OVERHAULING (dismantling and assembling) CYLINDER COVER IN MAIN ENGINE on ship

SAFETY PRECAUTIONS

-On FWE get immobilization permission and propeller clearance from bridge.
-under piston spaces and scavenge space ventilate by blower.
-Stopped engine
-Shut off starting air supply At starting air receiver
-Block the main starting valve
-Shut off starting air distributor/distributing system power supply
-Shut off safety air supply
-Shut off control air supply
-Shut off air supply to exhaust valve – Only with stopped lubricating oil pumps
-Engage turning gear
-Shut off cooling water
-Shut off fuel oil
-Stop lubricating oil supply
-Lock the turbocharger rotors
-isolate expansion tank than only drain jacket drain jacket cooling water and open purging valve so that air pressure helps in draining.

TOOLS REQUIRED -
Grinding tool for exhaust valve seat,Milling and grinding wheel for fuel valve seat,Milling and grinding wheel for starting valve seat,Grinding handle,Cylinder cover tightening tool,Cylinder Cover - Lifting Tools,Hydraulic pump, pneumatically operated,Hose with unions (1500 mm), complete,Hose with unions (3000 mm), complete.

Shut off Oil and Water Supply

1. Check engine blocking.
Check that the engine is stopped and blocked according to the safety precautions given on the data sheet.

2. Shut off the oil supply.Close the fuel oil supply for the unit concerned.
3. Shut off the water supply.see fig 3
-Close the water outlet above the exhaust valve.
-Close the water outlet on the exhaust side of the cylinder cover.
-Shut off the water supply placed on the exhaust side below the exhaust gas receiver.
-Open the drain next to the inlet valve.
-Open the venting cock or purging valve next to the outlet .so that air pressure helps in draining the water.

Dismantling of Pipe Connections

4. Disconnect the oil pipes.
-Remove the hydraulic high pressure pipe for the exhaust valve. See Procedure.

-Unscrew the drain pipe for the exhaust valve.
-Remove the fuel oil high pressure pipes.See Procedure.
-Disconnect the pipes for return fuel oil from the fuel valves.
5. Disconnect the water pipes.Unscrew and remove the water outlet pipes.
6. Exhaust gas compensator.
Remove the protective jacket enclosing the insulation for the intermediate pipe or compensator. Remove the insulation.Remove the screws in the flange between the intermediate pipe and the exhaust receiver.

7. Disconnect the starting air pipe.
Unscrew and remove the control air pipe for the starting air valve.Unscrew and remove the air pipe for the starting valve.
8. Cylinder cover loosening.Remove the protective caps from the cylinder cover nuts.Loosen and remove the cylinder cover nuts, see Data.For use of hydraulic tools, see Procedure
9.Cylinder cover lifting.

Hook on the engine room crane to the lifting attachment on top of the exhaust valve.Check that all cylinder cover connections
have been loosened and removed.Lift away the cylinder cover complete.

10.Cylinder cover landing.see diag
Land on a couple of wooden plan.

11.Remove sealing ring.
Remove and discard the sealing ring between the cylinder cover and cylinder liner.

Overhaul Preparations

1. Dismantle valves and pipes.
-Dismantle all valves and pipes from the cylinder cover. See Procedure
-Dismantle the starting air inlet block and the cooling water outlet block from the exhaust side of the cylinder cover.
Remove all studs on top of the cylinder cover.

2.Cooling Water Jacket

2. Remove the cooling water jacket. Mount four eyebolts and the lifting chains as shown in the sketch. Remove the four screws which secure the cooling jacket to the cylinder cover. Lift the cylinder cover free of the cooling jacket and land it on a couple of planks. Remove and discard the O rings from the
cover, and carefully clean the cooling jacket and the cylinder cover.

3. Mount the cooling water jacket.
Provide the cylinder cover with new O rings, well lubricated with oil. Lift the cylinder cover and guide the jacket/ cover into position, using the guide pin as a reference (manoeuvre side). Fit and tighten the screws for the cooling jacket.

Reconditioning of Bores

4. Seat reconditioning tools.
The tools for reconditioning of the valve seats are found on tool panel.

5. Fuel valve bore.
The tool consists of a common spindle with a handle, a guide, a carbon cutter, a seating face cutter and a grinding mandrel.
Clean the fuel valve bores using the carbon cutter. If required, recondition the fuel valve seating with the appropriate cutter.
Grind the seating with the grinding mandrel and a grinding compound (e.g. Carborun-dum No. 200). After the milling/grinding, clean the bore and seating carefully, and check that the seating is not damaged.

6. Exhaust valve bore.

7. Starting valve bore.

8. Indicator safety valve bore. Clean the bores for safety valve/indicator

Preparations before Mounting.

9. Fitting of studs.

Lubricate the threads with ‘Never Seize’ or molybdenum disulphide (MoS2) and fit the valve studs.Tighten up the studs in accordance with the screwing in torque stated on the data sheet.
Fill up the grooves between the valve studs and the bores for the valve studs with permatex to prevent water or oil from entering the bores during operation of the engine.

10. Mounting of valves.
Install the valves on the cylinder cover, see Procedures.

Landing Preparation

1. Sealing ring.
Check that the liner sealing surface is clean.Place a new sealing ring on top of the cylinder liner.If necessary fit a new ‘klinger’ sealing ring in the groove of the flange of the intermediate pipe.

2. Water connections.
Check that the water connections are clean and provided with new O rings. Lubricate the O rings with Vaseline and fit them on the cylinder liner.

Cylinder Cover Mounting

3. Cylinder cover landing.
Lift the cylinder cover by means of the crane and lower it carefully into position. During the landing, carefully check that the cooling water connecting pipes engage correctly with the holes in the cooling jacket.

4. Cylinder cover stud check distance.
If the cylinder cover studs have been re- moved and reinstalled, check the distance the stud is protruding from the cylinder
cover. If necessary, adjust to the distance D01 05
by turning the stud

5. Cylinder cover tightening.
Fit and tighten the cylinder cover nuts.For operation of hydraulic jacks, see Procedure 913 1. Fit the protective caps on the cylinder cover studs.

Fitting Pipe Connections

6. Mount the exhaust gas compensator. Fit the screws of the flange between the intermediate pipe and the exhaust receiver.
Fit the insulating jacket around the intermediate pipe.

7. Connect the starting air pipe.
Connect and tighten the air pipe for the starting valve.Connect and tighten the control air pipe for the starting air valve.

8. Connect the water pipes.
Mount and tighten the water outlet pipes.

9. Connect the oil pipes.Mount the hydraulic high pressure pipe for the exhaust valve. See Procedure
-Connect the drain pipe for the exhaust valve.
-Connect the fuel oil high pressure pipes.
-Connect the pipes for return fuel oil from the fuel valves.
-Open Oil and Water Supply.

10. Close the drain and open the water supply.Close the venting cock next to the outlet valve. Close the drain next to the inlet valve.Slowly open the water supply valve, placed next to the cylinder liner cooling water jacket on the exhaust side.Vent the unit by releasing air through the venting cock next to the outlet valve.
When the venting is finished, close the venting cock. Open the two water outlet valves on the exhaust side of the cylinder cover.

11. Open the oil supply.
Open the fuel oil supply for the unit concerned.

ASSEMBLY AND OVERHAULING OF FUEL PUMP OF AUXILIARY ENGINE ON SHIP

THE PROCEDURE FOR OVERHAULING A FUEL PUMP OF AUXILIARY ENGINE ARE AS FOLLOWS:

1.Dismounting of fuel injection pipe.

1) Remove the high pressure pipe.

2.Dismounting of Fuel and Drain Pipes

2) The lock ring (1), see fig 2 must be shifted into the groove in the center of the pipe.
3) Push the fuel and drain pipes into the adjacent pump until the injection pump is free, see fig

3.Removal of Fuel Injection Pump

4) Separate the spring loaded lever from the regulating rod on the fuel injection pump.

5) Remove the screws in the bottom flange and take the fuel injection pump away.

4.Disassembly of the Pump Element

1) Loosen the 4 nbs. holding screws (63)
see fig
2) Press in the roller  (26) by means of the installation device, see fig .

3) Screw off the blocking screw (349) which is the locking arrangement for rollar and pump spring .

4) Loosen the spring force and demount the installation device.
5) Take off the roller (26) and the roller pin (38).
6) Loosen the 2 nbs. Bolts(63) and take off the roller guide(51).

7) Pull out the thrust piece (171).
 afterwards the pump spring (291), the spring plate (205), and control sleeve (266).

8) Turn the injection pump vertically by 180 degrees.
9) Loosen the cylindrical screws (421)

10) Remove the delivery socket (230) and the pressure valve complete(122)
14) Screw off the buffer bolt (242) which are two in nos on both side, it is the locking arrangement for plunger.

15) Carefully take out the pump element (87) with plunger and barrel

INSTALLATION

16) Pump elements can be exchanged as component groups only. (plunger and barrel).

17) Insert the barrel (99), see fig 1 carefully into the injection-pump casing (229) with an aluminum arbor and a non-fuzzing cloth to protect the high-pressure surface, and screw in the blocking screw (349).Tightening torque 5 Nm.

18) Further assembly see under "Exchange of pressure valve".
19) Turn the injection pump vertically by 180 degrees.
20) Install the control sleeve (266) - care for the marking! - control sleeve (266) milled tooth, control rack (254) groove around circumference.

21) The further assembly is carried in reciprocal order of disassembly (driving pin of the plunger in the direction of the slot of the control sleeve).
22) Marking on the driving pin, installed towards the boring of the control rack.

WORKING AND CONSTUCTION of auxiliary engine fuel pump

 JERK TYPE FUEL PUMP(B&W) make.

LETS TALK ABOUT CONTRUCTION OF FUEL PUMP                                                                     

The figure shows a fuel pump parts which is used in auxiliary engine of ship.The part no 87 shows a pump element complete, which consists of plunger 109 which resciprocates in barrel 099.

The key on the plunger fits over the sleeve 266. The sleeve on the outside has pinion  machined on it ,which engage with the rack. In this way the the plunger may be rotated by movements of rack. 

The lower part of plunger sits on the sloted peice 183 and thrust piece 205. The pump spring sits 291 sits on the thrust peice 205. The thrust peice 205 sits over the top of rollar guide 051 . The rollar pin 38 engages the rollar 26 to the the rollar guide 051. 

As the fuel cam rotates ,the rollar moves up . As the rollar is connected to rollar guide the rollar guide moves up with the thrust peice and compresses the spring ,and moving the plunger in barrel up . As the cam comes to base circle ,the spring force brings back the rollar to the base circle of the cam with the plunger to move down. The trailing flank of cam brings back the plunger to the bottom of its stroke to allow the chambor to refill. The plunger and barrel assembly house in the pump casing 229. 

The top part of the fuel pump is the constant pressure valve 146 in pressure valve housing 134. It is a non return spring loaded discharge valve arranged to reduce pressure on its discharge side as it closes ,ensuring positive Closing of the fuel injector needle and reducing Cavitation within the pump. 

Function of contant pressure valve- 

1.When the plunger of the fuel pump moving upwards the pressure of fuel keep on increasing , and at a time when it covers the spill port  the injection commences. But the time when short circuit take place that is  when helix comes in contact with spill port  so sudden pressure drop above the fuel pump plunger, so due to this the high pressure oil in the pipeline after the fuel pump try to come back to fuel pump.  But it is not possible because of discharge valve is of non return type. This high pressure oil then gets trapped into the high pressure line after the fuel pump and this high pressure fuel can lift the needle valve and  secondary injection can take place so this is the reason we have stagnation control valve.  This is a control valve which will not open during normal injection but if there is a high pressure on the discharge side then it will open and will maintain a constant pressure Above and below the high pressure pump . 

2.After the end of the delivery stroke as the plunger moves down and still it cover the spill port ,so no oil is present above the plunger, because fuel is not coming from spill port to the upper side of the plunger so whatever oil is present it start boiling because vaccum is created on top of the plunger so Cavitation can occur which can damage the plunger so in this case stagnation control valve helps and give oil from the high pressure line to the upper side of the plunger so that the space above the plunger should not go to  vaccum.

NOW LETS SEE HOW FUEL INJECTION TAKE PLACE.

A helix is machined on the plunger. The barrel has two ports one for inlet of the fuel oil and other is spill port . Let mark two points in helix- mark A the top part and mark B the lower part of helix. See the diagram above. 

As the plunger is moved up by the cam .

Start of fuel delivery -when the mark A of helix is alligned with the inlet and spill port. The pressurized oil above will go to the delivery valve and injection take place.

End of fuel delivery- when the mark B of helix alligned with the spill and inlet port. This allows the fuel pressure above the plunger to fall because the oil is given a path through the vertical slot and spill port.

The quantity of fuel delivered is regulated by the vertical lenght of helix where it is in line with the inlet and spill port. This setting may be  altered by rotating the plunger via sleeve 266 through rack and pinion arrangement. The rack is connected to the governor which moves the rack depending upon the load on the engine.

The fuel cam is designed to raise the plunger at the rate required to build up fuel pressure and maintain this for the corresponding period to operate the fuel injector . Since the pump only discharges on its upstroke ,only one flank of the cam operates the timing. The trailing flank of the cam returns the plunger to the bottom of its stroke to allow the chamber to refill.

Oil supply to the pump suction is by means of a continuously operating supply or surcharge pump which causes flooding of the fuel pump chambor as soon as the suction port is uncovered by the plunger.

TAPPET CLEARANCE IN AUXILIARY ENGINE ON SHIP

Alignment of valve tappet clearance

1. Dismantle the cylinder cover.
2. Turn the crankshaft until the cylinder in question  is in TDC position. The valve push rod must rest on the cam circle.
 3. Clean the surfaces, if required.

 4. Insert the feeler gauge (P3 = 0.01 mm). See fi gure 1.
5. Fix the torque spanner (P4) on the coupling of the socket wrench (P2).
6. Attach the socket wrench (P2)
7. Attach the socket wrench (P1)
8. Tighten the adjusting screw with P1 until the feeler gauge is fi xed without clearance.

Note ;Check with the feeler gauge that the clearance is between 0.01 and 0.02.

Adjustment of inlet and exhaust valve clearance.

1) Take all safety precaution before ( like take out from standby , close the breaker , close priming pump etc)
 1) Clean the surfaces, if required.
2) Insert the feeler gauge (P6), see figure 3.between the inlet rocker arm and inlet valve bridge or between exhaust rocker arm and exhaust valve bridge.

 Feeler gauge (P6):
 - L16/24: 0.4 mm inlet valve
 - L16/24: 0.5 mm exhaust valve

4) loosen the lock nut of the the rocker arm by open end spanner
4) Tighten the adjusting screw with screw driver(P5) until the feeler gauge is fixed without clearance.

6)Now Tighten the nut with spanner and keep the adjusting screw in position by means of the screw driver(P5)
7) check by feeler guage the suction valve clearance as 0.4mm and exhaust valve clearance as 0.5mm.

ON THE 3 location clearance in measured as shown 1 ,2 ,3 in diagram

1-between inlet valve bridge and one inlet valve spindle( for alignment of tappet by filler guage of 0.01mm)
2 -mostly between rocker arm and valve bridge.(by feller guage 0.35 and 0.45 mm ,in between one rocker arm and valve bridge of 2 inlet valve and other in other rocker arm and exhaust valve bridge of 2 exhaust valve)
3- Between rocker arm and push rod(rarely)

Note
The feeler gauge must be clean and inserted as equally as possible between the adjusting screw and the valve bridge. The valve clearance of inlet and exhaust valve is 0.6 mm for a cold engine .
 - The spanner must be placed straight on the hexagon lock nut.
 - During tightening the feeler gauge must be moved from side to side, however, it must stay between the adjusting screw and the valve spindle. The screw is tightened until a slight squeeze can be felt. The rocker arm must be pressed against the tappet during the adjusting process to remove the clearance.

Risk advice:
 - Danger of slipping during adjusting process.
Attention: Risk of hand/finger injury.
 - Risk of injury because of sharp-edged feeler
gauge. Attention. Do not put your fingers between adjusting screw and valve spindle.

HONING OF CYLINDER LINER IN SHIP

Honing the Cylinder Liner


When we are going to insert a new liner it is mirror finished,if oil is added it will slip and effective lubrication will not be there . So wear of liner will take so to prevent it honing is done to make a honing groove so that the the oil can retain in liner.

 In order to obtain a round cylindrical cylinder liner a factory honing is required. A honing as described below can only be regarded as a second best solution and might have an impact on the time between
overhaul as well as on the lub. oil consumption.Renovation is made in the workshop.Prior to honing, deposits of coke and possible wear edges at the top of the liner must be removed by scraping.
A used flame ring must be used during the honing process.
The used flame ring must be cleaned in water. Subsequently, the flame ring is remounted in the cylinder before carrying out the honing process.
Note: Upon completion of the honing process the used flame ring is discarded. A new flame ring is always mounted in the cylinder when replacing the piston rings.

The honing is made by means of a flex-honer with grain fineness 80-120. A revolution speed between 80 and 160 rpm is chosen.In order to achieve a required angle between honing grooves, see fig 3, the vertical speed is adjusted to about 1 m/sec. which corresponds to about 2 sec.
for one double movement (the flex- honer is led from below up and down in 2 sec.)
The procedure must be continued until the cylinder wall is covered by honing grooves and the surface has a slightly matt appearance without any signs
of glaze.During the honing it is important to lubricate freely with honing oil or cutting oil.After the honing, the liner is carefully cleaned with gas oil. Make sure that all abrasive particles are removed.

LT WATER COOLING OR CENTRAL WATER COOLING SYSTEM AND COOLING SEA WATER AND SERVICE SYSTEM ON SHIP

Please don"t refer to the old books there they have shown the diagram of system which was used in 90 s .i have sailed on 2013 built ship and all modern ship nowadays uses this type of system which i will show you in my blog with practical explanation.

The corrosion and other problem associated with salt water circulation can be minimized by using central cooling system which uses a LT water which is a distilled water  produced from fresh water generator  with additives added in it.

NOW first take a look at S.W and service system on ship and then we will go into LT cooling water line diagram on ship.

The diagram shows a SW  system on ship.
The sea water is drawn from( high sea chest when the ship is in port and from changeover to  low sea chest when the ship sails away from port in high seas) sea chest through filter . The sea chest are incorporated with filter ,air vent for purging , MGPS (marine growth prevention system), drain hole. The all sea water system is on bottom platform .
 From the sea water manifold the sea water is distributed for various purpose. Many pump such as
1.sea water pump for cooling.
 2.ballast pump for ballasting and de ballasting .
3.fire and gs pump for fire fighting and deck washing.
4.fire and bilge pump for de ballasting aft peak tank , for pumping out bilges during an emergency (rare)  and pumping out cargo hold bilges by the help of eductor
5. Ejector pump for fresh water generator.

In dia you can see all this pump are connected through a common manifold line
Now we are interested in sea water pump only ,we have two s.w pump which take suction from sea water common manifold with changeover arrangement. The sea water pump with a pressure of 3.5 bar approx send sea water to a height to

1. No 1 & No  2 F.W cooler or central cooler
2. Sewage treatment plant.
3. Atmospheric condensor.

And finally after cooling all this equipment it goes overboard.


Now lets talk about LT F.W cooling system line diagram.

As you can see in diagram the LT water i.e distilled water with additives is circulated all around the ship equipment to be cooled.
As the temperature of water is low around 35 to 50 degree than a HT water cooling system which is around 70 to 84 degree celcius ,so it is called low temperature cooling water system.

The low temperature water after cooling all equipment and machine onboard gets heated up and comes to LT F.w Cooler. Here the LT Water is cooled by heat exchanger by sea water on one side . A pneumatic controller continuosly control the LT Cooling water outlet temperature to around 40 degree. If suppose when the ship is in port only air condenser , reefer condensor ,air compressor , 1 generator is running ,so after cooling only this machinery the temperature of LT water will be less . In this case the bypassed to cooler valve is closed see dia.
When the ship is sailing all the machinery are running such as air cooler of ME, lube oil cooler ME , ME jacket cooling water , All the 3 generator etc. In this case the LT water temperature will be high enough, so the  controller will open the bypass valve to cooler so that the LT water will be cooled by the LT FW COOLER.
Now lets talk about all the equipment which is to be cooled by LT water;
 The LT water after LT F.W cooler passes to 3 pipeline:
They are
1.First pipeline goes to cool Engine control room condensor , main air compressor for intercooler, accomodation air conditioning,  bridge control room condensor . All this after cooling meet at a point 3 as shown in figure.
2. Second pipeline is divided into again 3 pipeline. 1st pipeline for ME LO COOLER after cooling it ,it than goes to ME Jacket FW cooler (check my blog HT COOLING FW system). 2nd pipeline goes to cool ME air cooler and the 3rd pipeline goes to cool Intermediate shaft bearing. All this 3 after cooling meets at a point 1 as shown in figure.
3. The third pipeline goes to cool all the 3 generator on ship. The outlet then goes to LT expansion tank. After cooling in generator the outlet goes and meet at point 2 as shown in diag.
The outlet of LT expansion tank meets at point 4 in the diagram.

The LT cooler PUMP than suck the heated water from all  1 ,2 ,3 ,4 point and leads the water to LT FW cooler. This is how the circuits complete.
Note we do not have any controller in sea water cooling circuit.

Thus we can conclude there are 3 circuits 
1) HT JCW FW COOLING
2)LT FW COOLING SYSTEM
3)SW COOLING SYSTEM.

ADVANTAGE OF ALL THIS SYSTEM LT/HT FRESH WATER COOLING ARE AS FOLLOWS;

1. Low maintenance cost -as the system runs with fresh water the cleaning ,maintenance and component replacement reduces .
2. Less corrosion
3. High speed of fluid hence better heat exchange . Higher speed is possible in fresh water system which results in reduced piping and low installation cost .
4. use of cheaper material since corrosion factor decreases, expensive material are not required for valves and pipelines.
5. Constant temperature level maintained -since the temperature controlled is irrespective of sea water temperature, stable temperature is maintained which helps in reducing machinery wear down ,due to thermal expansion if different maintained as for ex in sea water cooling system.
6. Less wear of engine parts - less wear of cylinder liner as the jacket is maintained warm avoiding cold corrosion.
7.  Ideal for unmanned engine room the greater reliability and temperature controlling of the system offered by central cooling system.

 DISADVANTAGE

1.high installation cost
2.limitation of low temperature