RTA PISTON REMOVAL

RTA PISTON REMOVAL

Preparations:

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      Engine shut down.

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      Start air shut off and turning gear engaged.

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      Air to exhaust valve spring isolated

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      Fuel oil to unit isolated.

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      Cooling water to unit isolated and drained down.

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      Lubricating Oil off.

Start Air Shut Off

           

Engage Turning Gear

Remove cooling water, fuel oil and start air pipes and connections to the cylinder cover and the bellows piece between the exhaust valve and manifold. Disconnect air spring connection, oil drain and hydraulic pipe from exhaust valve

Removing Exhaust Bellows

           

Disconnecting Fuel Distribution Block

Disconnecting Air Start Branch Pipe

           

Disconnecting Exhaust Valve Hydraulic Pipe

Clean the threads on the cylinder cover studs, and the contact surfaces for the jacks. Lower the tensioning jacks onto the studs, connect the hydraulic pump snap connectors, and screw on the locking ring until the piston in the jack is pushed down. Next slacken the locking ring back by about a turn and a half. This is important, otherwise when the cylinder head nuts are slackened the jacks will not be able to be removed.

Lowering Jack Onto Cylinder Head Stud

           

Jack With Locking Ring Screwed On

Start the hydraulic pump for the jacks and vent the air from the jacks. Close the vents and raise the pump pressure to 1000bar. This will stretch the cylinder head studs, allowing the nuts to be slackened back using a tommy bar. The jacks are then removed and the cylinder head stud nuts removed.

Venting Jacks

           

Raise Pump Pressure

Slacken Nuts With Tommy Bar

           

Remove Nuts

The cylinder head lifting tool is now attached, the head and water guide ring lifted using the engine crane and landed in a safe position on blocks of wood to protect the seating faces.

Lifting Tool Attached

           

Lifting Cylinder Head

Before the piston can be lifted removed from the cylinder liner, the wear ridge at the top of the liner must be removed. If this is not done, then the piston rings will jam against the wear ridge as the piston is removed.

Grinding Wear Ridge From Liner

           

It is important to use the proper grinding tool to remove the wear ridge. Use of an angle grinder may may damage the liner below the position of the top ring when the piston is on TDC, leading to blowby.

The Piston rod is disconnected from the crosshead. The engine is turned to bottom dead centre, and the two jacks screwed on  to the threads of the studs securing the piston rod to the crosshead. The jacks are positioned diagonally as shown in the photographs.

Ensure the jacks are backed off about half a turn, so that they can be removed after the nuts have been loosened. Attach the hydraulic hose snap connectors and ensure that the jack pistons are at the bottom of the cylinders. Vent the air from the jacks using the vent screws and then raise the pressure to 1000 bar (or the recommended pressure) using the hydraulic pump and slacken the nuts using a tommy bar. After relieving the pressure on the jacks, the process is repeated for the other two nuts.

Hydraulic Jacks Screwed to Piston Rod Nuts

           

Removing Nuts From Piston Rod

Bolt two distance pieces to the piston rod foot. These push the stuffing box out of its housing when the unit is turned to TDC and prevent damage to the scraper rings in the stuffing box. Unbolt the stuffing box and turn the engine unit to TDC.

The Distance Pieces Bolted to the Piston Rod Foot

           

The Stuffing Box Pushed out of its Housing

Clean out the threaded holes in the Piston Crown with a tap using water to soften the carbon. Bolt on the lifting tool to the piston and attach the engine room crane. Lift the piston from the engine and place in the cradle ready for cleaning and examination.

Cleaning Out Threaded Holes

           

Lifting Tool Attached to Piston

Lifting Piston

           

Lifting Piston

Piston Cradle

           

Landing Piston in Cradle