Over the past few years, rapid innovation in marine propulsion has occurred as a direct result of the growing need for ships that are both reliable and cost-effective to operate. As nations’ stocks of natural resources and consumer products run short, they are becoming more reliant on a dependable transportation industry to facilitate international commerce.

Consequently, new marine propulsion engines have been developed over the past several years that are designed to be more powerful and efficient.

Engines that deploy an enormous amount of horsepower are what propel the world’s largest ships. These contemporary ship engines may differ in construction and function, but they all deliver the physical force that is required to propel gigantic vessels through monstrous waves.

The Wärtsilä 31DF dual-fuel engine, designed by the Finnish engine manufacturer Wärtsilä, is now regarded as the world’s most powerful ship engine. However, it does not compare to the company’s mammoth record-breaking RTA96-C, in terms of size.

The RTA96-C is 44 feet high and 87 feet long and has a horsepower of 110,000, whereas the Wärtsilä 31DF measures 15.4 feet heightwise and 28.8 feet lengthwise, with a horsepower of 13,142. The latter is primarily intended for medium-sized ferries and cruise ships.

Manufacturing company Of the World’s Most Powerful Ship Engine

Those who have an interest in maritime machinery would not want to miss the opportunity to check out the Wärtsilä production setup in Finland. The next time you’re in Finland, be sure to include it on your must-see list. The manufacturing team at Wärtsilä is responsible for the creation of some of the most remarkable and powerful engines that have ever been produced.

Over the course of its history, Wärtsilä has established itself as the industry pioneer in the development of novel technology and maritime automotive solutions. Research and innovation in environmentally friendly practices and technologies are given a substantial amount of priority at Wärtsilä.

The centre results of Wärtsilä incorporate advancements for the energy area, including gas, multi-fuel, fluid fuel, and biofuel power plants and energy stockpiling systems; innovations for the marine area, including voyage ships, ships, fishing vessels, vendor ships, naval force ships, extraordinary vessels, pulls, yachts and seaward vessels.

Transport plan capacities incorporate ships, pulls, and boats for the fishing, trader, seaward, and extraordinary segments. Service contributions include internet-based administrations, submerged administrations, turbocharger administrations, and other benefits for the marine, energy, and oil and gas markets. By the end of June 2018, the organization had over 19,000 specialists.

Wärtsilä is a company that is traded on the Nasdaq Helsinki exchange and had over 4.8 million Euros in net sales in 2021. Additionally, Wärtsilä is active in the markets of hybrid solutions, energy storage and optimization technologies, as well as future-fuel enabled balancing power plants.

Wärtsilä 31Df – The most efficient ship engine

The 31Df was introduced by Wärtsilä in 2015. The latest upgrade of the same model increased the output range to 4.6 – 12 MW from the previous, 4.2 – 11 MW. The upgraded output range has been achieved with the 600 kW/cylinder at 750 rpm and 580 kW/cylinder at 720 rpm. The upgrade also lowered greenhouse gas emissions by near about 750 tons per annum.

Along with that, Wärtsilä 31 DF, also meets the IMO Tier 3 regulations when operating on gas and with SCR when using diesel fuel. Reliability is guaranteed through validation and Wärtsilä’s vast manufacturing experience, supported by its extensive global services network.

Efficiency of the Most Powerful Ship engine

Three models with different functionalities are available to choose from. Customers can either opt for the diesel version, the natural gas-driven one or the dual-engine. The former uses high-quality fuel and an advanced injection system along with valve timing.

RTA96-C delivers 0.278 pounds per horsepower-hour compared to the 0.271 pounds of the diesel version. Hence, recording a difference of 2.6 per cent in the efficiency. Though it may seem a mere difference, in reality, it is a huge difference. It translates to 85,000 pounds of oil being saved in a day, in the case of 31DF.

Taking all these features into consideration, Wärtsilä has another entry in the Guinness Book of Records, after RTA96-C, for the world’s most efficient 4-stroke diesel engine. Wärtsilä 31DF also has a low level of exhaust gas emissions which adds to the sustainability factor.

As of 2020, over 100 Wärtsilä 31DF engines have already been sold with more than 60,000 field operating hours. When it comes to maintenance, the upgraded Wartsila 31 wins hands, as it does not require much upkeep.

The engine is designed in such a manner, that it can be taken out and replaced without much effort. It can act as a propulsion engine and also contains diesel-electric configurations as an auxiliary engine. It can be customized to operate either at a constant speed or along a propeller curve.

What makes the Wärtsilä 31Df so special?

Energy efficiency– Consumes on normal 8-10g/kWh less fuel contrasted to the nearest contender across its whole range.

Fuel flexibility– The Wärtsilä 31 can use a diverse range of energy supplies including bunker fuel, distillate marine diesel, natural gas, ethane and liquified petroleum gas.

Cost-effective– The cost of overall maintenance decreases by twenty percent.

Low maintenance– Provides more amenability. The first support stop comes after 7,000 hours contrasted with 950 hours for conventional motors of similar configuration and features. The accessibility of the trade modules guarantees short margin time for upkeep.

Easy to Operate– Completely functional, all over the place. The double fuel motor empowers a simple change to gas while transforming to the third-tier region with no adjustment of speed. It can undoubtedly be adjusted for various working profiles and has numerous future possibilities.

Lesser emissions– Altogether, it produces fewer carbon and sulphur emissions and adheres to the International Maritime Organisation’s environmental guidelines, which were implemented in 2016.

Future prospects of the most efficient ship engine

The modular external and internal designs of this engine don’t just work with instant fixes, it additionally upholds the upgrades for the distant future. The manufacturer Wärtsilä Corporation has the sole objective of making it highly adaptable to future requirements.

With technological advancements, whenever a new technology is being developed by the company, it can be easily upgraded by installing a module that holds all the updates. Eventually, this will be convenient for the ship owners to tackle future amendments in the maritime sector. For instance, this will be especially helpful when new emission guidelines are presented, yet may likewise apply to future fuel types.

This product has been designed in such a way that it can adapt to any future circumstances. Due to its flexible design and use of common technologies on the different variants, the engine can be converted from one variant to another with only minor mechanical changes.

Conclusion

In recent years, there has been a growing movement towards the utilization of renewable and alternative energy sources for the purpose of fueling engines. This development has occurred in conjunction with governments’ efforts to reduce pollution in the maritime sector.

The Wärtsilä 31DF engine launched for energy markets is a step closer to realizing Wärtsilä’s vision of a 100 per cent renewable energy future, thanks to its decreased environmental footprint and operational flexibility.

When each of these qualities and essential considerations is taken into account, the Wartsila 31DF emerges as the most efficient engine in the world. Even though there is a possibility that some other engines could overtake Wartsila 31DF, as the most popular choice in the future, the firm that makes it will continue to innovate and will maintain its position as the market leader.

You might also like to read: 

• How Spark Erosion Can Damage the Main Propulsion Engine of a Ship?
• Watch: Ship’s Main Engine Exhaust Valve Working
• How Ship’s Engine Works?
• Slow Steaming of Ships: Optimization of Ship’s Main Engine
• How to Test Ship’s Main Engine for Slow Steaming?

Disclaimer: The authors’ views expressed in this article do not necessarily reflect the views of Marine Insight. Data and charts, if used, in the article have been sourced from available information and have not been authenticated by any statutory authority. The author and Marine Insight do not claim it to be accurate nor accept any responsibility for the same. The views constitute only the opinions and do not constitute any guidelines or recommendations on any course of action to be followed by the reader.

Which is the Most Efficient Ship Engine in the World? appeared first on Marine Insight - The Maritime Industry Guide

The Variable Injection Timing (VIT) function of a marine diesel engine comes into play during load dependent adjustment of the combustion pressure. Variable Injection Timing (VIT) allows to achieve maximum combustion pressure during part load operation which helps in decreasing the fuel consumption and also achieve efficient combustion in the engine.

By controlling the injection timing of the fuel in the fuel delivery pump and advancing the fuel pump injection timing, VIT increases the maximum pressure in the engine.

When working with a ship’s Main Engine, which is equipped with Variable Injection Timing (VIT) device, a marine engineer must know the following points for smooth engine operation:

1. Freeness of Mechanical Parts: The actuator of Variable Injection Timing (VIT) operates on the movement of eccentric shaft of suction and spill control valves. Marine engineers must ensure that these valves are free from any obstruction or excessive play. The eccentric shaft spring should also be regularly checked for proper operation in order to avoid any kind of breakdown.

2. Checking Load Indicator Values: The regulating fuel linkage transmits the movement of the governor output lever and determines the fuel feed to the cylinder accordingly. Ship’s engineer’s must check the correspondence between the load indicator position in the setting plate provided in the linkage, and the load indicator value at the local manoeuvring stand and at the remote control position when the VIT is set to “0”. If there is deviation in any of the three values, it has to be corrected before commencing any action on the fuel pump timing.

3. VIT Actuator Setting: Check the actuator stroke when VIT is “0” by inserting the distance sleeve between the suction valve regulating lever and the blocking unit. Move the VIT to its maximum advance and minimum retard position respectively and note down the values in the load indicator in the setting plate. Also check the stroke of the actuator at the remote control system. Lastly, note and compare any deviation prescribed in the manufacturer manual.

4. VIT Clearance: When fitting the VIT after maintenance, the clearance and alignment between the stop plate and the linkage must be checked with cylinder in fully retracted position. If there is no clearance, the stop plate must be ground until the clearance is achieved.

5. Electrical Connection: For electronically operated Variable Injection Timing (VIT), all the cable connections between the connecting box and VIT terminal must be checked regularly.

6. Pneumatic Cylinder: The Pneumatic cylinder which acts as the positioning unit of the VIT linkage is sometimes provided with a mechanical stoppage which should be checked for jamming. This will be useful to move the cylinder manually in the event of failure of automatic positioning system.

7. Running in Period: When the marine diesel engine is under breaking in/ running in period due to rent overhauling of the engine components, VIT should be disconnected or turned off for the complete time period until the running in is completed.

8. Engine running with Unit Cut Off: If the main engine is running with one unit cut-off due to major problem in the parts of that unit, the VIT to be set at zero or switched off as there will be uneven load distribution within the engine.

9. VIT Failure: When the failure of VIT occurs, the combustion peak pressure is no more controlled by the pneumatic actuator. During such situation, the distance sleeve must be installed to fix the neutral position of the VIT.

This is not an exhaustive list but comprises of all the important points that must be considered while working on an engine with VIT.

VIT is used to reduce the overall fuel consumption and to achieve maximum pressure even at low load but poor maintenance and operation of VIT can reverse the result and even lead to major damage of main engine parts.

Do you know any other important point that should be added to the list? Let’s know in the comments below.

Variable Injection Timing (VIT): What Marine Engineers Must Know? appeared first on Marine Insight - The Maritime Industry Guide

The reciprocating action of piston is converted into rotary motion for crankshaft by means of the cross head where the piston rod and connecting rod are attached on both sides.

A routine maintenance has to be performed on crosshead bearing as per maker’s instruction. Following procedure is to be followed when carrying out crosshead bearing removal of a MAN MC-C engine:

1)       Inform company and take permission.

2)       Take immobilization certificate from port.

3)       Read the manual and have a toll box meeting with everyone involved in the job. Discuss the procedure.

4)       Prepare important tools and spares to be used in this operation

5)       A risk assessment of all personnel doing the operation to be prepared and documented

6)       Shut main engine starting air

7)       Engage turning gear to the main engine crankshaft

8)       Open indicator cocks of all cylinders

9)        Stop main engine lube oil pump after cooling down of engine

10)    Open crank case doors of fore and aft unit

11)    Open crank case doors of that unit in which maintenance is to be carried out.

12)    Put blower and ventilate the crankcase thoroughly as it is an enclosed space.

13)    Prepare enclosed space entry checklist.

14)    After sufficient ventilation wearing proper PPE you can enter the C/C.

15)    Turn the crank throw to 90° before BDC.

16)    Check the bearing clearance by inserting feeler gauge b/w bearing cap and crosshead journal exactly next to the landing surface of the piston rod foot.

17)    The wear limit for a cross head bearing shell is limited to 50% reduction of the oil wedge length (L).[ L=10mm]

18)    Turn the crankshaft down enough to give access to nuts and screws on piston rod.

19)    Mount two chain blocks on the top of the crankcase for suspending the piston rod.

20)    Loosen and remove the locking wire and screws on the piston rod foot.

21)    Mount the lifting eye bolt on each side of the piston rod foot.

22)    Turn the crosshead to TDC.

23)    Hook the chain blocks to the eye bolt on the piston rod foot. And turn the crosshead down so that piston is now suspended on the chain blocks.

24)    Turn to BDC.

25)    Mount the hydraulic jack on the crosshead bearing cap nut and loosen them. [pressure : 1500-1650 bars]

26)    Mount the lifting attachment on the head of the connecting rod.

27)    Suspend the two chain blocks from the lifting brackets in the athwart ship direction.

28)    Mount the 2 eye bolts on the top of the cross head bearing cap.

29)     With the help of the two chain blocks lift the bearing cap. Take it out of the engine and place it on a wooden base.

30)    To check the upper bearing shell, remove the locking screws and push the shell out.

31)    Mount the chain blocks to the lifting brackets on the frame box wall.

32)    Turn the crosshead up until the piston rod lands on the crosshead. Ensure that the guide ring in the crosshead fits correctly in the centre hole of the piston rod.

33)    Do not remove the chain blocks or the lifting eye bolts.

34)    Turn the crosshead to TDC and attach the chain blocks to the lifting arrangement and haul it tight.

35)    Mount the four supports for the guide shoes on the crosshead guide.

36)    Carefully and slowly turn the crankshaft towards to exhaust side and make sure the crosshead guide sits on the supports.

37)    Turn the crank throw towards BDC slowly while following with the chain blocks, thus continuously supporting the connecting rod.

38)    In case it is necessary to remove the lower bearing shell, tilt the connecting rod towards the door on the cam shaft side with means of chain blocks.

39)    Dismount the locking screws and turn the bearing shell so far up that an eye bolt can be mounted. Lift the bearing shell out.

Top clearance in crosshead bearing Max: 0.29mm,  Min: 0.17mm

Procedure for Cross Head Bearing Removal of Marine Engine – MAN B&W S50MC-C appeared first on Marine Insight - The Maritime Industry Guide

Moreover, the main bearing of a ship’s main engine must be overhauled when its running hours as stated by the engine maker have been completed. Apart from this, if there is any sign of bearing worn out or if the bearing temperature is going high, it is imperative to open the main bearing for inspection.

The procedure for opening of the main bearing is as follows:

1)       Inform company and take permission.

2)       Take immobilization certificate from port state Authority stating that the main engine will not be available for a particular period of time.

3)       Read the manual and have a toll box meeting with everyone involved in the job. Discuss the procedure.

4)       Prepare important tools and spares to be used in operation.

5)       Prepare risk assessment with the personnel involved in operation.

6)       Shut starting air valve for main engine.

7)       Open indicator cocks of all the units.

8)       Engage turning gear and put it in remote control. The remote control switch to be operated by in charge of the operation.

9)       Stop main lube oil pump.

10)    Open crank case doors.

11)    Put blower and ventilate it thoroughly.

12)    Prepare enclosed space entry checklist.

13)    After sufficient ventilation, wearing proper PPE enter the C/C.

14)    Make sure that the main bearing measuring tool (depth gauge) is calibrate and set to ‘0’.

15)    Open the screws of lube oil pipe connection and insert the depth gauge and measure the clearance between upper bearing keep and journal.

16)    Compare this reading with the earlier reading in the record or the new bearing reading.

17)    Now disconnect the lube oil pipe line.

18)    Turn the crank throw so that it is towards the exhaust side.

19)    Now mount the hydraulic jacks and loosen the main bearing stud nuts.

20)    Mount the lifting tool for main bearing keep and lift the keep using a pulley and a wire rope.

21)    Note the marking on the main bearing keep before lifting for correct direction of the keep.

22)    Guide the keep safely outside with a help of another chain block and place it on a wooden base once it is out.

23)    Mount the tool for lifting the upper bearing shell and place it safely outside.

24)    Place the strong back (cross piece) support on the bed plate so that its ends rest on the cross girders.

25)    Mount the hydraulic jack on the cross piece placing it such that it lies beneath the crank webs.

26)    Mount a dial gauge on the adjacent main bearing so that the lift of the crank shaft can be recorded.

27)    Now with hydraulic pressure (1500-1650 bar) lift the crankshaft corresponding to the main bearing clearance to the adjacent main bearing, and check the lift with the help of a dial gauge.

28)    Remove the lock screws from the lower shell.

29)    Place the dismantling tool on the lower bearing shell such that the flap enters the oil groove.

30)    Pull the bearing shell round and up so that it lies on the journal and take it out safely.

Note: Top Main bearing clearance: max- 0.58mm, min- 0.40mm

Here is a rare You Tube video for MAN MC engine main bearing overhaul

You may also like to read-Everything You Ever Wanted To Know About Crankcase Inspection on a Ship

Reference: MAN B&W MC-C Engine maintenance manual

Procedure for Removing Main Bearing of MAN B&W MC-C Engine appeared first on Marine Insight - The Maritime Industry Guide

Indicator diagrams are used to assess the performance of each unit of the ship’s main engine. It is based on the indicator diagram that the overall performance of the engine is assessed.

Indicator diagrams are taken at regular intervals of time and matched with that of the ship’s sea trial diagrams to check if there is any significant difference in performance. If there is any difference, it is important that the problem is rectified before starting the engine.

Understanding Indication Diagram

There are four types of indicator diagrams:

1. Power card
2. Draw card
3. Compression diagram
4. Light spring diagram

With the help of these diagrams, we can determine and interpret the following:

• The compression pressure inside the cylinder
• peak pressure generated inside the cylinder
• The actual power generated
• Faulty combustion chamber parts (worn out piston, liner, rings, etc.) of the particular unit
• Faulty injection parts and wrong fuel timing
• Exhausting and scavenging process

High loading is to be prevented on main engine’s units or else it can lead to several problems such as bearing damage, cracking, etc. It is therefore very important to read these diagrams correctly as they provide several details about the cylinder working pressures and load.

In earlier days, the indicator diagram was taken with the help of mechanical indicator which was to be fitted on top of the indicator cocks.

But nowadays digital pressure indicator instrument is used which is a compact hand held unit. A pressure transducer is mounted on the indicator cocks and connected to the hand held unit know as data acquisition unit with the help of which the indicator diagram can be taken at any moment and displayed on the computer.

An incremental encoder is fitted on the engine and plugged into the data acquisition unit during the time of operation, which provides accurate data about the position of the top dead centre, or of the crankshaft angle.

Preparation and procedure for taking indicator diagram:

• Check the battery of Data Acquisition unit and change/ charge if needed
• Prepare the Digital Pressure indicator instrument and check all the wires/sensors are visually ok
• Do proper PPE, especially high-temperature gloves and eye protection
• Take the reading of all the relevant engine parameters
• Ensure the ship, and its engine is running at a constant speed in open sea
• ensure the weather is calm
• Use correct tool to open the indicator cock valve
• Connect the probe from incremental encoder to data acquisition unit
• Connect the pressure transducer probe to hand held data acquisition unit
• Carefully open the indicator cock of the cylinder for few seconds and blow out the cylinder. It is done to remove any stuck impurity (soot and other combustion particles) inside the cock
• Fix the pressure transducer unit on indicator cock and open the cock  to register the cylinder data
• Repeat the procedure for all the cylinders
• After finishing the process, disconnect the pressure transducer probe and keep it aside for cooling it down
• Disconnect the incremental encoder probe from hand held data acquisition unit
• Fill the required data in the Digital Pressure Indicator software and wait for result to be generated

It is possible that the digital pressure indicator instrument is not available in all ships or is not working. A mechanical engine indicator device is provided which consists of springs, drums and pointer to draw the diagram from the engine cylinder’s pressure via indicator cock.

Related Reading:

Why 2-stroke engines are used over 4-stroke engines

How to use main engine performance curve for economical fuel consumption

Procedure for taking indicator diagram using mechanical engine indicator instrument:

• Do proper PPE, especially high-temperature gloves and eye protection
• Take the reading of all the relevant engine parameters
• Ensure the ship, and its engine is running at a constant speed in open sea
• ensure the weather is calm
• Use correct tool to open the indicator cock valve
• Take the paper provided with the instrument and fix it firmly over the drum
• Carefully open the indicator cock of the cylinder for few seconds and blow out the cylinder. It is done to remove any stuck impurity (soot and other combustion particles) inside the cock
• Fix the instrument on the indicator cock so that the cord is firm.
• Draw the atmospheric line with the cock shut
• Slowly open the indicator cock and press the stylus against the paper lightly. Make straight vertical lines as the piston moves up and down and then pull the roller string, till the cycle is drawn on the paper
• Close the indicator cock and remove the instrument
• Ensure the tool does not get exposed to high temperature for an extended period as its mechanical parts like springs, the stylus will respond differently and may affect the accuracy

Similarly, take compression pressure line with the fuel cut off.

How Can You Assess or Interpret Just by Looking at the Card Diagram

The indicator diagram shown above is a normal diagram (Diagrams taken before the use of the engine), and the diagrams that are drawn from the engine are adopted and compared for the deficiency.

Related Reading:

1o Extremely Important Checks For Starting Marine Engines

12 Terminologies Used For Power of Marine Engines

Types of Deficiencies

We will take a look at some of the common defects found in indicator diagrams.

Deficiency type 1

When the above diagram is compared with the general graph, it can be seen that the compression pressure is normal and the maximum firing pressure is too high.

This can be due to early injection, a result of incorrect fuel timing of the cams, wrong VIT setting, or leaking fuel injector.

Deficiency Type 2

In this diagram, it can be seen that the compression is same, but the peak pressure is too low.

This effect can be a result of following factors:-

• Bad quality of fuel
• Fuel injector nozzle blocked
• Fuel pumps leaking
• Low fuel pressure

Deficiency Type 3

This diagram shows that the compression pressure is low, and the peak pressure is also too low.

This can be due to the following:

• Leaking exhaust valve
• Leak through piston rings i.e., broken or worn out piston rings
• High Liner wear
• Burnt piston crown
• Low scavenge pressure

Deficiency Type 4

This diagram shows high compression pressure together with high peak pressure.

This can be as a result of the following:

• Exhaust valve opening too late i.e. incorrect exhaust valve timing
• Overload of the engine

Disclaimer: The authors’ views expressed in this article do not necessarily reflect the views of Marine Insight. Data and charts, if used, in the article have been sourced from available information and have not been authenticated by any statutory authority. The author and Marine Insight do not claim it to be accurate nor accept any responsibility for the same. The views constitute only the opinions and do not constitute any guidelines or recommendation on any course of action to be followed by the reader.

The article or images cannot be reproduced, copied, shared or used in any form without the permission of the author and Marine Insight. 

Understanding Indicator Diagram and Different Types of Indicator Diagram Deficiencies appeared first on Marine Insight - The Maritime Industry Guide

Water from the Main Engine fresh water expansion tank is used for cooling purpose in the ship’s main engine. The water in the tank needs to be kept at the required level at all times to ensure that sufficient water is supplied to the engine.

In this article, a peculiar situation has been described, wherein the main engine fresh water tank had to be replenished five or more times a day to supply the necessary amount of fresh water to the engine – Of course, this is excessive.

In a well maintained engine room wherein maintenance of the main engine is carried out properly, the makeup water in expansion tank for main engine is not more than 0.5 Cub m per day (0.2 Cub m is common).

Excessive leakage of the fresh water tank can be because of several reasons. Some of the main ones are listed below along with their troubleshooting:

1)      Leakages from Cylinder Head “O” rings

This happens mainly because of insufficient preheating (below 45 °C) but stops when the engine is running and the jacket cooling water outlet temperature is 80-82 °C due to thermal expansion.

Regular maintenance with use of correct size and type of O-ring and good cleaning of surfaces is the key to resolve this problem.

In some engines, there is an intermediate cylindrical piece, which forms a part of the jacket. If this is not correctly fitted (Mind the dowel pin and see if rubber ring is not oversized), this piece may crack. To cut off this unit, we may need to close the inlet and outlet valves of the concerned cylinder. However, it has been noted that these valves do not hold and a blank is difficult to put.

The jacket cooling water inlet and outlet valves of the main engine must be overhauled on all units during dry docking. Engineers also need to practice how to cut off the fuel to a particular cylinder in correct manner. Trying to figure this out at the last moment is not a good idea.

2)      Leakages from Cylinder liner “O” rings.

During cylinder overhauling, engineers should try to pull out the liner and renew the “O” rings after good cleaning of the landing surface.

This process requires time and immobilization of the ship at the ports one of the biggest concerns these days. However, we should be on the look out to carry out this work whenever possible.

3)      Leakage from Main Engine Turbocharger Water Cooled Casing:

The turbo charger casing should be cleaned chemically on the water side (do not hard scrape or hammer the casing) after 10 years of operation. Ultrasonic gauging of the casing at the top (near air vent) and at the bottom (mud collects here and circulation is inadequate in this area) is required.

If, unfortunately, the casing develops a crack, it is very difficult to trace and equally difficult to repair. Rigging of air cooling may be resorted to ensure that the oil temperature does not go more than 120 ° C (attached pumps and individual sumps).

4)      Leakage from Pump Gland: With improvement of pump designs (Shinko) and use of mechanical seals, the leakage from pump glands is quite minimal these days.

However, on older engines, renew the pump sleeve and use correct size gland packing, ensuring very less leakage at the gland (follow maker’s advice).

5)      Leakage in Fresh Water Cooler: Maine engine’s fresh water cooler for jacket cooling water should regularly be cleaned and pressure tested as per the planned maintenance system of the engine room. Any leaking tube must be plugged as per the maker’s instruction.

6)      Degraded Cooling Water Property: Maintaining cooling water quality is of prime importance. Once in 6 months, engineers should send cooling water sample for analysis and also try to keep PH of the water about 8.0-8.5 by giving regular chemical dozing.

There are training videos provided by the chemical suppliers and these should also be viewed by engine room staff to understand the process in a better way.

7)      Improper Maintenance and Overhaul: Marine engineers often overhaul the exhaust valves but do not pay minute attention to the cooling water side by removing the plugs.

It is to note that cylinder heads may also develop cracks with time mostly around air starting valve area. Ship superintendents often ask to get all cylinder heads shifted to workshop for cleaning (during dry dock) and carefully testing for cracks on cylinder head using modern techniques.

Troubleshooting: Excessive Loss of Water from Main Engine Fresh Water Expansion Tank appeared first on Marine Insight - The Maritime Industry Guide

The best thing about being a marine engineer on a ship is controlling the most powerful thing in the world ever created by man- the ship’s main propulsion engine.

The Wartsila Sulzer RT-Flex 96 C is the world biggest and most powerful engine ever made with an output of approx 80000 KW or 108900 BHP.

The overall operation of the ship is highly dependent on the performance of its main propulsion engine, measured in terms of its power rating.

There are several terminologies for “Power” rating used for Marine Propulsion Engine and each of these gives different value of engine performance under various parameters and situations.

Following is the list of “Power” Terminologies used for a Marine Propulsion Engine on board ship:
1 . Effective Power: The Power available at the output side of the engine i.e. at crankshaft flange of the engine which connects it with the flywheel and rest of the intermediate shaft. It can be said that this is the developed power by the engine available to the flywheel. Effective power is determined by an engine’s size and by its mechanical efficiency.

Effective power estimation can be done by two methods:

1. Speed and torque measurement – using the propulsion shaft arrangement
2. Engine mean indicated pressure measurement – using the in-cylinder pressure transducer. This method is preferred if non-direct propulsion unit is present (i.e. gearbox is installed)

2 . Rated Power: It is the continuous effective power provided by the manufacturer of the engine for a desired or rated RPM of the crankshaft. Rated power includes the loads which act on the engine due to the auxiliary system running from the engine power. One of the most important factors for selection of an engine i.e. MCR (Maximum Continuous Rating) is determined from rated power

3 . Indicated Horse Power: The actual power generated inside the combustion chamber of the engine by combustion of fuel is IHP. Hence it forms the basis of evaluation of combustion efficiency or the heat release in the cylinder. It is calculated based on the design of the engine using a theoretical formula:

PxLxAxN
4500

Where P- Mean indicated pressure of the cylinder

L- Stroke of the engine

A-  Cross Sectional Area of the engine cylinder

N- Speed of the engine in RPM

4500 is a constant for conversion.

In this calculation, the frictional losses are not considered. Since it is calculated from indicated pressure of  the engine, it is called Indicated Horse Power or IHP and is used for calculating mechanical efficiency of the engine

4 . Shaft Horse Power: The horsepower delivered to a propeller shaft before being converted into thrust by the propeller. It is measured by an instrument known as torsion meter which is available on board.

Sp = 2pient

t- torque by torsionmeter

n- Rev Per Second of the engine

5 . Brake Horse Power: Brake Horsepower measures the HP of an engine without considering the loss in power that is caused by auxiliaries attached to the engine, such as the shaft generator, alternator, gearbox, and other auxiliary parts. This is the power measured at the crankshaft with the brake dynamometer and is always higher than the shaft horsepower. This is because the power available at shaft accounts for frictional and mechanical losses. The “brake” comes in as the machine used to measure the power is brake dynamometer.

6 . Gross Power: Continuous effective power provided by the manufacturer for a given RPM using defined number of auxiliaries at normal service running condition without any overloading of the engine.

7 . Continuous Power: It is the BHP measured at the power take off the end when the engine is running at continuous safe operation range outside any time limit. This is provided by the supplier.

8 . Overload Power: It is the power excess of effective power than the rated power for a short period of time when the same auxiliaries are used under similar service condition for a limited period.

9 . Minimum Power: The guaranteed minimum or lowermost power value by the manufacturer for an approximate crankshaft RPM is the minimum power of the engine. The total installed MCR of all main propulsion engines should not be less than the minimum power line value, where MCR is the value specified on the EIAPP Certificate. Engine makers has to follow IMO guidelines for determining minimum propulsion power to maintain the manoeuvrability of ships in adverse conditions.

10 . Astern Output Power: The maximum power engine can generate when running in the astern direction at the safe condition. The astern output power of the engine is always less than output power in ahead direction. This is because the propeller thrust adds to the force on the rudder when going ahead, but in astern that thrust is lost. Propeller blade section is designed for maximum efficiency in ahead. In astern direction, the angle of attack is high on the back of the blade.

11 . Maximum Continuous Rating or MCR: It is the maximum power output engine can produce while running continuously at safe limits and conditions. It is specified on the engine nameplate and in the Technical File of the marine diesel engine. Important engine parameters such as specific fuel consumption, engine performance etc. are derived using %MCR rating of the engine. Equipment like VIT also works in conjunction with the MCR rating of the engine to achieve better fuel efficiency.

12 . Standard Rating: This is the power output of the engine at normal service speed which gives the highest economical efficiency, thermal and mechanical efficiency. At this speed, the wear down of the engine is at the minimum rate.

13 . Power to weight ratio: Power to weight ratio is perhaps the most important criterion used when choosing an engine for a type of ship. With ships become ultra large in size (VLCC, ULCC, 20k TEU ships etc.), their heavyweight results in higher displacement equals lower speed.

By using equivalent horsepower in a smaller-sized engine, engine compartments can be made smaller, allowing greater cargo capacity, while maintaining high-speed capability. Hence to get better and efficient performance from the ship, it is recommended to have high power to weight ratio.

14 . Main Propulsion Power: The total power supplied by the prime mover/s installed on a ship to provide propulsion. It does not include the power units integrated into the propulsion unit which is not intended to provide propulsion during normal operation, e.g. shaft-driven generators.

Disclaimer: The authors’ views expressed in this article do not necessarily reflect the views of Marine Insight. Data and charts, if used, in the article have been sourced from available information and have not been authenticated by any statutory authority. The author and Marine Insight do not claim it to be accurate nor accept any responsibility for the same. The views constitute only the opinions and do not constitute any guidelines or recommendation on any course of action to be followed by the reader.

The article or images cannot be reproduced, copied, shared or used in any form without the permission of the author and Marine Insight. 

14 Terminologies Used for Power of the Ship’s Marine Propulsion Engine appeared first on Marine Insight - The Maritime Industry Guide

Marine Engine Repair is one of the most important tasks carried on board a ship. It involves repairing and carrying out of routine maintenance tasks on the marine engine of the ship. The repairs are generally carried out by marine engine mechanics, famously known as marine engineers.

Marine engine parts need to be checked on regular basis to avoid breakdown or heavy loss caused by ship going off charter. Marine engine repairs are carried out by the marine engineer as per his basic understanding of the machine, sound troubleshooting knowledge and correct techniques used for testing and overhauling.

Moreover, there are several agencies around the world that provide services for marine engine repairs, which cannot be done by marine engineers on board the ship due lack of special equipments and manpower. Some examples of heavy maintenance of marine engine repairs are metal stitching or metal locking, recondition of piston, honing of liners etc.

Understanding Marine Engine Repair

When we talk about marine engine repairs, they not just include maintenance and repair work on the mechanical parts of the engines but also include repairs on various electrical equipments as well. Thus, marine engine repair is categorized in two parts – electrical and mechanical.

For an effective performance of the marine engine and in order to prevent breakdown of the same proper procedures are to be followed as described in the manuals. Marine engine repairs have to be done at specific running hours as described in the planned maintenance system of the ship.

On board ship there is a team of marine engineers or marine mechanics, along with crew ratings such as motorman, oiler, fitter, etc. to carry out the work of marine engine repairs.

The team of engineers includes chief engineer, second engineer, third engineer and fourth engineer. Chief and second engineer are management level officers, whereas third and fourth engineers are operational level engineers.

The chief engineer looks after different surveys that are to be carried out on the marine engine and also plans out when they are to be carried out. The second engineer plans the marine engine repair work that is pending or scheduled to be due soon.

The second engineer also looks after main engine and different pumps in the engine room. The fourth engineer looks after the repairs of compressors and purifiers whereas third engineer looks after the boiler and auxiliary engines along with the help of crew ratings.

For electrical equipments the repairs are carried out by a separate dedicated electrical engineer, who looks after various motors, batteries, print card electronics etc.

Important Points for Marine Engine Repair

For marine engine repair, the most important thing is to make available several sets of spare parts on board the ship. If there is a shortage of any of these parts, then they need to be ordered by the respective engineer, who is looking after the particular machinery. Some special considerations also need to be given to emergency, safety and life saving equipments.

Marine engineer also have to make sure that all the equipments are working fine without any problem. External agencies such as port state control and flag state will detain the ship if equipments like emergency generator, life boat engine, and fire fighting system are not working properly. The agencies may fine the ship heavily for these abnormalities.

For this reason, proper checks and routine schedule have to be maintained to avoid unwanted circumstances related to marine engines on board a ship.

Do you want to know what exactly does a marine engineer do? Read it here.

How is Marine Engine Repair Done On board a Ship? appeared first on Marine Insight - The Maritime Industry Guide

Understanding the operations of intricately designed marine diesel engines involves knowledge of stresses, transmission and reversal in each of such engine type.

The connecting rod of the engine swings about the crosshead pin in 2 stroke engines and about the gudgeon pin in 4 stroke engines. The swinging movement is restricted by the crankpin bearing.

The mass of the connecting rod sets up an inertial load in the transverse direction, which demands the connecting rod to be light in medium and high speed diesel engines, mainly 4 stroke diesel engines. Thus, the connecting rods are manufactured in I or H sections to reduce the weight in spite of higher manufacturing costs.

Different types of internal forces acting inside the 4 stroke marine engine are:

• 4 Stroke marine diesel engines experience compressive and tensile forces alternatively.
• Immediately after combustion, the gases expand and force the piston downwards, thrusting the gases compressively until the inlet valve opens.
• The piston and the connecting rod now experience a tensile or centrifugal force which is in direct proportion to the mass of components and the square of velocity.
• The inlet valve and the exhaust valve both stay open and overlap each other for a small period, thereby relieving the components of compressive forces.
• Further, the exhaust valve closes during the induction stroke and the inlet valve closes on the compression stroke. The piston and the connecting rod are once again in compression, though the magnitude is minimal.
• Contrarily in 2 Stroke engines, the piston and connecting rod are always in compression i.e. during the expansion stroke and the compression stroke.
• The magnitude of compressive force is greater in expansion stroke as compared to the compression stroke as the gases expand after combustion and force the piston downwards.

It could thus be inferred that the components of a 4 stroke diesel engines (mainly piston and connection rod) are in compression and tension, alternatively for each revolution of the crankshaft. Due to the large centrifugal force experienced by the piston and the connecting rod, the bottom end bearing bolts that are always in compression, try to shear off as the piston and connecting rod have a tendency to fly off.

The bottom end bearing bolts thus have a restricted life and needs to be replaced depending on the manufacturer’s recommendations. There could be unprecedented, disastrous consequences, if the bottom end bearing bolts fail in their operation. Special care should be exercised when they’re removed from the engine during major overhauls. They should be inspected for cracks on the surface as well.

Furthermore, the piston in 4 stroke engines is made of heat resistant Aluminium alloy, to keep the mass as low as practically possible to minimize the effect of high tensile centrifugal force and reduce the whip loading. These considerations are not significant in 2 stroke engines as they’re always in compression.

Moreover, in 2 stroke engine, the connecting rod is in line to the piston rod and hence there’s an angularity when the crank moves from the top and bottom dead centre positions. The transverse thrust set up is transmitted by the guide slippers on to the engine or cylinder guides. This transverse thrust is termed as guide load, which comprises of the resultant of the piston rod and the connecting rod loads caused by the cylinder pressures (static load) and the dynamic loads caused by the inertia of moving parts. The alignment of the guides is very important as is the clearance between the guides and slippers. If the clearances become excessive then exorbitant wear will occur between the piston rod and the stuffing box and the piston and the cylinder liner.

The transverse thrust or the guide load is calculated by the triangle law of forces, drawn up from the force acting downwards on the piston rod along the line of the piston stroke and the reaction from the upper part of the connecting rod. When the line of the connecting rod is identical to the line of piston rod, then the magnitude of the guide load is zero i.e. when the piston is at its bottom dead centre or top dead centre. The magnitude of the guide load varies when the piston moves during its expansion stroke and acts in one particular direction. Similarly, when the piston is moving upwards during the compression stroke the guide load varies but acts in opposite direction.

Contrarily, in 4 stroke engines the side thrust from the piston pin or the gudgeon pin is transferred to the side of the piston skirt or trunk. The thrust from the side of the piston skirt is then transmitted to the liner and is balanced by the equal reaction from cylinder liner. The piston skirt should be carefully and effectively designed so that the area coming in contact with the cylinder liner is adequate for the loads it has to meet. The aim of designing should be such that when the piston comes up to its working temperature, then there should at least be a 90 degrees circumferential arc of contact on each side of the piston skirt and this circumferential arc should extend over the length of the piston skirt.

This is a general overview of the practical considerations of the stress reversal in 4 stroke and 2 stroke engines. The transmission of thrust requires the designers to work out precisions to minimize the losses and reduce the weight to power ratio, while maintaining the strength and sturdiness of the engine.

Do you have more information on the internal forces acting in marine engines? Let us know in the comments below.

How Internal Forces in Marine Engines Affect Their Operation? appeared first on Marine Insight - The Maritime Industry Guide

Crankcase explosion is one of the most dangerous reasons that can lead to massive accidents and fires on a ship. It is therefore imperative to prevent all the reasons that can lead to crankcase explosion on a ship. In this article we will learn about the various methods to prevent crankcase explosion on a ship.

The first and foremost thing to avoid any type of explosion on a ship, it is necessary to take the preventive steps right from the basic roots. In a main engine crankcase also there are safety features provided to detect the causes of explosion.

There are two main features provided on the crankcase to prevent crankcase explosion. They are as follows:

1. Oil Mist Detector

The Oil mist detector takes continuous samples from the main engine crankcase and check whether the sample concentrations of mist are well below the level at which a crankcase explosion can take place. The oil mist is drawn into the instrument with the help of small fan which takes suction from each crankcase through sampling tubes provided on each crankcase.

The oil mist detector consists of a small rotator with which it takes sample from one cylinder at a time and the rotator then turns to the next after approximately 4 seconds. The sample from the rotator goes to the measured cell and the reference cell takes sample from rest of the crankcase to evaluate the difference in oil mist.

An overall mist density of the crankcase is also measured by comparing the samples with the fresh air once every rotation of the sampling valve is done. A beam of light from a common lamp is reflected through mirrors and output is measured from a photo cell.

Under normal conditions the output from the reference and measured contact is same and hence no deflection is measured. However, a deflection in the output gives an alarm indication and the valve rotator stops at position to know which chamber has high mist concentration.

Some engines are even fitted with slowdown alarms so that when the oil mist alarm rings, the engine automatically slows down to prevent crankcase explosion.

2. Crankcase relief doors

The Crankcase relief doors are also fitted to prevent any damage to the crankcase and ingress of fresh air inside the crankcase.

The crankcase doors are spring loaded valves which lift up in case there is any rise of pressure inside the crankcase. Once the pressure is released they re-seat to prevent any ingress of fresh air. This helps especially in case of any ingress of air that can lead to a secondary explosion followed by a lot of surge and damage to the crankcase.

The opening pressure and sizes of the valves are specified by different classification societies, depending on the volume of the crankcase. The number of doors to be present also depends on the bore of the cylinder.

Reference: Instrumentation and control engineering by G.J Roy, Operation and maintenance of machinery in motor ship by N.E Chell

How to Prevent Crankcase Explosion on a Ship? appeared first on Marine Insight - The Maritime Industry Guide

Cylinder Liner in any kind of marine engine is an integral part of the combustion chamber, through which, power is generated on board. Like all other machinery and engine parts on ships, it also has to be overhauled after specific interval as described by the engine makers

Previously we have discussed Reasons for Cylinder Liner wear and ways to measure it, in this article we will discuss the liner removing procedure of Main two-stroke marine engine.

How to check wear in the liner and when to overhaul it?

The liner is an enclosed area and a part of the combustion chamber where the fuel is burnt and heat energy is transmitted to kinetic energy by use of piston, crosshead, bearings and crankshaft. For an engineer, it is important to know various ways to check the condition of the liner to ensure the combustion chamber is efficiently producing the required pressure.

Ways to check the condition of the cylinder:

1. Scavenge inspection
2. Routine Liner Ovality check
3. Piston Overhaul
4. Problem involving Liner

1. Scavenge inspection: Scavenge inspection is performed every time post the scavenge space of the engine is cleaned off from sludge and deposits.

After the cleaning is done, 2nd engineer or a responsible engineer must go inside the scavenge space to check the general liner condition using the following method:

• In order to inspect a larger area of the cylinder liner and piston, it is expedient to enter the scavenge air receiver and make observations from the “exhaust side”
• Dismount the small covers on the scavenge air boxes, and clean the openings
• When the piston has been turned below the level of the scavenge air-ports, inspect the cylinder liner walls and the piston crown
• A “tilt-able” mirror fixed to a telescopic rod can be used as illustrated. Use a powerful light source for inspection

2. Routine Liner Ovality check: As explained in the article, readings are taken at port and starboard position in different levels to calculate the change in the ovality of the liner.

3. Piston Overhaul: When the piston is overhauled as per the planned maintenance or due to breakdown reasons, the liner ovality must be checked and liner surface must be inspected for various defects.

4. Problems like leaking liner water ‘O’ ring, cracked liner, blow-past from piston and liner etc. will require an immediate action of checking and changing the piston and liner. After proper measurement and inspection of the liner, the problem source can be determined and a decision can be taken whether to change the liner or continue with the same.

Overhauling schedule of liner: The normal overhauling schedule of the liner will depend on the efficient operation of the engine, it’s operator, type of fuel used in the engine and how all the important engine parameters (temperature, pressure etc.) are maintained by the operator.

If the liner is working fine, the planned maintenance schedule is followed and the liner will be checked and gauged after completion of certain running hours as prescribed by the engine makers.

12000 to 16000 hrs are the normal running hours schedule to open and inspect/ gauge the liner of 2 strokes marine main engine, depending upon the maker of the engine.

The general lifetime of a cylinder liner will again depend on the way engine is operated and type of fuel oil used for combustion. The normal lifetime running hours of the liner will vary from 40000 RHs to 90,000 RHs. The size of the liner bore is directly related to the lifetime of the liner hence liner with small bore will have less lifetime with a liner with large bore and size.

Following Procedure has to be followed when opening Liner (common for all)

1) Inform company and take permission.
2) Take immobilisation certificate from port state control.
3) Read the manual and have a tool box meeting with everyone involved in the job. Discuss the complete procedure.
4) Prepare important tools and spares required for overhauling liner as given in the manual
5) Prepare risk assessment and make sure all personal safety equipment are used
6) Shut starting air for Main Engine and display placards
7) Engage turning gear
8) Open indicator cocks for all the cylinders
9) Stop main lube oil pump and switch off the breaker
10) Once the engine jacket temperature comes down, shut the inlet water valve for the unit to be overhauled
11) Keep other units in Jacket preheating system to maintain the jacket temperature
12) Drain the jacket water of the concerned unit from exhaust v/v and liner.
13) Shut the fuel oil to the particular unit whose liner is to be removed
14) Dismount the cylinder head using dedicated lifting tools
13) Discard the sealing ring from the top of the cylinder liner.
14) Turn the piston down far enough to make it possible to grind away the wear ridges at the top of the liner with a hand grinder
15) Dismount the piston by following the procedure given in Manual

Liner Removal procedure for MAN engine (MC and ME engines)

16) Ensure the Liner lifting tool is well maintained. Two lifting screws are used with a lifting hook connected via chain. Ensure chain, screw and lifting hook are fastened together with no deformation.

17) Ensure the safety strap in the lifting hook is working properly.
18) Tighten the two lifting tool screws in the liner as per the rated torque is given in the manual on both sides.
19) Measure that there is no gap between liner surface and screw landing surface after tightening, using a 0.05mm feeler gauge.

20) Disconnect the cylinder oil pipe connections. And screw of the non-return valves.
21) Dismount the four cooling water pipes between the cooling jacket and cylinder cover and clean them carefully.
22) Remove the screws of cooling water inlet pipe.
23) Attach the crossbar to engine room crane. This completes the lifting arrangement for cylinder liner.

24) Hook the chain from the lifting cross bar on the lifting screws and lift the cylinder liner with the cooling jacket out of the cylinder frame.

Liner Removal procedure for RTA and RTFlex Engines

25) Ensure the Liner lifting tool is well maintained, Suspension bridge beam does not have any loose connection or distortion. Right screw is used with the suspension bridge tool to lift the liner.

26) Remove the screw which fastens the supporting ring on the liner.
27) Disconnect the cylinder oil pipe connections. And screw of the non-return valves.
28) Dismount the cooling water pipes between the cooling jacket and cylinder cover and clean them carefully.
29) Remove the screws of cooling water inlet pipe.

30) Remove all the passages for lubricating quills as well as their protecting bushes.
31) Mount the suspension bridge beam over the top landing surface of the liner.
32) Fastens the screw of attached to the suspension bridge beam to a side of the liner and tighten it to the rated torque stated in the manual.
33) Attach the engine room crane to the lifting tools.

34) Lift the cylinder liner with the cooling jacket out of the cylinder frame.

What to do if Cylinder Liner is Stuck

A common way to remove a stuck cylinder liner is to use hydraulic jacks on the bottom of the cylinder liner and apply hydraulic pressure. Once the liner is slightly moved out of the stuck engine structure, it may be then lifted with the help of engine room crane and lifting tool

After Removing the liner from the engine:

• Place the cylinder liner vertically on a wooden plank
• Clean cylinder frame internally paying special attention to the contact surfaces for the cylinder liner at the top of the cylinder frame
• Discard the O-ring on the cooling water pipe
• Clean the pipe carefully

Make sure to inspect the liner for cracks and other defects

Disclaimer: The authors’ views expressed in this article do not necessarily reflect the views of Marine Insight. Data and charts, if used, in the article have been sourced from available information and have not been authenticated by any statutory authority. The author and Marine Insight do not claim it to be accurate nor accept any responsibility for the same. The views constitute only the opinions and do not constitute any guidelines or recommendation on any course of action to be followed by the reader.

The article or images cannot be reproduced, copied, shared or used in any form without the permission of the author and Marine Insight. 

Main Engine Liner Removal Procedure For Wartsila And MAN Engines appeared first on Marine Insight - The Maritime Industry Guide

Main engine and auxiliary engine are the two prime components in a ship’s engine room, on which, the entire operation of the vessel is dependent. There are several other important machineries that are necessary to support these two main components; however, one equipment without which any of the above mentioned machines cannot do away with is an air bottle or air receiver.

What is an Air bottle or Receiver?

The air bottle or air receiver is a large container acting as a reservoir to store compressed air supplied by the main air compressor of the ship at high pressure. This compressed air is very important to start main engine or auxiliary engine.

Purpose of Air Bottle

• The high pressure is used for initial starting of the marine I.C engines present onboard vessel.

• It also supplies control air to the marine engines.

• Service air is supplied from the air bottle.

• If the quick closing valves are air operated, safety air is supplied through air bottle.

• Spring air for exhaust valve is supplied through air bottle.

Apart from above mentioned ones, there are several other uses as well.

What are the Air Bottle Mountings and Connections?

The general mountings and connection present on air bottle of a ship are:

• Filling valve: This is a valve fitted in the supply connection from main air compressor to the air bottle.

• Outlet to Main engine: An outlet valve and pipe is fitted for connection from air bottle to main engine for supplying air during starting.

• Outlet to auxiliary engine: An outlet valve and pipe is fitted for connection from air bottle to auxiliary engines for supplying air during starting.

• Auxiliary connection: Other auxiliary supplies connections such as service air, safety air etc. is also provided with isolating valve.

• Relief valve: A relief valve is fitted on the air bottle to relieve excess pressure inside the bottle.

• Drain valve: A drain valve is fitted at the bottom of the bottle to drain accumulated condensate from the receiver.

• Fusible plug: A fusible plug is fitted in the bottle with a separate connection leading out of the engine room so that in the event of fire, this plug will melt and relieve all the air to the outside atmosphere.

• Manhole door: A manhole door is fitted in the bottle to carry out inspection of the same.

You may also like to read-Different Parts of a Marine Air Compressor used on Ship

References:

Book on Marine Aux. Machinery by H.D.McGeorge

Air bottle or Air receiver On board Ship appeared first on Marine Insight - The Maritime Industry Guide

There are several important factors that need to be taken care of for efficient running of the main engine on the ship, and one of them is the crankcase of the ship’s engine. The crankcase is one such part of the main engine which contains the most sensitive components of the main engine. Before doing crankcase inspection, are you confused as to what safety rules that are need to be followed or ever wondered what you should check and what not? If yes, then you have come to the right place. In this article we will learn the most important points that need to be considered for efficient working of the crankcase of the main engine. Learn the important checks on crankcase and what all things need to be included in crankcase inspection on a ship.

Checks Required and Done On board on Crankcase Lubricating Oil

The crankcase lubricating oil needs to be maintained in good condition for efficient running of the main engine. If not maintained and checked periodically, the crankcase lubricating oil can damage the bearings and other parts of the engine which can incur heavy loss and wastage of time in maintenance. Moreover if the damage is more, the ship might need to go off charter which is not acceptable in shipping activities.

Weekly Checks on Crankcase

In weekly test of crankcase, lubricating oil water test should be done. This is to ascertain that there is no leakage in the crankcase and it’s in fine condition. If water content is below 2 % of the total volume then it is acceptable and can be reduced with the help of purification.

However, if it is above 2% then investigation needs to be made if there is any leakage of water inside the crankcase. In case of any leakage, the cracks are to be checks and fixed and the causes of water ingress is to be found. Once this is done the oil in the crankcase has to be replaced completely.

Other checks also done during weekly checks are to ascertain TBN and viscosity of the oil. The crankcase must be topped up or change of oil needs to be done as per manufacturer’s recommendation.

Once every three months the oil has to be sent for laboratory analysis i.e spectrography analysis to ascertain that the amount of wear and fine metal particles are within acceptable limit. In case if it is off limit, the laboratory analysis report will recommend procedure or precautions to be taken to tackle the situation.

Crankcase Inspection in large Slow Speed Engines

The crankcase inspection is done every month whenever the ship is in port and there is sufficient time for inspection. Thorough inspection is required during this to analyze the condition inside and damage to the bearings.

Before inspection following procedures has to be followed

• Permission has to be taken before reaching port to make sure that the authority is not having any problem with this. This is called Immobilization permission of the main engine.
• After the permission is received the checklist has to be filled.
• Safety issues have to be discussed with the people taking part in the inspection.
• When the engine is in “stopped” condition, the lubricating oil pump and cross-head oil pump have to be stopped and the breaker taken out so that it doesn’t start on its own or by any other person by mistake.
• Proper sign and placards to be displayed regarding men at work.
• Since engine crankcase is an enclosed space, an enclosed space entry checklist is also to be filled.
• After stopping the engine and the pumps the crankcase doors have to be opened and sufficient time is to be given to cool and ventilate the space as the temperature inside is very hot and deprived of air.
• After the cooling and ventilating the space, the person entering the space should be with proper personnel protective equipments like boiler suit, safety harness, and anti slipping pads for shoes.
• Make sure there are no tools, pen etc in your pockets which might drop inside and cause damage to bearing and machinery parts
• Before entering, the person has to be detailed as what needs be checked inside. Special attention is also given if any other issue is specified by technical department or any major problem found on other ships.

Inside Crankcase Following Checks are to be Made

1.     Check the overall quality of oil whether it is clean or dirty with carbon particles.

2.     Check for any distinguished smell, if found, this could be because of bacterial contamination of oil. The smell is generally of rotten eggs.

3.    Check for any metal particles near the grating in the crankcase.

4.   Check the condition and damage to the gratings.

5.    Check the slip marks on the web; they should be in the same line. If slip is found then report is to be made to the company and classification society regarding this.

6.    Check for any bluish dark patches, this indicates that hot spots are caused by friction of insufficient lubrication.

7.    Check cross head for any damages.

8.    Check cross head guides for damages and marks.

9.       Check the bed plate for any welding cracks etc.

10.   Check any metal seen near the bearings coming out due to wiping.

11.   Check for piping and any loose connections between them.

12.   Check the locking wires and locking washers on bolts of stuffing box.

13.   Make any other checks specified by technical department.

14.   Before coming out make sure there is nothing left inside.

Everything You Ever Wanted To Know About Crankcase Inspection on a Ship appeared first on Marine Insight - The Maritime Industry Guide

Emission control areas are those designated regions at sea wherein the Sox and Nox emissions are regulated by the laws laid down under MARPOL Annex VI- Prevention of air pollution by ships.

Some local laws regarding air pollution are more stringent than those laid down by the IMO. For e.g. in Europe, while the ship is at the port, all the running machinery consuming fuel must use only the type of fuel having less than 0.1% sulfur content.

As the SOx emission is purely dependent on the quality and sulfur content of the fuel, while entering emission control areas, it is required to switch over to a lower sulfur content fuel including flushing of fuel from the system with a sulfur content of more than 1.0% sulfur before entering the ECA.

Fuel Oil Changing Over Procedure for Main Engine

Considering that most of the ships today run at high sulfur fuel oil, changing over of fuel at the right time is very important. Moreover, looking at today’s economic condition of the industry, it’s imperative to change over the fuel from high to low sulfur at the correct time as an early change over will lead to loss of low sulfur oil, which is quite expensive, whereas a delay in the changeover procedure will lead to violation of MARPOL annexe VI. This is to be done along with using other technologies to reduce SOx and NOx from ships.

Also, most of the ships today are equipped with one service tank and one (maybe two) settling tanks, which can result in the mixing of two different grades of oils while performing a changing-over of fuel. Needless to say, changing over of fuel includes several important factors under consideration.

Every ship is provided with a changeover Low Sulphur Fuel (LSF) calculator which tells the correct changeover time at which the system should be running on LSF before entering an Emission Control Area (ECA). This system requires some important factors –

1. The sulfur content of high sulfur fuel currently in the system
2. The sulfur content of low sulfur fuel
3. The fuel capacities of the main engine system including settling tank, service tank, main engine piping and transfer piping from the service tank to the main engine
4. The capacity of transfer equipment – Fuel oil transfer pump and fuel oil separators

Once the change-over-time is calculated which also accounts for the time of intermixing of two different sulfur grades oil (let’s suppose 48 hours), the following actions are to be taken 48 hours prior:

• Ensure that no transfer of high sulfur fuel is carried out any further to the settling tank
• Ensure that the low sulfur bunker tank steam is open for transfer and purification of fuel should not have any problem
• If two separate settling tanks are present, one can be dedicated to low sulfur oil which will reduce the changeover period
• Keep running the separator till the settling tank level reaches a minimum
• If filling of service tank with HSFO increases the calculated time period of changeover, then stop the separator and drain the settling tank
• Settling tank can be first drained in to fuel oil overflow tank, and then the oil drained can be transferred to bunker tanks containing the same grade of oil
• Once the settling tank is drained from heavy sulfur oil, fill the settling tank with low sulfur oil via a transfer pump
• As the separator is stopped, service tank oil will be consumed by the main engine system
• Remember not to lower the level of service tank below which the fuel pumps cannot take suction
• Start separators from settling to service tank which will be now filling low sulfur oil
• Fill the LSFO oil into settling and service tank as per the quantity required to cross the ECA calculated by the chief engineer as per the voyage plan

Records to Maintain

-Record all the fuel tank levels when changeover starts (48 hours prior)

-Mention date, time and position in the oil record book (ORB) when the changeover from high to low sulfur is carried out along with the quantity of low sulfur oil in the settling and service tank

– Same can be recorded in the engine logbook

Fuel Oil Change Over for Auxiliary Engine and Boilers

Some ports have regulations of using gas oil for generators and boilers while the ship is at port (for e.g. European ports). Change over generators and boiler to diesel oil with sulfur content less than 0.1 %.

Boiler

• Shut the steam to the fuel oil heaters of the boiler
• When the temperature drops below 90 degrees, open the diesel oil service tank valve going to the boiler system
• Shut the heavy oil valve for the boiler system slowly and observe the pressure of the supply pump
• Check flame and combustion of the boiler
• Let the heavy oil outlet be kept open and diesel oil outlet is not open for some time
• This is to ensure no heavy oil goes to the diesel oil system
• When the line is flushed with Diesel Oil, open the diesel outlet valve and shut the heavy oil outlet valve

Generators/ Auxiliary Engine

Generators must be changed over from one grade to another while at load as this will help in better flushing of the system.

If only one generator is being changed over, keep running another generator for emergency purposes in case something goes wrong.

• Shut the steam to the fuel oil heaters of the boiler
• When the temperature drops below 90 degrees, open the diesel oil service tank valve going to the generator system
• Open the local diesel inlet valve and shut the heavy oil inlet valve simultaneously and slowly, by keeping an eye on the fuel pressure and changing only one generator into diesel with the help of a separate diesel pump. Let the heavy oil outlet be kept open and the diesel oil outlet kept shut till the system is flushed thoroughly
• After some time open the diesel oil outlet and shut the heavy oil outlet
• If the complete system is to be changed into diesel oil, open the diesel oil inlet valve to the generator supply pump simultaneously closing the heavy oil inlet valve
• If the return line is provided to the diesel service tank, open it after some time, simultaneously closing the heavy oil return only after the system is flushed properly

The changeover procedure must include recording of every action and onboard oil quantity as proof of doing the job correctly.

Note: Once the changeover procedure is completed, remember to change the HMI setting of the Cylinder oil lubricator system (Alpha lubrication) or change over the cylinder oil daily tank suitable for low sulfur operation.

Disclaimer: The authors’ views expressed in this article do not necessarily reflect the views of Marine Insight. Data and charts, if used, in the article have been sourced from available information and have not been authenticated by any statutory authority. The author and Marine Insight do not claim it to be accurate nor accept any responsibility for the same. The views constitute only the opinions and do not constitute any guidelines or recommendations on any course of action to be followed by the reader.

Fuel Oil Change Over Procedure for Ship’s Main and Auxiliary Engines appeared first on Marine Insight - The Maritime Industry Guide

On ships, the work done by marine engines to keep the plant running for propelling a ship requires burning of fuel. The energy converted inside the cylinder of the engine is not 100% efficient conversion as part of it is lost in the form of exhaust gases.

The modern exhaust gas system of marine engines is designed in such a way that the unused gases coming out of the cylinders are further directed to turbocharger and exhaust gas boiler to recover most of the waste energy from the same.

Components for the Exhaust Gas system of Engine:

To utilise the maximum energy from the waste gases, the exhaust gas system of marine engine is provided with the following components:

• Exhaust gas pipes
• Exhaust gas boiler
• Silencer
• Spark arrester
• Expansion joints

Exhaust gas-piping system for marine engine:

The exhaust gas piping system conveys the gas from the outlet of the turbocharger(s) to the atmosphere. For designing the exhaust piping system, following important parameters must be observed:

• The exhaust gas flow rate
• Maximum back force from exhaust piping on turbochargers
• Exhaust gas temperature at turbocharger outlet
• Maximum pressure drop within the exhaust gas system
• Maximum noise level at gas outlet to atmosphere
• Sufficient axial and lateral elongation ability of expansion joints
• Utilisation of the heat energy of the exhaust gas.

The Exhaust gas from the cylinder unit is sent to exhaust gas receiver where the fluctuating pressure generated from different cylinders are equalised. From here, the gases which are at constant pressure are sent to turbocharger where waste heat is recovered to provide additional scavenge air to engine.

The most important thing to consider while designing the exhaust piping system is the back pressure on the turbocharger. The back pressure in the exhaust gas system at specified Maximum Continuous Rating (MCR) of engine depends on the gas velocity, and it is inversely proportional to the pipe diameter to the 4th power. It is general ship practice to avoid excessive pressure loss within the exhaust pipes, the exhaust gas velocity is maintained about 35m/sec to 50m/sec at specified MCR. The other factors which affect the gas pressure are the installation of EGB, Spark arrestor etc. in the path of exhaust gas travel.

At the specified MCR of the engine, the total back pressure in the exhaust gas system after the turbocharger (as indicated by the static pressure measured in the piping after the turbocharger) must not exceed 350 mm WC (0.035 bar). In order to have a back pressure margin for the final system, it is recommended at the design stage to initially use a value of about 300 mm WC (0.030 bar).

Exhaust gas boiler:

Exhaust gas boiler is considered to be one of the most efficient waste heat recovery system designed for a ship. When the ship’s propulsion plant is running at it’s rated load, the auxiliary boiler can be switched off as the EGB can generate the required steam for various ship’s systems. The exhaust gas passes an exhaust gas boiler, which is usually placed near the engine top or in the funnel.

The efficiency of the EGB will be affected by the pressure loss of the gases across the boiler and the parameters governing the pressure loss (exhaust gas temperature and flow rate) are affected by the ambient conditions. The recommended exhaust pressure loss across the EGB is generally considered as 150 mm WC at specified MCR. If the exhaust system is not provided with additional equipment (spark arrester or silencer), the pressure loss value can be considered little bit higher then the value stated above (150 mm WC at specified MCR).

Silencer

The engine room plays a major role in high Noise levels in the accommodation, which is now moderated under Maritime Labor Convention.

The Exhaust gas piping system are generally close to accommodation hence the reduction of noise form them is important. To get the noise level, it is recorded at a distance of 1m from the exhaust gas pipe outlet edge at an angle of 30° provided the exhaust gas system of the engine are without EGB or silencer.

Silencer is used to reduce the noise level in the exhaust gas manifold and they are generally placed after the EGB. The Conventional silencers consist of absorptive and reactive chambers. They are constructed for a gas velocity of 35m/s and the reactive chamber is only effective at one frequency.

The latest design of silencer consist of three chambers to overcome the limitation (of being effective at one frequency)

The three elements are composed of a reactive element for attenuation of lower frequencies, a resistive element-absorptive silencer to tackle with higher frequencies, and a combination element of both reactive and resistive elements. This set up will reduce the noise effectively without increasing the back pressure on the turbocharger by tuning the elements to match the engine over the noise range.

Spark arrester:

The low load operation of marine engine tends to produce partially burnt carbon deposits and soot with the exhaust gas piping system of engine. As the exhaust gases produced after combustion are rich with oxygen, these partially burnt carbon particles are discharged from the exhaust funnel as highly dangerous spark.

A spark arrester can be fitted in the exhaust piping system to prevent sparks from the exhaust gas being spread over deckhouse. It is placed at the end of the exhaust gas system of the engine.

The new design of spark arrester helps the gases to create rotatory movements by forcing them to pass through fixed number of angel positioned blades. The heavy carbon particles are smoothly collected in the designed soot box, which can be cleaned or drained as required.

They can be combined with silencer as one unit to save space or cost.

The main disadvantage of a spark arrester is considerable pressure drop. For main engine of a ship, it is recommended that the combined pressure loss across the silencer and/or spark arrester should not be allowed to exceed 100 mm WC at specified MCR.

Expansion joints

The Exhaust gas system of engine experiences huge temperature variations. It is not possible to construct the entire exhaust piping system in one single piece hence; multiple sections are joined to complete the system. When the engine is standstill, the temperature of the exhaust pipe may vary from 10 to 40 deg C (depending upon the surrounding environment or geographical location of the ship) and when the engine is up and running, the exhaust system temperature crosses 200 deg c. This major temperature variation requires need of joints to safely absorb the heat-induced expansions and contractions of pipes and tubing systems.

For this purpose, bellows and expansion joints are used. They are designed accurately to make sure that they are able to withstand the stresses and avoid cracks brought about by the continuous change in the temperature of the system. As per Boyle’s Law- When tubing is subjected to high-temperature fluids, pressure also builds up. Expansion joints are needed to bear the extra force that accumulates.

Expansion joints are used in tubing and piping systems and Bellows are generally used to connect exhaust gas pipes to the funnel.

The expansion joints are to be chosen with an elasticity that limits the forces and the moments of the exhaust gas outlet flange of the turbocharger as stated for each of the turbocharger makers.

The Expansion joints are placed at various places spreading it in the exhaust gas piping system of the marine engine.

Above we have discussed the most important components and functions of Exhaust Gas System of Marine Engine on ship. If you feel we have missed something, please feel free to comment.

Understanding Components and Design of Exhaust Gas System of Main Engine On Ship appeared first on Marine Insight - The Maritime Industry Guide