Marine engineering valve and cock

Marine engineering valve and cock

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• 2. IT IS THE ALLAH WHO SUBJECTED THE SEA TO YOU.THAT SHIP MAY SAIL THROUGH IT BY HIS COMMAND ,THAT YE MAY SEEK OF HIS BOUNTY,AND THAT YE MAY BE GRATEFUL (Al-Quran)
• 3. Marine Engineering Valves and cocks
• 4. Valves There are three types of valve mainly Globe valve Gate valve Butterfly valve
• 5. Globe Valve Typical Globe Valves Angle Globe Valves SDNR and screw both are include in the above categories.
• 6. Globe valve (Screw down nonreturn valve(SDNR) It a type of nonreturn valve It is used where fluid allowed to move in one direction only Several turns will open or shut the valve Usually used in air, lub, fuel oil line
• 7. Globe valve Screw lift valve Several turns will open or shut the valve Used in Ballast and De-ballast lines
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• 9. Gate Valve Flanged End Butterfly Valves Wafer Butterfly Valves
• 10. Gate valve Several turns will open or shut the valve Throttling of valve is possible Used in sea and fresh water circuit
• 11. Gate Valve Rising Stem Gate Valves – Wedge type Rising Stem Gate Valves – Double Disk type Non Rising Stem Gate Valves – Wedge type Non Rising Stem Gate Valves – Double Disk type
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• 13. Butterfly valve Half turns will open the valve-(viceversa) Used also in sea and fresh water circuit
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• 15. Various type Also ball and wedge type of valve are also used in marine practice.
• 16. Maintenance of valve If the seat and valve degree is damage Used the fine grinding paste with oil Spring is also corroded in nonreturn type
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• 18. Safety valve Safety valve is used where the pressure exceed it mawp then it lift and relief the pressure and then close at working pressure
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• 20. Relief valve Relief valve is used in various line eg oil and pneumatic hydarulic At the preset pressure it lift and and close immediately
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• 22. Author Introduction ZEESHAN AHMED , Marine Engineer . After doing FSc(pre-engineering) from PAF(fazaia) intermediate college Lahore cantt. I joined Pakistan Marine Academy and choose Marine engineering branch. Two years of training at academy (practical + theoretical) we learned a lot of thing like CNC (computerize numeric code), trained on various models (like control valve, solenoid valve, flow meter, refrigeration system, CPP propeller, Main engine model (TWO stroke), Boiler model (water tube) ……………………………….. in GEK (general engineering knowledge) lab, Mechanical and physics lab, Engineering workshop. ETC . After two years, we joined PNSC workshop for the training of ONE year Industrial training. That was also the golden time where we learnt a lot of things at different shops as well as onboard (repairing and watch keeping). I learn many thing on tanker E.g. MT Johar (learn how to dismantle turbine rotor from casing and what are the precautionary measurement while working on turbine, learn how to change the diaphragm(stationary blade) Plate type heat exchanger gasket change, shell and tube Cooler Anode replacement and (Cont.)
• 23. Introduction (cont.) cleaning of SALT WATER tubes etc.) , MT Swat (major thing which I learn in Swat is how to dismantle head of main unit and copper gasket replacement with a minor facing defect which is found during overhauling which is filled and faced by Belzona) , MT Lahore(About the DEAD MAN ALARM, Alpha lubricator for Cylinder Main Engine Unit, Pump operation and watch keeping), MT Quetta(Auto load sharing of Generator Set, MT Karachi (Dry washing of the main engine turbocharger with granules, water washing of IG Fan of Inert Gas system, sludge removal of from purifier(centrifuge) etc., . One thing I want to added is that the trend in ship building is more toward based on electronic and electrical application. So a marine engineer must strong in automation, instrumentation and control system. PLC (programmable and logic control) and SCADA (supervisory central access and data acquisition) are the upcoming technology that are using on modern ship. The latest engine of MAN B&W is based on Camless technology. Chain is removed ; fuel pump and exhaust valve actuation is control by hydraulic servo(lub) oil which is driven by Axial piston pump mounted on the Fly wheel. Regards, Z.A.
• 24. Author contact information zeetec4@yahoo/gmail/hotmail.com Social networking sites. Facebook: mariner46 Website: zeetec4.googlepages.com Zeeshan Ahmed 46th Batch PMA [email_address] [email_address] Any question and suggestion are welcome

Crankcase explosion relief valve

In the name of Allah who is the most beneficient and merciful

As a practical safe guard against crankcase explosion relief valves or doors are fitted. These valves serve to relieve excessive crankcase pressures and stop flames being emitted from the crankcase. The cause of crankcase explosion is a “hot spot” resulting due to hot running bearing or any other overheated machinery part. In normal condition air in crankcase contains oil droplets and if these oil droplets will come into contact of a hot spot it will be vaporized and will form explosive oil mist. Regulation demands that for engines of over 300 mm bore, one crankcase relief valves is fitted to each crankcase and chain drive casing. Figure shows a crank case relief valve is fitted to diesel engine crank case. It consists of a light spring loaded non return disc valve of simple construction. The valve disc is of aluminum alloy which reduces its mass and the inertia to be overcome when opening or closing valve rapidly. The large “diameter” light spring holds the valve closed against its seat. The valve landing must make a gas and oil tight seal when closed and a nonstick oil and heat resisting rubber ring is fitted to the disc face. A deflector is fitted on the outside of the engine to safeguard personnel from the out flowing gases, an inside the engine, other valve opening, and oil wetted gauze acts as a flame trap to stop any flames leaving the crank case after operation the valve will close automatically under the action of the spring. When wet with oil the gauze dissipated heat at greater rate and become more effective as a flame trap.

The valve spring is designed to allow the valve open under an internal pressure of approximately 5 KW/M2 and will close automatically when pressure has been relieved.

Crank case doors should be robust(determined) to prevent damages or rupture(break or burst suddenly) before relief valves operate to relieve pressure valves will required little maintenance but should be tested periodically by hand, the spring should be inspected and the guaze cleaned.

WRITTEN BY: S/C ZEESHAN AHMED
LECTURED BY: CH. ENGR. YASEEN SAHAB
DATE: 24/OCT/2009
TIME: 09:55 AM
LINK: ZEETEC4.GOOGLEPAGES.COM