Maintenance Step : Maintenance and Inspection Chart

Maintenance and Inspection Chart

   The followings indicate the kind of inspection that should be made and the nature of the action that be taken if required.

Part of Unit	Item	Examine for	Action Required
Blade	Shroud	Cracks, Rivet heads	Consult manufacturer
	Blade Edegese	Erosion, Nicks	File or grind smooth, Check boiler operation for carryover.
Oil Seal Rings	Seal Rings	Wear dents in Surface	If leaking oil, replace
Glands	Gland Diapragm	Scale, boiler compound	Clean thoroughly.
	Rings	Cracked segments, high spots, dirt	If cracked or broken, replace. Clean care-fully scrape high spots.
Governor	Internal Part	Wear, sediment	Clean carefully. If weared scarpe high spots.
Emergency Stop & Governor Valve	Stem	Scale, boiler compound	Clean with solvent. If necessary polish with crocus cloth.
	Bushing	Scale, etc.	Clean with solvent. If necessary ream to get proper clearance.
	Valve and Seat	Cutting, scaling, etc.	Clean, file or lap. If necessary replace.
	Strainer	Obstruction, breaks	Clean with solvent. If cracked or broken, replace.
Over Speed Trip	Internal Part	Dirt, corrosion	Clen all parts thoroughly.
	L.O. System	Wear, sediment	Clean, if weared replace.
Trip Cylinder	Trip Cylinder	Wear, sediment	Clean, if weared replace.
	Trip mechanism	Wear, cutting	Clean, file or grind.
Oil Relief Valve	Internal Parts	Wear, sediment	Clean, if weared replace.
Strainer	Internal Parts	Obstruction, breaks	Clean, if broken replace.
Reduction Gear	Pinion and Gear Teeth	Contact Markings	Correct alignment, or Scraper or replace bearings. Correct parallel these axes.
		Feather edges of teeth tips.	Removed by a fine oil stone.
		Burrs. Bruised spots.	Dressed up with a scraper. Do not file these teeth under any circumstances.
	Bearing Surface, Thrust Faces.	Wear, sings of foreign matter, scratches.	Scrape high spots. If clearance is excessive, replace check condition of oil system.
		Measure the thrust clearance.	Adjust the clearance by adjusting linier, or replace the thrust bearing.
Main Oil Pump	Gears and Bearings	Wear, sings of foreign matter, scratches.	Scrape high spots. If clearance is excessive, replace
		Feather edges of teeth tips.	Removed by a fine oil stone.

Maintenance step : Inspection

Inspection turbine

About every three years, depending upon the nature of the service, the unit should be dismantled and throughly cleaned and inspected.
All parts should be examined for wear.
In this way, the cause of excessive wear can frequently be found and corrected before any damage is done. All oil chamber should be cleaned thoroughly to insure removal of all foreign matters and sludge deposite.

Maintenance step: Maintenance of turbine

Maintenance of turbine

The old saying "a stitch in time saves nine" applies to mechanical devices as well as to clothing and many other things.
It not be too strongly emphasized that a small amount of regular attention to the unit may easily avoid a large repair bill at a later date.

1. Keep the machine clean.
2. Clean the emergency stop valve stem and governor valve stem as often as necessary to prevent the accumulation of boiler compound or other foreign matters. These part must be kept working freely. All drains must be kept open whenever the unit is shut down.
3. Trip the overspeed trip occasionally to see that it is in good working order.
4. If operating for long periods without shutdown, check the emergency stop and governor valve and the governor occasionally to make sure that it is free.
5. A heavy accumulation of the scale on the turbine blades with cause a reduction in the output and increase in steam chest pressure. Therfore if the operation record is checked, and should an increase in the steam chest pressure be found, it may be attributed to the scale accumulation.
6. Check the oil temperaturs and increase in temperature, clean the oil filter and purify the oil.
7. When the turbine stopped, ensure that the steam piping is completely drained and that all valves are closed.

Pipe Connections Turbine

1. Steam inlet line

The main steam line should be anchored at the header, receiver or manifold. Always at the header and make the connection at the turbine lest.

The line should be sufficiently flexible so that no under strains are exeried on the turbine when at operating temperature.

This flexibility can be obtained by having the pipe of sufficient length with loops or section of piping at right angles to each other.

It should be properly supported throughout its lenght with the last support. but not an anchor located adjacent to the turbine.

 Spring hanger and rollers are recommended as support for the larger machines and especially large compared to that of the turbine.

At the point where the steam line connects to the turbine, make sure that the flange faces are parallel and that no force is necessary to bring them together or to match the bolt holes.

In order to reduce to a minimum the force exerted on the turbine by the expansion and contraction of the pipe the alignment of the flanges should be made with full steam pressure and temperature up to the throttle valve.

The final alignment is then make at then at the joint between the throttle valve and the turbine.

Before finally connection the steam line to the turbine it should be blown out thoroughly with high-pressure steam to remove any foreign matter such as dirty, scale, pip-joint-compound, etc., which if carried into the turbine, might prevent the closing of the governor valves and cause over speeding, or plug part of the nozzle area, thus reducing the capacity and efficiency of the unit.

It is of utmost importance to install a drain in the steam line at its lowest point between the header and the turbine.

2. Exhaust Line

The exhaust line should similarly be provided with adequate inherent flexibility.

If space limitations prohibit this, the pipe should have a flexible-cooper expansion joint placed to the turbine.

The exhaust pipe should be anchored just beyond the expansion joint to prevent the pipe thrust from damaging the expansion joint or the turbine. 

Even though an expansion joint is used, the same care should be exercised in aligning the pipe flange to the turbine exhaust flange ad described for the main steam line.

Be sure that the expansion joint is made of material sufficiently light to provide flexibility. Some expansion joints are so stiff that their use is of little value.

Whenever the turbine coupling is to be aligned or the alignment checked, be sure to disconnect the main steam line and exhaust line in order to eliminate the possibility of these pipes exerting excessive starins on the turbine.

When reconnecting them, be sure that the faces can be made parallel and the bolt holes matched without using force.

After the steam and exhaust pipes have been reconnected the unit should be heated up to approximately normal operating temperature and then the bolts should be removed from the pipe connections to check whether or not any excessive spring of the joints takes place.

If so, the condition should be corrected before the machine is placed in operation. 

Foundation and Installation on Steel Work

The foundation may be fabricated steel.

The official outline drawing shows the space required and the location of the foundation bolts.

Set the turbine in position with the bedplate supported on steel wedges. Adjust the wedges to bring the unit as nearly levels as possible and place it at the correct height and on the correct centerline.

When the alignment has been authenticated, substitute fitted chocks for the temporary wedgas used during alignment, locate them immediately adjcent to the foundation bolts and secured to the steel work by screws to prevent them from being vibrated out of position.

The shims should be blued and scraped to make sure a good bearing is scured over the full surface, and that each chock carries it share of load.

General Installation Turbine

It is very important that the machine shall be installed property.

Misalignment, distortion of the bedplate or other errors of this kind may later bring about serious operation troubles even though the unit appears to run satisfactory at first.

It is desirable to have the bedplate as nearly level as possible, but in any case it is absolutely necessary to have the rotating shafts in proper alignment as determined by the couplinga, regardless of the levels.

In order to emphasize this point, the unit is shiped from the factory with the coupling bolts removed.

It is of the utmost importance that the machine be installed so as to have the correct alignment at the coupling faces before installing these bolts or attempting to operate the turbine.

Do not depend upon the stiffness of the bedplate to have maintened the alignment during transit from the factory.

In cases where the coupling is provided by the manufactured of the driven apparatus and the driving half is to be mounted on the turbine shaft in the field, the coupling hub should be carefully heated and shrunk onto the turbine shaft.

Use a gas-ring or a heating coil. Do not use a blow torch and do not overheat. Do not attempt to drive the coupling on with a hammer.

Requirements for Operation Turbine

1. Since Drain entry may cause damage to the thrust bearing or blade or other troubles, take due care of drain.
2. When remotely changing the rotational speed, be sure to observe persistenly the tachometer.

If the rotational speed does not change following the speed change operation, immediately stop the speed chenge operation to eliminate the possible cause of trouble as mentioned below.

It must be noted that if the governor motor is kept running after the speed setting dial comes in contact with the upper or lowe limits stopper, the clutch may be damage.

Cause of failure in following the speed change operation. In case of speed-up

• Over load
• Improper steam conditions (especially, excessively low inlet pressure or excessively high exhaust pressure).
• Mechanical trouble.

In case of speed-down

• Mechanical troubles.

Operation Stopping Turbine

Stopping

1. Degrease the turbine speed gradually with the speed setting under 50% rpm of rated speed.
2. Close the emergency stop valve.
3. Make sure the auxiliary oil pump is started.
4. Close the stop valve on the main steam line.
5. Close the sealing steam valve for condensing turbine.
6. Open the drain valves, for condensing turbine, open the casing drain valve after opening the exhaust valve.
7. Close the exhaust valve.
8. Close the cooling water valve to the oil cooler.

Running Turbine

Running

1. When the governing system assumes control, then adjust the speed fully open the emergency stop valve setting until the required speed, watching the turbinr speed following.
2. Put into service the load as required.
3. Make sure that bearing temperature is under 80C. When over 85 C, stop the turbine.
4. Check the bearing oil pressure gauge to see that the bearing oil pressure is 0.7 - 1.5 kg/cm2 G.
5. Adjust the supply of cooling water to the oil cooler to maintain oil temperature at outlet 30 - 50 C.
6. Watch the turbine for unusual sounds and vibrations and take proper action if should occur.

Starting Turbine

Starting

1. Open the emergency stop valve slowly and close it when the turbine starts to ratate. If the turbine does not start, push the starting lever. Listen for any unusual noise.
2. Open the emergency stop valve again and run the turbine at low speed, warming it up for about five minutes.
3. After the warming up finished, open the emergency stop valve and bring the turbine gradually up to about 2,000rpm. Listen for any abnormal noise with a listening rod and check for vibration. If any abnormal moise are heard or vibration is excessive, the unit should be shut down and cause should be found.
4. Close the drain valves when it becomes certain that the parts which they drain are free of water and the turbine is heated sufficiently to prevent additional accumulation of water.
5. Make sure the motor of auxiliary oil pump is stopped automatically.

Operation Before Starting of Turbine

Before starting turbine

1. Make sure oil reservoir is filled to teh normal level.
2. Open all drain valves of the steam inlet line, and exhaust line.
3. Supply lubricating oil into all bearings by operating a motor driven auxiliary lubrication oil pump.
4. Open the cooling water valve to the oil cooler.
5. Check the trip mechanism by pushing the trip nob and reset the trip and the emergency stop valve turning back the handle clockwise (Close).
6. Make sure the governor is minimum speed setting.
7. Open the exhaust valve after checking not to have drain on the exhaust fan. For condensing turbine, close the drain valve of the turbine casing.
8. Open the stop valve on the main stem line after checking the drain at the inlet line.
9. Open the stop valve, and adjust the pressure to 0,2 ~ 0,4kg/cm2G for condensing turbine.
10. Make sure of no drains at the steam inlet line.

Continue to Operation Starting Turbine

Lubrication And Governing System ENV-116G Turbine 4

11. Lubricant Specification

The informtion contained in this leaflet preset the recommendations of our shop regarding the caracteristics of lubricants suitable for use in the operation of the unit.

Quality

The oil shall be a refined mineral oil of highest quality and uniformity. It shall contain no grit, inorganic acid, alkali, soap asphaltum,pitch, resinous, or any other substance which will interface with the lubricating properties of the oil, or that will be detrimental to the oil or to the metals with which it will come in contact in service.

The oil shall be capable of preventing the formation of rust on steel parts bathed with oil, should small quantities of water enter the oil during service.

Flash Point	175˚ C (350˚ F) min.
Say bolt viscosity
Second at 38˚ C (100˚ F)	230 ~ 360
Second at 100˚ C (210˚ F)	46 ~ 60
Carbon Residue	1.00% max.
Neutralization No.	0.10 max
Sulphur Content
Corrosion Resistance Test	Shall pass

Corrosion in Lubricating System.

In the operation of a system turbine it is impossible entirely to exclude moisture from lubrication system.

The presense of very small quantities of moisture in a system using unsuitable oil has been found to be responsible for serious corrosion, which interferes with governor system operation and jeopardizes bearings.

Inhabited Oils : Purification System

It is known that some types of oil purification system using fuller's earth or filters materials may removw some corrosion or oxidation inhabitors from the oils.

It is recommended that before such system are applied, the oil supplier be consulted on this point.

Future of Technology

Lubrication And Governing System ENV-116G Turbine 3

8. Low Oil Pressure Trip

The Turbine is provided with a low oil pressure trip device, to prevent trouble due to failure of bearing oil pressure.

As with the low oil pressure trip, the pressure switch acts when the specified operation pressure is reached, and the solenoid valve is actuated to trip the turbine.

Since the overspeed trip device, excess back pressure trip device and low oil pressure trip device all tested and set in the manufacturer's shop test, never readjust them unless necessary.

9. Sentinel Valve

The sentinel valve is designed so that when exhaust pressure excessively rises, it pushes up the ball, overcoming the compression force of the spring to emit steam, thereby giving an alarm before the excess back pressure trip device to operate.

Its operating pressure can be adjusted by means of the adjust screw.

10. 3-way Solenoid Valve for Remote Trip

To remotely trip the turbine, push the remote trip push button provided in the cargo oil control room to demagnetize the solenoid valve which is provided in the hydraulic circuit let to the trip cylinder of the emergency stop valve.

In normal operation the solenoid valve is in energized state.

While it is energized, the oil circuit from the oil pump to the trip cylinder is opened and drain hole to the oil reservoir is closed. When it is deenergized, the solenoid valve inlet is closed, due to which the drain holes of solenoid valve trip and trip cylinder are opened.

Lubrication And Governing System ENV-116G Turbine 2

6. Over Speed Trip

The turbine is aquipped with an overspeed trip which prevents overspeed of the turbine by tripping the emergency stop valve and shutting off the supply of the steam to the turbine.

If the turbine speed increases by abnormal condition as much as predetermined value (about 115% rated speed), the over-speed operates and shuts the emergency stop valve through the emergency mechanism linkage.

It is an eccentric weight type and is equipped in the main oil pump end of the gear shaft.

The center of the gravity of the weight is slightly offset from the axis of ratation and is normally held in place by the compression of the spring.

When the turbine is operating at normal speed, the lever is kept in its normal position.

But when the turbine reaches the predetermined speed (about 115% rated speed), the eccentric weight due to centrifugal force, overcomes the spring compression and moves outward, and strikes the lever. The valve moves down-ward, supply oil to trip cylinder is cut off and be drained.

Supply oil press., from overspeed trip decreases, The oil piston moves up-watd and it rotates the trip lever through the trip pin.

The latch pin and spring seat hand wheel, spindle, coupling, pilot disc and disc are moved together by the spring.

Consequently, the emergency stop valve is shut down.

The tripping speed is tested at the factory and should not be changed unless absoulutely necessary.

When needed, loose sets screw then turn the adjust screw clocwise to increase the set speed or counter clockwise to decrease the set speed.

If should be taken that to lock the set screw after adjusting of the overspeed trip.

If the overspeed trip has been operated, pull the red reset knop before the emrgency stop valve is reset.

When manual trip is needed, push the trip knob the emergency stop valve is tripped.

7. Excess Back Pressure Trip

The turbine is provided with an excess pressure trip device to prevent trouble due to excessive back pressure rise.

When the turbine back pressure rises, the steam sentinel valve begins to emit steam.

When it rises further up the operating pressure, the pressure switch acts and actuates the solenoid valve provided in the hydraulic circuit led to trip cylinder of emergency stop valve, due to which oil pressure is shut off and discharged to drain.

Therefore, in the same manner as when the overspeed trip device acts, the trip mechanism of emergency stop valve, closes the emergency stop valve to shut off steam inflow.

The operating pressure of the excess back pressure trip device can be adjusted as required by turning the adjust screw of pressure switch.

Lubrication and Governing System ENV-116G Turbine 1

1. General

• The lube oil system for turbine and reduction gear. Lube oil is sucked up from the oil reservoir by the main oil pump or aux. Oil pump and supplied to the pinion bearing, gear bearing and gear teeth surface through the stariner and oil cooler, and the it returns to the oil reservoir.
• The bearing oil pressure is regulated by oil relief valve, and excess oil returns to the oil reservoir.

2.  Speed Governor

• The rotational speed of this turbine is controlled by the Wood Ward governor.
• This governor is driven by the drive gearounted on the front end of the main oil shaft.
• It ensures an exellent speed controlling, enabling to keep always constant the rotational speed of the turbine regardless  of variation of load and steam conditions.
• The speed setting point can be significantly changed by turning the speed setting dial with hand the remote control motor.

3. Main Oil Pump and Governor Drive Gear

• The main oil pump is driven at properly reduced or increased speed by the drive gear (drive) mounted on the upper end of the gear shaft and the drive gear (follow) fitted to the gear (drive).
• A governor driving gear (drive) is mounted on one end of the pump gear.
• This gear drives the governor through the gear (follow).
• A tachometer transmitter is provided at the upper end of the pump gear (follow).

4. Auxiliary Oil Pump

• This turbine equipped with auxiliary oil to furnish bearing lubrication during starting and shut down periods.
• The until has one motor-operated pump which providess auto-start and stop by means of a pressure switch.

5. Oil Relief Valve

• The oil relief valves is mounted on the bed plate. Usually, it serves to keep constant the bearing oil pressure and gear spray oil pressure.
• The optimum oil pressure during operation is 0.7 ~ 1.5 kg/cm2 G.
• The oil pressure is regulated by the compression force of the spring.
• It is recommended to set it to obtain 1.5kg/cm2 G at the optimum oil temperature (30~50^0 C at cooler outlet) with the turbine's specified rotational speed.

To be Continued: 
Lubrication and Governing System ENV-116G Turbine 12

Reduction Gear Turbine for Cargo Oil Pump ENV-116G

Type ENV-116G Turbine for Cargo Oil Pump, Reduction Gear

1. General

• This reduction gear is designed high reduction ratio and the pinion shaft end fits a turbine rotor in order to obtain high efficiency and economy of space.

2. Gear Casing

• These are made of close-grained cast iron and divided in the vertical plane through the axis of the pinion and wheel.
• The rear casing of the turbine is bolted on the rear gear casing. The rear gear casing is mounted on the bedplate and lub. Oil drains out to the bedplate.

3. Gear Wheel and Pinion

• The pinion is made from Ni-Cr-Mo steel, and the gear wheel is made from forged steel, and these are carefully heat-treated.
• The gear wheel is pressed on the gear shaft and secured with keys. The one end of the wheel shaft is connected with the load by the coupling through intermediate shaft and another end drives a oil pump and a tachometer through a drive gear.
• The gear and pinion teeth are of the involute single herical type and precisely machined.
• The pinion end thrust bearing of michell type supports against the thrust force.

4. Bearing

• The pinion and gear journal bearings is steel back lined with white metal and split in the vertical plane of the centerline to from bearing halves.
• The pinion bearings and two gear bearings is fitted gear casing rearby bearing cover with bolts firmly.
• The luch of bearing prevents to rotate and remove toward axis. Lubricating oil for bearings is supplied through the hole of the gear casing rear.
• Thrust force of pinion is supported by michell type, and the gear wheel position is by plen thrust bearing and liners.

Construction of ENV-116G Turbine 2

6. Emergency Stop and Governor Valve

The emergency stop valve is situated upper position and the governor valve is situated down position.

1. Emergency Stop Valve

• The emergency stop valve has two distinct purposes. First, to control throttling of steam when starting and bring the turbine up to speed; second, to act as quick-closing valve when tripped by hand or remote=trip, and as emergency stop valve when tripped automatically by safety device such as over speed trip, back pressure trip, low oil pressure trip.
• The spindle and the spring seat is threaded, the spring is compressed by the spring seat, and the pin on the spring seat is set by lever which is connected to the trip cylinder.
• The trip cylinder consist of the piston rod, the piston, the spring and the cylinder body. When the oil pressure in the cylinder body decrease, the piston is moved upward by the spring force together with the piston rod and the lever. At same time the pin on the spring seat is severed from the lever, so the spring seat, the spindle, the pilot disc and the disc are forced down by the spring.
• Thus, the emergency stop valve, the piston is situated at reset position by the oil pressure in thecylinder body. By hand the hand wheel is turned to the right, and by turning th hand wheel to the left is opened the emergency stop valve.
• The disc must be open after the pilot disc and being small deference pressure on the disc upper and lower face, by means of restricting the steam flow with the adjusting disc.

2. Governor Valve

• The Governor valve position is determined by movement of the governor and the governor valve controls the flow of steam to the steam chest.
• The governor valve consist of the adjusting disc, the disc guide and the stem, and is the balance type. The adjusting disc is guided by the bush and is controlled by the stem on account of the governor movement. The stem flows inter the steam chest through the port on the diec guide.

3. Governor Link

• The governing shaft of the governor and the governor valve stem are connected with the governor link. and that is consisted of ball joints, a lever, rods and fulcrum pins. The link conveys smoothly the movement of the governor to the governor valve.
• The link needs the adjustment for reassembly that the clearance between the governor valve stem and the stopper of the valve seat is about 2mm when the governor is full shutting. Changing the position of the pin needs in case the steam flow of the governor valve is reduced at full opening of the governor.