Property Risk Consulting

Guidelines
PRC.6.1.1.0.2
A Publication of AXA XL Risk Consulting

STEAM TURBINE LOSS PREVENTION INSPECTION

INTRODUCTION
Steam turbine loss prevention requires paying attention to how turbines, their driven objects, and
associated safety devices and systems are designed, applied, installed, operated, maintained and
repaired. Losses may result from a centrifugal rotor burst, an overpressure rupture, overspeed,
mechanical breakdown or other equipment failure.
This section suggests ways to minimize turbine losses by making periodic inspections. It focuses on
steam turbines driving generators rated at 750 kW and above and mechanical drive turbines rated at
1000 hp (750 kW) and above. The approach recommended also applies to smaller machines,
however, some features may not be necessary. Turbine fire protection is covered in PRC.17.12.1.

POSITION
Turbine Loss Prevention Management
Management commitment is the key to successful loss prevention. Loss prevention and control
programs must convey and enforce this commitment. Loss prevention inspection, one of the fourteen
interlocking management programs described in OVERVIEW, helps management evaluate the
effectiveness of all the other loss prevention programs. Every facility should formally adopt programs
similar to those in OVERVIEW.
Personnel at facilities having large turbines can perform most activities OVERVIEW recommends. If a
facility contracts out tasks, management must set up written procedures in advance to make sure the
contractors comply with all loss prevention programs.
The following management loss control programs apply to turbines:
New Construction - Submit plans to AXA XL Property Risk Consulting for installing new turbines or
substantially reworking existing units. Installing a large steam turbine is obviously a major
undertaking. The probable life-cost of the unit can be significantly reduced if various loss prevention
and control features are designed and built into the machine. API Standard 611, API Standard 612,
and ASME PWR - Vol. 8, Guidelines For Preparation Of Specifications For Steam-Turbine
Generators should be consulted. PRC.1.5.2 also contains recommendations.
Hazard Identification - Consider hazard analysis early when designing facility modifications and
expansions. Update the analysis periodically to incorporate operating experience and aging effects.
While turbine hazards are fairly well established, the turbine itself may be only a small part of the
exposure. Extraction steam flow to and from the turbine and driven equipment performance can
strongly influence the rest of the plant. Support system reliability influences the turbine hazards. Unit
failure probability can change significantly because of changes in operating conditions and unit aging.

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reports and other risk consulting services, as requested. In this respect, our property loss prevention publications, services, and surveys do not address life safety or third
party liability issues. This document shall not be construed as indicating the existence or availability under any policy of coverage for any particular type of loss or damage.
The provision of any service does not imply that every possible hazard has been identified at a facility or that no other hazards exist. AXA XL Risk Consulting does not
assume, and shall have no liability for the control, correction, continuation or modification of any existing conditions or operations. We specifically disclaim any warranty or
representation that compliance with any advice or recommendation in any document or other communication will make a facility or operation safe or healthful, or put it in
compliance with any standard, code, law, rule or regulation. Save where expressly agreed in writing, AXA XL Risk Consulting and its related and affiliated companies
disclaim all liability for loss or damage suffered by any party arising out of or in connection with our services, including indirect or consequential loss or damage, howsoever
arising. Any party who chooses to rely in any way on the contents of this document does so at their own risk.

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 PRC.6.1.1.0.2

Employee Training - Steam turbines and their associated equipment are large, complex and
expensive machines that are often critical to a facility’s operations. Provide an ongoing formal training
program for management, operation, maintenance and repair personnel.
Maintenance - Maintenance is the most important aspect of successful turbine operation. A properly
designed and protected turbine that undergoes continued quality maintenance may require fewer
overhauls. Maintenance programs are discussed in PRC.1.3.0.
Insurance Company Recommendations Provide a procedure for documenting and reporting
evaluation of, and compliance with, insurance company recommendations. Insurance company
surveys examine the effectiveness of loss control programs. Loss experience of turbines in many
industries supports such recommendations.
Pre-Emergency Planning - Provide a pre-emergency plan for each facility. Steam turbines are
usually vital to facility production. A turbine loss can severely upset the facility energy balance. A
large turbine rotor can require a year to replace; a complete machine can possibly require longer.
Spare rotating elements are one part of pre-emergency planning for turbines. This subject is
discussed in PRC.6.0.1.0. Explore alternate means of production and ways to make temporary
repairs.
Proper Housekeeping - Housekeeping and maintenance are strongly related. Sloppy plants seldom
have good maintenance; plants with good maintenance are seldom sloppy. Turbines require
cleanliness, corrosion control and minimal clutter.
Loss Prevention Inspection - Monitor loss prevention programs. Although properly trained
equipment operators continuously inspect equipment, a trained inspector who periodically monitors
the actual performance of the various loss prevention programs “on the ground” provides a more
direct line to management. Property Risk Consulting Guidelines is designed to help a technically
oriented person perform meaningful loss prevention inspections. When a turbine needs inspection, a
larger facility might consider a specialty inspector; a smaller facility might consider a contract service.
Turbine Loss Prevention Inspection
A loss prevention inspector performing a turbine inspection reviews, records and witnesses selected
operations and tests to determine that a turbine has been properly designed, constructed and
installed and that it is being properly operated, maintained and repaired. A facility’s loss prevention
inspector may be an employee, a corporate staff member or a consultant under contract. AXA XL
Risk Consulting clients may contact the AXA XL Risk Consulting Area Office to help set up an
inspection program or audit an existing program.
Inspection Guidelines
Turbines need several kinds of inspections. Each should be performed under a program that
produces suitable reports to management. The types of inspections are:
• Routine inspections by operators.
• In service inspections.
• At rest inspections.
• Dismantled inspections.
Specialized inspections, such as accident investigations, are not discussed in this section.
The following recommendations apply to any inspection:
• Provide the loss prevention inspector with access to a master maintenance data file for each
piece of equipment. Even if the necessary information is not in one place, it should be readily
accessible. PRC.6.1.1.0.2.A lists data that should be available. Any needed information which
does not exist should be generated over a reasonable period of time. Additional maintenance
systems which are needed should be recommended.

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• Observe and report on housekeeping. This is a good indicator of facility personnel and
management attitude toward the equipment.
• Review operating logs and records from the last inspection through the current date. There
should always be a properly maintained written system. This may be supplemented where
appropriate by electronic data systems. The condition and contents of the operating logs or
records tell much about the attitude toward loss prevention.
• Audit the written operating procedures. Operators should have written procedures covering
normal and emergency conditions. Normal operations include:
Startup and normal shutdown.
°
Transition between hot standby and other operating modes.
°
Steady state and transient operation at full and part load.
°
• The emergency conditions to be covered are site-specific, however, cover at least the
following at all facilities:
Loss of the normal electric power or lubrication source.
°
Load rejection.
°
Overspeed or other loss of control.
°
Abnormal noise or vibration.
°
Activation of other installed alarms and protective devices.
°
Weather emergencies, including above- or below-normal temperatures (where
° applicable).
• Verify the condition of major spare parts. If parts are not on the premises (pool spares, those
held by the manufacturer or in contract storage, etc.), confirm the arrangements.
• Review vibration monitoring and analysis programs; where applicable, audit data. Look for
adverse trends that might have been missed.
• Audit the following additional items on an as-needed basis, periodically or as suggested by
history.
Lubricating oil system reliability during any upset or utility outage. See PRC.6.1.1.0.5.
°
Trip valve, extraction valve and reheat intercept valve exercising and overspeed trip
° testing. See PRC.6.1.1.0.3.
Compliance with the ASME standard practice on water/cool vapor induction protection.
° See PRC.6.1.1.0.4.
Life extension analysis or activity for:
°
Major equipment more than 15 years old.
°
Reheat piping over 10 years old.
°
Other piping over 25 years old.
°
• Provide the loss prevention inspector with a checklist or a report guideline for each inspection
tour. PRC.6.1.1.0.2.B suggests items to consider for in service or at rest inspections and
PRC.6.1.1.0.2.C suggests items for dismantled inspections.
Routine Inspections by Operators
Routine inspections include most operator actions needed to monitor and control the machine.
Document all important activities and periodic observations in a log. Promptly and formally report
abnormal conditions to management. Operating specifics are outside the scope of this section,
however, the following operator and support staff activities are recommended:
• Measure unit steam consumption. Changes in steam consumption under constant load usually
indicate deteriorating conditions. A slow increase may indicate accumulated deposits or
erosion damage. A sudden increase may indicate blade failure or foreign object damage. If

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possible, measure steam consumption for the unit and for each casing, because problems in
one casing may be compensated by altered conditions in other casings.
• Calculate unit efficiency. If steam flow measurement is not practical, calculate unit and casing
efficiencies using inlet and outlet temperatures and pressures.
• Measure stage pressures. Changing stage pressures also indicate changes in the blading
condition.
• Conduct casing temperature scans. Casing temperature changes may indicate internal leaks,
which may be caused by damaged seals or distorted casings.
• Measure and analyze unit vibration. Vibration analysis can reveal more about machine
condition than any other on-line technique. Operators must report any change in the nature or
amount of machine vibration. Management must promptly respond to reported changes by
providing analytical support.
• Measure shaft and casing differential movement. Carefully tracking the differential expansion
between shafts and casings may reveal flexibility loss that may cause casing distortions and
rubs. Flexibility loss may be caused by seized expansion joints or sliding feet.
• Inspect foundation bolts. Loose foundation bolts may indicate serious problems which will
adversely affect the machine alignment. Promptly investigate any foundation looseness or
insecurity.
• Closely monitor bearings. Constant attention to bearing temperatures and lubrication
temperature differentials is needed to detect deteriorating bearings. Subtle changes in the
lubrication system pressure balance may indicate bearing deterioration before bearing
temperature increases occur. Wear particle analysis may signal deterioration before any other
symptoms appear.
• Perform the following inspections during jacking gear operation:
Listen for clanking or scraping noises, particularly near shaft penetrations. These noises
° may indicate misalignment or shaft or casing distortion.
Check the power required by the jacking gear and compare it to the power required
° during previous jacking gear operation. An increase in power consumption may reveal
binding or rubbing in the unit. Readings may need to be adjusted for different unit
temperatures or other factors.
• Perform the following inspections during shutdown:
Check rotor axial and radial position and shaft runout. This is most effective on machines
° that have borescope ports at suitable measuring points. Some measurements can be
taken at coupling flanges by using a dial indicator.
Inspect the internals through borescope ports, drain connections and other casing
° penetrations. Modern instruments can provide a reasonably thorough internal inspection
without the casing having to be lifted. Examining internal parts such as nozzles and
blading provides information that is critical to overhaul decisions. Therefore, machines
which require long intervals between overhauls should have borescope ports retrofitted to
allow the most complete internal inspection possible. Consult the turbine manufacturer
concerning the size and location of borescope openings.
Take bearing measurements. Depending on the bearing design, bearing inspections may
° also be possible if necessary.
In Service, At Rest and Dismantled Inspections
Turbines should be periodically inspected and their operating and maintenance records reviewed by a
trained person from outside the operating department. All turbines should have a monthly in-service
or at-rest inspection.
Turbine overhaul frequencies depend upon their size, age, service and history. It is recommended
that turbines be overhauled:

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• Every two years for turbines under 1000 hp (750 kW).

• Every three years for turbines 1000 hp (750 kW) to 10,000 hp (7,500 kW). If units are
monitored as described below, and they have no known adverse conditions, the interval for
machines in continuous service may be increased to five years.
• Every 50,000 equivalent operating hours ( Te ) for turbines over 10,000 hp (7,500 kW). Te is
determined by the following formula:
Te = Ta + 25ns
Where: Te = equivalent operating hours
Ta = actual operating hours
ns = number of starts, including cold and hot starts
If full monitoring is performed and there are no known or suspected adverse conditions, the
interval for machines in continuous service may be increased to seven years. The overhaul
interval should never exceed seven years. Full monitoring includes:
Installed vibration monitoring equipment including alarms and automatic shutdown for
° high vibration and rotor axial position out of limit.
All recommended protective devices in service.
°
Wear particle analysis performed.
°
Inspections conducted at least annually after three years of operation through borescope
° openings that permit all nozzles, blading and throttle valves to be inspected.

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STEAM TURBINE UNIT LOSS PREVENTION DATA

The master maintenance data file for each facility should include the following information. The
information suggested is minimal. Every installation will require additional site-specific data.

FACILITY INFORMATION
• A sketch or drawing of the steam system which identifies major steam sources and loads. Show all
reducing stations and cross connections. The following information should be available:
Capacity of each steam source, including steam turbine extraction, under all conditions.
°
Amount of steam required by each load under all conditions.
°
Priority of steam loads for emergency load shedding.
°
Capacity of reducing stations and cross connections, considering all required desuperheaters
° or attemperators.
• Copies of the facility pre-emergency plans which involve the turbine(s) and auxiliary equipment.
Where applicable, include a plan for cold start or emergency restart without the normal outside
power source. List the type, capacity and fuel availability for all backup engine or gas turbine-
driven emergency generators on site and for all available outside or emergency power sources.
• Copies of the normal and emergency operating procedures.
• The vibration analysis program manual, which should include descriptions of all unusual or
advanced techniques being used, such as remote condition analysis or on-line rotor crack
monitoring.
• Other maintenance program documentation, including:
Copies of all loss prevention inspection reports.
°
A summary of required activities and their frequencies.
°
Predictive maintenance parameters and the levels at which they require attention.
°
A list of time-based activities and the dates they were last performed.
°
An up-to-date file of contact persons for all maintenance contractors.
°
• A description of the instrumentation calibration and testing program.
• The manufacturers' recommended temperature rate-of-rise curves and the procedures to ensure
that they are being used.
• Measures being taken for equipment over 15 years old to monitor age-related conditions, such as
stress cracking, fatigue hardening or creep, that may signal the end of life.
• A copy of those portions of the facility hazard evaluation dealing with the turbine(s), driven
equipment and associated processes.
• A file showing the status of all insurance company recommendations involving the turbine(s) and
related equipment.

UNIT INFORMATION
Each unit file should identify the components associated with the unit, including the turbine, the driven
object, any gear set and all auxiliary systems. A description of the production exposure for the unit is
useful. A description of all hazards resulting from unscheduled shutdowns of the unit is essential.
The unit file should also contain:

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• An up-to-date set of prints for all unit systems, such as lubricating oil and cooling.
• Coupling data and data on all clutches, turning gear or other accessories.
• Location and plan for installing spare or alternate drivers or driven equipment.
• Details of foundations, piping flanges and other connections.
• A list of derates and forced outages. For each event, provide the date, components involved,
cause and resolution.
• Copies of all inspection and overhaul reports, including information concerning all modifications,
upgrades and major repairs.
• Log of overspeed, low oil pressure, vibration and other alarm and trip tests and results.
• Setpoints for all alarms and protective devices. Provide the data used to support current setpoints
for devices whose settings may be modified in response to operating experience, such as vibration
alarms and trips.
• Copies of inspection and test reports for valve exercising.

STEAM TURBINE INFORMATION

Each turbine file should include:
• Unit Number.
• Nameplate data, including the manufacturer and all ratings.
• Dates the unit was built, installed and commissioned.
• An up-to-date set of prints, including all modifications, alterations and repairs, and all
manufacturer's instructions.
• All steam and auxiliary fluid temperatures, pressures and flow rates.
• Prints and manuals for the governor, trip valve lubrication system and other accessories, including
the condenser, if applicable.
• List of major spare parts and their locations.
• Log of performance (heat rate) tests.
• Schedule and performance log for exercising and testing extraction and nonreturn valves.
• A record of any history of difficulty because of steam contaminants, and a description of the
monitoring performed or other action taken.
• An evaluation of the unit water/cool vapor induction protection.
• Records of borescopic or other partial internal inspections performed between overhauls.
• Complete records of all casing or rotor cracks and actions taken.
• Copies of all applicable manufacturer's suggested modification reports (TIL's, etc.).

GENERATOR INFORMATION
Each generator file should include:
• Unit Number.
• Nameplate data, including the manufacturer; all ratings and exciter data.
• Dates the unit was built, installed, commissioned and, if applicable, rewound.
• An up-to-date set of prints, including all modifications, alterations and repairs, and all
manufacturer's instructions.
• All auxiliary fluid temperatures, pressures and flow rates, including lubricant, cooling medium, and,
if applicable, hydrogen.
• A list of installed electrical protective devices provided and a log of all tests and results.

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• Log of electrical tests.

• List of major spare parts and their locations.
• Complete information concerning any retaining ring cracks.
• Records of borescopic or other partial internal inspections performed between overhauls.
• Copies of any applicable manufacturer's suggested modification reports (TIL's, etc.).

OTHER DRIVEN EQUIPMENT INFORMATION

The file for each piece of driven equipment should include:
• Unit Number.
• Type of object.
• Nameplate data, including the manufacturer and all ratings.
• Dates the unit was built, installed and commissioned.
• An up-to-date set of prints, including all modifications, alterations and repairs, and all
manufacturer's instructions.
• Temperatures, pressures and flow rates for all process and service fluids.
• Prints and manuals for protective systems such as surge control for compressors.
• Log of performance tests.
• Records of borescopic or other partial internal inspections performed between overhauls.
• List of major spare parts and their locations.

GEAR INFORMATION
Each gear set file should include:
• Unit number.
• Nameplate data, including the manufacturer and all ratings.
• Dates the unit was built, installed and commissioned.
• An up-to-date set of prints, including any modifications, alterations and repairs, and any
manufacturer's instructions.
• Temperatures, pressures and flow rates for externally supplied coolants and lubricants.
• Records of borescopic or other partial internal inspections performed between overhauls.
• List of major spare parts and their locations.

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STEAM TURBINE LOSS PREVENTION DATA

IN-SERVICE OR AT-REST INSPECTION

The following information should be gathered or observed during a steam turbine loss prevention
inspection. See PRC.6.1.1.0.1. A for a list of data that should be available to the inspector. Note that
the information suggested is minimal. Every installation will require additional site-specific data.
Reviewing logs and records is necessary for any inspection. The activities listed below apply to in-
service inspections. An at-rest inspection should involve similar observations. At-rest inspections
should, if possible, be scheduled to coincide with borescope inspections or other maintenance
activities.
Before conducting the inspection, review the operating and maintenance records collected since the
last inspection. The following items, as applicable, require particular attention:
• The most recent dismantled and inservice inspection reports.
• Records of all unscheduled maintenance outages, forced outages and derates since the last
inspection.
• All notices of overdue inspections, maintenance or testing.
• Records of adverse conditions found by loss control programs, including but not limited to:
Vibration monitoring.
°
Safety device testing.
°
Lubricating oil wear particle analysis.
°
• The list of outstanding insurance company recommendations.
Walk down the unit, noting visible deficiencies. The following suggestions may help to develop an
inspection checklist.
• Note the steam pressure(s), temperature(s), speed(s) and the load. If possible, calculate the
thermal efficiency of the whole turbine and each section. Compare the value(s) to previous
data.
• Examine exhaust or condenser overpressure protective devices. Verify proper test or
inspection procedures and frequency.
• Inspect the governor system for leaks, looseness, binding, or other adverse conditions.
• Verify the machine speed for preset governors; verify machine speed, responsiveness and
control limits for variable governors.
• Verify proper frequency and procedure for testing overspeed protection devices.
• Inspect the lubrication system; note bearing temperatures and oil flows and compare them
with previous readings. Test the backup oil pump(s) automatic start and the low oil pressure
alarm and trip.
• If possible witness, or otherwise verify written records of trip valve, control valve and extraction
valve exercises.
• Review records of all control system testing.
• Collect vibration readings to compare with previous data. If vibration monitors are not installed,
obtain a set of manual readings. Also, listen carefully for any abnormal noise.
• Examine piping systems for suitable support. Look for loose, damaged or “bottomed out”
hangers, and freedom of expansion. For steam systems in service, check for proper drain
operation.

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• Review written operating instructions, operator training records and results of all drills.
• Review the maintenance program and report all overdue activities or other deficiencies.
• During the tour, note all housekeeping deficiencies, including damaged insulation, improperly
stored materials, temporary structures of any kind or leakage of any substance.

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STEAM TURBINE LOSS PREVENTION DATA

DISMANTLED INSPECTION

The following information should be gathered or observed during a steam turbine loss prevention
inspection. See PRC.6.1.1.0.2.A for a list of data that should be available to the inspector. Note that
the information suggested is minimal. Every installation will require additional site-specific data.
Reviewing logs and records is necessary for any inspection. The activities listed below apply to
dismantled inspections. One inspector will probably not make all the suggested observations;
therefore, make records of activities available for review.
Before conducting the inspection, review the operating and maintenance records collected since the
last inspection. The following, if applicable, require particular attention:
• The most recent dismantled and in-service inspection reports, particularly any list of items
deferred from the last dismantled inspection.
• Records of all unscheduled maintenance outages, forced outages and derates since the last
inspection.
• All notices of overdue inspections, maintenance or testing.
• Adverse conditions found by loss control programs, including but not limited to:
Vibration monitoring.
°
Safety device testing.
°
Lubricating oil wear particle analysis.
°
• The list of outstanding insurance company recommendations.
Walk down the unit, noting any deficiencies. Several visits will be necessary. Also, most dismantled
inspections are coordinated or supervised by a manufacturer’s representative. Loss prevention
activities should be coordinated with this individual. These suggestions may help to develop an
inspection checklist.
• Witness lifting of the turbine casing. Visually examine and describe in writing or photograph
any obvious problems, including rubbed spots, foreign objects or foreign object damage,
missing parts, corrosion or deposits.
• Inspect the rotor “as-removed.” Make sure samples of deposits are taken for analysis before
the rotor is cleaned for nondestructive examination. Nozzle diaphragms should also be
examined after they are removed and before they are cleaned.
• Inspect the steam chest, nozzle block and all associated valves, linkages and other
components, including the main steam stop, the trip throttle valve and its mechanism,
nonreturn valves, reheat valves, the governor and the overspeed trip(s).
• Visually and nondestructively examine the steam strainer.
• Witness the testing or review the nondestructive test reports of all blades, blade attachments,
shrouds, lacing wires, nozzles, disks, and valve parts.
• Verify weld repairs of cracks and removals of minor damage by grinding or straightening.
• Inspect all bearings and measure clearances; inspect seals and packings.
• Examine the shaft adjacent to shrink-fit disks for any evidence of axial or radial movement or
fretting corrosion. Examine all keyways for cracks.
• Inspect all lubrication system components while dismantled, including main, auxiliary and
shaft-driven pumps and their prime movers, the sump and coolers.

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• For condensing units, inspect the condenser or review the inspection reports.
• During reassembly, check clearances between moving and stationary parts. Compare
readings with those on file.
• Witness or review the records of alignment checks.
• Examine piping systems for suitable support, loose, damaged or “bottomed out” hangers, and
freedom of expansion.
• Review the maintenance program and ensure all noted deficiencies are included in the scope
of work.
• During the tour, note all housekeeping deficiencies, including damaged insulation, improperly
stored materials, temporary structures or equipment or any leakage. Verify all tools and
materials in the work area are under control.
• Witness the initial startup of the unit and the overspeed trip test.

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