MEO Class 2 Misc Info!

8/4/2019 MEO Class 2 Misc Info!

1/17

INDEX1.BDN2.BOILER BLOWDOWN3.CATALYTIC FINES4.CRANKCASE INSPECTION5.BABITTING6.PROPELLER SHAFT AND RUDDER STOCK STRAIGHTENING7.CLEANING OF FUEL OIL TANK8.TURBOCHARGER SURGING9.SAE10.BOILER STARTING FAILURE11.ALUMINIUM WELDING

12.Dry dock inspection of anchor13.Diff between MC/MC-C AND ME/ME-C

14.Final Inspection Before UNDOCKING

Bunker delivery noteIt is a requirement of Regulation 18 that any fuel oil for combustion purposesdelivered to and used onboard shall be recorded by means of a Bunker Delivery Note(BDN). This implies that a bunker delivery note shall be presented for every barge

delivery and every grade.Bunker Delivery Notes are required to contain all specific information as follows:-Name and IMO number of receiving ship-Bunkering Port-Date of commencement of bunkering-Name, address, and telephone number of marine fuel oil supplier-Product name-Quantity (metric tons)-Density at 15 oC (kg/m3)-Sulphur content (% m/m)-A declaration signed and certified by the fuel oil supplier's representative thatthe fuel oil supplied is in conformity with regulation 14 and 18 (I.e. that the fuelsupplied has a sulphur level below 4.5% and that the fuel is free frominorganic acid, does not include any added substance or chemical wastewhich either jeopardises the safety of ships, adversely affects the performanceof the machinery, is harmful to personnel, or contributes overall to additionalair pollution).Further, Resolution MEPC.96(47) recommends that the seal number of theassociated MARPOL Annex VI fuel sample is included in the BDNs for crossreferencepurposes.The BDNs are to be kept on board and readily available for inspection at all times. It

shall be retained for a period of three years after the fuel oil has been delivered onboard.


2/17

BOILER BLOWDOWNEven with the best pretreatment programs, boiler feedwater often contains somedegree of impurities, such as suspended and dissolved solids. The impurities canremain and accumulate inside the boiler as the boiler operation continues. Theincreasing concentration of dissolved solids may lead to carryover of boiler waterinto the steam, causing damage to piping, steam traps and even process equipment.The increasing concentration of suspended solids can form sludge, which impairsboiler efficiency and heat transfer capability.To avoid boiler problems, water must be periodically discharged or blown downfrom the boiler to control the concentrations of suspended and total dissolved solidsin the boiler. Surface water blowdown is often done continuously to reduce the levelof dissolved solids, and bottom blowdown is performed periodically to remove sludge

from the bottom of the boiler.The importance of boiler blowdown is often overlooked. Improper blowdown cancause increased fuel consumption, additional chemical treatment requirements, andheat loss. In addition, the blowdown water has the same temperature and pressureas the boiler water. This blowdown heat can be recovered and reused in the boileroperations.Boiler Blowdown Benefits Less water, fuel and treatment chemicals needed; Less maintenance and repair cost (minimized carryover and deposits); Saves manual supervision for other tasks (with automatic control);

Cleaner and more efficient steam; Reduced operating cost (reduction in consumption, disposal, treatment andheating of water); Minimized energy loss from boiler blowdown can save about 2 percent of afacilitys total energy use with an average simple payback of less than one year.Flash Tank SystemThe flash tank system shown in the figure below can be used when expense andcomplexity must be reduced to a minimum. In this system, the blowdowns from theboilers are sent through a flash tank, where they are converted into low-pressuresteam. This low-pressure steam is most typically used in deaerators or makeup

water heaters.see diagrams on post dated 3-02-2011 by me(felix pinto)Flash Tank Heat Exchanger SystemThe system shown below consists of a flash tank and a heat exchanger. Thetemperature of the blowdown leaving the flash tank is usually still above 220F. Theheat of this flash blowdown can be used to heat makeup water by sending itthrough the heat exchanger, while cooling the blowdown at the same time. Heatingboiler makeup water saves on fuel costs. An additional advantage of coolingblowdown is in helping to comply with local codes regulating the discharge ofhigh temperature liquids into the sewer system.


3/17

Catalytic FinesCatalytic FinesOrigin:By-product from the catalytic cracking process in the refinery.

Catalyst consists of complex crystalline particles containing aluminium silicate.Catalytic fines result from catalyst particles breaking into smaller particlesCatalyst is expensive, i.e. refiners minimise loss but not 100%

Effects* Severe wear of Liners* Severe wear of Rings* Wear out of Cyl-grooves* Scuffing of liner* Abrasive Wear of Spindle-Guide & cut-off shaft & nozzles* Scuffing of Fuel Pump spindle guide

SpecificationVariable in size ranging from sub microic to about 30 microns even seen largerFrequently considered spherical but this is not necessarily the case.Hard particlesHardness not directly related to relative hardness of Al or SiCan cause abrasive wearISO 8217 specifies the catalyst fines by Al and SiISO 8217 limit is80 mg/kg Al+Si for marine residual fuels

(Note: ISO 8217 limit is for bunker not at engine inlet)

ReductionGravitational settling.Centrifuge(Note: Homogenisers will not reduce the amount of catalyst fines but might insteadbreak them into even smaller particles)Overhaul and maintenance intervals must be kept according to manufacturersRecommendation.Temperature control very important.

The higher the temperature the better the separation efficiency. Both density andviscosity of the oil decrease when the temperature rises, thereby increasing thesettling velocity (Stokess law)(If the separation temperature is lowered from 98C to90C the separatorthroughput has to be reduced by25-30% to maintain the same separationefficiency!!)

CRANK CASE INSPECTION (20 points)1. Firstly check the oil condition for any smell, discolouration or degradation.


4/17

2. Turn the Engine to BDC & start checking from under stuffing box area for anysigns of black oil, if so indication of stuffing box leaking.3. Check piston rod surface for scoring marks & roughness.4. Check Piston palm bolts & locking device for slackness & fretting.5. Check guide & guide shoe bearing general condition & area around frame where

guide is attached for any visible cracks.6. Check guide shoe end cover bolts in place & not slack.7. Check cross head general bearing condition.8. Top & Bottom end of the con rod bolt, nut & locking devices for slackness, sign offretting etc.9. Check sliding of bottom end bearing (floating of con rod).10. Check for slip of web & journal by checking the reference mark.11. Check the web in the area of stress concentration & check tie bolts (bottomside).12. Check cross girder , area around main bearing & bearing keep for signs of cracks& check the main bearing.

13. All bearings to be checked for silvery colour, (indicates bearing wiping)14. Check all the surrounding oil pan area of all units for any sludge deposits,bearing metal pieces etc.15. Check crankcase relief door (wire mesh should be wet, spring tension sealingcondition etc.)16. Check the teeth of transmission gears for signs of wear.17. Check chain drive for tightness.18. Oil mist detector sampling pipe to be checked for clear passage.19. Clear all foreign materials from the C.C. & tools accounted for.20. Start L.O.p/p & X-Hd p/p & check oil flow & distribution.

21Check C.C.door sealing condition & close the door.

BABBITTING is a process by which relatively soft metals are bondedchemically or mechanically to a stronger shell or stiffener, which supports the weight

and torsion of a rotating, oscillating, or sliding shaft. The babbitt, being softer than

the shaft and having excellent antifrictional qualities, prevents galling and/or scoring

of the shaft over long periods of use. Compositions and selected properties of

babbitts are summarized in Tables and Fig.. Babbitting is named for Isaac Babbitt,

who patented the process in the United States in 1863. Babbitt metals, which are

more widely known as white metals, are comprised principally oftin alloys

(hardened with copper and antimony) or lead alloys (hardened with tin

and antimony and, in some cases, arsenic). In the babbitting process, the

relatively soft bearing material (babbitt) is bonded to a stronger supporting base

metal, typically mild steel, cast iron, or bronze. The base metal may be in the form

of mild steel strip unwound from a coil, a half-round mild steel pressing or bushing,

or a bronze or iron casting. The bonded bimetal material is shaped and machined to

make plain, fluid film lubricated bearings for a wide variety of automotive, industrial,

and marine applications. Babbitt is used in small bearings for high-volume


5/17

applications, such as electric motors and internal combustion engines, and for large

rotating and reciprocating machinery with low to modest volume requirements, such

as high-speed turbines and low-speed marine diesel engines. In addition, babbitt has

been used for jewellery, shot, filler metals, and various other applications. Lead-

base alloys enjoy a cost advantage, while tin alloys offer modest technicaladvantages, particularly in high-speed centrifugal equipment. It should be

noted that government regulations now discourage the use of lead-base alloys for

health and hazardous waste disposal reasons. Babbitting of bearing shells can be

accomplished by three methods: Static babbitting (hand casting),Centrifugal

casting, Metal spray babbitting . Centrifugal casting and static (gravity) casting are

the two babbitting methods used in the manufacture and repair of large, low-volume

journal (radial) and thrust bearings. Centrifugal casting of journal bearings offers

both technical and economic advantages if special spinning equipment is available.

Flat shapes (thrust bearings) are usually statically cast. Repairing of industrial andmarine babbitted bearings is routinely accomplished by melting off the old metal and

rebabbitting the shells with new metal, following the same basic casting methods

described below for producing new products. Emergency repair methods using

proprietary tinning compounds, babbitt spray, or welding techniques can be

employed. Suppliers of such repair equipment should be consulted for operating

instructions. Thin-wall babbitted half bearings, rolled bushings, and flat thrust

washers are mass produced from bimetal strip stock. The strip stock is produced by

continuously feeding coils of low-carbon steel in ribbon form first through

appropriate cleaning and tinning baths and then through a stream of molten babbitt,which is gravity cast on the moving strip. The strip is immediately water-chilled from

below. After excess babbitt is removed, the stock is recoiled and is ready for press

blanking, forming, and finish machining operations.

PROPELLER SHAFT & RUDDER STOCK STRAIGHTENINGLarge diameter shafts, such as, for example, propellor shafts, rudder stocks etc.

are subject to bending which can occur during manufacturing, processing or in

subsequent use. Such bending can occur in the rough forging of the shaft and whenmachining to final dimensions. In lively forgings the final cut for a keyway or the likecan create bends. Under some circumstances, such shafts will become bent afterperiod of use or if a propellor, for example, strikes an obstruction. Acceptable limitsof bend or eccentricity have been established and as a norm, a permissibleeccentricity has been established at 7.4 thousandths of an inch for someoperational uses. Above such a figure, mechanical and technical difficulties arise.

Heretofore, methods for the straightening of shafts have been devised includinga "hot spot" method and a "peening" method.

The hot-spot method involves quickly heating a local spot (on the outside of a bend)to an elevated temperature. As a result of the local heat, the heated region tends to


6/17

expand, but also due to the elevated heat, the yield strength of the material isreduced. Due to these combined effects, the metal yields such that the shaft bulgesslightly in the heated region. When the heat is removed, the metal then hardens andremains in the bulged position and the residual tensile stresses introduced into theoutside of the bend of a shaft tend to straighten the shaft. The hot-spot method is

characterized by the following intrinsic disadvantages:1. The heating process is not accurately controllable. There is no precise method ofdetermining the amount of heat applied to the shaft.2. The metallurgy of the shaft can be adversely affected.3. The process is extremely slow; after each heating the entire shaft must beallowed to cool to a uniform temperature before the results can be assessed.

With the peening method, a hammer or equivalent technique is used to hammer orpeen the shafting surface on the inside of a shaft bend. The residual compressivestresses thereby introduced into the shaft tend to straighten the shaft. The peening

method entails the following intrinsic disadvantages:1. The magnitude of the peening effort required to straighten shafts of largediameter, especially those of high tensile strength, exceeds that which can beaccomplished with the usual peening techniques.2. The residual stresses introduced into the shaft are distributed non-uniformly.3. Peening subjects the shafting surface to possible damage.4. Due to the superficial nature of the compressive residual stresses introduced,efforts to improve the surface finish of the shafting after peening by cutting a smallamount of metal from the shaft will tend to destroy the effect achieved because theresidual stresses in the metal removed from the shaft will not be uniform around the

circumference of the shaft.

The selective cold rolling method involves the use of cold rolling equipment such asis commonly used in connection with propeller shafts & rudder stocks on ships,however, instead of using a constant roller load and introducing residualcompressive stresses uniformly around the circumference of a shaft, the roller load isvaried selectively so as to use a higher roller load, with consequent higher residualcompressive stresses, on the inside of a bend thereby tending to straighten theshaft. The selective cold rolling of a shaft is accomplished by pressing a small rolleragainst the shaft with alternating loads as the shaft is slowly rotated. A specifiedlength of the shaft is rolled by slowly advancing the roller along the shaft as itrotates.The roller has a crowned face and is sized with radii of curvature which are muchsmaller than those of the shaft such that a very small elliptical contact area existsbetween the roller and the shaft. The combination of a heavy roller load on the shaftand the small contact area results in very large contact stresses between the shaftand roller. These stresses cause a yielding of the shaft material near the surfacewhich then leaves a residual compressive stress in the material adjacent to thesurface. By controlling the roller load, the magnitude and depth of the residual stresscan also be controlled. The residual stress over the yielded depth actually produces aresidual force in the area adjacent to the shaft surface and it is this residual force

which is utilized to straighten a shaft.


7/17

Advantages associated with the selective cold rolling method include the following:1. The variables required to straighten a shaft can actually be calculated.2. The method is easily controlled such that predictable results can be achieved.3. The residual stresses introduced in the shaft are not distributed erratically.4. The results achieved can be assessed immediately after a rolling operation.

5. The straightening can be accomplished by introducing residual compressivestresses completely around the shaft circumference but more deeply on one side ofthe shaft than the other; this permits a small amount of metal to be removed fromthe shaft without affecting the straightening results achieved.6. The metallurgy of the shaft material is not adversely affected.

Procedure for Cleaning Fuel Oil Tanks on a Ship:

Preparations Done before Cleaning

The following steps are to be followed before starting the cleaning process:

1) Empty the tank as much as possible; strip the tank by trimming the ship forward or aft

depending on the suction valve location.

2) When the ship is going for dry-dock the keel plan is to be sent to the shore facility so that

they should not put any keel block in the way of the plug present in the bottom shell plating.

3) The tank has to be properly ventilated as it is an enclosed space and might contain

flammable gases.

4) It is to be made sure that the steam connections are closed and proper signs and

placards are displayed so that during cleaning nobody opens the valve and gets burnt or

hurt.

5) The tank has to be checked for flammable gases.

6) The tank has to be checked for oxygen content with the help of oxygen analyser.

7) The tank is drained off left over oil with the help of plugs.

8 ) The location of plug can be found out in shell plating diagrams.

9) Generally this plug is covered with cement and made streamlined with the shell plating.

10) Enclosed space entry checklist is filled out so that no safety issues are compromised or

left.

During cleaning

1) Entry is only to be made inside the tank if the oxygen level is 21% by volume and


8/17

flammable gases are vented out.

2) One person should always standby outside the manhole door and should be in

communication with the person inside.

3) The person outside should continuously communicate with person inside and with the

duty officer.

4) In case of hot work to be carried out, a fire line is to be carried inside. Also, a small fire

extinguisher for small fire should be there. Inform Port state authority before commencing

hot work.

5) The tank is cleaned manually with the help of brushes, rags etc.

6) The oxygen content is continuously monitored and in case the alarm indicates low level,the space has to be evacuated immediately without any delay.

After cleaning

1) Make sure no tool are left inside which may get stuck in the valve or damage the transfer

pump

2) The place where crack repair is done should be checked for leaks.

3) If it was a steam leak repair, the coils needs to be checked for steam leak inside.

4) In case of crack or plate renewal the tank has to be pressure tested and checked for leak.

If the repair is major it has to be inspected by class surveyor before putting it in operation.5) Close the manhole after inspection, repairs and cleaning.

6) Close and remove the sign permit to work.

Turbocharger Surging:Surging of turbocharger occurs when the air pressure after the compressor is higherthan the pressure compressor can internally maintain. This means, when thepressure of the air delivered by the compressor is higher than the pressure insidethe compressor a reverse flow of air is created towards the impeller and inlet of the

compressor, which reduces the speed of the turbine shaft and creates noise andvibration.

Surging can better be understood by drawing a graph of pressure ratio against massairflow of the system. From the graph it can be seen that surging is an unavoidablephenomena. The efficiency of compressor is highest near the surge line. This meansthat if high turbocharger efficiency is desired, a compromise between high efficiencyor surging needs to be made.

Surging leads to a sharp fall in the flow and acceleration of air mainlybecause of thereversal pressure. This imbalance in the demand and supply also leads to heavy damage ofthe turbocharger


9/17

Turbo charger surging may be defined as a high pitch vibration of audible level coming from

the blower end or compressor end of the turbocharger. Whenever the breakdown of gas

flow takes place, a reversal of scavenge air takes place throughdiffuser and impeller blades

into the blower side which causes surging. Surging is to be avoided as it interferes with the

combustion in the main engine and may cause damage to the thrust bearings.

There are mainly three things on which the functioning of turbocharger depends. They are :

Pressure ratio

Air volume flow

Speed

When the air enters the compressor it follows the direction of diffuser vanes. The radial

velocity attained by the rotational motion of the impeller is converted into pressure by the

diffuser. This increases pressure at the compressors outlet.

When surging occurs, due to the reverse air flow the velocity angles are disturbed which

causes breakdown of the boundary layers. Turbulence is created near the boundary which

reduces the air flow area, causing resistance. When the turbulence increases beyond acertain limit, the diffusion of air drastically reduces leading to reduced pressure. Thus the

pressure downstream of the diffuser goes higher than the diffuser pressure, leading to

increase in reversal of air flow.

Causes of Turbocharger Surging:

1) Improper power distributionbetween the main engine cylinders may cause turbocharger

surging as one unit is producing more power and other is producing less. Due to this the air

consumption required by both the turbochargers differs, which leads to surging.

2) Fouled compressor on turbine side In this case if the inlet filters are dirty then enough

air can not be supplied for combustion, which leads to surging. Similarly if the turbine side isalso dirty i.e. nozzle, blades etc enough air can not be produced for combustion.

3) Highly fouled exhausti.e. economizer, if fitted may cause back pressure in the

turbocharger and thus finally lead to surging.

4) Bad weather This is one more reason for surging. Due to bad weather the engine

suddenly starts racing and sudden load change takes place. This happens because during

bad weather or pitching the propeller moves in and out of the water, causing the change in

load on the engine.

It can also happen due to sudden change in the engine load or speed.Imbalance in cylinder power or faulty injectors
https://www.facebook.com/photo.php?fbid=188400801219281&set=o.101959376568633&type=1&ref=nfhttps://www.facebook.com/photo.php?fbid=188400801219281&set=o.101959376568633&type=1&ref=nf


10/17

Un-cleaned turbine nozzle ring.Damaged bladesDirty or choked filterThe capacity of turbocharger is larger than required.Increased back-pressure at the turbine side.

Sometimes a dirty hull that makes the ship run at full torque has also been shown as thereason for surging. Malfunction of engine's fuel system may also lead to surging.

How to Prevent Turbocharger Surging?

The following are the ways to prevent turbocharger surging. However, it is to note thatsome points may vary with design and construction of the turbocharger.

Keep the turbocharger intake filter clean.Water-wash the turbine and the compressor side of the turbocharger.Proper maintenance and checks should be done on turbocharger periodically.

Soot blow should be done from time to time in case of economizer or exhaust boiler.Indicator cards to be taken to assess cylinder and power distribution of individual units.

How to evalute t/c performance?

In order to evaluate the turbocharger performance it is necessary to carry out performance

measurements, including the temperatures and pressures before and after the turbocharger.

The performance measurements are then compared to earlier measurements, e.g. the sea

trial results, in order to ascertain whether the turbocharger performance has deteriorated.

However, as marine engineer, You should look at the following can affect the turbocharger

performance-AA) Exhaust side

- Exhaust gas economizer condition( Fouling, Excess back pressure, Many tubes plugged

etc.,)

- Fouled uptake pipes

- Fouled sealing air passages

- Choked drains and air blow lines in drains choked

BB) Blower side-

- Dirty air from Ventilation fans(Sucking the engine exhaust, dirty cargo dust, sand storms

micro dust and similar circumstances)

- Air cooler fouling is very common- always track the Differential pressure near to sea trail

value.

- Blower side duct passages- fouled oily adhesions to blower ducts,

Though the direct influence in not there for turbocharger performance, but the dirty

scavenge and under piston spaces influence turbocharger indirectly.

- Another Issue is Hot well steaming and locations of steam leaks near turbocharger is


11/17

another concern can deteriorate the performance

- Pressure charge in Engine rooms is another serious issue- if you left open the engine room

doors, there is no sufficient air charge for turbocharger suction.

- Exhaust leakages around turbocharger is another serious concern for turbo charger

performance deterioration.

Boiler Starting Failure Troubleshooting:

1) Fuel inlet valve to the burner is in close position:

The fuel line for boilers burner consists of several valves located at fuel tank, pumps

suction, discharge valve, or valve before the boiler burner. Any of these can be in closed

position resulting in starvation of fuel.

2) Line filter at the inlet of the fuel line for burner is choked:

If the system runs in heavy oil then there are chances of filters in the line getting choke. To

avoid this, boiler system are normally built for changeover from diesel to heavy oil during

starting and heavy to diesel during stopping. This keeps the filter and the fuel line clean.

3) Boiler fuel supply pump is not running:

There are two main reasons for fuel pump not running. Normally when the pumps are in

pairs, the change over auto system is kept in manual position, and if the operating pump

trips, the stand by pump will not start automatically. Another reason is tripping of pump due

to short circuit in the system etc.

4) Solenoid valve in the fuel supply line is malfunctioning

Nowadays most of the system adopts advance automation, but there can be a possibility

wherein the solenoid in the fuel supply line is malfunctioning and not opening.

5) Flame eye is malfunctioning:

A Flame eye is a photocell operated flame sensor fitted directly on the refractory to detect

wether the burner is firing or not. If the flame eye unit is malfunctioning, then it will give a

trip signal even before the burner starts firing.

6) Air or Steam ratio setting is not proper


12/17

For proper and efficient combustion, air fuel ratio is very important, if the supply of air is

less then there will be excess of smoke, and if it exceeds the normal level the combustion

will burn off causing flame failure.

7) Forced draft fan flaps malfunctioning

For removing excess gases trapped inside the combustion chamber forced draft fan (FDF)

are used for pre purging and post purging operation and are connected with a timer to shut

the fan flaps. If the flaps are malfunctioning then continuous forced air will go inside the

chamber, preventing the burner from producing a flame causing flame failure of the boiler.

8) Any contactor switch inside Control panel is malfunctioning

Boiler control panel consist of several contactors and PLC cards. Even one contactor

malfunctioning may result in trouble for boiler starting.

9) Trip not reset

If any previous trips like low water level, flame failure, emergency stop etc. has not been

reset than boiler will not start.

10) Main Burner atomiser is clogged

Main burners consist of atomizer for efficient burning of fuel. If the atomizer is clogged by

sludge and fuel deposits then burner may not produce flame and trip the boiler..

11) Pilot Burner nozzle is choked :

A Pilot burner nozzle is very small and can be blocked by carbon deposits and sludge

resulting in flame failure. Some pilot burner consists of small filter which can be clogged

after continuous operation resulting in flame failure because of carbon accumulation.

12) Electrodes are not generating spark

Initial spark for generating a flame is produced by electrode which may be due to carbon

The Welding of Aluminium

The most common commercial aluminium and aluminium alloy welding

methods use an electric arc with either a continuously fed wire electrode [with


13/17

DC current, with and without pulsed current] or a permanent tungsten

electrode plus filler wire [with AC current].

The arc is protected by argon gas (or argon-helium gas mix) to shield the weld

pool and the electrode from the surrounding atmosphere. Arc welding is easyto use, attains a high temperature, provides high heat input and is easy to

regulate.

To ensure an acceptable weld quality, there are two basic factors to consider -

breaking loose and removing the oxide film, and preventing the formation of

new oxide during the weld process.

It is essential that proper preparations and precautions always be taken before

welding commences. The surfaces to be joined and the area around the weld

zone [~50 mm] must be degreased using a solvent [acetone or toluene] and a

clean cloth. The area must be clean and completely dry as grease and moisture

can form gases and cause pores in the welded joint. The metal surface must be

lightly mechanically brushed in and around the weld, after degreasing, to

remove surface oxides and to avoid oxide inclusion in the weld. Use a brush

reserved for aluminium use only and kept free of oil contamination. The high

melting- temperature [~2000C] surface oxides must be removed just prior to

welding (at least within three hours or less).

Welding must not be done in draughty areas as draughts can easily reduce the

inert gas protection and interrupt the arc, resulting in a sub-standard weld. The

weld must be properly shielded with the inert gas at the correct flow rate, and

of the required purity, and nozzle distances must not vary from the weld point.

Welding Processes for Aluminium

A variety of welding processes can be used to join aluminium including thefusion methods GMAW (standard MIG, plasma and pulse) and GTAW (standard


14/17

TIG and plasma) giving high quality, all-position welding, manual, mechanised

or fully automatic. Also resistance, MMA (metal arc, stick) and advanced

processes such as solid state and friction stir welding. Choice of process is

based on technical and/or economic reasons.

For most structural economical and quality welds, TIG and MIG are

recommended for aluminium. TIG welding is generally preferred for light

gauge work up to 6 mm and for pipe work and intricate assemblies where

excellent control over weld appearance and penetration is possible. Thicker

material can be welded using TIG, but the very high currents needed, together

with the very slow welding speeds required, render the process uneconomic

for thick materials (> 12,5 mm). Butt, fillet, lap and edge welds can be carried

out using TIG welding.

MIG welding is preferred for thicker sections [to over 75 mm] and where high

productivity is needed for economic reasons. MIG welding can deposit up to

about 4,5 kg per hour with weld travel speeds of 500 to 1000 mm per minute.

Drawbacks of the MIG welding process are that control of penetration is

difficult and edge welds are not possible. Pipe welding using MIG welding is

not common because of the poor penetration control. Butt, fillet and lap joints

are the most common configurations for MIG welding. Joint preparation is

needed for thickness above typically 6 mm.

MIG advantages over TIG are greater penetration depths, narrower HAZs and

one-handed semi-automatic welding. MIG weld joint quality compared to TIG

welding gives better strength, penetration (especially into the root of fillet

welds), corrosion resistance, durability and finish appearance and less

distortion. MIG welding is easier to learn than TIG. TIG welding is preferred for

repair welding of castings, but MIG is preferred when welding castings to sheet

and plate and extrusions [fabrication].MIG welding speeds are about twice

that of TIG, and higher for thick section welding. High speeds result in fast

cooling of the weld area, which minimises distortion. High speeds and fast

cooling of the weld area prevent mechanical properties of the joint from being

reduced as much as they are by slower welding. Speed means corrosion

resistance of the base metal in the HAZ is not reduced as much by MIG as by

TIG. When TIG welding, the operator is limited to the length of weld that canbe made by the length of filler wire usually not more than 25 cm - without


15/17

breaking the arc. With MIG and the filler wire being added automatically,

welds of 60 cm are possible without breaking the arc. This results in fewer

weld craters and more cm of weld per hour. TIG manual filler addition means

the welder has complete control of the weld puddle at all times - a definite

advantage, and especially in butt welding of small and medium angles and

other shapes. This control is an advantage in welding of castings where

variable material thickness is often encountered. Good seam welds are

essentially a result of optimally set welding parameters. Good TIG seams have

a regular ripple finish and on both sides of the seam there is a narrow, white

de-oxidised zone.

The seam surface has a bright finish and is smooth and free of scaling deposits.

Good MIG seams have a uniform fine ripple finish on the seam with an

excellent transition to the basic material.

Dry Dock Chain Inspection

Anchor & Anchor Chain Cable

Anchors and anchor chain cable if ranged should normally first be

examined as follows:Anchor heads, flukes and shanks should be surface

examined for cracks. If any such defects are found they may be

weldable, otherwise renewal will probably be necessary. In such cases

welding may be attempted as a temporary measure pending availability

of the new equipment, which may take 3 to 6 months.Anchor head

crown pins and anchor shackle pins should be hammer-tested,

hardened-up if slack, or renewed if excessively worn or bent.Swivels if

fitted, should be closely examined so far as possible in way of thethreaded connection, as many have been lost in service due to

concealed wastage in this area. If in doubt the swivel should be

recommended to be removed. Consideration should be given to simply

eliminating any questionable swivels, they are normally not

essential.Patented type detachable connecting links should be opened

out and slack or corroded taper locking pins renewed their holes re-

reamed and new lead keeper plugs peened in."U" type connecting

shackles should be examined for excessive neck wear, slackness in the


16/17

pins and for shearing of keeper pins. The pin must be a snug fit all

around in these shackles, otherwise the keeper pin may shear when a

strain is put on the chain.Anchor chain cable should be surface

examined, hammer-tested and loose or missing studs replaced by

welding at one end of the stud only, at the end of the stud opposite the

link butt weld. The rest of the chain cable should be further examined

for excessive wear and gauged if necessary to ensure continued

compliance with the Rules.Verify that the number of shots of anchor

chain as fitted port and starboard, equal the total length required by the

Classification Rule Equipment Numeral.

Differences between MC/MC-C and ME/ME-C engines

The electro hydraulic control mechanisms of the ME engine replace the

following components of the conventional MC engine:

Chain drive for camshaft

Camshaft with fuel cams, exhaust cams and indicator cams

Fuel pump actuating gear, including roller guides and reversingmechanism

Conventional fuel pressure booster and VIT system

Exhaust valve actuating gear and roller guides

Engine driven starting air distributor

Electronic governor with actuator

Regulating shaft

Engine side control console

Mechanical cylinder lubricators.

The Engine Control System of the ME engine comprises:

Control units

Hydraulic power supply unit

Hydraulic cylinder units, including:

Electronically controlled fuel injection, and

Electronically controlled exhaust valve activation

Electronically controlled starting air valves Electronically controlled auxiliary blowers


17/17

Integrated electronic governor functions

Tacho system

Electronically controlled Alpha lubricators

Final Inspection Before UNDOCKING

Final Inspection B4 Undocking :-

Check paintwork is completed.

Hull repair is completed.

All Tank plugs are in place.

All Anodes are fitted, grease/paper used to cover them during painting is

removed.

Echo Sounder Transducer is cleaned of paper & grease.

Propeller rope guard is fitted properly in place.

Oil is not leaking from stern tube.

Propeller is free from paint & free from any other object.

Check freedom of movement of rudder with steering gear, smooth

movement.Jumping & Pintle clearances taken.

Rudder plugs are in place.

Sea Grids are in place & secured properly.

Ensure all sea v/v's are shut.

Ensure all tanks are at same level as when entry ~ to maintain same

trim when re-floating.

Documents

MEO Class 2 Misc Info!