A Technical Report On Industrial Training In Iocl Hmrbpl.docx

A TECHNICAL REPORT ON INDUSTRIAL TRAINING IN IOCL HMRBPL, ASANSOL

PREPARED BY SHASWATA BOSE PRADEEP KUMAR MODI DEPARTMENT OF MECHANICAL ENGINEERING NATIONAL INSTITUTE OF TECHNOLOGY, KARNATAKA

FROM DECEMBER 3, 2018 TO DECEMBER 24, 2018

ABSTRACT This Industrial training report presents the experience gained during our 3 weeks of industrial training undertaken at Indian Oil Corporation Limited (IOCL) HMRBPL, Asansol. The training was on the overview of transportation of crude oil products across pipelines, the various processes and maintenance involved, and the machineries involved in this. During this training, we acquired practical knowledge on the workings, internal construction, repair and maintenance of several of mechanical components including engines, centrifugal pumps and valve systems and the various safety procedures involved in such stations.

ACKNOWLEDGEMENT I would like to thank Mr. Chandan Kumar, our supervisor for guiding us through this training and helped us with all our questions and problems we had. I am grateful to Indian Oil Corporation Limited for providing us the training opportunity thus providing us exposure to the engineering services associated with oil transportation. I want to thank my H.O.D. Dr. Narendranath and Dr. Poornesh for their support

PUMPING STATION OVERVIEW Asansol is the intermediate pump station for Haldia-Barauni (HB) line, meant for boosting the pressure at Asansol. It is located near Kalla central Hospital at Asansol. It has 3 nos. of identical diesel run engines driven mainline pump units with a normal operating practice of running one pump keeping two as standby. Other station facility includes inline strainer, sump tank, oil water separator, scrapper launching / receiving facilities, emergency DG set and firefighting facilities. HB line is one of the longest and oldest pipelines in eastern India. As the oil flows through this pipeline, the flow rate and oil pressure gradually decreases which also decreases the rate at which oil is received at Barauni. To counter this problem, this pumping station was established in Asansol to increase the pressure and flow rate of the refined oil products coming from Haldia towards Barauni. For this purpose, the station is fitted with 3 410 HP Diesel Engines which drive 3 two statge centrifugal pumps which increase the flow rate and flow pressure of the oil before sending it towards barauni. A tank of 12 m height and 8 m diameter is used as storage for fuel for the engines. These engines have an efficiency of around 25% and consumes almost 55 kl per hour during pumping operations.

Schematic representation of the pumping setup According to standard operating procedures, one pump is usually driven and two pumps are kept at stand by. In normal pumping conditions with only one pump running, the station incoming pressure is generally around 7.0 - 18.0 Kg/Cm² and the station outgoing pressure is around 25.0-40.0 Kg/Cm². During pressing demand of product for Jasidih/BRN region two pumps are run with an average station incoming pressure around 3.0-10.0 Kg/Cm² and station outgoing pressure around 30.0-43.0 Kg/Cm². To increase the flow rate of the product, a chemical which goes by its trade name of Drag Reducing Agent or DRA is injected in measured quantities within the pipeline. The chemical separates out of the product and forms a protective coating between the product and the inner lining of the pipe. This decreases the friction between the product and the walls which reduces turbulence in the product and the drag as a result. The effect of DRA Injection was an average Increase of Flow rate by 15% towards JSD/BRN at the above rate of Dosing. This pipeline is used to transport petrol (MS), diesel (HSD) and kerosene (SKO). Since their densities are different, there is very little mixing between the two fluids. During the transportation of HSD and MS, SKO is used between them. The region of transition of one fluid into another is termed as interface. During the operation of the pumping station, Haldia notifies the time when interface will pass. At that time after every 1 hour, density reading of the product is taken. This is performed three times till change in density is noted. When the density changes, interface is said to be completed and the time is notified to Haldia and Jasidih. Samples of the product are and stored throughout this process

PIG LAUNCHING For the inspection and cleaning of the pipeline, pig is launched within the pipeline. This device consists of rubber discs and aluminum plates with radial slits alternately mounted on a steel rod and bolted in place. This device is launched within the pipeline to detect any scale formation or damage in the internal wall of the pipeline. For the purpose of pig launching and pig receiving, two Scrapper Launching Barrels are present in the piping system. During pig launching, the SLB is completely drained until the pressure on the gauge reads zero. Then the barrel is opened and the pig is pushed into the SLB. After ensuring that the pig is positioned correctly, the valves are opened and the SLB is filled with product. The mainline valves are then opened and the pig is launched into the mainline. Subsequent readings of the time of launch are also noted. The rubber covers should be large enough so that they fit tightly within the mainline. As the pig flows through the pipeline, the aluminum plates are damaged due to any scale formation or any protrusion within the pipeline. If the pig received at the SLB is damaged, an electronic pig equipped with sensors is then launched in the mainline. This pig is used to track the exact location of the defect within the pipeline so that repair work can be carried out by personnel.

Alternatively, scrapper can also be launched into the mainline. These devices are fitted with brushes instead of aluminum plates and are designed to remove rust and clean the inner surface of the mainline. The procedure involved in scrapper launching and receiving is almost similar to pig launching and receiving

PIPELINE MAINTENANCE The HMRBPL station has two valves; one in Andal and the other in Rupnarayanpur. Both of these valves can be operated through the control room in Asansol pumping station. These valves can be remotely opened or closed for any maintenance purposes.

CPs and valves under the jurisdiction of HMRBPL

The entire pipeline is fitted with pressure and flow rate sensors. The pressure sensors can detect a pressure change of more than 1% and this change shows up in the SCADA system in control room. When the demand of oil in Barauni is low and the station is not pumping any product, even minor changes in pressure can be detected and any leakage, howsoever small can be detected. This is because the pressure in the pipeline is constant throughout when no pumping is happening and thus any variation in suction and

discharge pressure readings allow the personnel to detect the presence and as a result the location of the leak. Patrols along the pipeline are then send to the location and the cause for leakage is identified.

SAFETY SYSTEMS In HMRBPL, one of the main concerns is safety, as the station is involved in constant handling of volatile fuels. The station has multiple safety features to prevent any disasters. A state of the art firefighting system is present in the station and the system is tested for 10 minutes in every 8 hours to ensure smooth functioning of the system There are multiple Manual Call Points (MCPs) which can be used to raise an alarm in case of an emergency. If a personnel is in trouble and wishes to call for help, he can activate the MCP which will activate the SCADA system in control room and a response team will be send to that MCP. To operate these MCPs, glass is to be broken with hammer provided at the same point and pressing the push button. There are total 5 indoor MCPs and 5 outdoor MCPs The station is also outfitted with Emergency Shutdown switches (ESDs) at strategic locations. Once any one of these switches is activated, the incoming MOV, the outgoing MOV along with the three Main Line Pumping Unit (MLPU) Engines will be shut down. There are three outdoor ESDs and an indoor ESD. Emergency Shutdown can also be initiated through SCADA in control room. Color coding of ESD and MCP has been differentiated; ESD is painted with yellow color while MCP with red color.

Overview of the firefighting system in HMRBPL

To cope with any classes of fires, there are water pipelines throughout the station. Two water tanks are maintained which provide water for firefighting. In order to maintain pressure in the water lines, several pumps; both engine driven and electrical are installed in the station. There are two diesel pumps, three jockey pumps and one electrical pump are installed in the station.

Jockey pump

Diesel Pump

Is

Electrical Pump

The two diesel engines drive centrifugal pumps which maintain the water pressure in the pipeline during firefighting. 2 600 kL fuel tanks are used to fuel the two engines. Monthly firefighting drills are organized

to ensure all personnel know how to operate the equipment and know the protocols they must follow during an emergency. Foam tanks are present near the water outlets which can be connected to spray foam along with water. Fire extinguishers and sand buckets are also provided throughout the station. Two emergency gates are provided for quick evacuation of personnel in case of emergency.

MEASUREMENTS AND READINGS The station is equipped with various sensors and measuring instruments. The mainline is equipped with pressure sensors, flow rate sensors, hygrometers, thermometers which feed the readings to the SCADA system. Any deviation from the defined range trips the alarm and shuts down the mainline to avoid any accidents.

SCADA system showing various readings taken throughout the pipeline

Besides there are handheld measuring instruments like Vernier calipers, micrometers, dial gauge, tachymeter, viscosity meter, vibration meter and pipe thickness meter. We witnessed one of the measurements during our training. For the maintenance of the main line engines and pumps, regular vibrational analysis is performed. For this, vibrations are measured at various points on the engine and pump and three graphs are plot; namely displacement, velocity and acceleration vs. RPM. The vibrations in three directions are taken for this purpose; horizontal, vertical and axial (along the axis of the driveshaft). All these readings are noted down for all the three engines. Such readings are taken at regular intervals. Once these readings are obtained, they are sent for analysis. These readings can be used to identify any kind of internal problem within the engine or the pump. The engine is also fitted with thermometers which measure the temperature within the engine cylinders. A personnel checks these values at regular intervals to ensure smooth functioning of the engine. Lube oil is also analyzed from time to time to detect any malfunctioning of the engine. If any problem is detected, the engine is isolated

1.ENGINE

The engine used in this pump station is four stroke ignition compression engine and a total of three engines are installed in this station, which runs on both mixture of fuel and air and on compressed air, the core of each engine comprises of twelve the cylinder arrangement of V6 type configuration, with each cylinder consisting of piston moving up and down inside the cylinder and this takes place in a four-stroke process, which are intake, compression, Power and Exhaust. The piston moves down on the intake stroke, the intake valve is open and the fuel air mixture is admitted into the cylinder, and the piston moves up during the compression with stroke both valves are closed, compresses the trapped fuel air mixture that was brought during the intake stroke, thereafter the spark plug fires, igniting the compressed air and fuel mixture which produces a powerful expansion of the vapor which is used to drive the crankshaft and this is the power stroke. Finally, during the exhaust stroke, where the piston is at the bottom of the cylinder the exhaust valve opens to allow the burned gas to be expelled to the exhaust system.

1.1 Details of engine at Asansol station 1.1.1 Serial no.

MLE – 1- 4768 MLE – 2-4810 MLE-3- 4766

1.1.2 Make and Model FIAT STABILIMENTO GRANDI MOTORI, C-MARCONI-20, ITALIA.

1.1.3 Specification ENGINE TYPE: FIAT 236, 4-STROKE DIESEL ENGINE No. of Cylinders : 6-IN- LINE Firing Order : 1-4-2-6-3-5-1 Cylinder Bore : 230 mm Piston Stroke : 270 mm Direction of rotation : Anticlockwise looking from flywheel side towards radiator Rated R.P.M. : 1000 Rated B.H.P. : 410

1.1.4 Maintenance Each engine is set to work for 16,000 hours and then each part of the engine is separated out for the checking and repairing and after proper checking it is again set to 0 hours for working, moreover in between the engines are also checked so that no issue of failure to it’s working can occur.

1.2 Some important engine parts 1.2.1 Spark plug The spark plug supplies the spark that ignites the air/fuel mixture so that combustion can occur. The spark must happen at just the right moment for this to work properly.

1.2.2 Piston head

The piston head sits over the piston cylinder and it comprises of four valves and four springs, two valves are inlet valves while the other two are exhaust valve, the valves are controlled by the cam shaft follower and the springs controls by how much amount the valves have to be opened or closed according to the need.

1.2.3 Valves The intake and exhaust valves open at the proper time to let in air and fuel and to let out exhaust.

1.2.4 Piston Piston is a cylindrical piece of metal that moves up and down inside the cylinder.

1.2.5 Piston rings

Compressor ring

Oil scraper ring

Bevel ring

Piston rings provide a sliding seal between the outer edge of the piston and the inner edge of the cylinder. They are basically of four types: 1. Compressor ring 2. Oil scraper ring 3. Bevel ring 4. Oxidize ring These rings basically serve two purposes: 1. They prevent the fuel/air mixture and the exhaust in the chamber from leaking into the sump during compression and combustion. 2. They keep oil in the sumo from leaking into the combustion area where it would be burn and lost.

1.2.6 Connecting rod

The connecting rod connects the piston to the crankshaft and it is connected to the piston through gaugeon pin, it rotates at both ends so that its angle can change as the piston moves and the crankshaft rotates.

1.2.7 Crank and cam shaft

Crank shaft The crankshaft turns the piston’s reciprocating motion in the cylinder into circular motion while, the camshaft in an internal combustion engine makes it possible for the engine’s valve to open and close, the asymmetrical lobes of the camshaft correspond to the engine valves.

1.2.8 Fuel Injector

Fuel Injector

Fuel Injector nozzle

The main function of fuel injector is to inject the air and fuel mixture to the piston for the combustion, it comprises of a thin shaft, a spring and a fuel injector nozzle. The fuel injector nozzle comprises of very fine small holes which are barely visible from naked eyes which is used to spray the fuel mixture at high speed and moreover the opening and closing of the nozzle is governed by the spring system in the fuel injector.

1.3 Lubrication system Oil is the life-blood of the engine. An engine running without oil will last about as long as human without blood. Oil is pumped to all the moving parts of the engine by and oil pump which receives power from the engine through belt and pulley arrangement. The oil pump is mounted at the bottom of the engine in the oil pan and is connected by a gear to either the crankshaft or camshaft. This way, when the engine is running the pump is pumping simultaneously. The oil pump creates suction to the oil sump due to which the oil gets collected and filtered through the oil strainer in the sump and the oil is sucked to the pump. This sucked oil is supplied to the secondary oil filter with a high pressure and a pressure regulator between the oil pump and filter ensures that the oil pressure is maintained properly, the oil filter removes any dust particle present in oil and supplies clean oil in oil lines with a high pressure that flows through the oil lines and galleries meant to lubricate the moving parts. And then the oil from the main galleries flows through the holes drilled inside the crankshaft and main bearing to lubricate them. An oil sprout connected with the gallery forces the oil upwards to lubricate the piston and its parts from the inside. Inside the cylinder, the oil flows through the oil rings to lubricate and form a thin film around the cylindrical walls and in the second gallery, the sprouts connected to it help in lubricating the camshaft, valves and valve springs. Finally, after lubricating the engine parts oil begins to flow downwards through a separate passage to the oil sump and the process continues.

1.4 Cooling System A system, which controls the engine temperature, is known as a cooling system.

1.4.1 Necessity The cooling system is provided in the IC engine for the following reasons: • The temperature of the burning gases in the engine cylinder reaches up to 1500 to 2000°C, which is above the melting point of the material of the cylinder body and head of the engine. (Platinum, a metal which has one of

the highest melting points, melts at 1750 °C, iron at 1530°C and aluminium at 657°C.) Therefore, if the heat is not dissipated, it would result in the failure of the cylinder material. • Due to very high temperatures, the film of the lubricating oil will get oxidized, thus producing carbon deposits on the surface. This will result in piston seizure. • Due to overheating, large temperature differences may lead to a distortion of the engine components due to the thermal stresses set up. This makes it necessary for, the temperature variation to be kept to a minimum. • Higher temperatures also lower the volumetric efficiency of the engine.

1.4.2 Types of cooling system There are two types of cooling systems: (i) Air cooling system and (ii) Water-cooling system. Water cooling system is mostly used in large IC engine and is used in this Asansol station.

1.4.2.1 Water cooling system It serves two purposes in the working of an engine: a) It takes away the excessive heat generated in the engine and saves it from over heating b) It keeps the engine at working temperature for efficient and economical working. This cooling system has four types of systems: (i) Direct or non-return system (ii) Thermo-Syphon system (iii) Hopper system and (iv) Pump/forced circulation system The type of water-cooling system used in this pump station is

Force circulation system

In this method, a water pump is used to force water from the radiator to the water jacket of the engine. After circulating the entire run of water in jacket, water comes back to the radiator where it loses its heat by the process of conduction. To maintain the correct engine temperature, a thermostat valve is placed at the outer end of cylinder head. Cooling liquid is by-passed through the water jacket of the engine until the engine attains the desired temperature. Then thermostat valve opens and by-pass is closed, allowing the water to go to the radiator.

Parts of Liquid Cooling System The main parts in the water-cooling system are: (i) water pump, (ii) fan, (iii) radiator and pressure cap, (iv) fan belt (v) water jacket, (vi) thermostat valve, (vii) temperature gauge and (viii) hose pipes.

Water Pump This is a centrifugal type pump. It is centrally mounted at the front of the cylinder block and is usually driven by means of a belt. This type of pump consists of the following parts: (i) body or casing, (ii) impeller (rotor), (iii) shaft, (iv) bearings, or bush, (v) water pump seal and (vi) pulley. The bottom of the radiator is connected to the suction side of the pump. The power is transmitted to the pump spindle from a pulley mounted at the end of the crankshaft. Seals of various designs are incorporated in the pump to prevent loss of coolant from the system.

Fan The fan is generally mounted on the water pump pulley, although on some engines it is attached directly to the crankshaft. It serves two purposes in the cooling system of an engine. (a) It draws atmospheric air through the radiator and thus increases the efficiency of the radiator in cooling hot water. (b) It throws fresh air over the outer surface of the engine, which takes away the heat conducted by the engine parts and thus increases the efficiency of the entire cooling system.

Radiator The purpose of the radiator is to cool down the water received from the engine. The radiator consists of three main parts: (i) upper tank, (ii) lower tank and (iii) tubes. Hot water from the upper tank, which comes from the engine, flows downwards through the tubes. The heat contained in the hot water is conducted to the copper fins provided around the tubes. An overflow pipe, connected to the upper1 tank, permits excess water or steam to escape. There are three types of radiators: (I) gilled tube radiator, (ii) tubular radiator (Fig. b) and (iii) honey comb or cellular radiator.

2.PUMP 2.1 Description The pump used in this station is horizontal type multi-staged centrifugal pump. The case is horizontal split and the suction and the discharge nozzles are cast integral with the lower half of the case in order to permit the pump disassembly without disturbing the piping connections. The impellers, close type, are assembled on the shaft with a slight shrink fit and are locked by eyes; they are mounted to provide the axial balance over the entire operating range. The sleeves, threaded to the shaft at one end, are locked at the other end with set screws; a gasket is provided between the shaft and shaft sleeve correspondently the retaining ring to prevent liquid leakage under the shaft sleeve. The impellers wear rings as well as the shaft intermediate sleeves are mounted with a slight shrink fit and pinned, I position. Horizontal pins, seated at the case split, prevent the rotation of the case wear rings (consisting of a single piece) and the separating rings (in the two pieces), that are free assembled and the pins provide the rotation of the throttle bushing consisting of two pieces while the splitters are screwed at the case split of the lower half.

2.2 Details 2.2.1 Serial no. Pump 1-P-2063 Pump 2 P-2165 Pump 3 P-2065

2.2.2 Make and Model M/s NUOVO PIGNONE FIRENZE; 2, VIA. F MATTEUCCI P.O. Box - 4 Italy

2.2.3 Specification Differential Head (M) P1-290 ,P-2 370, P-3-290 Capacity (M3/Hr)P-1 255 P-2 220, P-3 255 Speed (RPM) P-1 3720,P-2 3690, P-3 3720 Service Temp. P-1 4oC - 49 oC,P-2 4oC - 40 oC ,P-3 4oC - 49 oC

Specific wt. of fluid P-1 0.87Kg/D, P-2 M3 0.73 Kg/ M3 ,P-3 0.87 Kg/D M3 Power absorbed by pump (HP) P-1 322 ,P-2 305.5 ,P-3 322

2.3 operation 2.3.1 Starting Start the driver and bring the unit to the continuous running speed as fast as possible. Start the pump with the pump with the discharge valve closed; when the continuous running speed is reached and the manometer shows the full shutoff pressure, open the discharge valve slowly until the required capacity and discharge pressure are obtained.

2.3.2 Minimum capacity The allowed minimum capacity in continuous service is set forth in section “MAIN FEATURES”. Do not operate the pump below the indicated minimum capacity without the approval of Nuovo Pignone Engineering Department. Do not adjust the pressure and capacity by valves placed on the pump suction side, all throttling must be made by valves placed on pump discharge side.

2.3.3 Inspections As soon as pump is running check the following items: 1. Check if the oil rings are rotating freely and the bearings are properly lubricated. 2. Check the eventual cooling and circulation lines on the seal are properly operating. 3. Check if the manometers on the suction and the discharge show the normal operation conditions. After the pump has worked a few hours check the following items: 4. Check the bearing temperature (maximum 80-degree C). 5. Check the differential manometer placed on the suction, to remark eventual pressure differences between strainer upstream and downstream. 6. Check eventual leaks of lube oil by a white paper sheet placed, close the rotating part. The machine periodic inspection can avoid eventual works. Troubles connected with the most common items, such as packings, bearing and mechanical seals can be removed if corrective works are taken in the early stage when the first warning signs of improper operation appear.

2.3.4 Alignment check Check the pump and the driver alignment after the pump has operated a few hours; moreover, it is recommended to check the unit after a few days of normal operation.

2.3.5 Stopping Close the discharge valve and stop the pump immediately. Before restarting the pump, it must be primed following the instructions of the relative para.

2.3.6 Freezing

If the pump is exposed to freezing temperatures drain it completely after it completely after its stopping.

2.4 Working

For multistage pump, when the impeller rotates driven by the motor or the engine at high speed, the liquid in the impeller under the effect of centrifugal force, from the centre of the impeller thrown to around the impeller along the flow path between the blades. Since the liquid subjected to the action of the blade, the pressure and speed also increase, the liquid is directed to secondary-level impeller through the flow path of guide housing, so that successively flows through all of the impeller and guide housing, further increases the pressure energy of the liquid. Each impeller progressively superimposed to get some delivery lift. Multistage pump is equivalent to series connection of single-stage and multi-stage centrifugal pump, its pressurized stage by stage, so centrifugal pumps get a higher pressure to meet delivery lift.

2.5 Maintenance Schedule The maintenance schedule are as follows:

2.5.1 Daily Be sure the seal is properly lubricated and the lube oil of bearings is at the proper level. Check the bearing temperature and watch for vibration.

2.5.2 Every 2000-3000 hours of operation

Drain the bearing housing, wash with a suitable solvent and fill with new lube oil to the proper level. Check the pump driver alignment.

2.5.3 Every 4000-5000 hours of operation Check the wear of shaft sleeve for the packing of seal and repack the stuffing box. Replace the seal rings of the mechanical seal if an excessive wear is remarked or leaks appear. Moreover, check the bearings or replace them as requested.

2.5.4 Every 9000-10000 hours of operation Dismantle completely the pump and check the wear, corrosion and erosion of the component parts and replace all gaskets. Check the valves, manometers etc.

3.Gates and valves Valve is a device that regulates, controls or directs the flow of a fluid by opening, closing, or partially obstructing fluid flow. So basically, it controls flow & pressure. These are technically fittings, but are usually discussed as a separate category. In an open valve, fluid flows in a direction from higher pressure to lower pressure Basically, valves are characterized into three categories:

Isolation valves:

An Isolation Valve is used in fluid management to stop the flow of process fluids in a pipeline, this is usually for maintenance or safety purposes.

Pressure control valves (PCV): Pressure control valves influence the system pressure in a specific, predetermined manner. This is achieved by altering the throttling cross-sections with the aid of mechanical, electrical or hydraulic movements.

Flow Control valve (FCV): A flow control valve is the type of valve which regulates the flow or pressure of a fluid. Types of valves used in this station are:

1. Gate valve:

Gate valves are primarily designed to isolate or fully pass flow through the valve, and when a flow of fluid with a minimum flow restriction are needed. In service, these valves generally are either fully open or fully closed. The design of a gate valve is such that the disk is completely removed when the valve is fully open leaving an opening the same size as the inside diameter at the pipe in which the valve is installed.

2. Non-return valve (NRV) A non-return valve allows a medium to flow in only one direction. A non-return valve is fitted to ensure that a medium flow through a pipe in the right direction, where pressure conditions may otherwise cause reversed flow. The flow through the non-return valve causes a relatively large pressure drop, which has to be taken into account when designing the system.

3. Ball valve (Spherical valve)

A Ball Valve is a quarter-turn rotational motion valve with a straight through design that uses a ball-shaped disk to stop or start flow. If the valve is opened, the ball rotates to a point where the hole through the ball is in line with the valve body inlet and outlet. If the valve is closed, the ball is rotated so that the hole is perpendicular to the flow openings of the valve body and the flow is stopped.

4. Tappet valve:

A hydraulic tappet, also known as a hydraulic valve lifter or hydraulic lash adjuster, is a device for maintaining zero valve clearance in an internal combustion engine. Conventional solid valve lifters require regular adjusting to maintain a small clearance between the valve and its rocker or cam follower.

5. Butterfly valve:

A Butterfly valve is a quarter-turn rotation valve that is used to regulate flow in a piping system. Butterfly valves are fast and easy to open and a 90° rotation of the disk provides a complete isolation or fully open position of the valve. Butterfly valves main advantages is the weight and space saving over gate, globe, plug, and ball valves. Typical Butterfly valves applications are for the control or isolation of large flows of liquids or gases at relatively low pressures and for the handling of slurries or liquids with large amounts of suspended solids.

and the stand-by engine is used while the repair and maintenance work is going on.