Skip to main content

Posts

Showing posts from December, 2019

Measuring of K-value of T\C

K- From bearing flange face to end face of shaft. K1- for measuring K1 , slacken compressor side bearing by around 5 to 6 mm and pull it out using extractor tool .Then push the shaft towards compressor side. Screw the extractor device on to the inner bearing bush of the compressor end and pull out the bearing about 5 to 6 mm Push the rotor towards the compressor side measure K1. Same way for measuring K2  , pull the rotor towards turbine side measure the dimension K2 L =K-K1              M =K2-K In manual required valus of K ,L and M will be given . Basically we are measuring the end play  ie, distance between turbine wheel and casing on either side. K value will give an indication of thrust bearing weardown

Lacing wire , Damping wire and Binding wire of T\C

  Lacing wire It is fitted at anti node provided very effective form of dampening. It passes through blades and are braced or welded in blades. Damping wire All same purpose of Lacing wire , but free moving through holes and crimmed  at either end. Centrifugal force of wire when it gets thrown out , dampens the vibration , but can cause fretting in blades and need to be dynamically balanced. Binding wire  It is used to strengthen the trailing edge of the blade

Miller cycle

Only for 4stroke  engines. In Miller cycle inlet valve closes early. NOx reduction , As inlet valve close early when the piston moves down little bit of expansion of inlet air will occur , exhaust temp drops and NOx emission reduces. Normally inlet valve should close around 29 degree after BDC , as the miller cycle introduces , the inlet valve closing is earlier. Draw back of Miller cycle. Since the closing of inlet valve is early , the amount of air inside the cylinder is reducing . So further we have to combine it with multistage T\C (To compensate the loss in air )

Air bottle pressure testing How?

All hydraulic test has to done by water because in pressure testing we are checking for weakness in air bottle .Hydraullic pressure test to be done above 50% at design pressure . If the air bottle was actually having a hole , then it will take atleast half hour  for the pressure to be released , till that time the weak air bottle is pressurised .But in hydruallic pressure test even one drop escapes , the pressure is released because the water is incompressible

Stern tube

Seal is gripping on to the chrome liner.Chrome liner is bolted on to propeller boss(aft) Fwd chrome liner is fitted on to a clamp ring . Clamp rings are of 2 halves and have holes. Aft  sealing assembly consist of 2 main and 1 aux sealing rings.All sealing rings are spring loaded .Fwd sealing ring prevent oil leakage to sea .Lip seals hold oil within Stern tube and accepts small misalignment Chrome liner act as rubbing surfaces for lip seals .The chrome liner at the aft end protects the steel shaft from seawater and corrosion .Grooving will not happen on the shaft because of liner, so that the chrome liner can be machined or can be shifted axially by putting spacer.If grooving occurs leak will start. As per diagram the space between  #2 and #3 is connected to header tank ,#3s is the spare seal  If water content found on the stern tube that means along with #1 and #2 , then #3 seal is also leaking.Then we have to put #3s seal in use.

Thrust pad lubrication

By LO branching pipe coming from main LO pump through the nozzle and sprayed on to the thrust collar. Rotation of thrust collar causing the formation of LO wedge. Hydrodynamic fluid film to be formed between rotating and stationary part . This film prevents metal to metal contact .ie between the thrust pad and collar . Pad is same material as white metal bearing

Advantage of fitting thrust block inside engine

Ship structure already is strengthened for engine seating , so no need of additional strengthen There are more no: of nodal points Cross sectional area is more , so strengthening required is less. No need of separate LO arangment as the chain\ gear LO supply can be tapped for using in thrust bearing. Thrust collars outside is having the sproket , so space saving. Both side of the collar have thrust pads

Advantages of Jack bolts

Jack bolts are used in Sulzer RTA engines Tie rod should always be as close as possible to the crankshaft Adv of bringing tie rod closer is to reduce the bending moment on transverse girder. If there is bending moment on transverse girder cracks would propagate ie why Sulzer has employed a jack bolt so that the bearing top cover is held in position by the jack bolts. In B & W main bearing top cover is in two pieces.ie bearing cover  or keep in of 2 pieces.

Synthetic oil and Mineral oil

Mineral oil are exracted from crude oil in distillation process. Mineral oil contain lot of contamination or substances which are no lub oil property to oil. Hydrocarbon molecule are non -uniform in crude oil. Synthetic oil is not distilled from crude oil .It is made through a chemical process known as Fischer Troph process.Starting with raw material like , methane ,CO,CO2 doesnot contain any contaminants and hydrocarbon molecule are uniform

Batch purification

Engine stop, Immobilization permit from port authority Entire oil charge should be pumped by Px or transfer pump to LO settling tank. It is allowed to settle for 24 hrs with heating about 60 degree celcius, Water and Sludge should be drained out periodically. Cleaning of interior sump tank and careful examination. The oil should be passed through the Px at its optimum purification efficiency and then pumped back into the sump tank. Batch purification is required when If oil is suspected containing strong acid. High insoluble content due to poor combustion or water due to leak in cooling system Suspecting biological contamination

Super long stroke

Long stroke: 3.2 - 4.0 Super long stroke:4.0 -4.7 Ultra long stroke :>4.7 Advantages of super long stroke : Power to weight ratio is more. R educed fouling, smoke, NOx Increased thermal efficiency:  Simple geometric relationships show that an engine cylinder with longer stroke-to-bore ratio will have a smaller surface area exposed to the combustion chamber gasses compared to a cylinder with shorter stroke-to-bore ratio. The smaller area leads directly to reduced in-cylinder heat transfer, increased energy transfer to the crankshaft and, therefore, higher efficiency. Low quality fuel can be burnt as more time is available for fuel combustion. Slow rpm is possible so large diameter propeller can be used and hence propeller efficiency increases. More time for heat dissipation to cooling water. Better scavenging:  Scavenging is the process in which the exhaust products in the cylinder are replaced by fresh air. As the stroke-to-bore ratio increases, so fresh air has

Ship Implementation plan (SIP)

The Ship Implementation plan addresses issues related to preparing the vessel for use of compliant fuel oil and includes items such as risk assessment and planning for actions needed to ensure compliance on 1 January 2020. Preparing a good plan can enable a smoother transition into 2020. The plan is not mandatory and is not subject to endorsement by the flag state or a recognized organization (RO). However, PSC may consider the preparatory actions described in the SIP when verifying compliance. Items covered by the plan can include, as appropriate, but are not limited to: Risk assessment and mitigation plan (impact of new fuels) Fuel oil system modifications and tank cleaning (if needed) Fuel oil capacity and segregation capability Procurement of compliant fuel Fuel oil changeover plan (conventional residual fuel oils to 0.50% sulphur compliant fuel oil) Documentation and reporting Benefits of the web-based Ship Implementation Plan app: Save time & effort wit

Camshaft timing check and adjustment

Checked by pin gauge. Pin gauge must be fitted between the camshaft and engine frame housing wall poop marks. Max allowed variation is 2 degree ie 4.8mm If >2 degree , then adjust the camshaft by hydraullic pressure and the special spanned attached to the tackle Position of the engine is no:1 cylinder in TDC, confirm in flywheel.

How to run main engine with piston cracked?

Cut out the fuel pump by lifting and securing the roller guide. Put the exhaust valve out of action , so that valve remain closed. Dismantle the starting air pipe.ie Blank the main pipe and Control air pipe for the cylinder. Suspend piston and crosshead. Take connecting rod out of crankcase Blank off the oil inlet to the crosshead. Set the cylinder lubricator for the unit to zero discharge.

Tri - Metal type thin shell Bearing

1st layer( Flash )       - 1 micron thickness of lead\tin for corrosion prevention before installing. 2nd layer( Overlay )  - 20 micron thick white metal. 3rd layer( Inter lay )  - 5 micron thick nickel\Ag helps to reduce corrosion of white metal 4th layer( Bearing )   - 1mm thick lead\bronze ,tin\Al 5th layer ( Steel backing shell )-5-15mm for strength and stiffness

Air Purging method in Refer system.

Indication High condensor pressure. Small bubble in sight glass of condensor\reciever. Compressor discharge pressure and temp high. More super heat. Pressure fluctuations, Insufficient working(Temp of room is not coming in time) Pressure temp relations at compressor discharge and reciever would not match with P-T chart of the refrigerant. Procedure for Purging During normal running , measure liquid refrigerant pressure , temp at outlet of condenser\receiver. Check corresponding saturation temp for the recorded pressure from P-T chart of the refrigerant Compared the measured temp with the determined saturation temp for any sub cooling \under cooling.Adjust the flow of cooling water through condenser to achieve the saturation condition. Purging of Air. Close condenser outlet valve,  Circulate cooling water . Pump refrigerant to the condenser/receiver till the compressor trips on LP cutout.(Reduce the LP cut out setting above the atmosphere pressure) Circulate c

How to test leaking Air start valve?

How to test leaking Air start valve? Open all the valves for starting main engine except distributor valve. Open all units indicator cocks. Start the main engine from ECR by moving the telegraph of AHD direction. Now the engine wont start , but automatic main air starting valve will open and starting air will be available to all units air start valve. If any air start valve leaks , then the air will go to units and comes out from indicator valve. For checking this personnel should be employed near all indicator cocks

Slow turning

Slow turning If a slow turning valve is fitted , then this will open instead of the main automatic valve if the engine has been stopped for more than 30 minutes during maneouvring. It will only supply enough air to turn the engine over very slowly . This is a precaution in case a cylinder has oil or water leak into it which would cause damage to engine when starting. If the engine completes a full revolution on slow turn , then the main automatic valve opens and engine will not start

Suction valve purpose in MAN B &W

Oil is supplied to the barrel through the spill port and a suction valve The suction valve situated at the top of the barrel opens when the pressure in the barrel falls below the supply pressure.ie during the downward stroke of the plunger , while spill ports are covered by plunger

Advantages of Chain drive

Flexibility in positioning of camshaft , so fuel pump is located near to cylinder head and HP pipe leakage is reduced Can cope up with some amount of misalignment High transmission efficiency ie 98% Easier to adjust camshaft timing. Less spare requirement Factor safety is high 40-50

Piston pressure testing

Fill the piston and piston rod with LO. Mount the pressure testing tool at the base of piston rod Connect air supply and apply air pressure to 7 bar( 10 minutes) Check the contact surfaces of piston crown , piston skirt , piston rod and sealing rings for tightness Check no crack on piston crown

Inerting ,Gas freeing ,Purging ,Topping up

Inerting Replacement of hydrocarbon in a cargo tank by using inert gas Gas freeing The process of creating normal atmosphere condition inside the tank where oxygen level is 21% Purging Inerting inert gas in the tank when it is already having less than 8% oxygen to reduce oxygen and hydrocarbon value even further that. Topping up Inerting inert gas into an already inerted tank just for raising the pressure to positive level wit respect to atmosphere

Parametric rolling

Parametric rolling is an unstable phenomenon, which can quickly generate large roll angles that are coupled with significant pitch motions. The rolling occurs in phase with pitch, and on containerships introduces high loads into the containers and their securing systems Causes of Parametric Rolling The size of container ships is increasing drastically as companies are looking forward to monster ships; for e.g. Maersk’s Triple-E Vessels. The new container ships coming to the market have large bow flare and wide beam to decrease the frictional resistance which is generated when the ship fore end passes through the water, making it streamlined with the hull. As the wave crest travels along the hull, it results in flare immersion in the wave crest and the bow comes down. The stability (GM ) varies as a result of pitching and rolling of the ship. The combination of buoyancy and wave excitation forces push the ship to the other side. The similar action takes place as the bow goes down

Rudder checks

Remove plug for any water Hammer test to check condition of plates. Gauging of vessel more than 5 years. Condition of Zn block Pintle and Jumping clearance Wear down and Rudder drop. Corrosion , Pitting cracks Rudder pressure test 2.4 m water height. Check position correct or not..

Differance between flame screen and Flame arrestor?

Flame Arrestor Prevent the passage of flame complying with all relavant requirement of this schedule It is based on the principle of quenching , made of permiable matrix of metal , ceramic or other heat resisting material which can cool a flame. Flame Screen A portable device incooperating corrosion resistan wire of very small mesh which used for preventing sparks from entering tank or vent opening for short time preventing passage of flame.

Continous Survey of Machineries (CSM).

All classification society or IACS requires tha all machinery under their rules must be surveyed every 5 years due to heavy load . They allow some items to be surveyed in rotation curve of anual cycle (20%) .Then survey will over by 5 years . So it is called CSM. Class will allow C\E to survey that class surveyor to credit the survey at anual levels

Substance prohibited from incineration

Residues of cargo subjected to Annex 1 , 2 & 3. Poly Chlorinated benyl(PCB) Garbage of Annex V , contain more than traces of heavy metal. Refined petroleum compounds like halogen compounds. Sewage sludge and sludge oil either of which is not generated onboard. Exhaust gas cleaning system residues. PVC proibited

CO2 bottle stamping

Manufacturing  " * " means 10 year pressure test . If no " * " then pressure test 5 years. Hydraullic test pressure and date Weight and cylinder capacity. Serial no: Standard Non flammmable Empty bottle height

CO2 bottle level measurement

Check temp of the room Put sensor on the bottle and keep moving it up and down until it indicates 100 on the panel by using ultrasonic level sensor. Measure the height Put values in the calculation sheet and final values

Position 1 & 2 of a ship

Position 1 Any location upon exposed free board deck and raised quater decks and exposed super structure with forward 0.25L Position 2 Exposed superstructure deck situated aft 0.25L from forward perpendicular and poop deck , bridge deck

Difference between ISM external and internal audit?

Internal Audit After July 2010 mandatory 12 months , 3 months can be extended. Tool to monitor how SMS is maintained onboard. Helps to check whether company safety and enviroment policy is continously compliance with requirement of this code , changes in SMS system. Helps to do external audit survey. Company DOC validation. External Audit Done by classification society. 5 years or 2-3 years Provide DOC and SMC after this audit. Will cehck internal audit details

Damage Control booklet

Gives idea to show how to control the effect of damage , specific actions Sounding of alarms to alert the crew. Closing of all watertight doors and compartment, Sounding of tanks , rate of flooding.  Ways to reduce the flooding , pumping out. Some ship have a flow chart. If the ship is seaworthy will full fill intact and damage stability

Damage Control plan

Layout of all compartment such as cargo tank , ballast tank , fuel tank etc. Means of clossure such as valves water tight doors, hatches or cofferdams and its position. Arragment for correction of the list during flooding , location and capacity of fire and  ballast pump .

Condition of assignment.

All opening on weather deck are water tight. Height of the coaming , air pipes and door sills above weather deck. The change in freeboard depend on degree of water tightness. Water in deck should be removed immediately , bulwark need freeing ports , scupppers. In type A ship due to small freeboard open rails should be fitted instead of bulwark. Hatch coaming , hatch cover , Air pipes should be strong enough to resist pounding from sea

Cargo hold fire CO2

Remote detector fitter at CO2 room can detect smoke on concerned cargo space. Operation done by master order. After ensuring no person left in cargo space .Seal off the cargo space ie, close ventilation fan , fire damper , hatch cover. Operate  3 way valve for concerned hold and manually open required bottles

Fuction requirement of ISM

Safety and enviromental protection. Instruction and procedures for safe operation and protection of enviroment. Defined lines of authority and lines of communication between shore and ship. Procedures for reporting accident. Procedures for emergency situation. Internal and External audit

Purpose of IG.

Even with no cargo on hold there may be harmful flammable gases. When vapour produced by an oil cargo is mixed wit certain concentrations of air primarly containing Oxygen , it can result in explosion

Procedure for renewal of Indian CDC

PROCEDURE FOR RENEWAL OF INDIAN CDC Use windows  Mozilla Firefox for better resolution. Go to google and type dgshipping. and open dgshipping website. Click on the egovernance link and select Seafarers registration, a new page will open. if you are a new user then register first enter INDoS no & DOB. If already registered then use your INDoS no as user ID, Password ( INDoS no followed by digit 1 or changed password) Before apply for CDC renewal make sure you have updated your seafarer profile if not updated. Update seafarers profile fill out all your documents details and voyage related details. Go to “CDC management and CoC as a cook ”new page will open. However on “Submit Application” Select your desired option as explained above “Renewal CDC (New)”, “Replacement of the CDC”, “Duplicate CDC ”. Fill out all the data & Generate Application No. Under office Select “ SHIPPING MASTER OFFICE MUMBAI”( nearest shipping master) and fill

Safeties in Refer System

Safeties in Refer System LP cut outs HP trip LO differiential trip Low LO pressure trip Relief valve in condenser. Belt driven Cooling water high temp alarm' Cooling water non flow alarm Motor overload Drier Oil separator Sight glass Crankcase heater Unloader Safety spring loaded liquid shock valve on compressor head Superheat setting on expansion valve. Master solinoid 

Short cycling in refer compressor

Short cycling in refer compressor  Undercharged. LP cut out not properly adjusted. Filter/Drier chocked. Moisture in system.(icing of exp v/v or Exp v/v filter chocked) Unloader not working properly. Expansion valve not properly adjusted. Solenoid valve malfunction.

Turbocharging Principles and Construction

Turbocharging Principles and Construction By turbocharging an engine, the following advantages are obtained: Increased power for an engine of the same size OR reduction in size for an engine with the same power output. Reduced specific fuel oil consumption - mechanical, thermal and scavenge efficiencies are improved due to less cylinders, greater air supply and use of exhaust gasses. Thermal loading is reduced due to shorter more efficient burning period for the fuel leading to less exacting cylinder conditions. The turbocharger consists of a single stage impulse turbine connected to a centrifugal impeller via a shaf t. The turbine is driven by the engine exhaust gas, which enters via the gas inlet casing. The gas expands through a nozzle ring where the pressure energy of the gas is

Slow Steaming

Slow Steaming Slow steaming has become more of  a normal operating procedure due to the following factors: The worldwide downturn in the global economy leading to reduced demand for manufactured goods. This has led to reduced capacity demand. Shipowners are reluctant to lay up vessels and there are also  a large number of new ships being delivered. Increase in fuel and other operating costs such as lubricating oil and maintenance Falling freight rates The simplest way to reduce operating costs is to reduce the fuel bill. Most vessels are propelled by a slow speed two stroke engine directly coupled to a fixed pitch propeller. If the speed of the engine is reduced, then although the vessel will slow down, the amount of fuel required to travel each nautical mile is reduced. This is because the correlation between speed and shaft power is not linear, but cubic. (P a V 3 D 2/3 ) Fo

Sulphur Limits For Ships in EU Ports

Sulphur Limits For Ships in EU Ports   From 1st January 2010 the European Parliament Directive2005/33/EC came into force. As well as reinforcing the limits of sulphur for vessels operating in SECAs, and limiting the sulphur content of fuels used ashore in the EU, it also introduced legislation governing the maximum sulphur content of fuels used by inland waterway vessels and ships at berth in Ports which are part of the European Community. The limit placed is 0.1% Sulphur, which is the maximum sulphur content of Gas Oil The rules state that the limit applies for ships at berth in EU ports allowing sufficient time for the crew to complete any necessary fuel change over operation as soon as possible after arrival at the berth and as late as possible before departure. The change over must be recorded in  ships log books. It does not apply to ships in port for less than 2 hours, t

Miller cycle and emission reduction

The Miller cycle was developed by Ralph Miller in the 1940s. With the introduction of turbocharging to the 4 stroke diesel engines, the Mean Effective Pressure and thus the power output of 4 stroke engines rose by 50 - 60%. However this was about the limit; If the  inlet air pressure was increased further, then the charge air reached excessive pressures and temperatures on compression causing burning of the LO film and thermal stressing. Miller challenged the thinking of the day by closing the inlet valve before the piston reached bottom dead centre. This had the effect of lowering the cylinder pressure as the piston continued downwards, as well as dropping the temperature of the air (Boyles and Charles' Law). Although the engine is still doing work as the piston is descending on the inlet stroke, there is a saving in work during the compression stroke, and the maximum air temperature and pressure is red