.
Inspect seal liners, aft and forward seals.
Class surveyor witnesses examinations where required.