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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

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

Function of Hooper tank in Bulk carrier ?

Hopper tanks are classified into bottom hoppers and top heavy wing tanks. For bottom hoppers, the main purpose is to take ballast, so as to rapidly increase the vessel immersion, simultaneous reduction in metacentric height, and a change in Centre of gravity. For top heavy wing tanks, the idea is to rapidly correct list of the vessel and act as active ballast tanks, for vessels such as Lakers where passages are narrow and cargo loading is often scattered. Except for this, they contribute in cargo loading also because the side slopes allow the cargo to slide off and collect at the centre, thereby making the cargo collection easier at the end Also, the hoppers are strengthened by additional transverse and longitudinal members, thereby supporting the port and starboard fuel tanks, and also distributing the cargo loading in a dynamic way to make sure the load is not concentrated at one point for higher loading speeds

Stamping on CO2 bottles

  W - Manufacturer stamp/symbole + - fill 10% excess on psi ✬ - 10 years testing, if no ✬ then every 5years hydrostatic test. 2005/03 - year/month of manufacture 6831611 - serial number pw200 - cylinder pressure 5L- cylinder capacity Stamp for testing lab