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Showing posts from 2020

Engine Balancing

To  make  small  adjustments  to  each  unit  make  uniform power  generation in every unit. Pmax  by  timing  of  fuel  pump(vit  or  by  shims  to  pump  or  cam  floating and readjusting) Pcomp in ME engines by exh valve timing change. Pmax- Pcomp not more than 35 bar to avoid piston ring failure. Pi adjusted by fuel index. (But limits are The peak pressure difference can't be more than 3 to 5 for AE And max 10 for ME. Exhaust gas temp diff 40deg C. Fuel  rack  should  not  be  adjusted  more  than  10% Otherwise  we  have  to change the plunger and barrel)

Self locking nuts

lf-locking nuts provide tight connections that will not loosen under vibrations.  They meet critical specifications as to strength, corrosion resistance, and heat-resistant temperatures.  New selflocking nuts must be used each time components are installed. There are two general types of self-locking nuts.  They are the all metal nuts and the metal nuts with a nonmetallic insert to provide the locking action.  The elastic stop and the nonmetallic insert lock nut are examples of the nonmetallic insert type.  All metal self-locking nuts are constructed either of two ways. The threads in the load-carrying portion of the nut that is out of phase with the threads in the locking portion is one way.  The second way is with a saw-cut top portion with a pinched-in thread. The locking action of these types depends upon the resiliency of the metal.

Advantages of MLC

A comprehensive set of basic maritime labour principles and rights Simplification of international requirements A strong enforcement regime, backed by a certification system Verifiable compliance with basic minimum employment and social requirements Application to all ships including those of non-ratifying Members Improved working and living conditions for seafarers A more secure and responsible maritime workforce A more socially responsible shipping industry Improved social dialogue at all levels Seafarers better informed of their rights and remedies Improved supervision at all levels: the ship, the company, the flag state, the port state, and the ILO Global and uniform compliance and verification Improved possibilities of keeping labour conditions up to date Permanent review of maritime labour situation Positive impact on safety at sea Positive impact on the protection of the environment

Angle of Repose

Angle of Repose is the maximum slope angle of non-cohesive (i.e. free-flowing) granular material It is the angle between a horizontal plane and the cone slope of such material The angle of repose is a characteristic of non-cohesive bulk cargoes, which is indicative of cargo stability, and the purpose of which is to minimize the risk of bulk material shifting;  The cargo should be trimmed reasonably level to the boundaries of the cargo space Jn

Safe Manning

SOLAS CHAPTER V, REG 14 The principles of minimum safe manning set out in section 3 to ensure the safe operation of ships to which article III of the 1978 STCW Convention, as amended, applies, and the security of ships to which chapter XI-2 of the 1974 SOLAS Convention, as amended, Principle : The capability to  Maintain safe navigational, port, engineering and radio watches in accordance with regulation VIII/2 of the 1978 STCW Convention, as amended, and also maintain general surveillance of the ship;  Moor and unmoor the ship safely;  Manage the safety functions of the ship when employed in a stationary or near-stationary mode at sea; Perform operations, as appropriate, for the prevention of damage to the marine environment; Maintain the safety arrangements and the cleanliness of all accessible spaces to minimize the risk of fire; Provide for medical care on board ship; Ensure safe carriage of cargo during transit; Inspect and maintain, as appropriate, the structural integr

Maritime TORTS and types

Maritime law torts is a term covering cases where injury, loss or damage is caused to a person or their interests by another party’s action or negligence. Types of torts 3 types Intentional torts An intentional tort is a civil wrong that occurs when the wrongdoer engages in intentional conduct that results in damages to another. Negligence Careless conduct that results in damage to another is negligence Strict liability Generally, liability because of a tort only arises where the defendant either intended to cause harm to the plaintiff or in situations where the defendant is negligent.  However, in some areas, liability can arise even when there is no intention to cause harm or negligence. For example, in most states, when a contractor uses dynamite  which causes debris to be thrown onto the land of another and damages the landowner’s house, the landowner

Reamer and types

The function of a reamer is to produce a smooth accurate surface in a bore such as that of a bearing or bush, for the shaft, pin or bolt to enter with a very good fit. In engine room Reamers are used for The stern tube hole in stern frame is cast/fabricate roughly under size. When Main Engine is aligned with centre line of the stern frame hole, this hole is reamed to required diameter to fit the stern tube. Fitted bolts on rudder palm and rudder carrier bearing housing for the press fit. They are to be reamed to exact diameter to avoid relative movement. If a hole is drilled for internal threads then before we start with the procedure of making threads (tapping) we have to make sure we get a smooth finish for the threads. In this respect, a reamer is a much better tool than a drill and can also produce finishes superior to normal machining on lathes. In fact, bores machined on lathes are often finished with reamers to improve the surface and bring them to size. Holes to be reame

How will you repair the coating in FWG & what coating is there on FWG?

The internal of the Fresh Water Generator is coated with 2 layers of Nordtec Ceramic 2212 FDA (Food grade coating).  It is developed for Freshwater generators. It is designed as an abrasion resistant and fluid flow ceramic coating.  It coating is reinforced with ceramic and carbide particles to obtain a high level of abrasion and erosion resistance and physical, mechanical strength. The outside of the Fresh Water Generator, is primed and coated with two component paint. As per manual – shell is coated with Neoprene coating and top cover- pure epoxy coating & bottom cover- Neoprene coating

Ship security alarm system (SSAS)

International Maritime Organization (IMO) legislation states that the ship’s security alert system shall: Be initiated by pressing a dedicated SSAS button and transmitting a ship-to-shore security alert to a competent authority designated by the administration, which may include the company, identifying the ship, its location and indicating that the security of the ships is under threat or has been compromised Not send the ship security alert to any other ships Not raise any alarm on board the ship, and Continue the ship security alert until deactivated and/or reset. SSAS is not part of the GMDSS communication requirements but its equipment can be used to support the system. Ship security alerts can be sent using Inmarsat C and Mini C, SSAS regulations is that security alerts are required to be routed only to the Company Security Officer and the Flag. SSAS resetting after take over with change vessel particulars email address and flag contact address

High voltage

Voltages up to & Including 1000V is known as Low voltage system and Voltages 1001 and above is called as High Voltage system in maritime practice for ships. Why High Voltage in Ships Higher power requirements onboard vessels is the foremost reason for the evolution of HV in ships. Higher power requirements have been necessitated by development of larger vessels required for container transort particularly for reefer containers. Gas carriers needing extensive cooling electrical propulsion. For ships with a large electrical power demand it is necessary to utilize the benefits of a high voltage HV installation. The design benefits relate to the simple ohms law relationship that current (for a given power)is reduced as the voltage is increased.  Working at high voltage significantly reduces the relative overall size and weight of electrical power equipment. As per Ohms law, POWER = VOLTAGE x CURRENT For a given Power, Higher the Voltage, Lesser is the Current 440 KW = 440,

Different types of Ballast water exchange

Sequential : In this method the ballast tanks are emptied until the ballast pumps lose suction and then the tanks are further stripped by eductor systems. This is followed by taking fresh ballast into the tank. Flow through method:  In this method water in pumped into the tank and to allow it to overflow through the air vent or dedicated overflow vents. Three times the volume of the tank is to be pumped through to get a 95 percent efficiency of exchange. Dilution Method:  In this method the tank has two openings; water is pumped in from one opening and flows out through the other.


The design measures incorporated in TriboPack are: Multi-level cylinder lubrication Liner of the appropriate material, with sufficient hard phase Careful turning of the liner running surface and deep-honing of the liner over the full length of the running surface Mid-stroke liner insulation, and where necessary, insulating tubes in the cooling bores in the upper part of the liner Pre-profiled piston rings in all piston grooves Chromium-ceramic coating on top piston ring RC (Running-in Coating) piston rings in all lower piston grooves Anti-Polishing Ring (APR) at the top of the cylinder liner Increased thickness of chromium layer in the piston-ring grooves.

Port of Refuge

Port of refuse is a port or a place that vessels divert to when her master considers it unsafe to continue the voyage due to peril that threatens the common safety Situation in which u call a port of refuge are Dangerous shift of cargo Serious breakdown of machinery Serious fire on board Shortage of bunkers Rough weather Collision Grounding Any other damage affecting seaworthiness of vessel  HOW A SHIP CAN CALL A PORT OF REFUGE? As soon as the decision is taken to discontinue the voyage and make for a place for refuge, inform the owner and the charterer (if any) stating the reasons for deviation. Give relevant details to attending superintendent. He will inform the necessary insurance manager and class. Record the ship’s position. Sound tanks for quantity for bunker on board. From the point until departure from the port of refuge, keep accurate records of events and expenditure. Request the owner to arrange the appointment of an agent at the port of refuge to handle t

Engineroom Crane safeties

Limit switch for all 6 directions-fwd, aft, port, starboard, lowering and hoisting. Mechanical stoppers in case limit switch fails. Overload trip. Electromagnetic brake. Release by availability of electric power.- Fail safe arrangement Rail guard over the pulley Mechanical locking arrangement for rough weather Locking arrangement and hook for safe carriage of load. Clear marking of Safe working load on crane. Breakers at various places. One in engine room and another in ECR. It shall be operate in 50 list and 20 trim.


Piston ring scuffing is consists of local micro welding, or material adhesion, between a piston ring and a cylinder liner. Various causes of Scuffing are following Lack of Lubrication If the engine doesn't have enough oil, the cylinders will not be properly lubricated. As the ring rubs against the liner of the cylinder, dry spots will cause it to scuff. Symptoms of scuffed piston rings include dirty exhaust and excessive oil consumption. Engine Dry Starts If an engine has sat idle for even a short time, it may have a "dry start" when next used. This occurs because the existing lubricant sheen in the engine has dried up, and these dry parts of the engine run without lubricant in the first few seconds after the engine starts before lubricant is fully circulated. If an engine is dry-started after a new piston ring is installed, scuffing could result. To avoid this, lubricate the ring before installing it or add a secondary engine oiler that squirts oil into the engine

4-stroke connecting rod Specialty.

Big end and big end bearings are of split type Big end is in an oblique direction to reduce the width of big end, reduce the load on bolts and increase the crankpin diameter Top end is having bush type bearing Rectangular or I-shaped is expensive to manufacture but necessary to resist high transverse inertia whip load, gas loads and to fulfill the weight to strength requirement Connecting rod is forged from Magnesium Molybdenum. Edges are serrated  It is subjected to high compressive and low tensile bending stress as well as of axial type  It connects crank pin direct to gudgeon pin

Boiler Bulging

Formation of layer of scales on the furnace wall at the water side can cause overheating and bulging defect on the furnace shell. Bulging in water tube is due to calcium scale deposition on tube walls which cause improper heat transfer. In smoke tube due to carbon deposits bulging is caused. Low water level in boiler. Misalignment of burner can cause overheating which will further cause bulging.

Hydrophore pump short cycling.

Pressure switch faulty- check pressure switch Pressure switch wrongly set Non return valve after pump leaking, hence water under pressure going back to storage tank- that would be indicated by monitoring of the concerned pump if reverse rotation is taking place. Check on/off controller from pump main panel-contacts opening/closing Check if system is overcharged Check if system in undercharged- Since water is incompressible as soon as water is filled up pressure rises but just on little consumption pressure will drop drastically and pump restarts Check for any air leaks Faulty automatic air volume control Not enough water in tank due to clogged pipelines Air  leaking from relief valve Tank is about to empty

Actions in case of Main Engine liner cracked

The engine cannot be run long in this condition. The leaking water is finding its way into the lubricating oil. The liner has to be changed. The most logical step to take then is to isolate the faulty cylinder. It can be done. Stop engine, isolate systems and allow to cool Ensure a procedure is written that minimises the risk to personnel during the operation. Discuss the task and written procedure with the engine room personnel to ensure they are familiar with the risks, and the methods to be used to minimise these risks. Ensure the fuel pump is de-activated by lifting roller and locking. Lift exhaust valve actuators so exhaust valve remains closed during running. (Note: the air spring supply to be left open) Dismantle air start supply line, and blank with suitable steel plates, the main and control air pipes Blank off main lube oil inlet to crosshead within the crankcase with a blanking plate. Isolate the cylinder lubricator for that cylinder by placing all lubricators on

Propeller slip

When the vessel is moving ahead the propeller exerts pressure on the water to create the forward motion.  Propeller slip occurs because water is not a solid medium and there is some slip related to it. Slip may be considered as the difference between the speed of the vessel and the speed of the engine.  It is always expressed as a percentage. Propeller Slip = Actual forward speed/ Theoretical forward speed. The calculated value of slip will be increased when the wind and sea are ahead and if the vessel has a fouled bottom.  The differing values of slip are especially noticeable after a vessel has been cleaned in drydock. Theoretically a vessel should never have negative slip, but this may occur in one or more of the following conditions:--  A strong following sea.                                                                          A following current or a strong following wind How to find the Propeller Slip Mean Apparent slip = Distance run by propeller - distance r

Engine room procedure to follow after grounding

The engineering staff may not be in a position to ascertain that the ship is aground and in normal circumstances will be informed by the bridge. However any grating noises along the ships hull in the machinery space should be considered a possible grounding or collision. In the event of grounding no attempt to re-float the ship will be made without first carrying out a thorough inspection to ascertain any damage.The following actions should be taken if the bridge informs the engine room that the ship is aground. The initial response may be to Stop the Main Engine as quickly as possible and secure it, simultaneously with this start the Main Diesel Generator. Please note though with regard to the Main Engine it is our duty to obey Telegraph Orders as long as it possible and sensible to do so. Stop and secure the steering gear, be aware that the Rudder may be aground/damaged. Carry out a thorough inspection of the machinery space for structural damage and ingress of water. Due to t

Functional requirements for a Safety Management System (SMS)

Every company should develop, implement and maintain a Safety Management System (SMS) which includes the following functional requirements: A safety and environmental protection policy; Instructions and procedures to ensure safe operation of ships and protection of the environment in compliance with relevant international and flag State legislation; Defined levels of authority and lines of communication between, and amongst, shore and shipboard personnel; Procedures for reporting accidents and non-conformities with the provisions of this Code; Procedures to prepare for and respond to emergency situations; and Procedures for internal audits and management reviews.

Variable Exhaust Valve Closing (VEC)

In order to optimise the exhaust valve operation over the normal load range, the closing point of the exhaust valve is changed over 70-85% x MCR. During VEC operation the exhaust valve is closed EARLIER which means that the compression stroke of the piston is increased. This will lead to higher compression pressures and temperatures. For instance if the normal closage of the exhaust valve is 130o BTDC, and this gives a compression ratio of 10.6, then by closing the valve 10o earlier, the compression ratio will increase to 11.2, and the compression pressure will rise by 4 bar, for the same scavenge air/load setting. The unit achieves this by leaking some of the oil contained in the high pressure pipe when the valve is in the OPEN position. This will cause the valve to slightly close, but will mean that the exhaust valve will be fully closed EARLIER than normal. Hence the piston can start to pressurise the cylinder contents earlier. The amount the valve closes is dependant on the pos

Ballast Water Managment plan

Ship particulars Explain of ballast water management plan like purpose, usage, crew training, port state requirements Ballast water tank, its line, pump capacity Safety consideration like hazards in sequential method, condition under which Ballast water exchange shouldn't  be carried out. Duties of ballast water management officer. Control and disposal of sediment Ballast water reporting form. Crew training Ballast water exchange procedure Ballast water record book, BWTS

Steam trap

Steam is formed when water vaporizes to form a gas.  This is done by giving latent heat of vaporization to water.  By this water will convert into vapor.  When the work is done (i.e. steam has given up its latent heat), steam condenses and becomes condensate.  Now the condensate will not be able to work same as the steam.  So now the thermal efficiency will reduce as efficient steam is mixed with the condensate.

Boiler Survey

Boilers are inspected to maintain the regulatory requirement. Regular internal and external examination during such survey constitutes the preventive maintenance schedule the boiler goes through to have a safe working condition. Interval : Boilers require to be surveyed at 2-year intervals until they are 8 years old, thereafter they become due for survey annually. Procedures: Planning : Discuss with Master and Chief Engineer to confirm time available, manpower and time required and steam requirement for next port. Checks before shutting down boiler: Sufficient spares (joints, packing, gauge glass, etc) Past reports and manual for special attention need to be take care Special Tools required Meeting and brief with all engineers involved Mark all valves, safety valve setting and spigot clearance  Before shutting down boiler Inform Chief engineer Inform duty deck officer Top up DO service tank Change over M/E, A/E and boiler to Diesel oil Stop all purifier Shut all

Shell Expansion Plan

It is a two dimensional drawing of a three dimensional surface of the ship’s hull form. This plan is very useful for the following information:It is used for marking the location of a hull Damage on this plan by identifying the strake number , letter and frame number so that the exact location of the damage and also suggested repairs are marked in a localised copy. The shell expansion can be used for finding areas of painting surfaces such as topside, boot topping and bottom areas by applying Simpsons rules directly.  In the shell expansion the vertical scale used is different from the horizontal scale and a suitable adjustment has to be made when calculating areas. This becomes useful in solving disputes concerning areas of preparation and painting. It gives information on the thickness of the original strake which is indicated by the number in the circle shown in the strake.  The quality of steel used is also shown by letters A,B,D E and AH, BH,DH, EH.

Drydock Stability

When the ship enters a dry dock, it must have a positive metacentric height; and is usually trimmed by stern. The floor of the dry dock is lined with keel blocks, which are so arranged such that they can bear the weight of the ship. When the ship enters the dry dock, her centerline is first brought in line with the centerline of the keel blocks by using a combination of plum lines and Leica theodolite. The dock gates are then closed and the water is pumped out of the dock in stages. Since the ship has a trim by stern, the stern of the ship will first sit on the keel blocks. The rate of pumping out water is reduced as the stern is almost about to touch the keel blocks. The reason is, it is from this stage of the docking procedure when the stability of the ship starts getting critical. The interval of time from when the stern takes the blocks to the moment when the entire ship’s weight is borne by the blocks is called Critical Period. We will understand the details a little later. Wh


A step by step guide of how to operate ODME and principle of its operation How does ODME do it ODME controls the operation of two valves Valve to slop tank. Valve to overboard tank. These two valve will never be open or close together. If one is open, the other will be in close position. The formula for Instantaneous rate of discharge is Now if ODME need to measure IRD, it surely need values for oil content in PPM and Flow rate. Speed connection is usually given either from log or GPS. All these values are fed to the computing unit of the ODME.  Computing unit does all the mathematical calculations to get the required values.  Most of the times you will find the computing unit in Cargo control room. Flow rate ODME computing unit gets the flow rate from flow meter.  A small sample line goes from the main line, pass through the flow meter and goes back to the main line.  Flow meter calculates the flow in m3/Hr and gives this value to the computing unit through a

Measures for improving ship efficiency

Maintaining the Engine and equipment in order as Per PMS. Fuel injector, T/C, EGB routine maintenance, proper  Injection timing , VIT adjustment. Regular Propeller and Hull cleaning . ICCP proper use of right amp and current to avoid the fouling. Avoid unnecessary running of DG unless safety requirement. Achieve optimum trim (not by head down) Efficient operation of deck cranes Closing boiler steam for undesirable bunker tanks

Power to weight ratio

Power to Weight ratio is the ratio of horsepower produced to the weight of the engine itself. With high-speed or high-performance vessels, it is the most important criterion to use when comparing engines between two different makers since weight on these vessels is often critical, with vessel speed being the most important aspect of many military missions. Higher weight always equals higher displacement equals lower speed On commercial vessels, displacement is critical due to cost. Higher displacement requires more fuel to move the vessel. More fuel means higher cost of operation.

Carbon foot print

The total amount of greenhouse gases produced to directly and indirectly support human activities, usually expressed in equivalent tons of carbon dioxide (CO2). Carbon dioxide is a so called greenhouse gas causing global warming . Other greenhouse gases which might be emitted as a result of your activities are e.g. methane and ozone. These greenhouse gases are normally also taken into account for the carbon footprint. They are converted into the amount of CO2 that would cause the same effects on global warming (this is called equivalent CO2 amount). Your carbon footprint is the sum of all emissions of CO2 (carbon dioxide), which were induced by your activities in a given time frame. Usually a carbon footprint is calculated for the time period of a year.

Water Ingress Alarm

The water ingress alarm is in place seeing as the ingress of water may taint or corrupt the cargo/commodity being carried on a bulk carrier. For example, SOLAS states that “In each cargo hold, giving audible and visual alarms, one when the water level above the inner bottom in any hold reaches a height of 0.5m and another at a height not less than 15% of the depth of the cargo hold but not more than 2.0 m”. Also, check and maintain water ingress alarm in the area located at the forward of the cargo area.

Actions in case of Main Engine liner cracked

The engine cannot be run long in this condition. The leaking water is finding its way into the lubricating oil. The liner has to be changed. The most logical step to take then is to isolate the faulty cylinder. It can be done. Stop engine, isolate systems and allow to cool Ensure a procedure is written that minimises the risk to personnel during the operation. Discuss the task and written procedure with the engine room personnel to ensure they are familiar with the risks, and the methods to be used to minimise these risks. Ensure the fuel pump is de-activated by lifting roller and locking. Lift exhaust valve actuators so exhaust valve remains closed during running. (Note: the air spring supply to be left open) Dismantle air start supply line, and blank with suitable steel plates, the main and control air pipes Blank off main lube oil inlet to crosshead within the crankcase with a blanking plate. Isolate the cylinder lubricator for that cylinder by placing all lubricators on n

Difficulties during manoeurvring with M/E one unit isolated

Ln one engine cylinder is isolated, then one problem that may occur is a “dead spot” during manoeuvring.  This is due to the air start valve being isolated for that unit, and is more likely when a smaller number of cylinders are present.  The Master must be informed that this could occur, and the remedy would be to kick the engine in the opposite direction, and then restart in the required direction

Overheating of Main Engine Piston

Reasons:  Inadequate circulation of cooling media and or supply not sufficient Excessive deposit in cooling space (scale or carbon) Lubrication not sufficient Faulty piston ring : clearance inadequate.  Too high temperature  top ring groove area – blow by. Distorted cylinder liner Misalignment of piston Overloading of unit – excessive fuel Excessive water content in fuel Insufficient air from turbocharger or manifold Late injection of fuel – timing or fault injectors Engine running slow speed – full flow of coolant not maintained Action: Slow down the engine to a very low speed but NOT complete shutdown. This results in considerable reduction of heat in the relevant piston. Since not all pistons would likely develop this fault simultaneously (unless you are totally out of luck that day) so first identify the particular cylinder in which the problem has occurred using parameters such as temperatures, sound etc. The fuel supply to the affected cylinder should be cut-

Double evaporation boilers

A double evaporation boiler uses two independent systems for steam generation and therefore avoids any contamination between the primary and secondary feedwater. The primary circuit is in effect a conventional watertube boiler which provides steam to the heating coils of a steam-to-steam generator, which is the secondary system. The main reason for the adoption of this design of boilers is to allow use of modern high efficiency watertube boilers witghout fear of damage through contamination by cargo or fuel oils.The basic design consists of a D-Type boiler design upon which is mounted a Steam/Steam generator drum. The steam generated by the main boiler heats water in the Steam/Steam generator which produces steam requirements. The primary drum is initially filled with high quality feed water and suitably dosed. The  main  reasonfor  the  adoption  of  double  evaporation  boilers  in  tankers are  concerned  of  damage  caused  by  oil  and  sulphur  which  enters  the  feed 

Regulations and Requirements for IG Blowers

Minimum 2 number of blower to be fitted in I.G system. The capacity of each blower must be 1.25 times the overall capacity of the cargo discharge system fitted on board. This is to ensure that Inert Gas is always present in the cargo hold. Only 1 blower may be permitted by the administration if it fulfills the requirement stated in above point i.e. capacity must be 1.25 time cargo pumps and required spares are always available. A shut off arrangement must be provided in the suction and discharge connection side of the blowers. Generally the blowers are used for gas freeing hence an n air inlet with blanking arrangement must be provided. At normal operation, blanking arrangement is to be secured. Cargo tanks are pressure tested at 2500 mm water gauge and 700mm water gauge on the vacuum side. The blower pressure must not exceed the test pressure else the tank will get damage.  Minimum pressure to be maintained by blower is 200 mm water gauge in cargo tank. There must be high tem

Condition Monitoring

Condition monitoring (or, colloquially, CM) is the process of monitoring a parameter of condition in machinery (vibration, temperature etc.), in order to identify a significant change which is indicative of a developing fault. It is a major component of predictive maintenance.  The use of condition monitoring allows maintenance to be scheduled, or other actions to be taken to prevent failure and avoid its consequences.  Condition monitoring has a unique benefit in that conditions that would shorten normal lifespan can be addressed before they develop into a major failure.  Condition monitoring techniques are normally used on rotating equipment and other machinery (pumps, electric motors, internal combustion engines, presses), Condition monitoring techniques Vibration and shock pulse data measured from all machinery. On the spot analysis and interpretation of results. Thermo graphic inspection of all electrical and some critical mechanical systems. Pressure and vacuum leak d

Wear rate of liner

For Two Stroke engine a wear rate of 0.1 mm per 1000 hour is normal. Maximum acceptable rate is 0.25 mm per 1000 hr. Maximum total wear is acceptable is 0.75% of bore. Useful life span: 70,000 - 80,000 hours For Four Stroke engine the wear rate is 0.02 mm per 1000 hours

Heating Rods for Refrigeration Compressor Oil Heating

The refrigeration compressors are delivered in a standard execution with built-in heating coils or rod in the crankcase. The purpose of the heating coil or rod is to keep the oil in the crankcase warm even during standstill of the compressor. This ensures a low content of refrigerant in the oil. Too much refrigerant in the oil makes it loose its lubricating properties. This may lead to damage of the movable parts in the compressor. Further, the danger exists that the oil, during start-up of the compressor, foams so vigorously that the lubricating pressure will disappear. Before start-up the heating rod should be switched on for at least 8 hours. The heating coil or rod must not be switched on if the oil level in the vessel is below minimum in the sight glass. While the compressor is operating, it is usually switched off. Further, remember to switch off the heating rod if the compressor crankcase is opened for inspection.

Destructive and Non-Destructive test

Destructive test Test on test pieces Damaged after test. Determine mechanical properties of test piece under test. Tensile test  Impact Test    Fatigue Test Bend test  Hardness Test  Creep Test Non-Destructive Test Test on components. Not damaged after test Determine flaws or imperfection during manufacture (or) service. Liquid penetrating   Electrical test method Ultrasonic method   Radiographic inspection Magnetic crack detection Destructive test Tensile Test Tensile test is used to determine the behaviour of a material up to its breaking point. A special shape specimen of standard size is gripped in the jaws of a testing machine. A load is gradually applied to draw the ends of the specimen apart such that it is subject to tensile stress up to yield point. The highest value of stress is known as the ultimate tensile stress (UTS) of the material. Bend Test Specimen is bent through an angle of 180 with internal radius of 1.5 times the thickness of

Consequences of running an engine with slack Tie bolts:

Cylinder beam would flex and lift at the location of the slack bolt landing faces of the tie bolt upper and lower nuts, landing faces of the cylinder beam on the frame would fret and machined faces would eventually get destroyed. The fitted bracing bolts between the cylinder jackets will also slacken and the fit of the bolts would be lost. If fretting has occurred in an uneven pattern where the cylinder beam lands, and the tie bolts are tightened, the alignment of cylinder to the piston stroke will be destroyed. The fitted bracing bolts between the cylinder jackets will also slacken and fit of the bolts will be lost. Fretting may make the nut landing face out of square and if tie bolts are tightened on the damaged face, a bending moment will be induced in the tie bolt, this may cause an uneven stress pattern in the tie bolt which could lead to early fatigue failure. Damage may take place in the bedplate in way of cross girder.                                                       

Difference between Slow speed , Medium speed and High speed engines

Operating Cycles

OTTO CYCLE (Constant Volume Combustion Cycle). It is the ideal air standard cycle for Petrol engine, the gas engine and the high-speed oil engine. The engines based on this cycle have high thermal efficiency but noisiness results particularly at higher power due to higher pressures in the cylinders. DIESEL CYCLE (Constant Pressure Combustion Cycle). It is the ideal Air standard cycle for Diesel Engine, especially suitable for low speed Diesel Engine but not for high speed Diesel Engine. The thermal efficiency is lower than Otto cycle engines but engines run smoothly due to lower pressures in the cylinder. DUAL COMBUSTION CYCLE (Constant Pressure and Constant Volume Combustion Cycle). Modern Diesel Engines do not operate purely on constant pressure combustion cycle but some part of combustion process takes place at constant volume while the rest is completed at constant pressure. In general, this cycle resembles Constant volume combustion Cycle more than constant pressure c

p Alkalinity and m Alkalinity

What is p Alkalinity? The  term  p  Alkalinity  stands  for  “Phenolphthalein  –  Alkalinity”.   It  is  the  measurement  of Hydroxide and carbonate ion amount.  It is determined by titrating a water sample with an acid of a known concentration in the presence of phenolphthalein as the indicator.  What is m Alkalinity? The  total  measurement  of  Hydroxide  bicarbonate  and  carbonate  ions amount is given by m Alkalinity. The letter m refers to Methyl orange. It is the indicator that is used to determine the total alkalinity given by the above hydroxide and carbonate species. When methyl orange is added, it gives its color change only  in its pH range which is, 3.1  –  4.4. Since only  trace  concentrations  of  other  acids  are  dissolved  in  water  except  for  carbonic  acid,  m Alkalinity can be considered as the total alkalinity because it gives the total carbonate alkalinity. What is the difference between p Alkalinity and m Alkalinity? p Alkalinity vs m Alk

Timing diagram and Power card of 4 stroke cycle

The timing diagram shows the closing and opening of the valves. The working cycle is illustrated as a ‘P - V’ diagram (pressure-volume). The line ‘l – l’ represents atmospheric line. The piston is considered to have just moved over the ‘top dead centre’ and is on its way down. The air inlet is already open and because of the partial vacuum created when the piston moves towards its bottom position, fresh air is sucked into the cylinder. This process is represented in the 'p-v' diagram by the line ‘1-2’ which is termed suction line. This movement of the piston is called 'Suction Stroke". After the piston has moved over bottom dead centre, the suction valve closes and the volume of air in the cylinder is compressed during the course of the up stroke of the piston. This is represented by the line ‘2-3’ in the above diagram and termed as compression line. This movement of piston is compression stroke. The ignition takes place at point 3 and combustion continues for th

Slide Valves : Simple things that mean a lot

Exhaust valve Materials and Treatments

Material Requirements. The material should retain its greatest strength at high temperatures. No tendencies to air harden. Critical temperature above 800*C. No tendency of high temperature scaling. Hot and cold corrosion resistant. Able to be forged and machined easily. Capable of consistent and reliable heat treatment. Most diesel engines use an Austenitic heat-resisting alloy steel. The seating surface can be stellited. Typical heat treatment:  Heat up to 950*C and cool in air to give a Brinnel Hardness of 269. Surface Treatment: Surface treatment is frequently used to improve or modify valve steel characteristics. Chrome-cobalt-tungsten alloy available in various grades of hardness is widely used. The hardness when deposited is in the order of 375 to 425 Brinnel. The valve head is treated to more than 430*C to reduce contraction stresses. The value face is now sweated by an oxyacetylene flame and the alloy deposited continually by welding (1.02 mm to 1.52 mm).

Construction and Working Principle of Indicator

An engine indicator consists of a small bore cylinder containing a short stroke piston which is subjected to the same varying pressure that takes place inside the engine cylinder during one cycle of operations.  This is done by connecting the indicator cylinder to the top of the engine cylinder in the case of single-acting engines, or through change over cocks and pipes leading to the top and bottom ends of the engine cylinder in the case of double-acting engines. The gas pressure pushes the indicator piston up against the resistance of a spring, a choice of specially scaled springs of different stiffness being available to suit the operating pressures within the cylinder and a reasonable height of diagram. A spindle connects the indicator piston to a system of small levers designed to produce a vertical straight-line motion at the pencil on the end of the pencil lever, parallel (but magnified about six times) to the motion of the indicator piston. The “pencil” is often a brass

Procedure for opening Main Engine Liner

Following Procedure has to be followed when opening Liner Inform company and take permission.Take immobilisation certificate from port state control. Read the manual and have a tool box meeting with everyone involved in the job. Discuss the complete procedure. Prepare important tools and spares required for overhauling liner as given in the manual Prepare risk assessment and make sure all personal safety equipment are used Shut starting air for Main Engine and display placards Engage turning gear Open indicator cocks for all the cylinders Stop main lube oil pump and switch off the breaker Once the engine jacket temperature comes down, shut the inlet water valve for the unit to be overhauled Keep other units in Jacket preheating system to maintain the jacket temperature Drain the jacket water of the concerned unit from exhaust v/v and liner. Shut the fuel oil to the particular unit whose liner is to be removed Dismount the cylinder head using dedicated lifting tools Dis

Refrigeration Compressor Starting Unloader

At a star-delta start of electric motors it is often considered necessary to limit the compression work of the machine at the starting moment in order to reduce the starting torque of the electric motor.  Usually, a solenoid valve is used in a by-pass arrangement which in the starting up phase short circuits the discharge side to the suction side of the compressor.  At the same time, a non-return valve must be fitted in the discharge line to the condenser preventing the return flow of discharge gas to the compressor. When the electric motor has reached its max. number of revolutions per minute, a switch takes place from star to delta start.  The solenoid valve is closed and the compressor now works under normal conditions.