Preparation for AE Decarbonization (Decarb) is the first step for effective decarb of units as it’s affect the process and safety.
Here we’ll start with isolating the system (AE) from FO, LO, FW, SW & Air.
- TBT (Tool Box Talk)
- Drain Jacket water
- Cut off Fuel oil supply
- Stop LO priming
- Air-starting line valve close
- Sign board on MSB, ECR & AE
- Arrangement of proper tools lie hydraulic jack & bolt, spanners, box spanners, allen keys, special tools etc.
- Cleanliness of respective areas
- Hydraulic jack oil & hose connection check
- No obstruction near AE
- Proper lighting and ventilation
Note: Open and cover following lines of respective units with clean cotton rags.
Exhaust manifold & Cylinder head cover
High pressure (HP) line
Jacket water line
Starting air line
Rotate crankshaft to bring respective piston to ignition TDC, so that all inlet and exhaust valve are closed.
Remove protection caps from cylinder head studs.
Mount hydraulic device in diagonal way and slack cylinder head bolts.
Lift cylinder head slowly-slowly by using chain block.
Before lifting make sure all the connections are isolated properly. Also ensure that liner is not coming out along with cylinder head.
Remove all mountings, air starting valve, indicator cock, relief valve, exhaust valve & inlet valve assembly.
Cylinder Head Checks:
Cylinder head pressure test
Fuel injector test
Starting valve test
Rocker arm – Tappet clearance
Piston and Connecting Rod
After lifting cylinder head, check liner surface for corrosion, scores, blow past etc.
(Buffing or cleaning of upper part of liner for easily removal of piston with rings should be done.)
Open crankcase door and remove bottom end bearing bolts.
Remove bottom half of the bottom end bearing.
Bring piston to TDC, make sure bolt holes on piston top, lifting tool holes are clean from deposits (specially threads).
Open bottom end bearing’s lower shell and fastened upper shell properly.
Fit eye-bolt on piston top and lift by chain block.
Now crankshaft bearing’s pin is covered to avoid foreign material.
Place the piston assembly (piston + connecting rod) on piston stand and remove piston rings using special tool.
Mount suspension and withdrawing device.
Pull out of its guide in engine housing by spanners or special tools.
Put ring nut on withdrawing device and lift the cylinder liner by chain block.
Observe all parts condition.
Take clearances and set as prescribed.
Clean deposits (carbon deposits), renew if possible.
Do pressure test as required.
Take shaft deflection, before and after bearing removal.
Clean piston rings (renew if required), grooves, gudgeon pin.
Calibrate liner and act as recommended.
If all jobs regarding satisfactory operation of AE is done then assemble them properly.