Instruction Manual for Single Stage 350, 500, and 700 Frame Steam Turbines

Troubleshooting

No.

Symptom

Probable Cause

Corrective Action

Excessive

Misalignment.

Check the alignment when the turbine is hot.

vibration or

Disconnect coupling between turbine and driven

noise

machine; run the turbine alone. If the turbine

runs smoothly, there is either misalignment, a

worn coupling, or the driven equipment is at

fault. To check alignment, refer to Section C. If

the turbine drives a coupled gear, and the gears

run together at the top, allow for the pinion

running in the top of its bearing when under

load.

Worn bearings

Replace bearings. Refer to Section L.

Worn coupling to driven

Check condition of coupling. Replace if

machine.

necessary.

Glands fitted too tightly.

Tight carbon rings may cause vibration and

overheating. Refer to Shaft Packing Section for

proper clearance.

Loose wheels are extremely

Rotor should be returned to the factory to be

unusual, but may be caused by a

repaired.

runaway,

excessive

steam

temperature or shock loading.

Bent shaft

May be caused by hot bearings (see “Bearing

Heating and Wear”), tight glands (see “glands

Fitted too Tightly”), or mechanical damage.

Check the shaft runout near the center, as well

as at the shaft extension. Replace the shaft if

runout is excessive. Refer to Section L.

Unbalanced coupling to driven

Remove coupling halves and check for

machine

unbalance.

Unbalanced wheel

Check if turbine wheel has become unbalanced

due to fouling, over-speeding, or loss/damage to

shrouds or blades. Check if the turbine has been

standing idle for a long period without drainage

of the exhaust casing. Solid matter can build up

in the lower half of the wheel, causing

unbalance. The turbine wheel must be cleaned,

re-balanced or replaced. Refer to Section L.

Table K-1. Troubleshooting Guide

184

Troubleshooting

No.

Symptom

Probable Cause

Corrective Action

Piping strain

Both the inlet and exhaust steam lines should be

properly supported to prevent strains from being

imposed on the turbine. Sufficient allowance

should be made for thermal expansion. Refer to

Section C.

Excessive end play

Check the axial position of rotor. If the endplay

exceeds 0.020”, replace thrust bearing. Verify

that coupling is cleaned and installed properly

so that excessive thrust is not imposed on

turbine from driven equipment.

Bearing

Improper lubrication

Refer to Section F to verify that the proper

Failure

lubricant is being used. Check oil periodically to

ensure that it is free of condensate and sediment.

Improper water cooling

When water-cooling is required, the water flow

must be adjusted to maintain bearing oil sump

temperature in the normal range, as shown in

Table F-2.

Wear and/or scratches in sleeve

Replace the sleeve bearings, drain oil reservoirs,

bearing

clean bearing housings, and add new oil. Inspect

journal surfaces.

Rough or untrue thrust collars.

Rough or untrue thrust collars on single-stage

(shoe-type bearing)

machines may cause rapid wear on thrust

facings of the sleeve bearings. This could

eventually increase thrust clearance to a point

where the turbine wheels would rub on the

guide or reversing ring. Rough or untrue collars

should be replaced or repaired at the first

opportunity.

Misalignment

Misalignment is one of the common causes of

bearing failure. Refer to remedies for

Misalignment under Vibration above.

Table K-1. Troubleshooting Guide (Cont.)

185

Troubleshooting

No.

Symptom

Probable Cause

Corrective Action

Bearing fit

Ball bearings should fit on the turbine shaft with

a light press fit. Too tight a fit can cause

cramping; too loose a fit will allow the inner race

to turn on the shaft. Either condition results in

wear, vibration, overheating, and ultimate

bearing failure. Replace the shaft if worn below

recommended or specified size. Refer to Section

Excessive thrust

Verify that the coupling is clean and is installed

so that excessive thrust is not imposed on the

turbine from the driven equipment. If a fairly

high thrust is imposed on the turbine, consult the

factory to determine whether the thrust bearing is

suitable for the application.

Excessive belt pull

On belt driven units, verify that belts are not too

tight and consult the factory to determine

whether the turbine bearing is suitable for the

application.

Unbalance

Refer to Unbalanced Wheel under Vibration

above. Unbalance can cause excessive bearing

wear and early failure.

Excessive tension

The tension on the speed changer spring must be

spring

type

speed

sufficient to hold the governor lever firmly

changer.

against the governor spindle connection under all

conditions. Avoid any unnecessary loading on

this spring, as this would impose excessive load

on the thrust bearing.

Speed governor trying to

Leaking or stuck valve should be corrected, as it

close a leaking or stuck

constitutes a safety hazard, besides being

governor valve.

detrimental to the thrust bearing. Excessive wear

is also imposed on the governor ball thrust

bearing.

Heavy slugs of water in

This condition can be avoided through proper

the steam.

boiler control. Damage to the thrust bearings

and wheels will result from water slugs.

Table K-1. Troubleshooting Guide (Cont.)

186

Troubleshooting

No.

Symptom

Probable Cause

Corrective Action

Rust

Rust may develop on bearing surfaces when the

turbine is improperly stored; refer to Section A

for details. Rust may also develop when the

turbine is out of service for long periods, without

receiving proper attention; refer to Section J.

Excessive steam

Dirt under rings

Steam leaking under carbon rings may carry

leakage past shaft seals

scale or dirt, which can foul the rings. Remove

rings and clean, as per Section L. The rings

should be free to float axially, and the

downstream face of the ring must seat perfectly

against the smooth, true and clean surface of the

adjacent carbon ring spacer.

Shaft scored

The shaft surface under carbon rings must be

smooth to prevent leakage. Factory-supplied

shafts are hard chrome plated. Polish minor shaft

imperfections or replace the shaft, per Section L.

Worn or broken carbon

Replace with new carbon rings, as per Section L.

rings

Although there are

3 segments per ring, the

entire ring must be replaced. Carbon rings

should have a slight clearance on the shaft when

cold, as carbon expands much less with heat than

steel.

Corroded, worn or dirty

Steam will leak past the carbon ring partition

partition plate surfaces

surface if dirt, corrosion or scoring prevents a

good seal. Polish sealing surfaces. Replace

partitions (when used) if badly worn or pitted.

Refer to Section L.

Labyrinth steam seal

Refer to Sections L and Supplemental Data for

improperly installed

proper installation procedure.

Worn or broken labyrinth

Replace labyrinths. Refer to Sections L and

steam seal teeth

Supplemental Data for proper installation

procedure.

Excessive

exhaust

Packing cases are designed for a pre-determined

pressure

backpressure. Excessive backpressure causes

leakage, which is a common cause of water in

the lubricating oil.

Excessive joint sealing

When replacing carbon rings, use joint

compound in gland

compound sparingly. Excess compound may

housing

foul carbon rings and gland housing sealing

surfaces.

187

Troubleshooting

Table K-1. Troubleshooting Guide (Cont.)

No.

Symptom

Probable Cause

Corrective Action

Leak-off pipe plugged

Verify that all steam and condensate can

discharge freely. Refer to Section C.3.10.

Oil leaks past laby seal

High oil level

Reduce the oil level to coincide with marks on

bearing housings. Refer to Section F.

Scratched or rough shaft

Polish the shaft under the laby seal and install a

under laby seal

new laby seal. Refer to Sections F and L.

Seal improperly installed

Refer to Sections F and L for proper installation

procedure.

Shaft vibration

Refer to all causes under Vibration above. Install

a new laby seal, if necessary, as per Sections F

and L.

Insufficient

power

Too many hand-valves

Open additional hand-valves. Refer to Section I

(turbine does not run at

closed

for proper adjustment of hand-valves.

rated speed)

Oil relay governor set too

Refer to Section D for speed adjustment and

low

speed range limits.

Inlet steam pressure too

Check the steam pressure at the turbine inlet and

low or exhaust pressure

exhaust pressure close to the exhaust casing,

too high

using accurate gauges. Refer to the turbine

nameplate for intended steam conditions. Low

inlet pressure may be the result of auxiliary

control equipment such as a pump governor

which is too small, improper piping size,

excessive piping length, etc.

Load higher than turbine

Determine the actual load requirements of the

rating

driven equipment. In some instances, modifying

a few components can increase available turbine

power. Consult the factory for this

determination.

Throttle

valve

not

Close the main inlet valve and disconnect throttle

opening fully

linkage. The valve lever should move freely

from fully open to fully closed. If not,

disassemble the throttle per Section L and free

up the assembly, as required.

Low governor oil level

Refill—Refer to Section D.

188

Troubleshooting

Table K-1. Troubleshooting Guide (Cont.)

No.

Symptom

Probable Cause

Corrective Action

Nozzles plugged

Remove the cover and rotor and inspect nozzle

openings. Remove nozzle block to clean nozzles

as required.

Steam strainer

Remove all foreign matter from steam strainer.

Refer to Section L.

Speed increases

Throttle valve not closing

Refer to governor valve not opening fully under

excessively as load is

fully, governor responds

Insufficient power above. Free the sticking valve

decreased

slowly due to worn parts

and inspect all pivot points in linkage for signs

or sticking.

of sticking or binding or excessive wear.

Throttle valve and valve

Remove governor valve, as per Section L. Check

seats cut or worn

valve and seats for wear or steam cutting.

Replace if necessary.

Excessive speed

Governor

droop

An increase in the internal droop setting will

variation

adjustment

reduce speed variation or hunting. Refer to

Droop Adjustment in the Woodward Governor

Manual.

Governor lubrication

Low governor oil level, or dirty or foamy oil

may cause poor governor operation. Drain, flush,

and refill governor with the proper oil. Refer to

Section D.

Governor valve assembly

Disassemble the governor valve per Section L.

friction

Inspect for free and smooth movement of all

moving parts. If required, polish throttle valve,

governor valve and bushing assembly, and valve

stem with very fine Emery cloth. Inspect valve

stem for straightness and for build-up of foreign

material. Replace components as required.

Governor valve seal

Check the valve stem for free and smooth motion

friction

through the throttle bonnet assembly. If friction

or binding occurs, disassemble throttle bonnet

assembly and repair or replace seal components,

as necessary. Refer to Section L.

Rapidly changing load

Rapidly changing load can sometimes cause

governor hunting. Consult the factory, providing

details of the application.

189

Troubleshooting

Table K-1. Troubleshooting Guide (Cont.)

No.

Symptom

Probable Cause

Corrective Action

Governor knife edges

These must be replaced if badly worn. There is

worn.

no effective repair for these parts.

Lost motion so the

This is usually the result of excessive wear at the

governor valve does not

pivot points in the linkage. Bearing in the

always follow the motion

linkage should be replaces, as well as the linkage

of the governor.

pins.

Light load and high inlet

In some cases, where the turbine provides a large

steam pressure

amount of reserve power and the inlet steam

pressure is quite high, there is a tendency for

excessive speed variation. Try operating the

turbine with additional hand-valves closed. This

condition can sometimes be corrected by

replacing the governor valve and bushing

assembly. Consult the factory, providing details

of the application.

Sluggish governor

Governor

droop

Reduce the droop setting. Refer to Droop

response.

adjustment

Adjustment in Woodward Governor Manual.

Turbine carrying very

Open necessary hand-valves to increase

heavy load, little reserve

horsepower.

power.

Slow start-up

General

Refer to all causes under Insufficient power

above.

High starting torque of

Obtain the required starting torque from the

driven equipment

driven equipment manufacturer and consult the

factory to determine whether the turbine is

overloaded in the application.

Governor not operating

Governor valve travel

Refer to Governor valve not opening fully under

restricted

Insufficient power above.

190

Troubleshooting

No governor control on

If the speed increases continuously on start up

start-up

and the governor does not close the throttle

valve, the governor pump may be installed in the

wrong direction of rotation. Also verify that the

installed governor operates in the proposed speed

range. If pump rotation appears to be the

problem, remove the governor according to

Section L. Replace it with a governor of the

proper rotation. Refer to the Woodward

Governor Manual for instructions on changing

governor rotation or consult the factory.

Table K-1. Troubleshooting Guide (Cont.)

No.

Symptom

Probable Cause

Corrective Action

Governor oil leakage

General

Isolate the source of leakage. If leakage is at the

cover plate gasket, drain plug or oil breather,

replace the gasket and/or tighten these

components to stop the leak. If leakage occurs at

terminal shaft seals or the drive shaft seal,

replace the governor per Section L.

Drive assembly vibration

Vibration of the turbine shaft or governor drive

coupling may induce leakage at the governor

drive shaft seal. Refer to all causes under

Excessive vibration or noise above. Inspect and

tighten the coupling per Section L. Check for

misalignment or bent turbine or governor shaft.

Overspeed trip actuates

Overspeed trip set too

The over-speed trip should be set at

on load changes

close to turbine operating

approximately

16% OR 21% above the rated

speed

speed, depending on the NEMA rating (D or A)

of the governor. Refer to Section E.

General

Refer to all causes under Speed increases

excessively as load is decreased above.

Light load and high inlet

Refer to Light load and high inlet steam pressure

steam pressure

under Excessive speed variation above.

Overspeed trip actuates

Excessive vibration

Replace the trip lever and/or trip latch if latching

at normal operating

surfaces are worn, after resolving cause of

speed

excessive vibration.

191

Troubleshooting

Trip speed setting too

If the turbine consistently trips at or close to the

low

same speed, the trip setting may be set too low.

The setting should be approximately 16% OR

21% over rated speed, depending on the NEMA

rating (D or A) of the governor. Refer to Section

E for adjustment procedures.

Overspeed trip does not

Trip speed setting too

If the overspeed trip has not actuated when the

actuate at overspeed

high

turbine reaches 25% above rated speed, the trip

speed setting may be too high. The setting should

be approximately

16% OR 21% over rated

speed, depending on the NEMA rating (D or A)

of the governor. Refer to Section E for

adjustment procedures.

Table K-1. Troubleshooting Guide (Cont.)

No.

Symptom

Probable Cause

Corrective Action

Overspeed cup

Examine mechanism. Verify that it is clean and

mechanism

in good working order, and that the trip weight

can be moved easily by a small screwdriver or

similar tool.

Improper adjustment or

The trip valve must be tested frequently. To test

poor condition of the

the valve, trip the over-speed mechanism by

tripping

mechanism,

hand. Make sure the trip valve closes promptly

springs or latches.

and stops the turbine.

Excessive friction in trip

These serious faults should be corrected by

valve spindle packing.

cleaning, repairing or replacing parts so that this

Scaling,

wear,

important safety device can operate effectively.

mechanical damages in

trip valve or its supports.

Governor does not trip at

Gain access to and examine the overspeed

or near the proper speed.

governor. Make sure it is clean, in good order,

and that the emergency weight can be easily and

freely moved in the governor cup by a small

screwdriver or similar tool. Adjust as described

in Section VI. Test the unit by actually over-

speeding. If it still does not trip at the proper

speed, adjust the setting of the emergency

governor as required. If low oil pressure trips,

solenoid trips, high back pressure trips, or similar

devices are provided, check them at the same

time.

192

Troubleshooting

Overspeed trip valve

Overspeed trip valve may be frozen in place due

unable to close

to steam deposits, corrosion, or other

contaminants. Disassemble and clean valve

assembly according to Section L.

A broken steam strainer, or other foreign objects,

may interfere with proper seating of the over-

speed trip valve. Disassemble and inspect

combination valve according to Section L.

Excessive steam

Load

greater

than

The operator, after acquainting himself with the

consumption.

realized.

correct hand valve use on the turbine, must make

sure the correct combinations of hand valves are

open for various loads.

Table K-1. Troubleshooting Guide (Cont.)

No.

Symptom

Probable Cause

Corrective Action

Speed below normal.

Check the steam pressure and backpressure. Make

sure the governor is fully opening the valve. Check

and see if the hand valves are in use as designed.

Too many hand valves

This situation gives a turbine excessive capacity

open.

which requires throttling by the governor valve to

maintain the proper speed. This is inefficient and

uses more steam than necessary. Close the hand

valves to eliminate throttling.

Steam pressure low, or

These conditions must be corrected if the turbine is

exhaust pressure too

to carry a full load. Better boiler control will

high.

provide steam pressure correction. Horsepower

goes down as exhaust pressure goes up over

designed pressure.

Steam is wet, or the

This condition not only causes loss of power, but

super- heat low.

also is dangerous since it causes excessive erosion

on the nozzles and blades. Adjust steam conditions

as per manufacturer's recommendations.

Worn or damaged

This adversely affects the efficiency of the turbine.

nozzles and blades.

Nozzles and/or blades should be replaced or

repaired at the earliest opportunity.

Table K-1. Troubleshooting Guide (Cont.)

Refer

the certified drawings and the appropriate vendor manual for

Troubleshooting Guidelines for optional equipment.

193

Section L

Disassembly and Parts Replacement

L.1 Warnings/Cautions

DANGERS

DO NOT attempt to ADJUST, REPAIR, DISASSEMBLE OR

MODIFY this turbine WHILE IT IS IN OPERATION, unless such

action is expressly described in this instruction manual.

NEVER DISCONNECT INLET OR EXHAUST FLANGES of the

turbine without first isolating the turbine from inlet and exhaust

systems by CLOSING AND TAGGING ISOLATING VALVES

and de-pressurizing the turbine casing and steam chest by

opening all drains. Open connections not protected by isolating

valves should be covered with blank flanges.

Do not remove any covers, guards, gland housings, drain

covers, etc. while the unit is operating.

WARNING

After operating the turbine, allow sufficient time for the turbine

to cool down prior to performing inspection, repair or

maintenance functions.

195

CAUTION

Do not operate the turbine above Maximum Continuous Speed

or below the Minimum Allowable Speed as shown on the

nameplate, for sustained periods of time.

WARNINGS

Modification of, incorrect repair of, or use of non-DRESSER-

RAND repair parts on this turbine could result in serious

malfunction or explosion that could result in serious injury or

death. Such actions will also invalidate ATEX Directive &

Machinery Directive Certifications for turbines that are in

compliance with European Directives. Refer to Section M -

Replacement Parts/Factory Service

NEVER REPLACE ANY ORIGINALLY SUPPLIED BOLT WITH

A SUBSTITUTE BOLT OF UNKNOWN or LESSER GRADE.

DO NOT MIX BOLTS during disassembly. Failure to use the

proper grade bolt could result in SERIOUS FAILURE of

pressure-containing components. Refer to Section B, Technical

Data.

MAINTENANCE PERSONNEL should be THOROUGHLY

FAMILIAR with the TURBINE AND ITS CONTROLS AND

ACCESSORIES, before attempting any maintenance or

service. A complete reading of this manual is recommended.

196

CAUTIONS

If the turbine is equipped with a throttle valve manufactured by

a party other than Dresser-Rand refer to Appendix B for

installation, operation, repair, and maintenance instructions.

If the turbine is equipped with a trip valve manufactured by a

party other than Dresser-Rand refer to Appendix B f this

manual for installation, operation, repair and maintenance

instructions.

WARNINGS

Dresser-Rand turbine components are manufactured from a

variety of materials, depending on steam pressure, steam

temperature, speed and horsepower. Before replacing any

components, be absolutely certain that the REPLACEMENT

PART was INTENDED for use in the TURBINE UNDER

REPAIR.

When RESTARTING a turbine after repair, maintenance or

rebuilding, always TREAT the turbine as if it were a NEW

TURBINE being started for the first time. Refer to Section I,

Start-Up and Operation.

CAUTION

CLEANLINESS is ESSENTIAL for long, trouble-free service

from BEARINGS and the GOVERNOR. Take care to ensure

that no foreign material enters bearing housings, the governor

or constant level oilers when performing maintenance, checking

oil, adding oil, or making adjustments.

L.2

General

This section describes disassembly and parts replacement for Dresser-Rand SST

turbines. Some parts of a SST turbine can be replaced in the field using instructions

197

presented in this section, if qualified personnel and facilities are available. If not, it

is recommended that a Dresser-Rand service representative be employed to make

the field repairs, or that the turbine be returned to the factory, where a complete

inspection can be made. If returned, the factory will prepare an estimate of the cost

of cleaning the turbine, replacing parts as required and restoring the turbine to

practically new condition. After factory repair, the turbine will be no-load tested

and preserved just as a new machine would be. A factory-rebuilt turbine receives a

new turbine warranty.

L.3

Turbine Case Upper Half Removal and Replacement

The upper half of the turbine case must be removed to gain access to the shaft

packing and turbine rotor. NOTE: Make sure that the steam inlet and the exhaust

line shut-off valves are shut before starting work.

In some applications, special bolting is supplied. Consult the factory before

replacing or torquing the bolts in the turbine.

WARNING

NEVER REPLACE THE ORIGINALLY SUPPLIED BOLT WITH

A SUBSTITUTE BOLT OF UNKNOWN or LESSER GRADE.

DO NOT MIX BOLTS during disassembly. Failure to use the

proper grade bolt could result in serious failure of pressure-

containing components.

If the applicable bolt torque is not specified in the Assembly/Disassembly section,

the following table may be used as a guideline.

The procedure for removing and replacing the case upper half is specified below.

Refer to the following figures:

L-1

Case Upper Half Removal

L-2

Flange Bolt Torque Sequence

L-3

Flange Bolt Torque Sequence, 700H Casing

L-9

Hand Valve Assembly

M-8

Case, Rotor and Mechanical Gland Seals

M-9

Case, Rotor and Carbon Ring Gland Seals

Turbine Cover Removal (Upper half of the exhaust casing)

a. Remove the bolts from the horizontal flange of the turbine.

198

b. Break horizontal joint (cover/case mating surfaces) by inserting jacking bolts

in holes provided at the four corners of the cover flange.

c. Using a hoist and center eyebolt at the top of the upper case half, lift turbine

cover slowly and carefully so as to avoid damaging the rotor inside. Refer to

Figure L-1 Case, Upper-Half, Removal.

Place turbine cover on a clean surface so as to prevent damage to its sealing

face.

Figure L-1. Case Upper-Half Removal

Turbine Cover Replacement (Upper half of the exhaust casing)

a. Inspect the interior of the turbine cover and exhaust casing. Remove any

foreign material.

b. Remove all old sealant from both surfaces of the horizontal joint. Do not file,

gouge or scratch these surfaces. If the surfaces are warped, steam-cut or

otherwise damaged, a leak-tight seal may not be possible.

c. Apply joint sealant after cleaning the split surface on case and cover. Apply a

light coat of Hylomar (recommended by Dresser-Rand) to sit for 15 minutes

before putting the cover on the case.

199

Approximate

location if string or

tape is used

Steam End

Figure L-2. Flange Bolt Torque Sequence

TORQUE — STUDS AND STUD BOLTS

TORQUE VALUES BELOW ARE TO ATTAIN APPROXIMATELY 45,000 PSI STUD

STRESS

SIZE

THREADS PER INCH

TORQUE (FT.•LBS.)

0.500

0.625

106

0.750

188

0.875

303

1.000

455

Table L-1. Applied Bolt Torques for Case Flange Bolts

1. After the joint is properly prepared, the threads that protrude through the flange

should be lightly coated with a thread lube/anti-seize compound.

2. Tighten all nuts in the sequence shown to approximately 50 percent of the

specified torque for the first pass and to the full torque value for a second and

third pass.

3. Check and, if required, retighten after the turbine is at normal operating

temperature using the sequence shown.

201

d. Apply anti-galling thread lubricant to the threads of all bolts.

e. Lower turbine cover onto lower half of casing. Ensure the cover seats evenly.

Install and tighten the horizontal flange bolts in accordance with Figure L-2,

Flange Bolt Torque Sequence and Table L-1, Applied Bolt Torques for Case

Flange Bolts. Tighten all nuts uniformly to approximately 10% of the specified

torque; then using the illustration as a guide, tighten to full torque. Check and

re-tighten after turbine is at normal operating temperature, using the sequence

shown.

g. For the SST 700H casing, tighten all bolts in sequence indicated in Figure L-3

to level 1, and then repeat the sequence at level 2, and then at level 3 indicated

in table L-2.

Figure L-3. Flange Bolt Torque Sequence, Series 700H

BOLTS

#1-#24

#25-#38

FIRST PASS

2601-FT-LBS

2001-FT-LBS

SECOND PASS

5251-FT-LBS

4001-FT-LBS

THIRD PASS

5251-FT-LBS

4001-FT-LBS

Table L-2. Applied Bolt Torques Case Flange Bolts

202

h. Complete installing flange bolts using the sequence in Figure L-3 and the

applied torques in Table L-2.

After the turbine is completely re-assembled and the coupling is made up, it

should be brought up to operating temperature and the bolts checked again.

There should be no slacking off of the bolts as a result of heating and cooling.

When removing or replacing the top half of the casing, great care must be

exercised to avoid damage.

L.4

Carbon Ring Removal and Replacement

L.4.1

Carbon Ring Removal

Refer to the following figures:

L-4

Carbon Ring Assembly, Non-Condensing Turbine

L-5

Carbon Ring Assembly, Condensing Turbine

Figure L-4 Carbon Ring Assembly, Non-Condensing Turbine

When removing the packing rings, be sure to keep each ring by itself. Note that the

ring segments are marked; these marks should be placed together when fitting or

replacing the rings in the turbine. When gland leakage indicates the necessity of

packing ring maintenance, it is recommended that new rings be installed.

203

New packing rings furnished by Dresser-Rand will be made with the correct

diametral clearance, based on the original contract steam conditions. A packing

ring diagram, EW-33275 located in Appendix A, shows the part number and

location of each ring in the turbine.

When it is necessary to refit old rings (due to emergency condition) remove a small

amount, approximately

0.001”/0.025 mm from the ends of each segment,

maintaining flat square ends. The diametral clearance between the carbon rings

and the shaft should be as specified in the Packing Ring Diagram.

When installing new rings, the shaft surface should be smooth and highly polished,

clean and free of dust, water or oil. The spacer rings should be clean and smooth

with a true surface. If the sealing surface of the spacer ring is warped, the carbon

ring cannot seal. Warped spacer rings should be replaces. To install new carbon

rings, see Figure L-6 for procedure.

Figure L-5 Carbon Ring Assembly, Condensing Turbine

a. If there is a leak-off connected to the cover disconnect this and remove the

pipe from the cover.

204

b. Remove turbine cover according to the procedure specified in Section L.3.1.

c. Disconnect the garter spring ends. Remove the garter springs and carbon ring

segments. Note that the anti-rotation pin in the packing case may interfere

with carbon ring segment removal. If so, simply rotate the segment in the

opposite direction, or rotate the partition plate.

d. Inspect and clean the spacer rings. If the spacer rings are damaged they should

be replaced. The shaft will have to be removed. Refer to Section L.9 Rotor

and Turbine Wheel Removal and Replacement.

e. Clean the stainless steel high velocity oxy fuel-coated surfaces of the shaft

with stainless steel high velocity oxy fuel spray. Inspect the stainless steel

plating. If plating is bubbled, split or peeling the shaft must be replaced.

L.4.2 Carbon Ring Replacement

a. Thread the garter springs into the slots between the spacer rings.

b. Install the carbon ring set one complete set at a time. Be certain to maintain

the correct relationship between carbon ring segments by matching dots

stamped on each segment. Dots should face toward the wheel. The anti-

rotation notch must engage the anti rotation pin.

c. Connect the garter springs to retain the carbon rings.

d. Replace the turbine cover per Section L.3.1.

205

Figure L-6. Typical Carbon Packing Installation

L.5

Casing Labyrinth Seal Removal and Replacement

No field repairs of labyrinth are recommended. Slight deposits of the labyrinth on

the turbine shaft is an acceptable condition.

When installing new labyrinth rings, polish the shaft clean to remove any deposits

which may have formed.

Make sure that the quadrants of each ring are matched and that the rings are

installed in their proper position as identified in the packing ring diagram, EW-

33275. On installation of each quadrant of a gland-packing ring, make sure a

compression ring is installed in each hole. (See Figure L-7)

All SST turbine designs require removal of the turbine cover to remove, inspect,

and replace labyrinth seals. Refer to the appropriate section below to service these

labyrinth seals.

L.5.1

Casing Labyrinth Seal Removal

206

Refer to the following figure:

L-7 Labyrinth Seal Assembly

a. Remove the turbine cover according to the procedure specified in Section

L.3.1. The labyrinth seal segment(s) in the cover will be removed during this

operation.

b. Remove leak-off piping before removal of seals.

c. Inspect labyrinth seal segments, locating springs, and the shaft for corrosion,

scoring, or other damage. Clean all components. Replace any part that is no

longer serviceable. Labyrinth seal segments must be replaced as a set. Severe

rubbing one side of all labyrinth teeth may indicate a worn or failed thrust

bearing. Refer to Section L.6.2, Thrust Bearing Removal and Replacement, if

the thrust bearing is suspect.

L.5.1

Casing Labyrinth Seal Replacement

a. Install labyrinth seal segments into the lower half casing by rotating them

between the shaft and casing. Install the locating springs in the depressions, in

the segment and compress the springs as the segment is rotated.

207

b. Install the labyrinth seal segments into the seal housing lower half with

springs. Note that the labyrinth seal segments are matched-marked. Insure

that they are installed with their match-marks next to each other.

c. Install the labyrinth seal segments and springs in the seal housing upper half.

d. Replace the turbine cover and gland-housing cap according to the procedure

specified in Section L.3.1.

L.6

Turbine Bearing Removal and Replacement

SST turbines can be supplied with two, split sleeve journal bearings and one ball

thrust bearing. Shaft journal and bearing dimensions are shown on the turbine data

sheets. When running clearance is excessive, the bearings should be replaced not

re-babbitted. Approximately 0.004”/0.101mm over the maximum clearance is

considered excessive. However, if conditions permit and the unit runs smoothly,

bearings may be kept in service when clearances exceed the recommended

maximum clearance. It is left up to the discretion of the operating engineer as to

when bearing replacement is necessary. The bearings are longitudinally split to

permit removal and installation without removing the shaft.

Refer to the following figures:

M-4

Bearing Housing Assembly, Exhaust End Simple Bearing Case

M-5

Bearing Housing Assembly, Exhaust End Hi Cap Bearing Case

M-6

Bearing Housing Assembly, Non-Drive End Simple Bearing Case

M-7

Bearing Housing Assembly, Non-Drive End Hi Cap Bearing Case

L.6.1

Sleeve - Type Journal Bearing Removal and Replacement

The journal bearing can be inspected and replaced without removing the turbine

upper case.

Sleeve Bearing Removal

a. Remove the bolts securing the governor mounting housing to the steam end

bearing cap.

b. Use a soft drift and hammer to loosen the upper half of the bearing housing.

Tap on the area where the upper half overlaps the lower half. Remove the

upper half.

c. Lift, raise, and slide oil rings over to allow removal of the upper bearing half.

208

d. Raise the shaft slightly (0.040 inch/1 mm) to expose the bearing split line and

remove the upper bearing half.

e. Rotate lower bearing half out of the bearing housing with the locating tab

exiting the housing upon initial rotation.

The shaft can then be rested on the labyrinth seal or optional Inpro/Seal after

the bearing is removed.

g. Inspect bearings for wear or scoring. Replace if necessary. Refer to Section

B.9 for recommended sealant.

h. Inspect shaft journals. If journals are worn or scored, the shaft must be

replaced. Slight scratches or nicks can be removed by stoning or with crocus

cloth.

Sleeve Bearing Replacement

Verify that the bearing journal is clean and undamaged. Coat the journal with

turbine oil.

Lift the shaft (0.040 inch/1 mm) to permit sufficient room to rotate the lower

bearing half into the housing.

Rotate lower bearing half into bearing housing with the locating tab correctly

aligned with the slot in the housing. Note that the bearing split line is below

the bearing housing split line. On installation, the bearing stops will act as

dowels and properly locate the bearings.

Lower the shaft onto the lower bearing half.

Snap the upper half of the bearing into the upper bearing housing half, aligning

the tab so that it fits into the milled slot. After installation, check clearance

using plasti-gage or lead wire.

Place the oil ring(s) into slot(s) on the upper bearing half and verify that they

are free to turn.

Drain and clean bearing housing reservoirs and refill to the proper level with

clean oil.

Apply a thin coating of sealant to the horizontal joint of the bearing housings.

Refer to Section B.9 for recommended sealant.

Replace the bearing cap carefully, so as not to crush the sleeve bearing tabs.

209

Insert and drive in the dowel/taper pin.

k. Install washer and nuts on studs. Torque the nuts first to 25 ft-lbs (34 N-m)

and then to 55-65 ft-lbs (75-88 N-m).

Install bolts and torque them to 55-65 ft-lbs (75-88 N-m).

m. Rotate shaft by hand and observe oil rings through inspection holes in the

bearing cap to verify that rings rotate freely.

n. Install bolts holding upper bearing housing half to governor mounting housing.

L.6.2

Thrust Bearing Removal and Replacement

The standard thrust bearing is a ball bearing located in the non-drive end bearing

housing. Tilting pad thrust bearings are supplied optionally on some turbines.

Refer to the appropriate vendor manual for details.

For turbines where the governor is coupled to the shaft, remove steam end bearing

case cap and then uncouple and remove the governor. For gear driven Woodward

governors disconnect the governor linkage without disturbing the length of the

connecting rod, then remove the bolts that fasten the governor to the housing and

lift off the governor.

The thrust bearing is properly positioned on the turbine shaft by shims at the

factory and should require no adjustment. These shims are used to adjust the

nozzle ring-to-wheel clearance. See figure L-8. Shims are also used to set the

running clearance (float) on a shoe or collar type thrust bearing. Recommended

running clearance for the thrust bearing is 0.010” to 0.020”.

Thrust Bearing Removal

a. Remove the turbine rotor according to the procedure specified in Section L.9.

b. Remove lock nut and lock-washer from the turbine shaft.

c. On turbines with ball bearing journal bearings, remove the oil ring and oil

ring sleeve.

d. Using a suitable puller, remove the thrust bearing from the shaft. Tag both

sets of upper and lower shims to facilitate re-assembly.

e. Using a suitable puller, remove the journal ball bearings from the

shaft.

210

CAUTION

When removing or replacing ball bearings mounted on a shaft,

NEVER PRESS OR APPLY FORCE to the OUTER RACE, as

this may damage the races or balls. NEVER HAMMER on

either the inner or outer races. Bearings should be pressed on

or off shafts with a steady force. Always inspect the shaft for

burrs or foreign material and remove them as necessary, prior

to removal or installation of bearings. If a BEARING BINDS

during installation or removal, DETERMINE THE CAUSE and

CORRECT it rather than apply more force. Installation should

be performed by heating bearings prior to assembly. Heat

bearings slowly and evenly to a temperature not exceeding

250F (120C). Special electrical heaters are available from

industrial suppliers for bearing heating. Alternatively, bearings

may be heated in an oil bath.

On turbines with sleeve journal bearings, take care not to lose the flat spring

located in the bottom of the bearing housing groove. This spring prevents

rotation of the outer race of the thrust bearing.

Thrust Bearing Replacement

a. Install thrust bearing on the shaft with the shield (if so equipped) facing out.

Make sure that the bearing is installed with the manufacturer’s marking, such as a

bearing number or “thrust here”, facing upstream (towards the steam end of the

shaft). Before installing the bearing case cap, check thrust bearing adjustments for

the proper thickness of shims: 0.050”, 1.27mm minimum with assembled shaft

moved fully towards steam end. Set the clearance by properly positioning the

thrust bearing. See Figure L-8 below:

Figure L-8 Nozzle Ring-To-Wheel Clearance

211

On turbines with ball bearing journal bearings, replace the oil ring sleeve and

the oil ring.

Replace lock-washer and lock nut.

Bend the lock tab(s) to lock the nut into position.

Replace the turbine rotor into the turbine casing according to the procedure

specified in Section L.9.

To replace a ball-type thrust bearing, see steam end bearing case assembly and

longitudinal section drawings in Appendix A and proceed as follows:

Remove governor.

Remove steam end bearing case cap.

Remove bearing case end cover.

Disassemble parts from steam end of turbine shaft as necessary to gain access

to the thrust bearing; then remove the bearing. Tag both sets of upper and

lower shims to facilitate reassembly.

Reassemble by reversing the removal procedure. Make sure that the bearing is

installed with the manufacturer’s marking, such as bearing number or “thrust

here”, facing upstream (towards the steam end of the shaft). Before installing

the bearing case cap, check the thrust bearing adjustments for the proper

thickness of shims.

L.6.3

Ball-Type Journal Bearing Removal and Replacement

Bearing removal and replacement on SST 500 and SST 700 turbines with ball

bearing journal bearings is accomplished using the same procedure as that specified

for the thrust bearing in section L.6.2, Thrust Bearing Removal and Replacement.

The only exception is that there is no lock washer or nut retaining the bearing on

the drive end of the shaft. Removal of the exhaust end bearing requires the

removal of the coupling and outboard bearing housing seal. Refer to Section L.5,

Casing Labyrinth Seal Removal and Replacement.

L.7

Bearing Housing Shaft Seal Removal and Replacement

Bearing housings are provided with either labyrinth-type oil seals or optional inpro

seals or magnetic seals. These seals prevent oil leakage from bearing housings and

also prevent penetration of steam, dust, and dirt into the housings.

212

Bearing housing shaft seals are mounted on the turbine shaft. There are two seals

on the drive end bearing housing and one on the non-drive end bearing housing.

Inpro seals & magnetic seals are optional, non-contacting bearing housing oil seals

that replace the three standard labyrinth-type bearing housing seals. The drive end

bearing housing has both an inboard and outboard seal. The non-drive end has only

an inboard seal.

Inpro or Magnetic Seal Removal (Steam End)

Refer to the following figure:

L-9

Bearing Housings With Optional Inpro/Seals

a. Remove the half-coupling from the shaft.

b. Remove the rotor from the turbine according to the procedure specified in

Section L.9.

c. On sleeve bearing turbines, remove the thrust bearing from the shaft according

to the procedure specified in Section L.6.2

d. Clean the turbine shaft outboard of the seal.

e. Slide the seal assembly off the turbine shaft.

Inpro or Magnetic Seal Replacement (Steam End)

a. Clean the shaft and remove any burrs that could damage the seal O-ring.

b. Lubricate the shaft and seal O-ring with turbine oil to facilitate seal insertion

on the shaft.

c. Slide the seal assembly onto the shaft, placing it at is approximate final

position.

d. On sleeve bearing turbines, replace the thrust bearing according to the

procedure specified in Section L.6.2

e. Replace the rotor according to the procedure specified in Section L.9, using

care to correctly position the seal when installing upper halves of the bearing

housings.

213

Replace half-coupling on the shaft.

Inpro or Magnetic Seal Removal (Exhaust End)

(Note: Rotor must be out of the turbine.)

a. Remove the half-coupling from the turbine shaft.

b. Remove journal bearing, oil slingers, and any other items located outboard of

the innermost seal.

c. Slide the seal out of the recess in the bearing housing and off the shaft.

Inpro or Magnetic Seal Replacement (Exhaust End)

a. Clean drive end of the shaft and remove any burrs that could damage the seal

O-ring.

b. Lubricate the shaft and seal O-ring with turbine oil to facilitate seal insertion

on the shaft.

c. Slide the seal onto the shaft, placing it into the recess in the lower bearing

housing half.

d. Replace the upper bearing housing half according to the procedure specified in

Section L.6.

e. Replace half-coupling on the shaft.

Reassemble rotor into the turbine along with the steam seals.

214

Figure L-9. Bearing Housings with Inpro/Seals

L.8

Bearing Housing Removal and Replacement

SST bearing housings are attached to the lower turbine casing with bolts. Two

dowel pins on each housing, maintain their position. Alignment of bearing

housings to the casing and to each other is essential for vibration-free operation and

long bearing life. Bearing housings are accurately aligned at the factory prior to

pinning. Should it be necessary to remove or replace a bearing housing, it is

essential that the alignment be checked and corrected, if necessary, prior to re-

installation of the rotor.

Bearing housing alignment is a precision process that requires skill, experience,

and precise measurement. If there is any question regarding the ability of site

personnel to properly align bearing housings, Dresser-Rand recommends that a

factory-trained serviceman be engaged to perform the service. Contact your

Dresser-Rand manufacturer’s representative or the Dresser-Rand factory to

schedule a service visit.

L.9

Turbine Rotor & Turbine Wheel Removal and Replacement

Refer to the following figures:

215

M-0

SST Turbine, General View

M-1

Trip Throttle Valve Assembly

M-2

Governor, Mounting Housing, and Trip Components

M-3

Gland Sealing Elements

M-4

Hi-Cap Bearing Case Assembly, Exhaust End

M-5

Bearing Housing Assembly, Exhaust End

M-6

Bearing Housing Assembly, Steam End

M-7

Bearing Housing Assembly, Steam End

M-8

Case, Rotor and Mechanical Gland Seals

M-9

Case, Rotor and Carbon Ring Gland Seals

L.9.1

Turbine Rotor Removal & Replacement

The governor, turbine cover, casing labyrinth seals (if so equipped), and carbon

rings must be removed or disassembled to remove the rotor.

Turbine Rotor Removal

a. For turbines where the governor is coupled to the shaft, remove the steam end

bearing case cap; then uncouple and remove the governor.

(See longitudinal

section, Appendix A). For a gear driven Woodward governor, disconnect the

governor linkage without disturbing the length of connecting rod, remove bolts

that fasten the governor to the housing and lift off the governor.

b. Remove the over-speed trip collar according to the procedure specified in

Section L.14.

c. Remove upper halves of bearing housings according to the procedure specified

in Section L.6.1.

d. Remove the top half of the turbine case according to the procedure specified in

Section L.3.

e. Remove shaft packing according to Section L.5.

Remove cap from the exhaust end bearing case and steam end bearing case (if

not already removed in step 1.

g. Remove both main bearing top halves.

216

h. Arrange a suitable support for the rotor assembly. Verify that turbine wheel

blades and bearing journal surfaces on the shaft will not make contact with any

surrounding object. Verify that the assembly will not roll off the support.

Use slings and a crane or hoist to lift the rotor assembly just out of the lower

half of bearings; then remove lower half of bearings. Use extreme care when

lifting the assembly to avoid damaging the wheel, blades, shaft, or sector.

Place rotor assembly on the support.

Turbine Rotor Replacement

Verify that the interior of the turbine casing is clean and that all foreign objects

have been removed.

Clean or replace journal bearings (if so equipped) and lubricate journal area of

the shaft to prevent scratching or scoring.

If so equipped, place lower journal half into the bearing housing. Position oil

rings so that they fit into openings provided in the bearing housings.

Using slings and a crane or hoist, lower the rotor assembly into the casing. Use

care to avoid damage to the wheel, blades, shaft, or sector.

Check clearance between first wheel and nozzle ring. This clearance is

obtained by properly locating the thrust bearing. See figure L-8 and thrust

bearing adjustment procedure in section L.6.2.

Replace casing labyrinth seals (if so equipped) according to the procedure

specified in Section L.5.

Replace turbine cover and gland housing upper halves

(if so equipped)

according to the procedure specified in Section L.3.1.

Replace the sleeve bearing upper halves (if so equipped) and bearing housing

upper halves according to the procedure specified in Section L.6.

Replace the governor mounting housing

Replace over-speed bolt trip collar according to the procedure specified in

Section L.14.

Replace governor drive coupling governor and associated linkage according to

the procedure specified in Section L.12.

L.9.2

Turbine Wheel Removal and Replacement

217

This operation is to be referred to Dresser-Rand service facilities.

CAUTION

DO NOT allow the heating FLAME TO IMPINGE on turbine

BLADES, as this could anneal and WEAKEN them.

WARNING

Exercise appropriate CAUTION in handling the HOT WHEEL

during disassembly and assembly.

CAUTION

Be certain to assemble the wheel and shaft with THE

SHORTER BLADES TOWARD the NON-DRIVE END OF THE

SHAFT. Otherwise, the rotor cannot be installed.

L.9.3

Turbine Rotor Balancing

Whenever a wheel or shaft is replaced, the wheel and shaft subassembly should be

dynamically balanced. This procedure must be performed by a Dresser-Rand

repair facility.

L.10

Nozzle Ring Removal and Replacement

Nozzle rings contain one or more nozzles which expand the inlet steam to a lower

pressure, creating the necessary kinetic energy (velocity) at the entrance of the first

wheel blading.

L.10.1 Nozzle Ring Removal

218

After the rotor and guide ring have been removed from the lower half turbine

casing—

a. Loosen and remove nozzle ring cap screws. This may, at times present

a problem. Broken screws will have to be extracted or drilled out.

Note: When nozzle ring is secured with inner and outer bolts, no caulking

strip is used.

b. The nozzle ring may now be lifted out of the casing. Mark the ring to

identify its location if reused (upper or lower half).

L.10.2 Nozzle Ring Replacement

Nozzle rings are caulked in at the outer periphery and bolted to the steam ring

nozzle bolting face of the main casing when a single row of bolting is used. When

a double row of bolting is used, there is not a caulking strip.

a. Identify the upper and lower half nozzle ring. If necessary check that the

valve port bridge walls match their seal surfaces using bluing or white lead.

b. Check that the clearance holes in the nozzle ring and tapped holes in the

steam ring face agree.

c. Thoroughly clean the sealing surface at the steam ring face. If the

surface is smooth, the most common sealing compounds are Turbo R or

Turbo 50. If the surface is rough, use Copaltite. If these compounds are

not available, use a key paste or a mixture of graphite and oil. If none of

these compounds is available, call Dresser-Rand Technical Support.

d. Bolt the nozzle ring half in place. The cap screws should be pulled tight

but not over-tightened. If Allen wrenches bend during tightening, the

screws are overstressed and their heads may snap off when the unit comes

up to temperature. Over-tightening of screws must be avoided. Prick-

punch head clearance holes at four positions so that cap screw heads (if

broken off) cannot come out into the steam path.

L.11

Hand-valve Removal and Replacement

Hand-valves are optional items. Depending on steam conditions, required power

and speed, and initial customer requirements, the turbine may incorporate no hand-

valves, one hand-valve, or two hand-valves.

219

The purpose of hand-valves is to isolate a nozzle or group of nozzles from inlet

steam, thereby allowing the turbine to operate at reduced power output without

excessive throttling. When operated at reduced power in this fashion, the turbine is

more efficient than it would be if all nozzles were active.

Hand-valves should be either fully open or fully closed, never in between.

Operating with a partially closed hand-valve is not only inefficient, but could result

in steam cutting of the seat resulting in excessive leakage. When putting the unit

into operation, do not close a hand-valve tightly until the turbine is up to operating

temperature and all parts are evenly heated. The reason for this is that the material

of the valve stem is subject to greater thermal expansion than the turbine casing,

and if the valve is closed tightly when cold, it may lock the valve in the closed

position making it difficult to open.

Refer to Figure L-10, Hand-valve Assembly.

L.11.1

Hand-valve Removal

WARNING

Close and tag inlet and exhaust isolating valves and open

drains to depressurize the turbine casing and steam chest

before maintaining hand-valves.

Note: Removal of the hand-valve is done from inside the turbine case.

a. Remove the turbine casing cover and bearing case covers, uncouple the turbine

rotor, and remove the carbon rings. See instructions in other sections of this

manual for these steps.

b. Remove the turbine rotor. Remove the nozzle ring.

c. Once the nozzle ring is removed you can see the hand-valve seat (761). Pull out

the hand-valve seat. The fit is on-line to 0.004” loose.

d. Remove the hand wheel (758). Remove the hand-valve bonnet (750).

e. Push the stem and disc assembly out towards the inside of the turbine. Remove

the old hand-valve packing (754). Note: Count the rings removed.

f. Clean the seat area, nozzle ring face, and all areas that might have sealant.

L.11.2

Hand-valve Replacement

a. Inspect the stem and disc assembly. Hand-valve collar (752) should be tight

and staked to the disc (751).

b. Insert the new stem and disc assembly into the turbine hand-valve location.

220

c. Make sure the seat (761) and the bore of the turbine case are clean. Insert the

seat into the hole where it was removed. If there is a slight interference, cool

down the seat in a freezer or with liquid Nitrogen.

d. Install the nozzle ring in accordance with instructions in other sections of this

manual.

e. Assemble new packing (754). Put in the same number of packing rings as

were removed.

Assemble bonnet (750) and hand wheel (758). Tighten the bonnet to compress

the packing until you feel a slight drag on the stem when you screw it in and

out.

L.11.3

Reassembly of the Turbine Rotor and Upper Half Casing

a. Clean all surface areas (turbine casing split-line, bearing case split-lines, etc).

b. Assemble the carbon rings, turbine cover, and bearing case covers per

instructions given in other sections of this manual.

L11.4

Handvalve Adjustment

a. One steam is admitted into the unit, re-tighten the hand-valve bonnet so there

is no steam leaking out of the steam area. This might have to be done again

when there is full pressure inside the casing to prevent leakage at the high

internal pressure.

b. The valve stem should be screwed fully closed or fully open. It should never

be partially open or closed.

221

Figure L-10. Hand Valve Assembly

L.12

Governor Removal and Replacement

Refer to the following figures:

M-2

Governor, Mounting Housing, and Bolt Trip Components

L-11

Direct Drive Governor Assembly

L-12

Gear Drive Governor Assembly

L.12.1

General

Field service on the oil relay governor is normally limited to yearly oil changes per

Section J, and droop setting adjustment, which is described in the governor manual

provided in Appendix B.

222

In the event that the governor exhibits operational problems, Dresser-Rand

recommends that the governor be removed as a unit and returned to the factory for

repair or overhaul, as required. In the meantime, a replacement oil relay governor

can be quickly and easily installed to keep the turbine in operation. The Dresser-

Rand factory maintains a stock of certain TG replacement governors for rapid field

delivery, and is equipped to perform comprehensive repair, overhaul, and testing of

oil relay governors.

For shipment, care should be exercised to support the governor by its mounting

flange and not by its shaft extension.

Some governors are direct-drive types coupled to the end of the turbine shaft by

couplings, as shown in Figure L-11. Others, due to speed requirements, are

connected by right-angle gear reduction units, as shown in Figure L-12.

L.12.2

Governor Removal (Direct Drive)

a. Drain oil from governor (300) at drain.

b. Disconnect connecting rod

(1075) at governor lever

(445) by removing

connecting rod end (1070). Do not disturb position of rod end (1070) bearing

on rod (to preserve open/close stroke adjustment).

c. Rotate turbine shaft (1), if necessary, to disengage coupling hub (303) by

loosening coupling setscrew.

d. Prop or support governor (300); then, unbolt governor from mounting housing

(201) and slide governor out of mounting housing. Be careful not to lose the

governor key.

e. Remove governor trip latch (446) (if same governor is not to be used as

temporary replacement) by loosening its setscrew.

223

Figure L-11. Direct Drive Governor Assembly

L.12.3

Governor Replacement (Direct Drive)

a. Install governor trip latch (446) and tighten lever set-screw securely.

b. Slip coupling spider between jaws of coupling (303) hub on turbine shaft

extension.

c. Install coupling hub (303) on governor shaft.

d. Slide governor (300) into place on mounting housing (201), verifying that

coupling (303) engages properly.

e. Install and tighten screws to secure governor to mounting housing (303). There

should be 1/16 inch (1.6 mm) play for the coupling spider between coupling

hubs. Coupling access is available through the open side of the mounting

housing. Tighten screw to secure coupling.

Reconnect connecting rod (1075).

g. Remove governor breather cap and fill governor with oil to proper level

indicated on sight glass.

224

h. Rotate turbine shaft (1) slowly by hand to ensure that governor and coupling

are free to turn when placed in operation.

L.12.4

Governor Removal (Gear Drive)

a. Drain oil from governor (300).

b. Disconnect connecting rod

(1075) at governor lever

(445) by removing

connecting rod bolt. Do not disturb position of rod end bearing on rod (to

preserve open/close stroke adjustment).

c. Remove cap screws securing governor (300) to gearbox (316) adapter; then,

lift governor vertically from adapter. The coupling (303) will remain on the

governor shaft at removal. Do not remove governor lever or coupling from

governor if same governor is to be installed again. If a new governor is to be

installed, transfer lever and coupling (with keys) to new governor. The lever

and coupling are secured to governor shafts by setscrews.

Note: The coupling, which joins the governor and gearbox shafts, is supplied with

the gearbox.

L.12.5

Governor Replacement (Gear Drive)

a. Verify that coupling and keys are installed on governor shaft, and that the

governor lever is mounted to its shaft at the side of the governor.

b. Lower governor (300) on gearbox (316) adapter with coupling key slots

positioned to allow mating of keys and key slots of shaft and coupling (303) as

governor and adapter flanges meet.

c. Rotate governor to align cap screw holes; then, install cap screws tightly.

L.12.6

Governor Drive Gearbox Removal

The governor (300) must be removed according to the procedure specified in

Section L.12.4, above, before the gear (310) and governor drive shaft (306) can be

removed.

a. Drain oil from steam end bearing case (200).

b. Remove pin (304) from coupling (303) to release coupling from governor

drive shaft (306).

225

c. Remove lock-nut (313) and lock washer (312) retaining gear onto governor

drive shaft (306). Slide gear (310) up off of shaft (306), being careful not to

lose key (311).

d. Remove shim (308) being careful to document order of removal/replacement.

e. Remove snap ring (318) retaining bearing into housing (301). At this point the

governor drive shaft (306) can be extracted from the housing (301).

f. Prop or support governor drive shaft (306) in a vice being careful not to scar the

shaft surface and remove the snap ring (318) retaining the ball bearing (339).

At this point both ball bearings (339) and (305) can be pressed from the

governor drive shaft (306) for replacement.

The Dresser-Rand factory maintains a stock of replacement governor drive shaft

parts for rapid delivery to the user, and is equipped to perform complete repair and

overhaul service on gearboxes.

L.12.7

Governor Drive Gearbox Replacement

a. Install governor drive shaft (306) into housing (301) and install snap ring

(318). Replace shim (308), locate key (311) into slot on governor drive shaft

(306) and install gear (310), lock washer (312) and lock-nut (313) securing

gear onto governor drive shaft (306).

b. Install coupling (303) and pin (304) into and onto governor drive shaft (306).

c. Before installing the governor, check and record the backlash of the new gear.

In future inspections, use this dimension as a guide in determining the

necessity for replacement. If backlash is questionable use Dyken layout blue

or printers ink to check for proper mesh of gears. When a good mesh is

indicated, the gear may remain in service.

c. Mount governor (3004) onto housing (316), verifying that the splines on the

governor shaft slide into the coupling (303) easily. Install mounting bolts to

secure governor (300) onto housing (316).

d. Fill hydraulic governor with oil. Refer to Woodward Bulletin

25071 in

Appendix B.

e. Fill steam end bearing case (200) with recommended lubricant to required

level, as indicated by oil sight gage plug.

L.12.8

Governor Valve Travel and Linkage Adjustment

227

Refer to the following figures:

M-1

Trip Throttle Valve Assembly

M-2

Governor, Mounting Housing, and Trip Components

L-11

Direct Drive Governor Assembly

L-12

Gear Drive Governor Assembly

L-13

Trip Valve Linkage

Adjustment of the linkage between the governor and throttle should be carried out

whenever linkage components, or the governor itself, are replaced. Rig the throttle

linkage as follows:

a. Check that the governor linkage is approximately at right angles to governor

connecting rod.

(See upper view of figure L-13). Adjust the length of the

connection rod as necessary.

b. Back off the lock nuts on both sides of the governor lever block.

c. Pull the connecting rod out of the Woodward governor as far as it will go.

d. Push the connecting rod back toward the governor 3/16”/4.76mm. (To hold

this position while making the adjustment, place a block equal to the existing

clearance between the connecting rod end and the mating fitting on the

governor—see lower view in Figure L-18.

e. Push the valve stem in until the valve just seats.

f. Tighten the lock nuts on both sides of the governor lever block to secure

the ajdustment.

L.13

Trip and Throttle Valve Maintenance

CAUTION

228

If the turbine is equipped with a throttle or trip valve

manufactured by a party other than Dresser-Rand refer to the

accessory documentation section of this manual for installation,

operation, and repair and maintenance instructions.

Refer to the following figures:

M-1

Trip and Throttle Valve Assembly

M-2

Governor, Mounting Housing, and Trip Components

L-13

Trip Valve Trip Linkage

L-14

Throttle Valve Trip Linkage

The design of the Dresser-Rand trip and throttle valve assembly permits routine

maintenance (disassembly and assembly) procedures while still mounted on the

turbine and without disconnecting the inlet piping. For major overhaul or

necessary machine work, remove the valve as indicated below.

WARNING

BEFORE SERVICING ANY COMPONENT of the combo valve,

verify that the ISOLATING VALVE in the INLET LINE is

CLOSED AND TAGGED. If the turbine is connected to the

exhaust steam header, CLOSE the ISOLATING VALVE in the

EXHAUST LINE AND TAG IT. OPEN ALL TURBINE DRAINS

to ensure venting of all pressure before disassembly begins.

CAUTION

In the following procedures, remove and replace all parts slowly

and carefully to avoid damage (digs, bends, scoring, chipping,

etc.) to conditioned surfaces. DO NOT use excessive force to

remove parts. Use backup bracing for unsupported parts when

taper pins or dowels are removed by hammer and drifts.

L.13.1

Valve Removal from Turbine

The steam strainer should be removed and cleaned at least once a year and

replaced every three years. Since it is necessary to remove the governor

valve before the strainer can be withdrawn, the governor valve and its seats

should be inspected and reground if necessary. To replace either the

229

governor valve or the steam strainer, proceed as follows:

(See Figure L-

14).

Remove valve adjusting nut and washer.

Note: Do not disturb settings of lock nuts and connecting rod-ends (17 and 19) on

rod (18) unless parts need to be replaced. These are factory-set to provide

the required stroke for the rod.

b. Remove snap ring from the governor lever pin; then remove the pin and

carefully slide the governor lever off the governor valve stem.

c. Remove the nuts that secure the steam chest cover to the steam chest and

carefully remove the cover without contacting the valve stem.

d. Pull out the governor valve (see governor section, Appendix A).

e. Remove bolting at turbine flange; then, lift valve by slings and hoist to service

area for further disassembly.

Remove as an assembly together with the steam strainer.

g. Perform necessary maintenance and reassemble by reversing the removal

procedure.

h. After completing installation, set the following:

Overspeed Trip

Overspeed Trip Linkage

Governor Valve Travel

230

Finger 22

3 Valve Seat Bushing

Stem

Strainer

Figure L-13. Overspeed and Governor Valve Linkage

Legend

15. Lockscrew

1. Cap

8. Case - Steam End

16. Lever - Governor

2. Lever

9. Steam - Bellows

17. Pin

3. Lever - Trip

10. Bracket - Low Oil Trip

18. Rod End

4. Lever - Trip Connection

11. Low Oil Trip

19. Rod - Connecting

5. Rod - Trip Connection

12. Governor Cup

20. Shaft - Trip

6. Plate - Top

13. Adjusting Screw

21. Collar

7. Latch - Trip Assembly

14. Emergency Weight

22. Trip Finger & Lever

231

Figure L-14. Throttle Valve Linkage

Legend

1. Bushing - Valve Seat

8. Stem - Valve

14. Cover - Steam Chest

2. Bushing — Valve Stem

9. Pin

15. Lever - Governor

3. Valve

10. Bearing

16. Pin

4. Steam Chest

11. Bushing - Valve

17. Rod End

5. Gasket

Stem-Outer

18. Rod- Connecting

6. Bracket - Governor Lever

12. Block - Pivot

19. Rod End

7. Bushing - Valve Stem - Inner13. Block - Sliding

20. Lever

L.13.2

Woodward TG Governor Valve Travel Setting

a. Remove pin that connects the governor lever to the connecting rod end.

(See Figure L-15.)

b. Push the governor lever in until valve just seats and hold this position.

c. Push connecting rod toward the valve closing direction (see arrow on

illustration) as far as it will go and hold this position.

d. Adjust the length of the connecting rod so that the hole for the pin in the

rod end is approximately 1/8”/3.75mm beyond the mating hole in the

governor rod.

e. Release the connecting rod and insert the connecting pin.

L.13.3

Woodward TG-13L Governor with Fisher Control

232

The Fisher pneumatic speed mechanism acts in conjunction with the Woodward

TG-13L governor to adjust the turbine speed to refined limits. If speed re-

adjustment is desired, re-locate the pin to another hole in the lever (see Governor

Speed Control Schematic, Appendix A).

The Fisher control can be used as a direct or reverse type control; either to increase governor

speed settings as control air pressure signal increases, or the reverse type to increase governor

speed as control air pressure signal

decreases.

Figure L-15. Governor Valve Travel Setting - Woodward TG Governor

233

L.13.4

Alternate Governor Valve Stem Connection

Some Dresser-Rand turbines may be equipped with an alternate method of securing

the governor valve stem to the rotating governor lever. This connection should be

installed so that the inner and outer washers are tight against the alignment pin.

The operator should be able to turn the washers by hand with no lost motion after

tightening the inner and outer jam nuts.

Figure L-16 Alternate Governor Valve Stem Connection

234

L.14

Emergency Valve Maintenance

WARNING

BEFORE SERVICING ANY COMPONENT of the Overspeed

Trip Mechanism, verify that the ISOLATING VALVE in the

INLET LINE is CLOSED AND TAGGED. If the turbine is

connected to the exhaust steam header, CLOSE the

ISOLATING VALVE in the EXHAUST LINE AND TAG IT.

OPEN ALL TURBINE DRAINS to ensure venting of all pressure

before disassembly begins.

The overspeed trip mechanism may be readily disassembled or assembled at a

workbench and then mounted to the turbine as a subassembly. Prerequisites for this

process are removal of the governor and coupling according to the procedure

specified in Section L.12, followed by removal of the overspeed trip collar (90)

from shaft (1), as described below.

It is important that the entire emergency trip system be properly adjusted and free

of binding or lost motion. The operation of the overspeed trip should be tested as

often as possible, especially at times that maintenance is performed and a

permanent record should be kept of these tests. The over-speed trip should

function to shut down the turbine within 2% of the speed specified on the turbine

data sheets. If the operational tests in Section I.6 indicate a requirement for

adjustment, proceed as follows:

L.14.1

Governor Cup Removal

Refer to the following figures:

L-13

Overspeed and Governor Valve Linkage

L-14

Throttle Valve Linkage

L-15

Governor Cup Assembly

a. Gain access to the overspeed governor cup.

For turbines with a Woodward gear driven governor - remove bearing

case end cover.

For turbines with a Woodward governor that is coupled to the shaft -

remove the steam end bearing case cap.

235

b. Manually rotate the turbine shaft (1) until the lock screw (P/N 15, Figure L-13

or P/N 92, Figure L-15) is accessible; then loosen the lock screw.

CAUTION

If the Overspeed Governor Cup Assembly is replaced, the rotor

may need to be re-balanced with the new assembly attached.

Figure L-17. Governor Cup Assembly

Legend:

90. Cup - Governor

94. Spring

91. Screw - Adjusting

95. Bushing - Weight

92. Set Screw

96. Ring - Retaining-Open type

93. Weight

97. Ring - Retaining-External type

b. Using a suitable spanner tool, turn the adjusting screw (91) clockwise to raise

the tripping speed or counterclockwise to lower, as necessary.

c. Tighten the lock screw (15 or 92) (setscrew) securely to lock the adjustment

position, then repeat the over-speed trip test (see warning below).

236

WARNING

The overspeed trip assembly should be locked in place before

starting the turbine. Four checks to make are as follows:

1. The overspeed governor cup must be tightly screwed into

the shaft.

2. If supplied, one of the tabs of the lock-washer is bent into

the miller slot of the overspeed cup.

(The overspeed cup will

have two milled slots for the tabs of the lock-washer, but it will

only be possible to line up one of the tabs. This is due to the

fact that the tabs are not symmetrically located around the

outer diameter. There is no need for concern as long as one of

the tabs can be completely bent over into the slot.)

3. If the overspeed cup has drilled and tapped holes for half

dog point set screws, the shaft must be drilled at final assembly

with the overspeed cup in accordance with the table below to

ensure the tip of the dog point locks into the shaft. The set

screws must be tightened and staked into place.

4. The run-out of the cup must also be checked and adjusted

to within 0.002 inch (.05 mm) total indicated run-out.

L.14.2

Governor Cup Replacement

237

CAUTION

The adjusting screw/spring combination has been pre-set at the

factory for the trip speed originally set when the turbine was

shipped. Refer to Section L.14.7, Trip Linkage Adjustment, if

minor trip speed changes are to be made.

WARNING

Adjusting Screw (91), spring (94), and setscrew (92) are a

FACTORY-CONFIGURED SET, selected to obtain the proper

trip speed for a specific turbine. DO NOT MIX OR

INTERCHANGE THESE PARTS with similar parts from other

turbines or attempt to modify these components. Consult your

local Dresser-Rand manufacturer’s representative or the factory

if replacement parts are needed.

L.14.3

Trip Mechanism Disassembly

For 4” and 6” trip and throttle valve systems, the clearance between the overspeed trip

lever (Figure L-13) and the emergency weight (P/N 14) or (P/N 93 in Figure L-14) is

properly set at the factory for 0.060”/1.524mm plus or minus 0.010”/0.254mm. Gain

access to the over-speed governor cup as described in the preceding section L.14.1.

For 4” and 6” Venturi trip systems, the clearance between the over-speed trip lever

(figure L-13) and the emergency weight (P/N 14 or P/N 93) is properly set at the factory

for (0.090”/2.286mm plus or minus 0.010”/0.254mm. Gain access to the overspeed

governor cup as described in section L.14.1.

Rotate the turbine shaft (1) to position the overspeed weight adjacent to the overspeed

trip lever and measure the clearance. If adjustment is necessary, proceed as follows:

a. Loosen lock screw that secures the valve lever trip connection to the valve

spindle.

b. Slide valve lever connection along the valve spindle away from the steam

chest to increase the clearance, toward the steam chest to decrease the

clearance.

c. Tighten the lock screw to securely hold the valve lever connection.

238

L.14.4

Emergency Valve Travel

a. Unlatch valve lever (P/N 3, Figure L-13) to close emergency valve.

b. Manually pull out on the governor linkage to close the governor valve. On the

turbine, it may be necessary to remove the pin from the connecting rod. (See

lower view of Figure L-18)

c. With the governor valve fully closed, raise the valve lever until the emergency

valve will not open further (do not spring the valve lever).

d. Measure the clearance between the latch surface of the valve lever and the

latch surface of the trip lever. The clearance should be approximately ¼”/6.35

mm.

e. If adjustment is required, loosen the lock screw in the valve lever connection;

then reposition the valve lever connection and serrated valve spindle clockwise

or counter-clockwise as necessary to obtain the correct clearance.

NOTE: After making this adjustment, it will be necessary to re-check the

setting of the over-speed trip linkage.

L.14.5

Emergency Valve Removal and Replacement

a. Remove governor valve and steam strainer as described in section L.13.1.

b. Remove lock screw in the valve lever connection; then slide the valve lever

connection off the serrated valve spindle.

c. Remove access plug in the steam chest located above the valve spindle; then

remove the lock screw that secures the valve spindle to the valve link.

d. Remove access plug in the steam chest in line with the valve spindle and

withdraw the valve spindle.

e. Remove the valve link by sliding up and away from the valve stem.

d. Remove the valve portion of the assembly and inspect the valve seat.

NOTE: If the valve seat must be replaced, the steam chest must be removed from

the turbine.

e. Re-assemble and install the emergency valve by reversing the removal

procedure.

239

Overspeed trip

Overspeed trip linkage

Governor valve travel

Emergency valve travel

L.14.6

Trip and Throttle Valve and Steam Strainer

The following are procedures for replacement of the steam strainer:

a. Close the main steam valve.

a. Disconnect the pressure and drain line connections at the oil cylinder flanges.

c. Disconnect the linkage from the governor lever.

d. Remove the bolts that fasten the trip throttle valve body to the valve body

cover.

e. Remove the bolts that fasten the valve body cover to the valve body; then lift

off the valve body cover.

Lift out the emergency valve guide.

g. Pull out the steam strainer.

h. Perform the necessary maintenance and re-assemble by reversing the removal

procedure.

For procedures on a vendor valve, see Appendix B.

NOTE: The 6” trip and throttle valve cover is equipped with a throttle screw that

regulates the amount of steam from the inlet side of the valve to the chamber

above the main disc. If chattering of the main disc is encountered when

opening the valve, it is necessary to increase the leakage to the chamber by

turning the throttle screw counter-clockwise. If, however, the hand-wheel

effort appears excessive, it can be reduced by turning the throttle screw

clockwise, thus decreasing the leakage to the chamber. A pipe tap is provided

in the cover to be used for a pressure gauge to check the pressure chamber

after the pilot valve has been opened. This leakage pressure should be

approximately 25% of the line operating pressure.

241

Section M

Replacement Parts/Factory Service

M.1

Factory Replacement Parts

Dresser-Rand Turbine recommends that only Dresser-Rand-supplied parts be used

in Dresser-Rand turbines. The use of Dresser-Rand parts ensures that replacement

components are manufactured from the highest quality materials, to exacting

tolerances and specifications, thereby assuring safe, efficient, long-lasting, and

maintenance-free operation under service conditions for which the turbine was

designed and built.

Dresser-Rand and selected Dresser-Rand manufacturer’s representatives maintain a

supply of the most frequently requested spare parts for immediate shipment

worldwide. Parts requested less frequently can be manufactured quickly on an

emergency basis when required.

Your Dresser-Rand manufacturer’s representative can supply you with a stocking

list of recommended spare parts for your turbine or turbines, allowing you to stock

spare parts at your facility. Refer to Section M.4, Recommended Spare Parts.

M.2

Turbine Identification

Dresser-Rand SST turbines are marked with a serial number, which appears on the

nameplate and is also, stamped on horizontal flange of the inlet casing. This serial

number is used by the factory to identify the turbine and should be used in all

inquiries and parts orders.

M.3

Parts Identification

When inquiring to determine parts availability, or when placing an order for spare

parts, the following minimum information is required:

Item

Typical Example

Turbine serial number:

XXXX

Part description:

Shaft

Reference number:

242

Section Drawing

LE-169235-N

If the turbine parts list is available, then the Dresser-Rand part number should also

be specified.

WARNING

Modification of, incorrect repair of, or use of non-DRESSER-

RAND repair parts on this turbine could result in serious

malfunction or explosion that could result in serious injury or

death. Such actions will also invalidate ATEX Directive &

Machinery Directive Certifications for turbines that are in

compliance with those European Directives. Refer to Section M

- Replacement Parts/Factory Service.

M.4

Recommended Spare Parts

The recommended spare parts for a turbine owner is provided in the service

manual. The inventory recommendation for spare parts is based on Dresser-Rand’s

long experience with turbine applications.

M.5

Ordering Parts

Contact your local Dresser-Rand manufacturer’s representative to order parts. Your

representative will be pleased to provide any assistance you may require, as well as

to quote prices and delivery dates.

The following information is required when placing a parts order:

Your purchase order number.

Complete billing, shipping, and marking instructions.

Turbine serial number--from nameplate or horizontal flange of inlet casing.

4. Turbine frame size--from nameplate, i.e., 300, 500, 700, etc.

5. Quantity of each part or assembly.

Part or assembly reference number from drawing, illustration, or text.

7. Section drawing the reference number was taken from.

8. Description of part or assembly.

243

Instruction Manual for Single Stage 350, 500, and 700 Frame Steam Turbines - page 4