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Sulzer fuel pump timing adjustment

Engine should have run 30 mins of diesel oil before stoppage Open the indicator cocks, shut the main air starting valve and engage the turning gear close the fuel supply and ruturn valve on the fuel pump Drain the remaining fuel from the fuel pump Inspect the cams and rollers The stagnation pressure control valve has to be dismantled Note the valve desiganation S-suction , D- delivery and U- for spill valve Remove the valve cover and the springs Pressure bushes are released using special wrench The vavles are removed using a withdrawal device Examine valve seats and contact surfaces. Defective should be reconditioned or replaced The valve contact surface in fuel pump block should be in good condition.Damaged surfaces must be reconditioned After cleaning the fuel pump block throughly the suction and spill valves are cleaned in diesel oils and fitted back respectively without their springs The pressure bushes are tightened to 300Nm The dial gauges should be inspected before mounting it t

Shaft earthing device

A turning propeller is electrically insulated from the hull by lubricating oil film in bearings Electrical potential is generated between the shaft and the hull  As a result the cathodic protection of the ship will not protect the propeller Electrical potential can cause currents in the bearigngs resulting in pitting of the bearing surfaces Problems can be avoide if the shaft is earthed with a propeller shaft slip ring This shaft earthing assembly comprises a pair of high silver content\graphite compound brushes mounted in a balanced brush holder, running on a copper slip ring with solid silver track

Overboard valve regulation

Should not be of cast iron Must be Class approved Fitted at easily accessible location as far as practicable readily visible Indicators are to provided local to the valve ie ,showing whether they are open or shut Valve spindle are to extend above the lower platform. Valves and distance pieces extended for the installation on the ship side below the load water line are to be tested by hydraulic pressure not less than 5 bar.

Problems associated with welding cast Irons:

1) Cast iron is that the metal is filled with impurities. When you melt the metal the embedded dirt and sand contaminated the weld and tend to not mix well with the cast iron filler rod.What you end up with is not a fused intermixed metal bead but a porosity filled weld that can be easy to chip away with a chisel because it has not bonded to the base metal.  2) Pre heat & Post Heat required.And different as per its composition.Pre heat to stress relieve & post heat to control rate of cooling.  3) The large amount of carbon in the base metal tends to segregate itself along grain boundaries as the weld puddle solidifies and cools. What this does is lower the tensile strength even lower so that in the weld fusion boundary the shrinkage force pulls the metal apart as it cools, ie it tends to crack along the weld when cools.  4) Cracking. If it cools down too quickly you will get cracks along the weld.  5) Proper selection of filler rod & flux required as per the grade and compo

Why Negative cam or Inward cam used in Air distributer of MAN B&W starting air system .why not a possitive cam

The cam for the air distributer serves its purpose only while starting the engine . Actually if you see there is no other requirement of this particular cam while the engine is continue in operation.  Therefore if a cam ( normal possitive ) is used then wear of this particular cam will be abviated and will be expensive to repair / replace this cam. So when the engine has started and the vessel is enroute a voyage , then this particular cam turns without any running gear touching it. It comes into play only starting

Boiler Turndown

Boiler Turndown Boiler turndown is the ratio between a boiler’s maximum and minimum output. Depending on the burner’s design, it may have a turndown ratio between 4:1 and 10:1 or even higher.  A 4:1 turndown means the boiler’s minimum operating load is 25% of the boiler’s full capacity (100% capacity divided by 4).  A 10:1 turndown means the minimum operating load is 10% of the full load capacity (100% capacity divided by 10). Why is Boiler Turndown Ratio Important? Turndown ratio is important for boilers that are required to operate at a wide variation of capacities. A boiler with a higher turndown ratio will usually handle fluctuating loads more efficiently than one with a low turndown. A boiler’s burner will modulate or “turn down” as the demand for hot water or steam decreases, in an attempt to meet only the required load. The turndown ratio tells you the minimum output the boiler can handle before turning off and then cycling on and off frequently. If the demand goes below the bur