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.

Maintanance step: Disassembly of Rotor and Gear Turbine

Disassembly of Rotor and Gear Turbine

1. Remove thermometer of the bearings.
2. Remove the steam chest with the emergency stop and governor valve.
3. Unbolt the turbine casing cover, then remove it lifting horizontally far enough to clear the rotor blades in order to prevent the possibility of damage to the blades.
4. Remove the gland rings and garter springs.
5. Remove the stationary blade retainer of the casing base.
6. Unbolt the gear cover.
7. Remove the main oil pump body with governor and tachometer.
8. Remove the bolts of the thrust cover. (only front half)
9. Remove the gear cover lifting horizontally.
10. Fit the eye bolt to the upper part of the pinion shaft and lift slightly not to incline when the bearing cover is removed.
11. Remove the oil seal ring of the pinion on the gear base.
12. Remove the bearing cover, bearings and thrust bearings of the pinion. Be careful not to fall front half of the thrust washer.
13. Draw out the turbine rotor horizontally. Be careful not to damage the blade.
14. Remove the coupling bolts between the gear and intermedite shaft.
15. Fit the eye nut after removing the nut of the oil pump drive gear and lift slightly the wheel shaft.
16. Remove the bearing covers and bearings of the wheel. Be careful not to fall front half of the thrust washer.
17. Draw out the gear horizontally. Be careful not to damage the gear.

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.