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

WARNINGS

If the turbine is supplied with oil mist lubrication oil mist could escape

from the bearing housing vents or constant level oiler. If there is the

possibility that these could be ignited by equipment of processes in

the proximity of the turbine they should be piped to a safe area.

Lighting must be installed in the installation area to insure that

operators can see the turbine and its controls.

Do not install the turbine where ambient temperature could be -20°

F or less unless this was specified in the original order and LOW

TEMPERATURE materials have been provided. Refer to Section F,

Lubrication System, for ambient temperature limits based on

lubrication.

Proper installation of the turbine and driven equipment is vital for successful

operation of the system. It is for this reason that competent, experienced personnel

should be employed during installation. Before installing turbine refer to the

certified drawings in Appendix A of this manual.

Dresser-Rand recommends that API Recommended Practice RP-686 be consulted

for additional guidance in regard to the installation of the turbine and driven

equipment package. It provides recommended procedures, practices and quality

assurance checklists covering the installation and de-commissioning of turbines,

compressors, fans, motors, gear reducers and pumps for use in petroleum,

chemical, gas industry and other facilities.

The following subsections, C.2 through C.11, provide basic installation and

decommissioning procedures. Follow them in the indicated sequence for complete

and correct installation. These recommendations and instructions are provided to

assist the purchaser and/or his contractor. Fully qualified labor, including qualified

supervision, is required for proper installation, start-up, and subsequent operation

of the equipment. The services of a Dresser-Rand serviceman are recommended for

the final on site installation review and the initial commissioning and start-up of the

turbine.

As a minimum the following steps must be carried out in sequence to achieve

satisfactory operation.

Speed Control System

WARNINGS

NEVER CONNECT the steam turbine to inlet or exhaust

sources of UNKNOWN PRESSURE OR TEMPERATURE, or to

sources whose pressure or temperature EXCEED limits stated

on the NAMEPLATE.

Misalignment with driven equipment or overload due to driven

equipment could result in excessive wear and bearing failure.

This could create sparks or hot surfaces could ignite lubricant

or flammable gasses.

Refer to the certified drawings in Appendix A and carefully read all

installation notes, piping connection details, dimensions and clearances, and

any other special data.

Provide a proper and adequate foundation for the turbine.

Provide a proper piping installation, in accordance with NEMA SM23, that

will accommodate pressure forces and thermal growth without imposing

excessive force on the turbine.

Remove all protective coatings and foreign matter from the turbine and all

piping. If the turbine was prepared for long-term storage, reinstall the matched

carbon ring sets, springs and washers into the turbine gland housings.

Refer to coupling alignment instructions supplied by the coupling

manufacturer, as well as those supplied in this manual.

Perform an accurate cold alignment.

Grout the base-plate or sole plate to the foundation, as required.

Carefully check hot alignment at operating temperature and adjust it, if

necessary, to establish accurate alignment.

Dowel turbine and driven machine in place to maintain proper alignment.

C.2

Foundation

WARNING

If the turbine is installed in a location where there is the

possibility of an earthquake this must be considered in the

design of the piping and foundation.

The foundation is one of the most influential factors governing overall reliability of

a turbine. A foundation must maintain alignment under all normal and abnormal

conditions. This includes the way a foundation is supported on the soil and/or

superstructure, soil settling, soil resonances, thermal distortion, piping forces, and

vacuum pull or pressure forces in expansion joints.

The turbine, gear reducer (if used), and driven equipment should all be mounted on

a common foundation.

Sufficient space should be provided around and above the foundation to allow for

proper installation and maintenance.

The foundation must minimize vibration by being as heavy as possible and non-

resonant. It is important that the turbine be isolated from external vibration. Neither

the foundation nor related support structure should be resonant within the operating

range of the turbine.

Vibration transmissions may occur from the unit to the surroundings, or vice versa;

vibration may also be aggravated by resonance at transmission frequencies. Piping,

stairways, and ducts may also transmit vibration, which should be prevented by

proper isolation.

A certified outline drawing is furnished with each Dresser-Rand turbine and is

included in this manual in Appendix A. This drawing includes dimensions for

locating anchor bolts, equipment weights, and general information required for

determining foundation dimensions and design.

A generous safety factor should be used when determining foundation thickness.

The foundation length and width should extend at least 6 inches (152 mm) beyond

the anchor bolts.

Anchor bolts must be positioned accurately and provided with sleeves. The sleeve

bore diameter should be approximately twice the bolt diameter, but should provide

not less than 1/2” (13 mm) clearance all around the bolt.

Carefully constructed templates are required to hold bolts and sleeves in position

while the foundation is cast. Templates are usually made of wood and secured to

the foundation forms. Experienced workers should be able to set anchor bolts to a

tolerance of 1/8” (3 mm) by locating and drilling holes in the template after they

have been secured to the braced forms.

Speed Control System

Anchor bolts should be threaded at both ends and be of sufficient length to extend

one-and-a-half to twice the bolt diameter above the top of securing holes in the

base plate or the sole plate. The lower end of each bolt is enclosed in a sleeve and

passes through an anchor plate, where it is secured by a nut to which it is welded.

Anchor plates can be either washers or plates of cast iron or steel. They should

have a diameter or side dimensions of approximately twice to two-and-a-half the

outside diameter of the sleeves.

Notes:

Templates must be rigid enough to prevent bolts from shifting while the

concrete is being poured.

After concrete has been poured and before it has hardened, recheck positions

of the anchor bolts.

Allow a 1-1/2” (38 mm) gap above the top of the foundation surface for

grouting under edges of the base plate or sole plates.

C.3

Piping

WARNING

Improperly designed or installed piping can lead to turbine

misalignment and failure of the turbine or driven equipment. It

is the user/installers responsibility to insure that the piping

system is properly designed, installed and that it meets local

codes and regulations. All references to piping design in this

section are for reference only.

WARNING

If the turbine is installed in a location where there is the

possibility of an earthquake this must be considered in the

design of the piping and foundation.

Proper piping of a steam turbine is essential. Correctly designed and installed

piping contributes to safe, trouble-free operation and can improve ease of turbine

operation and maintenance.

Before installing any piping, installation personnel should read and become

thoroughly familiar with this section.

The effects of possible earthquakes should be taken into account when designing

the inlet and exhaust piping systems.

C.3.1

Piping Forces

Any pipe connected to the steam turbine casing, valves, gland housing, or bearing

housings can exert forces and/or moments on the turbine. This can misalign the

turbine with its driven equipment or distort the turbine casing, resulting in internal

misalignment of the turbine shaft with bearings, seals, and other components. Such

misalignment can cause vibration, premature wear or failure of bearings, seals,

couplings and shafts, and casing leaks.

Steam supply (inlet) and exhaust piping, being relatively large and subjected to

higher temperatures and pressures, can, if improperly installed, exert relatively

large forces and moments on a steam turbine. Leak-off, drain, lube, cooling water

and gland seal piping does not normally transmit significant piping forces.

To prevent excessive piping forces or moments, the customer must ensure that the

piping is designed and installed so as to comply with NEMA SM-23, Section 8,

Allowable Forces and Moments on Steam Turbines. The maximum allowable

forces and moments are a function of inlet and exhaust flange sizes. Flange sizes

are tabulated on the Certified Drawing appearing in Appendix A.

Piping forces can be reduced or eliminated with proper piping design, the use of

expansion joints, and correct piping support systems. Figure C-1, Suggested Steam

Inlet and Exhaust Piping Arrangement, suggests inlet and exhaust piping systems,

showing typical expansion joints, piping loops, and spring supports in the piping

system.

Speed Control System

Optional constructions, which include third-party throttle and/or over-speed trip

valves or other equipment configurations, may require the use of additional supports.

Refer to the certified drawings in the Appendix A.

Refer to a separate sketch in Appendix A for the estimated thermal movement of the

inlet flange and exhaust flange. The estimated thermal movements of the inlet and

exhaust flanges are used in the design and analysis of the piping support system.

Figure C-1. Suggested Steam Inlet and Exhaust Piping Arrangement

C.3.2

Isolating Valves

Inlet and exhaust lines to a turbine must be provided with isolating valves. The

purpose of these valves is to isolate the turbine from inlet and exhaust systems,

allowing the turbine to be shut down, along with sealing inlet and exhaust lines if

the turbine is to be moved or serviced.

DANGER

NEVER DISCONNECT inlet or exhaust piping of the turbine

without first CLOSING and TAGGING the ISOLATING VALVES

and then OPENING DRAIN VALVES SLOWLY to relieve any

pressure within the turbine. Failure to do so may expose

PERSONNEL to SERIOUS INJURY if steam was to be

introduced into the piping or captured in the turbine. As an

added precaution, always install blank flanges on inlet and

exhaust lines after removing the turbine.

The inlet piping isolating valve should be installed immediately upstream of the

turbine. Refer to Figure C-1, Suggested Steam Inlet and Exhaust Piping

Arrangement.

The exhaust piping isolating valve should be installed immediately downstream of

the full flow relief valve. Refer to Figure C-1, Suggested Steam Inlet and Exhaust

Piping Arrangement.

C.3.3

Full Flow Relief Valve

An atmospheric relief valve must be installed between the turbine exhaust flange

and the first exhaust line shut-off valve (Refer to Figure C-1, Suggested Steam Inlet

and Exhaust Piping Arrangement). The purpose of this relief valve is to protect the

turbine casing from excessive exhaust pressure. The relief valve must be of ample

size to pass the maximum quantity of steam flowing through the turbine at the

maximum inlet temperature and pressure steam conditions without allowing the

turbine casing pressure to exceed the limit defined below. It is the user’s

responsibility to install the relief valve in the piping.

The full flow relief valve shall begin to open at 10% or 10 PSIG (69 kPag) above

maximum exhaust pressure, whichever is greater, for non-condensing turbines; and

at not more than 10 PSIG (60 kPag) for condensing turbines. The valve shall be

fully open with an additional rise in pressure not to exceed 10%. Refer to NEMA-

23, Steam Turbines for Mechanical Drive Service, for further details.

Speed Control System

WARNINGS

It is the USER’S RESPONSIBILITY to INSTALL A FULL-FLOW

RELIEF VALVE in the exhaust line between the turbine exhaust

casing and the first shut-off valve. This relief valve should be

sized to relieve the FULL AMOUNT OF STEAM THAT THE

TURBINE WILL PASS, in the event that the exhaust line is

blocked.

The optional SENTINEL WARNING VALVE, located on the

turbine casing, DOES NOT SERVE as a RELIEF VALVE. The

sentinel warning valve WILL NOT PASS SUFFICIENT STEAM

FLOW to relieve the turbine casing of EXCESSIVE EXHAUST

PRESSURE. The purpose of the sentinel warning valve is to

warn visually and audibly that excessive pressure is building in

the turbine exhaust casing.

C.3.4

Inlet Piping

As shown in Figure C-1, Suggested Steam Inlet and Exhaust Piping Arrangement,

inlet piping should come off the top of the steam header and form an expansion

relieving loop or other strain relieving device, before coming down to the turbine.

A valved condensate drain should be installed in the inlet line upstream of the

isolating valve, allowing condensate to drain prior to opening the isolating valve

and feeding steam to the turbine. Piping must be supported in such a manner as to

allow thermal growth of the turbine and piping, without imposing excessive forces

and moments on the inlet flange. Properly installed piping should mate squarely to

the turbine inlet flange, without any need to force flanges by twisting them into

alignment when connecting them.

The inlet line should be well lagged to prevent heat loss and to avoid burns.

Pipe sizes should be large enough to maintain rated steam pressure at the turbine

inlet flange under maximum load conditions. In determining pipe size, proper

allowance should be made for pressure drop due to long sections of pipe, elbows,

valves, or other fittings between the boiler and the turbine.

If wet or saturated steam is used, it is very important that piping be arranged so that

condensate cannot be carried over into the turbine. A steam separator of the proper

size, with a trap of ample capacity, should be installed before the turbine inlet. All

horizontal runs must be sloped up in the direction of steam flow, with drains at the

low points.

The importance of protecting the turbine against slugs of water cannot be

overemphasized. The issue is not “wetness” of the steam, but with condensate,

which is separated out as water. The harmful effects of water are:

1. Rapid erosion of blading and valves.

2. In the case of turbine wheels with inserted blades, water may have a hammer-

blow effect, tearing out the blades and destroying the rotor.

3. Governing is adversely affected.

The rotor may be permanently distorted and/or the turbine may be seriously

damaged.

A danger of thrust bearing failure and consequent destruction of the turbine.

C.3.5

Exhaust Piping

Figure C-1, Suggested Steam Inlet and Exhaust Piping Arrangement, shows

exhaust piping together with the full flow relief valve and support system. Note that

the exhaust line should slope down toward the header or create an overhead loop,

to prevent condensate at the header from flowing back toward the turbine. Valved

drains should be installed before and after the exhaust-isolating valve.

On each installation, the length of run, elbows, valves, and other fittings in the pipe

must be considered, together with all factors, which may cause back-pressure on

non-condensing turbines or reduced vacuum on condensing turbines, and a final

decision on piping size made accordingly. On non-condensing turbines, back-

pressure which is higher than what the turbine was designed for will cause

reduction of power and an increase in steam consumption. It may also cause gland

leakage, and in extreme cases, can rupture the turbine casing. On condensing

turbines, decreased vacuum will have an even greater effect on capacity and

economy.

The exhaust pipe must be installed and anchored so that no excessive stress is

placed on the turbine from either the weight of the pipe or its expansion and

contraction. In cases where such an arrangement cannot be made with certainty, an

expansion joint near the turbine can be useful in low pressure lines and is usually

required on large pipe sizes. The use of an expansion joint does not of itself avoid

undue stress. It is not as flexible as many people assume and when installed, it must

be properly aligned and not indiscriminately exposed to shear or torsion. In the

majority of applications, axial thrust created on the cross-sectional area of the

largest bellows, by internal pressure, must be restricted by the use of tie rods. They

are most effective when the expansion joint is used in shear, instead of tension or

compression. When used in either a vacuum or a pressure line, tie rods must be

Speed Control System

arranged accordingly. They are useless where a joint moves under tension or

compression, as they bypass the joint and transmit pipe forces directly to the

turbine. Provision must be made to anchor the piping in such a way that excessive

forces will not be transmitted to the turbine during shutdown and operational

running. Connection to a header must be made at the top, never from the bottom or

side, and great care must be taken to avoid draining water back into the turbine. All

horizontal runs must be sloped away from the turbine exhaust connection.

Properly installed piping should mate squarely to the turbine exhaust flange,

without any need to force flanges by twisting them into alignment when connecting

them. The exhaust line should be well lagged to prevent heat loss and avoid burns.

C.3.6

Piping Blow Down

Newly constructed steam piping should be blown-down to remove scale, weld slag

and any other foreign material. Such material can cause severe damage if it enters

the steam turbine.

After inlet piping has been installed, but before connecting it to the turbine, steam

should be blown through the line and into the exhaust line to remove welding slag

and debris.

Refer to NEMA SM-23, Steam Turbines for Mechanical Drive Service or a reliable

piping contractor for a blow-down procedure.

CAUTION

INLET STEAM LINES MUST BE BLOWN DOWN PRIOR TO

CONNECTING them to the turbine. Debris and welding slag

can cause serious damage to valves, nozzles, and turbine

blading if allowed to enter the turbine.

C.3.7

Steam Strainer

Standard SST Dresser-Rand turbines are provided with integral inlet steam

strainers to prevent entry of foreign material into the turbine. Part of the throttle

valve is located in the same chamber with the steam strainer. The steam strainer

will allow small debris particles to pass through the turbine and does not preclude

the need for inlet piping blow-down prior to connecting the turbine. The steam

strainer should be removed and cleaned at least once a year and replaced at least

every three years or as needed.

When a turbine is supplied without an integral or separate y-type strainer, the

purchaser must install an appropriate steam strainer in the inlet steam piping.

C.3.8

Check Valve

Where a turbine exhausts or bleeds steam into another system, and a check valve

(commonly referred to as a non-return valve) is installed for prevention of reverse

flow to the turbine, adequate bracing must be installed to absorb any forces created

by water hammer effects occurring in the exhaust line downstream and acting on

the check valve. The maximum relief valve settings are found on the turbine data

sheets. The sentinel relief valve on the turbine case is a warning valve only.

C.3.9

Expansion Joints

Low pressure and vacuum lines are usually large and relatively stiff. It is common

practice to use an expansion joint in these lines to provide flexibility. If an

expansion joint is improperly used, it may cause a pipe reaction greater than the

one that it is supposed to eliminate. An expansion joint will cause an axial thrust

equal to the area of the largest corrugation multiplied by the internal pressure. The

force necessary to compress or elongate an expansion joint can be quite large, and

either of these forces may be greater than the limits for the exhaust flange. In order

to have the lowest reaction; it is best to avoid absorbing pipeline expansion by axial

compression or elongation. If it is found that expansion joints are required, it is

essential that they be properly located and their foundation rigid. Refer to NEMA

SM-23, Steam Turbines for Mechanical Drive Service or a reliable piping

contractor for steam piping system design and installation guidance.

See Figure C-2 Unrestrained Expansion Joint (not recommended).

Figure C-2. Unrestrained Expansion Joint (Not Recommended)

The axial thrust from the expansion joint tends to separate the turbine and the

elbow. To prevent this, the elbow must have an anchor to keep it from moving. The

turbine must also absorb this thrust, and in so doing, it becomes an anchor. This

force on the turbine case may be greater than the allowable force. In general, this

method should be discouraged.

Speed Control System

Figure C-3 Expansion Joint with Tie Rods (Acceptable) below shows the same

piping arrangement as in the previous figure, except for the addition of tie rods on

the expansion joint.

Figure C-3. Expansion Joint with Tie Rods (Acceptable)

The tie rods limit elongation of the joint and take the axial thrust created by the

internal pressure so it is not transmitted to the turbine flange. The tie rods eliminate

any axial flexibility, but the joint is still flexible in shear, meaning that the flanges

may move in parallel planes. The location of this type of joint in the piping should

be such that movement of the pipe puts the expansion joint in shear instead of

tension or compression.

Figure C-4 Expansion Joint with Tie Rods for Non-condensing Operation

(Preferred) below is an arrangement frequently used, with tie rods as indicated.

Figure C-4. Expansion Joint w/ Tie Rods Non-Condensing Operation (Preferred)

This arrangement will prevent any thrust, due to internal pressure, from being

transmitted to the exhaust flange. It retains the axial flexibility of the joint and may

be used for either vacuum or pressure service.

Figure C-5. Expansion Joint w/ Tie Rods Condensing Operation

(Preferred)

Figure C-5 shows a suggested arrangement for a condensing turbine with an up exhaust. This

arrangement is recommended and frequently used. Due to the large exhaust pipe size normally

encountered on condensing turbines, the exhaust piping will be relatively stiff and an

expansion joint must be used at some point to take care of thermal expansion. An

unrestricted expansion joint placed at the exhaust flange of the turbine will exert an upward

or lifting force on the turbine flange, which in many cases is excessive. Figure C-5

provides the necessary flexibility to take care of thermal expansion without imposing a

lifting force on the turbine. The expansion joint is in shear, which is the preferred use. The

relatively small vertical expansion will compress one joint and elongate the other, which

causes a small reaction only and will be well within the turbine flange limits.

On smaller and high-pressure exhaust lines it is frequently better to rely on the flexibility of

the piping than on an expansion joint. Only after a careful analysis of the piping shows the

need for an expansion joint should they be used.

In order to have flexibility in piping, short direct runs must be avoided. By arranging the

piping in more than one plane, torsional flexibility may be effectively used to decrease the

forces.

Speed Control System

Figure C-6. Short Runs to Exhaust Header

Figure C-6 shows a short direct run to an exhaust header. If the header is free to float in

a horizontal plane, thermal expansion of the exhaust line will put very little direct

thrust on the exhaust flange. If the header is fixed, the thermal expansion will tend to cause

either the turbine or header to move and may cause damage. If thermal expansion causes

the header to move in an axial direction it will transmit a force and moment to the exhaust

flange. Figure C-6 is not recommended, as it is difficult to prevent excessive forces

from being transmitted to the exhaust flange.

C.3.10

Leak-Off Piping

WARNINGS

Leak-off and drain connections of turbines operated on

flammable or noxious gas must be piped to a safe location to

avoid the possibility of ignition of the gas or poisoning of

operating personnel.

LEAK-OFF AND DRAIN LINES MUST NOT BE

INTERCONNECTED. A leak-off from a high pressure upstream

location connected to a steam chest drain or throttle valve leak-

off/drain could supply sufficient steam TO ALLOW THE

TRIPPED TURBINE TO CONTINUE RUNNING, since such an

interconnection would bypass the overspeed trip valve.

LEAK-OFF PIPES that are left UNCONNECTED will allow the

escape of HIGH TEMPERTURE STEAM that could cause

PERSONAL INJURY or contamination of lubricating oil.

Standard SST Dresser-Rand turbines are supplied with leak-off connections at the

gland housings, throttle valve, and overspeed trip valve. Leak-offs are piping

connections that allow steam leaking past seals to be carried away to a safe area.

Shaft and valve stem seals depend on some leakage for lubrication and to minimize

wear. Leakage is therefore acceptable and necessary.

The leak-offs must be pitched down and away from the turbine and connected to

open, unrestricted, separate, non-manifolded drain lines, which discharge to a safe

and visible area. There should not be any valves on leak-off lines. Leak-off piping

should be arranged to insure that no pressure build-up occurs in the system,

avoiding any low points where condensate could accumulate and may be connected

to a gland condenser, eductor or ejector. No vertical upward pipe runs are to be

included in leak-off piping. Unavoidable low points should be trapped.

On gas operated turbines, leak-offs must be piped to a safe area away from the

turbine site.

Locations and sizes of leak-off connections are shown on the certified drawing in

Appendix A.

Gland housings on turbines operating with vacuum exhaust or at high back pressure

require special Gland Seal leak-off systems.

For turbines operating with vacuum exhaust refer to Section C.3.11 Gland Seal

Leak-Off Piping-Vacuum Exhaust

Turbines operating with high back pressure may have intermediate leak-off

connections on their gland housings. Refer to Section C.3.12 Gland Seal

Intermediate Leak-Off Piping - High Back pressure Exhaust.

C.3.11

Gland Seal Leak-Off Piping - Vacuum Exhaust

On turbines exhausting to a vacuum, sealing steam at 5 to 10 PSIG (34 to 69 kPag)

pressures must be furnished through the carbon ring glands to prevent air from

entering the exhaust casing.

Speed Control System

Figure C-7. Typical Gland Sealing System without Gland Condenser

If gland seal piping is not furnished with the turbine, sealing steam connections

should be piped via a common connection to the user’s steam supply. A

recommended piping diagram for gland seal piping is shown in Figure C-6 Gland

Seal Leak-Off Piping - Vacuum Exhaust.

Frame

Relief

Gauge

Customer’s

Gauge

Angle Control Valve

Composition

Valve

Connection

Ashcroft

Kunkle

No. 1009

1/2” pipe 12.7 mm

Cat.

KGSC

Max. Press. 600

Vogt No. 1971 3/8”

Range 30”

Vogt No

Fig. No.

lbs. 750F 42.18

All Sizes

600 lbs. Steel 9.52 mm

to 30 lbs.

9871

40R

Kg/Cm2 399C

272 Kg.

760 mm to

Stainless

2.109

Steel

Kg/Cm2

Table C-1. Gland Intermediate Leak-Off Piping—High Back Pressure

Exhaust

Turbines to be operated with high back pressure may have intermediate gland leak-

offs that must be piped to a steam header with a pressure not less than 35 PSIG

(241 kPag) and not exceeding 70 PSIG (483 kPag). This intermediate leak-off

piping must include, for start up purposes, an atmospheric vent with a shut off

valve near the turbine and a check valve installed between the vent and the steam

header to prevent back-flow. Do not connect the intermediate leak-off piping with

other leak-off connections. Refer to Figure C-8 Gland Seal Int. Leak-Off Piping

High Back Pressure Exhaust.

Figure C-8. Gland Seal Intermediate Leak-Off Piping-High Back Pressure

Exhaust

C.3.12 Gland Seal Intermediate Leak-Off Piping—High Back Pressure Exhaust

In certain turbines with a high exhaust back pressure, a gland leak-off system is used. Figure 8

shows a typical system using gland ejectors connected to the leak-off piping of both packing

cases. The ejectors maintain a constant vacuum in the gland packing case leak-off lines. When

the ejectors are shipped separate from the turbine, the piping leak-off connections from the

turbine are shown on the outline drawing, Appendix A. If gland ejectors are required for your

turbine, the specific part number is listed on the Appendix A contents sheet. On certain designs,

a drip drain connection is located adjacent to gland leak-off on each packing case. These drain

connections must be plugged.

For leak-off systems that use a gland condenser, a system schematic diagram with operating

instructions is included in Appendix A, along with a description of the major components that

comprise the system.

Leak-off and drain connections of turbines operated on

flammable or noxious gas must be piped to a safe location to

avoid the possibility of ignition of the gas or poisoning of

operating personnel.

LEAK-OFF AND DRAIN LINES MUST NOT BE

INTERCONNECTED. A leak-off from a high pressure

upstream location connected to a steam chest drain or throttle

valve leak-off/drain could supply sufficient steam TO ALLOW

THE TRIPPED TURBINE TO CONTINUE RUNNING, since

such an interconnection would bypass the over-speed trip

valve.

Drains are low-point piping connections at valves and casings that allow release of

condensed water. Drains are opened before starting the turbine, to allow any

accumulated water to escape. They are left open during the start-up cycle to allow

water condensing in the cold casings to exit. Once the turbine reaches normal

operating temperature, drains should be closed.

The user must install drain valves when not supplied by Dresser-Rand.

Drains can be automated with properly sized steam traps, if desired. Refer to C-10

Suggested Steam Inlet, Exhaust and Drain Piping, Manual Start and Figure C-11

Suggested Inlet, Exhaust and Drain Piping, - Auto Start.

Sizes and locations of drains are shown on the certified drawing in the

Supplemental Documentation section, supplied at the end of this manual.

C.3.14

Water Cooling Piping to Bearing Housing Water Jackets

Depending on service conditions and the type of lubrication system supplied with

the turbine, bearing housings may require water cooling to maintain an acceptable

bearing oil temperature.

Refer to Section F, Lubrication, for cooling water application requirements,

suggested piping, water flow, pressure and temperature requirements, and oil sump

temperature.

C.4

Alignment Requirements

Many problems experienced with turbines, gears, and driven equipment is due to

misalignment. Units must be properly supported and their alignment accurately and

permanently established if the installation is to be successful.

WARNING

Misalignment with driven equipment or overload due to driven

equipment could result in excessive wear and bearing failure.

This could create sparks or hot surfaces could ignite lubricant

or flammable gasses.

CAUTIONS

ALIGNMENTS performed by the factory on turbines with gears

or other driven equipment mounted on base plates MAY SHIFT

during rigging or shipment. These alignments must be

RECHECKED before startup.

Never put a steam turbine into service without first carefully

ALIGNING it to the driven equipment under cold conditions and

then again at operating temperature. Failure to do so may

result in premature FAILURE of both TURBINE and DRIVEN

EQUIPMENT components.

Excessive vibration, bearing edge loading, and high shaft loads can result from

incorrect alignment. Factors affecting alignment can be settling of the foundation,

growth in shaft heights due to temperature changes, machine movement of either

unit with respect to the foundation due to vibration, worn bearings, or distortion of

the casing due to loads from connecting structures (such as piping). A dependable

turbine drive system requires that all of these factors be given proper attention prior

to and during alignment.

The turbine and driven equipment should always be aligned cold, checked later at

operating temperature, and re-aligned if necessary. Both shafts should be parallel

and their axes concentric so that there is no offset at operating temperature.

Two types of misalignment must be identified and corrected (if necessary) to be

within defined limits.

As previously noted, alignment is influenced by the thermal growth of both the

turbine and the driven equipment. This must be compensated for during cold

alignment by calculating the growth of each machine and intentionally creating a

parallel offset that will disappear when the equipment is hot.

C.5

Couplings

WARNING

A coupling guard must be installed at the coupling between the

turbine and driven equipment.

When the coupling guard is to be installed, refer to the coupling

guard manufacturer’s instructions to insure that it does not

contact the running shaft or coupling which could cause a spark

that could ignite hazardous gasses in the environment in which

the turbine is installed.

CAUTION

Coupling weights should not exceed the allowable limits on the

coupling drawing without approval from Dresser-Rand. A

heavier than allowed coupling could create a lower critical

speed, which could cause excessive vibration within the

operating range of the turbine.

A flexible coupling is required to connect the turbine to the driven machine.

Couplings should be selected based on power, speed, and characteristics of the

driven machine, using selection and balancing guidelines established by the

coupling manufacturer.

Correct installation of the coupling hubs is vital to proper operation of the turbine

and driven unit; great care must be exercised in assembling hubs onto shafts.

Before mounting a coupling, check the coupling bore and shaft diameter with a

micrometer to determine that the interference fit is as specified by the coupling

manufacturer. Also, inspect the key and keyways, making sure that the key is a

drive fit into the shaft keyway and a push fit into the coupling hub keyway. The

Speed Control System

key should also sit positively on the bottom of the shaft keyway, with clearance on

the top of the key to allow expansion within the hub keyway.

If the shaft key extends beyond the back of the coupling hub, the key should fill the

entire keyway. The exposed portion of the key must be removed so that it is flush

with the coupling back face and must be profiled flush to the circumference of the

shaft so that only the keyway in the shaft is filled, maintaining shaft balance. When

installing coupling hubs on shafts, it is important to heat them uniformly, taking

great care to avoid overheating. A recommended method is to use an oil bath with a

temperature control or an induction heater.

When fitting the coupling onto the shaft, it is helpful to have a chamfer on the sides

and top of the key, making alignment easy with the hub keyway. Also, a temporary

block should be used, to prevent the hub from sliding too far onto the shaft.

Do not use hammers to drive coupling hubs onto the shaft, as this would damage

the coupling, shaft, or bearings. As coupling hubs are frequently used for reference

in alignment, runout or eccentricity of hubs, which may be caused by damage to the

shaft, hubs, or badly fitted keys, must be avoided.

CAUTION

DO NOT drive the coupling on or off the shaft with a HAMMER.

The force of the hammer will damage the rotor locating bearing,

resulting in internal turbine damage.

NOTE

Axial clearance between the coupling hubs and shaft end faces

should be in accordance with recommendations of the coupling

manufacturer, when shafts are in their normal running

condition.

Lubricate the coupling as required, by following the coupling manufacturer’s

instructions.

C.6

Preparation for Alignment

Use the following procedure:

Clean turbine mating support surfaces and mount turbine on the foundation.

Do not connect the turbine to inlet and exhaust piping.

Disconnect the coupling by removing the coupling spacer (if provided) and

pulling coupling sleeves away from the hub.

Insert suitable shim packs between supporting surfaces of the turbine and/or

driven equipment and their respective mounting surfaces. It is important to

insert sufficient shims under the equipment so that shims can be removed to

lower either piece of equipment if required during hot final alignment. A

minimum of 1/16 inch (1.6 mm) is recommended.

Level and square the turbine with respect to the driven equipment.

Check for base distortion and improper shimming by placing dial indicators in

vertical and horizontal planes on the driven equipment, with the indicators

detecting turbine shaft movement. Each turbine foot anchor bolt should then be

loosened and tightened, while observing the dial indicator reading. Readings

should not exceed 0.003 in. (0.075 mm); if they are exceeded, the cause must

be determined. Repeat this procedure for driven equipment.

Check that all anchor bolts (i.e., turbine, driven equipment and supports) are

tightened.

Check coupling hub face runout using the following procedure:

1. Install dial indicator

(refer to Figure C-13, Alignment Using Dial

Indicators) to read a point nearest to the outside circumference on the face

of one hub.

Rotate the shaft and hub on which the dial indicator is touching and record

the maximum and minimum indicator readings. Axial runout is the

difference between the two readings.

3. Re-position the dial indicator to read on the external outside diameter of

the same hub as in step 1 and measure coupling hub diametral runout, as

shown in Figure C-13, Alignment Using Dial Indicators.

Rotate hub and record the maximum and minimum indicator readings.

Lateral runout is 1/2 of the difference between the two readings.

Repeat steps 1 through 4 for the other coupling hub.

Speed Control System

Any runout exceeding 0.0015 inch (0.038 mm) should be corrected by

reinstallation of the hub and keys or their replacement.

7. Hub runout values should be subtracted from the desired alignment

setting.

Figure C-13. Alignment Using Dial Indicators

C.7

Compensation for Thermal Movement

During initial alignment, allowances must be made for thermal expansion of the

turbine and driven equipment. The shaft centerline of each unit will rise when they

reach operating temperature. Therefore, the difference between the two anticipated

growths must be incorporated into the cold alignments so that the shafts will come

into alignment when operating temperature is attained.

CAUTION

Thermal movement varies significantly with inlet temperature,

load, ambient conditions and time. Final hot alignment of the

turbine to the driven equipment must be based on actual

measured shaft rise under steady state conditions (after at least

a two hour run time).

Figure C-14. Centerline Height VS Centerline Rise per Ambient

Temperatures

On steam turbines, steam temperatures and insulation of the turbine case, proximity

of packing leak-off lines to the supports and type of lagging enclosure affect the

support temperatures. The average support temperatures may vary from 130F to

160 F (approximate oil drain temperatures). Judgment will have to be exercised in

estimating the support temperature for the initial cold alignment. The curves in

figure C-14 may be useful for checking and also for telling the effect of an error in

the estimate of support temperature. Refer to the certified drawings in Appendix A

for the estimated thermal movement of the turbine shaft extension.

Speed Control System

Thermal growth of the driven equipment, or its temperature change, must be

obtained from the driven equipment manufacturer.

The unit with the greater thermal growth must be set lower than the other unit, by

the difference between their thermal growths. Normally, the turbine has the greater

thermal growth.

CAUTION

The initial alignment established with this estimated thermal

growth is only approximate. An actual hot alignment must be

performed prior to putting the turbine into service.

C.8

Cold Alignment Check

Cold alignment must be completed at ambient temperature (turbine and driven

machine in cold condition) and in the proper sequence, with angular misalignment

corrected first, followed by correction of parallel misalignment.

C.8.1

Angular Alignment

Use the following procedure:

a. Clamp a dial indicator to one coupling hub and place the finger (contact point)

against the finished face of the other hub, as shown in Figure C-13, Alignment

Using Dial Indicators.

b. Scribe a reference mark on the coupling hub at the point where the finger

touches the hub face.

c. Rotate both shafts simultaneously (in the direction they were designed to

operate), keeping the finger against the reference mark on the coupling hub.

Note the dial indicator reading at each one-quarter revolution.

d. Angular misalignment of the shafts must not exceed the coupling

manufacturer’s recommendations or a total indicator reading of 0.001 inch

(0.025 mm) for each radial inch of the coupling hub.

e. When the distance between coupling hubs does not permit the use of dial

indicators, angular misalignment can be established using one of the two

following methods:

Use feeler gauges to determine the gap between coupling faces at four

locations, 90 apart. Adjust the turbine or driven equipment to obtain

equal clearance within 0.001 inch (0.025 mm) between coupling faces at

each 90 location.

Use a dial indicator mounted on a flexible arm to measure run-out on the

back surface of the coupling hub, as shown in Figure C-13, Alignment

Using Dial Indicators.

C.8.2

Parallel Alignment

Use the following procedure:

Mark both hub rims so that their relative positions can be maintained at all

times during the alignment check.

Mount the dial indicator on one of the coupling hubs and position the indicator

finger on the rim of the opposite coupling hub, as shown in Figure C-13,

Alignment Using Dial Indicators.

Scribe a reference mark on the machined diameter of the coupling hub at the

point of indicator finger contact, or align match marks on the hub rims.

Rotate both shafts at the same time, while retaining the indicator finger at the

reference mark and the two match points aligned.

Note indicator readings at 90 locations (90, 180, 270, 360). Remember to

zero the indicator at the starting point.

Repeat steps d and e two or three times to verify accuracy of readings.

In installations where there is excessive coupling gap (when a coupling spacer

is used), it may be necessary to make a reading correction when determining

vertical parallel misalignment.

Parallel misalignment must not exceed the coupling manufacturer’s

recommendations or a total indicator reading of 0.002 inch (0.051 mm).

When parallel alignment is complete, connect inlet and exhaust piping, and recheck

angular and parallel alignment thoroughly.

C.8.3

If using laser alignment tooling such as Rotalign, you can eliminate Section C.B.1

and C.B.2. Follow recommended instructions included in the laser alignment

tooling.

Speed Control System

C.9

Grouting

When cold alignment is satisfactory (the turbine has been leveled, and the coupling

alignment has been checked), grout the base plate or sole plate to the foundation

using the guidelines specified below. (Epoxy grout procedures may differ--follow

manufacturer’s instructions.)

Mix a test batch of ready-to-use grouting material to verify that the material

overcomes settlement and drying shrinkage. This type of material is normally used

for clearances less than one inch in thickness, and where the size and shape of the

space make placement difficult.

Coarse aggregate is normally used for clearances over one inch

(2.5 cm) in

thickness, where free passage of the grout will not be obstructed. One part of pea

gravel or pea stone may be added to two parts of the ready-to-use grouting material

to form coarse aggregate grout.

CAUTION

Do not disturb alignment by removing shims or wedges under

the base plate or sole plate.

Grouting must be done with all steam and exhaust piping disconnected from the

turbine.

When prepared grout mixes are used, follow the manufacturer’s instructions and

applicable safety precautions. Be sure that there are no air pockets in the grouting.

A suitable form should be built around the base-plate or sole plate before grout is

applied.

With either of the above-described mixes, use the minimum amount of water

required to create a flowable grout that completely fills the required space.

Excessive water causes segregation and bleeding.

Apply grout quickly and continuously to avoid the undesirable effects from

overworking.

Once the grout has acquired its initial set, all exposed edges should be cut off

vertically to coincide with the base-plate. Paint the grout with waterproof paint

after the grout has thoroughly dried, or apply plaster with Portland cement-sand

mortar.

Do not connect the piping before the grout is thoroughly dry and

alignment has been rechecked.

C.10

Hot Alignment Check

After installation is complete, the grout is fully set, and the tightness of all hold-

down bolts have been checked, bring the turbine and driven machine up to

operating temperature (this normally takes about two hours run time), shut down

the unit, and make a careful and final check of the alignment using the procedure

outlined in Section C.8. This should be done as soon as possible after shut down, to

avoid erroneous readings due to cooling. Final adjustments should be made so that

both shafts are parallel and their axes concentric, resulting in zero offset at

operating temperature, consistent with the coupling manufacturer’s limits.

If the alignment is not satisfactory, check the following for possible causes:

a. Pipe strains distorting or shifting machines due to thermal growth (disconnect

piping and re-check alignment).

b. Springing of the base-plate or sole-plates by heat from the turbine, from a heat

source close to the turbine, or due to soft shims or partial shims.

c. Loose hold-down bolts.

d. Shifting of the entire structure due to variable loading, a change in the

foundation due to concrete curing, or improper grouting causing non-continuous

support.

When final alignment is satisfactory, dowel the turbine and driven equipment in

place to maintain proper alignment.

C.11

Fire Protection

All possible precautions should be exercised to avoid fire hazard to operating

personnel and equipment, particularly to the oil system. To guard against the event

of a serious fire around the turbine, the following protective features should be

provided at an accessible location near the unit.

Fire Extinguishing Equipment Type Best Suited for Oil Fires

Examples: Carbon Dioxide Multi-purpose Dry Chemical

Provision for emptying oil reservoir quickly by draining oil to waste or distant

storage.

A shut-off valve in the steam inlet line and in the steam inlet line to the turbo

auxiliary oil pump (if supplied).

Speed Control System

C.12

Decommissioning

WARNING

Prior to commencing the decommissioning operation, ensure

that the inlet and exhaust stop valve are shut, locked out and

tagged to eliminate the possibility of inadvertent start-up during

the decommissioning operation.

The decommissioning procedure is as follows:

Remove bolts from the inlet and exhaust flanges.

Disconnect all turbine piping from permanently installed piping.

Drain oil from the bearing housings and the governor. Dispose of the oil

in an environmentally responsible manner.

Drain cooling water from the cooling system and bearing housings.

Remove carbon rings, springs and stops from the gland housings.

Remove coupling guard.

Disconnect drive half coupling from driven half coupling. Remove

spacer coupling if one is installed.

Remove hold down bolts/nuts from the base-plate.

Sling the turbine and move it to a position where the inlet and exhaust

are exposed.

10.

Spray the internals with a rust preventative through all available

openings.

11.

Coat the non-painted machined surfaces with a water-soluble rust

preventative.

Seal all flanged connections with a rubber gasket, steel plate and through-bolts and

nuts.

Move the turbine to the selected storage location suitable for this type of

machinery.

Speed Control System

Section D

Speed Control System

D.1

General

Your Dresser-Rand turbine has been designed to produce the rated power, at its

rated speed, under the specified steam conditions. This information can be found on

the turbine nameplate, on the turbine data sheet at the beginning of this manual, or

on the certified drawings in the Appendix A.

When the turbine has been provided with a droop-type governor (WOODWARD

TG-13 governor or similar), and the load created by the driven equipment is less

than the rated power, the turbine would tend to run faster than the rated speed.

When the load is greater than the rated power, the turbine would tend to run slower

than the rated speed. Regulating the amount of steam admitted to the turbine can

counteract these tendencies. The governor and throttle valve provide this function.

The governor senses the speed, at which the turbine is running and opens or closes

the throttle valve; accordingly to maintain the turbine at its predetermined (set)

speed.

WARNING

Never operate the turbine with the governor or governor system

disabled.

D.2

Standard Governor

The basic hydraulic governor is the Woodward TG mechanical-hydraulic speed

control governor. The governor is attached to the governor mounting housing and

couples to the turbine shaft via a flexible coupling. The governor linkage connects

the governor to the throttle valve.

Speed Control System

BREATHER

SPEED ADJUSTING

SCREW

OIL LEVEL

INDICATOR

OUTPUT SHAFT

INPUT

SHAFT

DRAIN

Figure D-2. Woodward Oil Relay Governor Features

The instruction manual for the standard or optional governor is found in Appendix

Figure D-2 shows external features of the Woodward TG Governor.

Breather--this is a vent for the oil reservoir and also serves as a plug for the oil

filler hole.

Oil Level Indicator--a sight gauge on the side of the Governor for checking the oil

level.

Speed Adjusting Screw--this screw, located on the rear of the Governor, increases

the turbine speed setpoint when turned clockwise.

Output Shaft--opens and closes the Throttle Valve via the throttle linkage.

Input Shaft--is connected to turbine shaft, sensing turbine speed.

Drain Plug--oil drain on the bottom of the Governor.

Speed Control System

D.3

Lubrication and Maintenance

The hydraulic governor has a self-contained, 1.75 quart oil reservoir. Oil level can

be checked by viewing the oil level indicator on the side of the Governor.

The turbine is shipped with the governor reservoir filled with oil. Oil level should

be checked before starting the turbine and should be maintained at the proper level.

Oil should be changed according to recommendations in the Woodward manual,

included with this manual. If oil should become contaminated, quality

turbomachinery oil is recommended. Refer to Section F, Lubrication System, for oil

selection guidelines.

WARNING

Operating the GOVERNOR with DIRTY OIL or with a LOW OIL

LEVEL can cause the Governor to MALFUNCTION, resulting in

damage to the governor and possible overspeed causing

damage to the turbine and personal injury.

Refer to the governor manual for governor oil selection guidelines and for any

additional maintenance information.

D.4

Speed Range and Droop Adjustment

The hydraulic governor speed range is preset at the factory, with the purchaser’s

specified turbine rated speed within that range. The user, within the allowable

range of the supplied governor, may vary the speed set point by turning the speed

adjusting screw on the rear of the Governor. Clockwise rotation of the speed

adjusting screw increases turbine speed.

Droop, the variation in speed from no load to full load, can affect speed stability

and may need adjustment if the turbine hunts or surges. Refer to the governor

manual for details on droop adjustment.

D.5

Optional Governors

Dresser-Rand turbines can be supplied with a variety of optional governors,

depending on customer needs. If your turbine is equipped with an optional

governor, refer to the appropriate vendor manual in the Appendix B.

WARNING

Speed Control System

NEVER attempt to START the steam TURBINE without first

reading about and UNDERSTANDING the GOVERNOR

CONTROLS.

D.6

Throttle / Governor Valve

The SST throttle/governor valve (refer to Figure D-1, Throttle Valve Features)

consists of a balanced Venturi valve sliding in a cage contained within the valve

body. The valve stem extends through the valve bonnet, which contains a set of

hardened bushings. The bushings are captured in the cover, which is provided with

a leak-off to direct any steam that escapes past the stem bushings away from the

valve. Drain holes at the bottom of the steam chest are used to connect piping,

which drains condensate from the valve. The turbine is shipped with pipe plugs in

the drain holes. Refer to Section C.3.10, C.3.11, C.3.12 and C.3.13, for leak-off and

drain piping recommendations.

The throttle/governor valve needs no regular maintenance other than replacement

of the stem bushings if leakage becomes excessive. Valve stem freedom of

movement should be checked prior to starting a turbine that has been out of service

for any significant length of time.

The steam strainer screen, surrounding the throttle valve cage, prevents

foreign matter from entering the turbine. If foreign matter does appear in the steam

chest, turbine nozzles exhaust casing, or if blading is damaged, then the steam

strainer may be defective. Foreign matter that gets past an intact steam strainer

generally has a small particle size, or it could come from within the turbine itself.

Optional construction may include separate throttle and/or over-speed trip valves or

other equipment configurations. Refer to the certified drawings in Appendix A.

When a turbine is supplied without an integral or separate Y-type strainer, the

purchaser must install an appropriate steam strainer in the inlet steam piping.

100

Speed Control System

Figure D-4. Woodward Governor Valve Linkage

D.7

Governor Linkage

The linkage between the governor and the throttle/governor valve needs no

lubrication or maintenance. However, it should be checked periodically for

freedom of movement and for worn parts.

D.8

Hand Valves

The steam turbine may be equipped with one or two optional hand-valves, located

on the steam chest. The purpose of the hand-valves is to allow the operator to open

or close passages to one or more of the turbine nozzles. Since the turbine is more

efficient when operating at the highest possible steam chest pressure, it is advised

to operate the turbine with the throttle/governor valve open as wide as possible,

while regulating power with the hand-valves. If operating at lower power is

necessary, this is accomplished by closing hand-valves one at a time until the

governor and throttle/governor valve are no longer capable of maintaining speed

(throttle/governor valve is wide open), and then opening one hand-valve. If the load

should increase while operating in this mode (more power is required), it will be

necessary to open additional hand-valves to maintain speed.

102

Speed Control System

WHEEL

NOZZLE

RING

HAND VALVE

(OPEN POSITION)

Figure D-5. Hand Valve Arrangement

Hand-valves must be fully open or fully closed. Operation with a partially open

hand-valve is equivalent to throttling, meaning that efficiency is lower. It will also

cause steam cutting damage to the valve seats.

When closing hand-valves, close the valve furthest from the inlet flange first. Open

hand-valves using the opposite sequence. This will prevent interrupted flow from

nozzles to the blades, which will subject blades to unnecessary stress cycles and

could reduce turbine efficiency.

103

Lubrication System

Section E

Overspeed Trip System

E.1

General

In the event of an overspeed condition, caused by a sudden loss of load or failure

of the speed control system, the supply of steam to the turbine must be quickly and

positively interrupted, preventing damage to or destruction of the turbine or driven

equipment and possible personal injury. The turbine has a fixed amount of stored

energy in the steam or gas already downstream of the trip valve at the time that the

trip valve is closed. The turbine converts that energy to rotating mechanical

energy and transmits it to the driven machine. As it does so, with no additional

energy entering the turbine, the turbine slows down and comes to a stop.

An overspeed trip valve, activated by the over-speed governor cup assembly and/or

electronic trip system, performs this function.

Per NEMA SM23, Steam Turbines For Mechanical Drive Service, normal turbine

trip speed is 15% over maximum continuous speed for NEMA A (Woodward TG)

governors and 10% over maximum continuous speed for NEMA D governors.

Maximum continuous speed is 5% over rated speed; therefore, trip speed is 16%

(NEMA D) or 21% (NEMA A) over rated speed. Occasionally the trip speed set

point may be lower or higher than normal due to a customer request and/or

technical reason. The factory trip setting speed appears on the turbine nameplate.

Standard SST turbines are supplied with an overspeed governor cup assembly

(refer to Figure E-2, Overspeed Governor Cup Assembly), located within the

mounting housing on the steam end of the turbine shaft, which contains a spring-

loaded weight, within which resides a speed-adjusting set-screw. The weight,

spring, and setscrew are selected and set at the factory so that the weight snaps out

of the bushing at a predetermined trip speed. This trip speed is recorded on the

turbine data sheet and the turbine nameplate.

When the weight snaps out of the overspeed governor cup assembly (refer to

Figures E-2, Trip System), it strikes the trip paddle, which in turn releases the trip

linkage, causing the trip valve to close. As turbine speed decreases, the weight is

pulled back into the bushing by spring action. The trip valve can then be manually

105

Lubrication System

E.2

Warnings

CAUTION

If the KW load on a turbine-generator cannot be reduced in the

normal manner, it indicates the possibility of unacceptable

deposits on the control valve components.

STUCK CONTROL VALVES ARE A DANGER SIGNAL THAT THE

TRIP VALVE MAY ALSO BE STUCK. UNDER THESE

CONDITIONS IT IS IMPERATIVE THAT THE GENERATOR LOAD

NOT BE REMOVED UNTIL THE TRIP VALVE IS CLOSED.

If the trip valve cannot be closed by normal means, then other valves in

the steam system must be used to cut off the steam supply to the

turbine.

THE UNIT CIRCUIT BREAKER SHOULD NEVER BE OPENED

WHILE LOAD IS ON THE UNIT AND TRIP AND THROTTLE /

GOVERNOR VALVES ARE INOPERABLE. FAILURE TO

FOLLOW THESE PRECAUTIONS COULD CAUSE A SEVERE

OVERSPEED WITH EXTREME DANGER TO THE TURBINE

AND OPERATING PERSONNEL.

DANGER

NEVER BLOCK OR DISABLE THE TURBINE TRIP SYSTEM

OR ATTEMPT TO ADJUST OR REPAIR IT WHILE THE

TURBINE IS OPERATING.

107

WARNINGS

TESTING, REPAIR AND MAINTENANCE of overspeed trip

systems must be performed only by trained and

EXPERIENCED PERSONNEL.

The OVERSPEED TRIP SYSTEM must always be TESTED

and adjusted, if necessary, when STARTING the steam

turbine.

The OVERSPEED TRIP SYSTEM must be TESTED WEEKLY

on turbines that operate continuously. This prevents build-up

of foreign material in the trip linkage and alerts the operator to

deterioration that may affect trip system performance.

The TRIP SYSTEM utilizes HEAVY SPRINGS; use CAUTION

when assembling or disassembling the mechanism.

The TRIP LINKAGE MOVES RAPIDLY WITH GREAT FORCE

when the turbine trips. Use CAUTION when ADJUSTING the

TRIP SYSTEM, MAINTAINING the turbine, or when

WORKING IN THE VICINITY of the OPERATING TURBINE.

WARNINGS

Always determine and CORRECT the cause of an

OVERSPEED TRIP BEFORE RESETTING THE VALVE AND

MECHANISM.

108

Lubrication System

DO NOT SET THE OVERSPEED TRIP SYSTEM to a speed

HIGHER than the factory setting without first consulting the

factory.

E.3

Description and Function

E.3.1

Overspeed Governor Cup Assembly

The overspeed governor cup assembly (Figure E-2) consists of the following parts.

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

Figure E-2. Emergency Governor Cup Assembly

The weight (93), which is contained via retaining rings (96 and 97) within the

emergency governor cup (90), is installed within a lateral hole in the emergency

governor cup body (90). The emergency governor cup assembly is installed on the

109

turbine shaft via key and set screw. The weight is heavy at the adjusting screw end

(upper part of Figure E-2, Emergency Governor Cup Assembly). As the shaft and

cup assembly rotates, centrifugal force tends to move the weight out of the cup,

compressing the spring (94). When turbine speed reaches the trip speed, centrifugal

force at the weight exceeds spring retention force, causing the weight to snap out,

tripping the trip linkage.

The speed at which the weight trips the linkage is a function of the weight (93),

bushing (95) shape and material, the spring rate of the weight spring (94), and the

position of the adjusting screw (91). The factory based on the desired trip speed

selects these components. In the field, trip speed is adjusted by changing the

position of adjusting screw (91). It is imperative that the setscrew (92) be tightly

turned into and locking the adjusting screw (91) from any movement. Refer to

Section E.5, Adjustment of Trip Speed, for adjustment and maintenance

instructions.

WARNING

Weight (93), spring (94), adjusting screw (91) 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.

E.3.2

Trip Valve

The standard SST turbine trip valve (Figure E-3, Trip Valve, E-4 Trip System) is a

positive shut-off, force-actuated, sliding trip valve that is spring-loaded to ensure

fast action.

When the turbine is running, the trip valve is fully open, held in place by the trip

linkage (valve linkage lever (444), latch (445) and trip lever (490)), which is in

turn held by trip lever (583) action against the trip finger (584).

110

426

Seat

427

Roll Pin

428

Valve

429

Stem

430

Cover

431

Cap Screw

432

Lock Washer

433

Plug

436

Bushing

437

Link

438

Set Screw

439

Packing

440

Gland Follower

441

Valve Spindle

444

Lever

1000

Valve Body

The trip linkage operates as follows:

Refer to Figures E-1, Typical Trip System Arrangement Drawing, E-2, Emergency

Governor Cup Assembly, E-3 Trip Valve and E-4, Trip System.

During trip valve reset, as the valve (428) approaches the fully open position, reset

handle (434) rotates trip lever and latch (444 and 445) into place with the knife

edge of the latch (445) into position into the slot on the trip lever (490). The trip

pin (577) then engages the trip lever (583), holding the valve in the open position.

There is a torsion spring, operating in the valve closing direction, applies tension to

trip pin (577). There is also a linear acting spring (510) that is pulling against lever

(444). This tension is transferred to the knife-edge, holding the linkage in the open

position. With the valve in the open position, inlet steam can now flow into the

turbine.

The trip valve can then be tripped, either manually or by an overspeed condition. If

overspeed occurs, the weight (93) will snap out of the weight bushing (95), striking

the trip lever (584), causing it to release trip lever (490). The trip shaft (441) is

rotated by retraction of torsion spring (510), extending the linkage, closing the trip

valve via stem (429) and link (437). The force of the longitudinal spring (510)

ensures positive closing of the trip valve.

When the system is tripped, a spring acting on pin (577) retracts, rotating lever

(490), thus allowing lever (444) and latch (445) to be pulled by spring (510) into

the closed position via the trip linkage, isolating the turbine from the steam supply.

112

Lubrication System

DANGER

Under no circumstances should the TRIP VALVE be blocked or

held open to render the trip system inoperative. Overriding the

trip system, and allowing the turbine to exceed the rated

(nameplate) trip speed, may result in FATAL INJURY to

personnel and extensive turbine damage. In the event the trip

system malfunctions, immediately SHUT DOWN the turbine

and remedy the cause.

Refer to Sections C.3.10, C.3.11, C.3.12 and C.3.13 for recommended drain and

leak-off piping configurations.

Optional construction may include a separate overspeed trip valve. Refer to the

certified drawings in Appendix A.

E.3.3

Trip Linkage

The standard SST turbine trip linkage, set in motion by movement of the weight

(93) in the governor cup assembly (90) Fig. E-2 controls the closing of the trip

valve. The linkage also allows the valve to be opened and latched in the open

position via reset handle (434), Fig. E-4. The design clearance at the end of the

governor controlled steam valve(s) and trip or trip and throttle valve stems are required

to minimize steam leakage from the turbine.

WARNING

NEVER OPEN A CLOSED TRIP VALVE without first preparing

the turbine and driven equipment for operation.

E.4

Trip System Operation

For SST turbines supplied with the standard trip linkage, if the overspeed trip valve

is tripped shut and the turbine stopped, either from an overspeed trip condition or

manual activation of the trip lever, the trip valve must be reset manually, as

described below.

E.4.1

Manual Reset

Use the following procedure to manually reset the over-speed trip valve:

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a. Close shut-off valve in inlet steam line as soon as possible after the turbine

trips.

b. Determine cause of the trip condition. It may be due to loss of the driven

machine load, a turbine fault, or a governor problem. Remedy the cause using

procedures detailed in Section K, Troubleshooting.

c. If the turbine is not at a complete stop, listen for weight retraction into the

weight bushing, or wait for turbine speed to drop to 75% of its rated value to

ensure resetting of the trip weight.

d. Lift reset handle (434 in Figure E-4) slightly (approximately 10-15 angular

degrees) to open trip valve (428 in Figure E-3).

e. When pressure in the valve body has bled off, continue lifting the reset handle

using minimal force, until the trip valve opens and the trip lever (490 in figure

E-4) latches on latch (445 in Figure E-4).

CAUTION

DO NOT try to FORCE or jerk open the TRIP VALVE.

g. Gradually open shut-off valve in inlet steam line to bring turbine up to normal

operating speed, allowing the governor to take control. Then open shut-off

valve to full open position and back off one-quarter turn.

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E.5

Adjustment of Trip Speed

E.5.1

Trip Speed Setting

It may become necessary to change the factory speed setting of the trip system due

to a change in the normal operating speed of the turbine.

Refer to the following figures:

Figure E-1, Typical Trip System Arrangement Diagram

Figure E-2, Emergency Governor Cup Assembly

Figure E-3, Trip Valve

Figure E-4, Trip System

Figure M-2, Governor, Mounting Housing, and Trip Components

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

For SST turbines supplied with the standard emergency governor cup assembly,

adjusting the position of the adjusting-screw (91) inside the governor cup (90) can

change this setting. Use the following procedure to set turbine trip speed:

a. Test the over-speed trip system per the Overspeed Trip Test Procedure specified

in Section E.6.2. Record the speed at which the weight triggers the over-speed trip

valve, stopping the turbine. Close isolating valve in inlet steam line to prevent

accidental restart.

b. For turbines with a Woodward governor with overspeed test device (type TG,

PG-PL and PG-D) remove test device cover located on top or end of the governor

(refer to Woodward instructions in Appendix B.)

c. Slide the end of the operating rod into its socket and turn it slowly. The turbine

speed will increase to tripping, and the turbine will trip out. For type UG

governors, the over-speed pin is located adjacent to the “Woodward” logo. Raise

up on this pin to over speed the turbine.

d. Turbines with Woodward governors without the over-speed device: Pry open

the governor valve, being careful not to damage the linkage. When trip speed is

reached, the turbine will trip out.

e. Turbines with electronic governors (Tri-Sen, CCC, and Woodward) -- refer to

the instruction manuals located in Appendix B for correct operating and testing

procedures.

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Lubrication System

WARNING

FIELD CONFIGURABLE GOVERNOR

Any change to the control limits, such as (but not limited to)

speed, over-speed trip, control logic, other than “tuning” (see

governor manual) requires the prior written approval of

Dresser-Rand Company to assure that safe operating limits are

not exceeded. Failure to comply may result in damage to

property, serious injury or death to personnel.

The new trip setting should be approximately 21% above the rated speed for a

NEMA A (Woodward TG) governor and 16% above the rated speed for a NEMA

D governor.

f. Open inlet isolating valve and test turbine tripping several times after final

adjustment. If the trip speed is not repeatable within 2%, or if erratic operation

occurs, investigate and correct the problem before placing the turbine in normal

service.

If possible, carry out a daily check of the tripping mechanism during the first week

after adjustment, by over-speeding the turbine.

Optional construction may include an electronic overspeed trip system. Refer to

the certified drawings and the appropriate vendor instruction manual in Appendix

A and Appendix B for instruction on how to adjust the trip speed set point.

E.5.2

Magnetic Pickup Clearances

When supplied, maintaining the proper clearance between the magnetic pickups

(located on the turbine mounting housing) and the turbine shaft mounted signal

gear/device is crucial to the operation of the turbine electronic trip systems and

electronic governor systems. Refer to Figure E-5.

Prior to initial start up of the turbine, the clearances must be checked, adjusted and

the pickups locked into position.

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As a part of the routine checking and testing of the turbine, the magnetic pickups

should be visually checked for damage and the clearances verified to be within

tolerance.

Figure E-5. Air Gap Between Signal Gear and Magnetic Pickup

E.6

Testing the Overspeed Trip Mechanism

E.6.1

General

Before testing the overspeed trip system, the turbine must be visually inspected for

defects. Pay particular attention to governor and overspeed trip components and

correct the defects prior to initiating any tests.

Exercising of the governor-controlled valves may be performed choking the trip or trip

and throttle valve. At the same time, the trip or trip and throttle valve is exercised.

WARNING

RAPID CLOSING OF VALVES SUPPLIED WITH THE

TURBINE IS ESSENTIAL TO PROTECT AGAINST

OVERSPEED AND POSSIBLE OTHER MECHANICAL

PROBLEMS.

DANGER

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Lubrication System

NEVER BLOCK OR DISABLE THE TURBINE TRIP SYSTEM

OR ATTEMPT TO ADJUST OR REPAIR IT WHILE THE

TURBINE IS OPERATING.

WARNING

The overspeed trip system may malfunction during testing. Use

caution when testing and be prepared to shut the turbine down

quickly with the inlet-isolating valve.

The overspeed trip system should be tested weekly to verify its operation, to

prevent build-up of foreign material on the trip linkage, and to alert the operator to

deterioration that may affect trip system performance.

Dresser-Rand recommends incorporation of testing into the plant

operating/maintenance program and the keeping of a log to record tests.

Any malfunction of the trip system should be investigated and corrected prior to

returning the turbine to service.

E.6.2

Overspeed Trip Test Procedure

Before testing of the overspeed trip system, the turbine must be visually inspected

for defects. Pay particular attention to governor and overspeed trip components and

correct any defect prior to initiating any tests.

Use the following procedure to test the SST Turbine over-speed trip system:

a. Start up the turbine per Section I.4.2, Initial Start-Up Procedure.

b. Manually trip the turbine by pressing on the trip lever (434). The over-speed

trip valve should close, shutting off the turbine steam supply and bringing it to

a stop. This confirms operation of the linkage and valve, but not the

emergency governor cup assembly. If the valve does not close, refer to Section

K, Troubleshooting. Otherwise, proceed to Step c.

WARNING

119

The TRIP LINKAGE MOVES VERY RAPIDLY and abruptly

through its full travel when the turbine is TRIPPED. To guard

against serious hazards to operating personnel, they must

STAY CLEAR OF THE LEVER.

c. Open and latch the overspeed trip valve according to Section E.4, Trip System

Operation.

d. Increase turbine speed using the governor speed adjusting screw or knob on

the governor until trip speed is reached. The turbine should trip within 2% of

the trip speed setting on the turbine nameplate, and come to a complete stop.

e. If the turbine fails to trip at a speed 5% greater than the trip speed setting,

manually trip the turbine by pressing down on the trip lever. Refer to Section

K, Troubleshooting, to determine why the turbine fails to trip properly.

Optional construction may include an electronic overspeed trip system. Refer to

the certified drawings and the appropriate vendor instruction manual for

instructions on how to test the overspeed trip system.

Section F

Lubrication System

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Lubrication System

F.1

General

Proper lubrication of turbine bearings and the governor is essential for long,

trouble-free service. Turbine oil must be clean, of the proper viscosity and

quantity, and maintained at the proper temperature. Oil levels should be checked

before starting the turbine and on a daily basis for turbines running continuously.

WARNING

Lack of lubricant or contaminated lubricant could result in

bearing failure. This could create sparks or hot surfaces, which

could ignite lubricant or flammable gasses.

CAUTIONS

Overloading the turbine drive shaft will cause the turbine to

slow down - possibly resulting in insufficient lubrication and/or

reduced function and damage to the driven equipment.

If the ambient temperature exceeds 110° F (43° C), cooling

water must be provided to the bearing housings to limit the

maximum temperature of the lubricating oil to 180° F (82°C). If

the ambient temperature falls below freezing a means must be

provided to maintain the lubricating oil in the bearing housings

to a minimum temperature of 130°F (54°C) and to prevent

cooling water from freezing and possibly cracking the bearing

housings.

Without immediate and constant oil feed, the heat generated by the shaft in the

turbine bearings, unless properly dissipated, can cause bearing failure. Oil ring

lubricated bearings receive immediate lubrication as the shaft begins to turn, so

long as the proper oil level is maintained in the bearing housings. With pressure

lubricated bearings, the lubrication system must be arranged such that oil fills the

supply lines and feeds the bearings when the shaft begins to turn.

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F.2

Lubrication Requirements

Lubrication requirements are a function of the turbine type, exhaust temperature

and required operating speed range. In many cases, several lubrication options are

feasible at a given set of operating conditions with the selected method determined

by the user.

Major oil companies produce satisfactory oil for turbine use. It is advisable to consult

with your oil supplier for specific recommendations. As a minimum, the selected oil

should meet the following:

(a) Properly refined highly filtered mineral oil.

(b) Maximum metal wetting ability and ability to prevent the formation of rust on

metal parts bathed in oil. High stability toward oxidation and corrosion resistance may be

accomplished by the use of rust and oxidation inhibitors, or as a result of a particular

refining process.

(d) Best possible ability to separate rapidly from water.

(e) Minimum tendency to oxidize or form sludge when agitated at actual operating

temperatures when mixed with air and water.

(f) Minimum tendency to emulsify or foam when agitated with water and/or air.

(g) High viscosity index. A fluid with a high viscosity index can be expected to

undergo very little change in viscosity with temperature extremes and is

considered to have a stable viscosity.

CAUTIONS

CLEANLINESS is ESSENTIAL for long and trouble free service

from BEARINGS and GOVERNOR. Care must be taken to

ensure that no foreign material enters bearing housings, the

governor, and constant level oilers or oil reservoirs when

performing maintenance, checking oil, adding oil or making

adjustments.

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Lubrication System

Overloading the turbine drive shaft will cause the turbine to

slow down - possibly resulting in insufficient lubrication and/or

reduced function and damage to the driven equipment.

The bearings are made to precision limits on a production basis. When bearing

clearances become excessive, new bearings must be installed. Bearing clearances

may be considered excessive when they become approximately 0.004”/0.101mm over

the normal maximum clearance. (Refer to the turbine data sheets for normal running

clearance of your turbine.) The bearings are longitudinally split to permit their removal

and replacement with the shaft in place. Procedures for replacements are given in

Section L-6.

The recommended bearing temperature limits are as follows:

Metal Temp. Oil Temp.

°F / °C

Maximum Normal - Pressure Lube

Operating

220/104

180/82

Alarm

230/110

185/86

Shutdown

250/121

195/90.5

Maximum Normal - Ring Oiled

Operating

220/104

180/82

Alarm

265/129

185/86

Shutdown

270/132

195/90.5

Table F-1 Bearing Temperature Limits

F.3

Oil Ring Lubrication

The basic method of lubrication for SST turbines is oil ring lubrication. Carbon

steel oil rings running on the turbine shaft pick up oil from reservoirs in the

bearing housings. As the shaft and oil rings rotate together, oil flows from oil rings

onto the shaft, ultimately flowing into the bearings, providing lubrication. The

thrust bearing, located inside the shell of the steam end main bearing, receives its

lubricating oil from this same action. The oil level within bearing housings must

be maintained at a sufficient level to allow the oil rings to run in the oil. An oil

level that is too high results in oil leakage past the shaft seals. Oil rings cease to

rotate sufficiently when the shaft runs below

950 RPM, no longer providing

adequate lubrication. Therefore, the turbine should not be run at minimum

governor speeds less than 950 RPM unless for slow roll speeds of 500 RPM for

warm-up purposes.

SST frame turbines must have simple bearing cases, the ambient temperatures must

be below 110°F (43°C) and the cooling water supply must not exceed 100°F

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Instruction Manual for Single Stage 350, 500, and 700 Frame Steam Turbines - page 2