Pumping Systems/Valves Flashcards

Question

whats the purpose of a lubrciation system?

Answer 1

The lubrication system of an engine provides a supply of lubricating oil to the various moving parts in the engine. Its main function is to enable the formation of a film of oil between the moving parts, which reduces friction and wear. The lubricating oil is also used as a cleaner and in some engines as a coolant. Large slow-speed diesel engines are provided with a separate lubrication system for the cylinder liners. Oil is injected between the liner and the piston by mechanical lubricators which supply their individual cylinder, A special type of oil is used which is not recovered. As well as lubricating, it assists in forming a gas seal and contains additives which clean the cylinder liner.

Answer 2

Lubricating oil for an engine is stored in the bottom of the crankcase, known as the sump, or in a drain tank located beneath the engine. The oil is drawn from this tank through a strainer, one of a pair of pumps, into one of a pair of fine filters. It is then passed through a cooler before entering the engine and being distributed to the various branch pipes. The branch pipe for a particular cylinder may feed the main bearing, for instance. Some of this oil will pass along a drilled passage in the crankshaft to the bottom end bearing and then up a drilled passage in the connecting rod to the gudgeon pin or crosshead bearing. An alarm at the end of the distribution pipe ensures that adequate pressure is maintained by the pump. Pumps and fine filters are arranged in duplicate with one as standby. The fine filters will be arranged so that one can be cleaned while the other is operating. After use in the engine the lubricating oil drains back to the sump or drain tank for re-use. A level gauge gives a local read-out of the drain tank contents. A centrifuge is arranged for cleaning the lubricating oil in the system and clean oil can be provided from a storage tank. The oil cooler is circulated by sea water, which is at a lower pressure than the oil. As a result any leak in the cooler will mean a loss of oil and not contamination of the oil by sea water. Where the engine has oil-cooled pistons they will be supplied from the lubricating oil system, possibly at a higher pressure produced by booster pumps, e.g. Sulzer RTA engine. An appropriate type of lubricating oil must be used for oil-lubricated pistons in order to avoid carbon deposits on the hotter parts of the system.

Answer 3

The open-loop circuit takes oil from the tank and pumps it into the hydraulic motor. A control valve is positioned in parallel with the motor. When it is open the motor is stationary; when it is throttled or closed the motor will operate. The exhaust oil returns to the tank. This method can provide smooth changes in motor speed. The live-line circuit, on the contrary, maintains a high pressure from which the control valve draws pressurised oil to the hydraulic motor (in series with it), as and when required. In the closed-loop circuit the exhaust oil is returned direct to the pump suction. Since the oil does not enter an open tank, the system is considered closed. Low-pressure systems use the open-loop circuit and are simple in design as well as reliable. The equipment is, however, large, inefficient in operation and overheats after prolonged use. Medium-pressure systems are favoured for marine applications, using either the open or closed circuit.

Answer 4

A cock is used in small-bore pipework and is joined to adjacent pipework by a compression coupling. A cock can restrict or close an internal passage by moving a central plug, usually by an external lever.

Answer 5

A globe valve has a somewhat spherical body enclosing the valve seat and valve disc. Flanges are provided at either side for connecting to adjacent pipework, and internal passages guide the liquid flow through the valve seat. Liquid flow is always arranged to come from below the valve seat so that the upper chamber is not pressurised when the valve is closed. A gland with appropriate packing surrounds the spindle where it leaves the valve bonnet. The upper part of the spindle is threaded and passes through a similarly threaded bridge piece. A circular handwheel is used to turn the spindle and raise or lower the valve disc. The valve disc and seat are a perfect match and may be flat or, more commonly, mitred. The material for both is often provided with a very hard stellite coating. Globe valves also exist in a right-angled form where the inlet and exit flanges are at 90° to each other. Unlike the gate valve, globe valve can be used for regulating flow or pressures as well as complete shutoff of flow. It may also be used sometime as a pressure relief valve or as a check valve.

Answer 6

Check valves are installed in pipelines to prevent backflow. A check valve is basically a one-way valve, in which the flow can run freely one way, but if the flow turns, the valve will close to protect the piping, other valves, pumps. non-return valve allows a medium to flow in only one direction and is fitted to ensure that the medium flows through a pipe in the right direction, where pressure conditions may otherwise cause reversed flow.

Answer 7

Gate valves are used to isolate specific areas of the water supply network during maintenance, repair works, new installations, as well as to reroute water flow throughout the pipeline. A gate valve should be fully open or closed; it is not suitable for flow control.

Answer 8

Quick closing valves are fitted to settling and service tanks within the machinery spaces, boiler room and the emergency generator space so that in the event of an emergency such as a fire, they may be safely closed from a remote location to prevent the fuel in the tank from feeding the fire. Oil tank suction valves are arranged for rapid closing from a remote point by the use of quick-closing valves. The collapsing of the 'bridge' results in the valve closing quickly under the combined effects of gravity and an internal spring. A manually operated wire or a hydraulic cylinder can be used to collapse the bridge.

Answer 9

Valve chests are a series of valves all built into a single block or manifold. Various arrangements of suction and discharge connections are possible with this assembly.

Answer 10

Mud Boxes are a coarse stariner (filter) device which installed in suction pipes aboard vessels to protect pumps against large solids.

Answer 11

A steam trap does as its name implies and permits only the passage of condensed steam. It operates automatically and is situated in steam drain lines. Various designs are available utilising mechanical floats which, when floating in condensate, will enable the condensate to discharge. Other designs employ various types of thermostat to operate the valve which discharges the condensate. An expansion piece is fitted in a pipeline which is subject to considerable temperature variations. One type consists of a bellows arrangement which will permit movement in several directions and absorb vibration (Figure 6.18). The fitting must be selected according to the variation in system temperatures and installed to permit the expansion and contraction required in the system. Drains are provided in pipelines and usually have small cocks to open or close them. It is essential that certain pipelines are drained regularly, particularly in steam systems. When steam is admitted to a pipeline containing a reasonable surface of water it will condense and a partial vacuum occur: the water will then be drawn along the pipe until it meets a bend or a closed valve. The impact of the moving water in the pipework will create large forces known as 'water hammer', which can result in damage to pipework and fittings.

Answer 12

Charging: This is the process of filling the hydrophore tank with water and compressed air to achieve the desired pressure range. To charge the system, follow these steps: * Close the outlet valve of the hydrophore tank. * Start the pump in manual mode and watch the level gauge on the tank. * Once the water level reaches about 70% of the tank capacity (some tanks have markings on the level gauge), charge the tank with compressed air using an air compressor or an air bottle. * Stop charging when the pressure gauge on the tank reaches about 5 bar (some tanks have markings on the pressure gauge). * Put the pump in auto mode and open the outlet valve of the tank. * Monitor and check the pump cut-in and cut-out pressures on the pressure switch.

Answer 13

Some of the tasks involved in maintaining marine hydrophore systems are: Cleaning: This is the process of removing dirt, dust, oil, grease, rust, or corrosion from the system’s components, such as the tank, the pump, the valves, and the pipes. Marine engineers must use suitable cleaning agents and tools to clean the system thoroughly and carefully. Inspecting: This is the process of examining the system’s components for any defects, faults, or damages that may affect their function or performance. Marine engineers must use visual inspection, as well as instruments such as callipers or pressure testers to check the condition and functionality of the components. They must also check the alignment, balance, and lubrication of the moving parts. Lubrication and Pump Maintenance Lubricate pump components as per the manufacturer’s recommendations. Check the condition of pump seals and gaskets and replace them if they show signs of wear. Control System Testing Test the control system to ensure it functions correctly. Verify that pressure switches are set to the appropriate pressure levels. Alarms and Safety Measures Ensure that any alarm systems associated with the hydrophore are functioning correctly. Test emergency shut-down procedures in case of system malfunctions.

Answer 14

See domestic FW system drawing Domestic freshwater system is designed to maintain consistent water pressure on vessels, ensuring a supply of fresh water for domestic purposes but also to be used for operational purposes for various systems on the ship like for example the purifiers and the jacket cooling water system. The system consists of a hydrophore tank, valves, pressure switch, pressure gauge, relief valve, air vent valve and two automatic pumps for supplying the liquid, which is pressurised by compressed air. The compressed air provides the head or pressure to supply the water when required. The pump is started automatically by a pressure switch which operates as the water level falls to a predetermined level. Fresh water supplied must meet purity standards. Water produced from most evaporator/distillers will not meet these standards and must be treated to ensure it is biologically pure and neutral or slightly alkaline. The water is sterilised by an excess dose of chlorine provided as hypochlorite tablets. It is then dechlorinated in a bed of activated carbon to remove the excess chlorine. Any colour, taste and odour which was present in the water will also be removed by the carbon. Excess chlorine is originally applied to ensure that complete sterilisation occurs. * The hydrophore tank is a pressurized reservoir that stores water and compressed air, to maintain a constant pressure in the water supply system. The tank can store water under pressure, ready for distribution. * The pumps are used to fill the tank with water and to deliver water to where it’s needed. The pumps transfer water from the freshwater tank and then supply it to hydrophore tank here its pressurized. * The pressure switches are used to control the start and stop of the pumps according to the pressure in the tank. pressure switch controls the pumps, maintaining the desired pressure level within the pressure tank. When water pressure drops below the set level (due to water consumption), the pump activates to replenish the pressure in the tank. * The valves are used to regulate the flow of water and air in the system. * The gauges are used to monitor the pressure and level of water and air in the tank.

Answer 15

A bilge system is a piping system installed on-board a vessel for the purpose of removing water that accumulates in enclosed spaces (holds, machinery spaces, cofferdams) as a result of condensation, leakage, washing, or fire fighting. It is also capable of controlling flooding in the Engine Room as a result of minimal piping system damage. Bilge wells are fitted with the float operated level alarms to draw engineers’ attention in case of high levels in the bilges. Routinely, the engine room bilges are transferred with the help of Engine Room Bilge Pump to what is known as Bilge Holding Tank. This tank is fitted with the heating arrangements to facilitate the efficient separation of oil and water. Such arrangements are normally steam operated coils inside the tank. At some point the contents of the Bilge Holding Tank need to be processed with the help of an OWS which is a type of a filtering equipment. The Bilge Separator Service Pump (usually a positive displacement type) is utilised to feed the OWS. The vessel’s bilge system consists of three main sub-systems: * Engine room bilge system * Cargo hold bilge system * bow thruster bilge system The engine room bilge system and cargo hold bilge system are interconnected and an isolation valve is fitted between these two systems. This isolation valve should normally be closed and sealed and seal recorded into engine room seal log book. The bilge system contains three pumps * The engine room bilge pump * The cargo bilge pump * The fire and general service pumps Under normal operating conditions the engine room bilge pump is used to pump from the engine room bilge main to either the clean bilge water tank or the oily water tank. Bilge water from the engine room system can be discharged overboard, while vessel is under way, only via the oily water separator. The cargo bilge pump is used to pump from the cargo hold bilge main to the cargo bilge tank if the ship is designed as such. If there is no designated cargo bilge tank, the bilge can be pumped directly overboard after has been visually checked for presence of oil, otherwise should be pumped into engine room bilge tank via interconnection valve. The bow thruster bilge system is operated by an ejector, which is driven by water, the driving water being supplied from the fire and wash deck system. The engine room bilge pump is, usually, of a self-priming type which can draw water from the various bilge suctions via the engine room bilge system and discharge to the oily water tank or clean bilge tank. It can take, also, suction from oily bilge tank, clean bilge tank, cofferdams, engine pit, void spaces, stern tube cooling tank etc. In general, all the bilge pump suction points are connected to the bilge pump via the engine room bilge system, except for the clean bilge tank, the oily water tank and the oily water separator. The engine room bilge pump is equipped with a suction strainer and, on modern vessels, the pump motor can be set to stop automatically if the pump runs dry. The pump can be stopped locally or from the shore connection stations on main deck close to the bilge & sludge shore discharge manifold. Under normal operating conditions the cargo hold bilge system is served by the cargo bilge pump which is, usually, a positive displacement pump but the pump suction is also equipped with a priming unit because of the length and large volume of the cargo hold bilge system. The pump will draw water from the various hold bilge suction points via the forward and aft cargo hold bilge systems and discharge to the cargo bilge holding tank or directly overboard. The fire and general service (GS) pumps are vertical centrifugal pumps and each pump is equipped with a priming unit. A cross-connection line is fitted between the pump suction and discharge and this line is arranged to ensure that bilge water cannot be discharged into the fire and wash deck main. The bilge system, especially the cargo hold bilge system must be periodically pressure and vacuum tested (6 monthly period) in order to check the valve proper sealing and pipe integrity. Failure to do so can result in cargo hold flooding and damaging of cargo. Usually, cargo hold bilge wells are equipped with non-return flaps which prevents the water back flow into the bilge wells. Checking the integrity of these flaps is one of the reason of the system pressure test that must be periodically done. The vacuum test is done in order to check the remote butterfly valves are sealing properly. The fire and general service pumps can only discharge water overboard or to the fire and general service system. These pumps should only be used to pump bilge water in an emergency.

Answer 16

The function of the ballast system is to pump to and empty all spaces in the ship in which ballast water can be supplied. The suction pipes for the ballast system will be completely separated from the bilge system. The ballast system can also be used for other purposes in emergencies, such as supplying water to the fire main. The ballast tanks holds water, which is used as ballast to provide stability for a vessel. Using water in a tank provides easier weight adjustment than the stone or iron ballast used in older vessels. It also makes it easy for the crew to reduce a vessel's draft when they enter shallower water, by temporarily pumping out ballast. Ballast water taken into a tank from one body of water and discharged in another body of water can introduce invasive species of aquatic life. The taking in of water from ballast tanks has been responsible for the introduction of species that cause environmental and economic damage. The ballast system is arranged to ensure that water can be drawn from any tank or the sea and discharged to any other tank or the sea as required to trim the vessel. Combined or separate mains for suction and discharge may be provided. Where a tank or cargo space can be used for ballast or dry cargo then either a ballast or bilge connection will be required. The system must therefore be arranged so that only the appropriate pipeline is in service; the other must be securely blanked or closed off. Where tanks are arranged for either oil or ballast a change-over chest must be Fitted in the pipeline so that only the ballast main or the oil transfer main is connected to the tank. The segregated ballast tanks (SBT) are dedicated tanks constructed for the sole purpose of carrying ballast water on oil tanker ships. They are completely separated from the cargo, and fuel tanks and only ballast pumps are used in the SBT. The Segregated ballast tanks avoid any chances of mixing oil and water which usually happens when cargo holds are used to carry ballast water. Clean Ballast Tanks (CBT) Oil tankers may travel without carrying cargo in its holds which may lead to stability issues. Especially in bad weather. Hence, the cargo holds which carried oil in the last voyage are cleaned and then filled with clean ballast water.

Answer 17

Some of the common problems that can occur in a vessel’s bilge system are:  Clogging and Blockages: One of the most frequent issues in bilge systems is clogging and blockages in the bilge pump and associated pipes. Accumulated debris, dirt, or even marine life can obstruct the flow of water through the system, leading to reduced pump efficiency or complete failure.  Bilge pump not working: Bilge pump failures can result from various causes, such as electrical malfunctions, worn-out components, or impeller damage. A dysfunctional pump can lead to excessive water accumulation within the vessel, risking its stability and safety.  Float Switch Malfunction: When bilge pump is running on AUTO mode, float switches are essential components that trigger the bilge pump to activate when water levels rise. Malfunctioning float switches can lead to either constant pump activation (even when unnecessary) or failure to activate when needed.  Leaks and Cracks: Leaks in the bilge system’s piping, hoses, or pump housing can contribute to the accumulation of water in the bilge area. Corrosion, wear, or cracks in these components can compromise their integrity and cause leaks.  Electrical Issues: Given the reliance on electrical components in modern bilge systems, issues like corroded wiring, faulty connections, or blown fuses can disrupt the proper functioning of the system.  Inadequate Maintenance: Neglecting regular maintenance can lead to the deterioration of pump performance and other system components. Lack of maintenance increases the likelihood of encountering issues over time.  Bilge alarm sounding: This can indicate that there is excessive water accumulation in the bilge due to leakage or damage.  Bilge water contaminated: This can be caused by oil, fuel, chemicals, or other substances that leak or spill into the bilge. This can pose a serious environmental and safety hazard, as well as damage the bilge system components.

Answer 18

Ballast water treatment – when the tanks are filled and when they are emptied, the ballast water is subjected to mechanical, physical and chemical treatment. There are a variety of ways in which water can be heated or subjected to UV radiation or ultrasound depending on the manufacturer, but the sediments are separated by means of filters. When using ballast water treatment system, prior to ballasting operations, the BWT unit lamps commence a start-up sequence at which time the units are cooled by sea water. The incoming ballast passes through the filter which performs the function of removing larger organisms and particles, after the filter, the ballast water passes through the UV or chemical injection units which treat the water to the required IMO standard before entering the ballast tanks. On completion of ballasting, an automated sequence flushes the treatment unit with fresh water, following this a Cleaning cycle commences to clean the unit, which takes approximately 15 minutes. The cleaning cycle may also be operated manually from the local control panel. During de-ballasting, the main difference to the ballasting procedure is that the filter is bypassed because the water would already have been filtered during ballasting. During the discharge process, water from the tanks is again passed through the UV or chemical injection units to destroy any organisms that may have formed during the time the ballast water has remained in the tanks. Ballast system is normally operated by vessel Chief officer or one of the deck officers during their watch keeping under Chief Officer supervision and the engine room should be informed when using the system. Under normal circumstances no more than one pair of ballast tanks (port and starboard) should be partly filled at any one time in order to prevent stability problems due to the effect of slack tanks. Tanks not currently being filled or emptied should be filled or empty. Check the quantity of ballast water to be removed from the particular pair of tanks. Water should normally be removed from the port and starboard ballast tanks at the same time with heeling being controlled by the anti-heeling system.

Answer 19

Ballast system The ballast system utilizes water tanks positioned in the double bottom, beneath the ship’s main deck. In order to keep the ship’s draught and trim proper, to provide maximum stability, and to keep the ship’s stress and bending moments within acceptable limits, water is added to or removed from the ballast tanks. One tank or pair of tanks should never be partially filled (slack) at any given moment, as slack tanks provide a free surface effect that is detrimental to stability. Ballast systems consist of tanks with pipes and pumps that may be filled or emptied in order to alter the ship’s mass and hence its draft. For ballasting operations, the ballast pumps can draw suction from the main sea water main crossing pipe in the engine room. As part of de-ballasting procedures, the ballast pump discharges directly overboard. The ballast system is controlled from the ship’s control centre panel which enables the pumps to be started and stopped and ballast system valves to be opened and closed remotely. Usually the valves are hydraulically operated and all of them are normally located outside of the respective ballast tanks which allows maintenance and inspections to be carried out on all of the valves without having to enter a tank. All ballast and de-ballasting operations for each tank must be entered into the Ballast Log Record Book, stating date, ship’s position, temperature, specific gravity, pumped quantity and tank quantity. The International Convention for Control and Management of Ship’s Ballast Water and Sediments applies to all vessels that carry ballast water. If there is no ballast system * The propeller may not fully immerse in water, affecting the engine efficiency of the ship * The ship may list or trim as the cargo capacity of the ship is not fully reached * The shear and torsion loads on the vessel may increase the stresses on the ship structure, leading to bending moments and slamming * The vessel may face issues of dynamic transversal and longitudinal instability Anti-heeling system Heeling systems on the other hand simply recirculate the ship’s ballast water to maintain a ship’s heel or trim. Heeling tanks are partially filled with water and are used to adjust the heel of the ship during loading and unloading operations. Water is transferred from the port heeling tank to the starboard heeling tank, or vice versa, in order to keep the ship in the upright position using a dedicated anti-heeling pump system. The heeling tanks are filled and emptied by way of the ballast pumping system. In the event of a failure of the anti-heeling system, the ballast pump is used to transfer ballast as required between the port and starboard heeling tanks. After an incident, the heeling system must be able to move huge amounts of water in a short period of time and give a heeling compensation