Scope and use. This field reference follows the supplied 600 MW steam turbine main-body overhaul procedure, including the generator journal-bearing and sealing-bearing work described in it. It retains the source's sequence and principal work items while adding headings and clearer bilingual terminology. It is intended to help plant teams prepare work packs, inspection records and review points; it is not a substitute for the complete approved plant procedure.
Important equipment boundary. The source is written for a particular 600 MW unit and cites the applicable construction/inspection standards, plant maintenance rules, manufacturer manuals, drawings and related technical records. Clearances, fits, bolt data, rotor dimensions, material criteria, test pressures and acceptance limits are equipment-specific. Use the original approved tables and current OEM/plant documents for every numerical value. Do not transfer a value from this procedure to another unit or treat OCR/transcription as authority.
Primary keyword: 600 MW steam turbine overhaul procedure. Related topics: steam turbine maintenance, turbine casing inspection, rotor inspection, journal and thrust bearing overhaul, turbine clearance measurement, generator seal bearing inspection. The procedure connects to steam turbine overhaul services and steam turbine spare parts.
1. Scope, governing documents and work boundaries
The procedure covers the steam-turbine main body and the generator journal-bearing and seal-bearing equipment identified by the source. Before work begins, establish which turbine sections, external steam pipes, valves, generator interfaces and auxiliary systems are included. Confirm the current equipment identity, drawings and revisions, manufacturer instructions, plant maintenance procedure, applicable inspection standards and prior repair records. Resolve conflicts through the plant's engineering authority before work.
The source's work list includes preparation and insulation/cover removal; high-, intermediate- and low-pressure casing disassembly; main and crossover steam piping; diaphragms, nozzle groups, balance pistons and sealing components; casing joints, bolts and locating pins; rotor, blades, shaft journals and couplings; journal and thrust bearings, oil deflectors and bearing housings; sliding-key/support arrangements, oil-injection and turning-gear equipment; generator journal and seal bearings; alignment, rotor balancing, generator pressure testing, insulation/lagging restoration and final records. The exact boundary should be checked against the unit's approved outage plan.
2. Tools, lifting equipment and work preparation
Prepare the special tools and general equipment listed for the unit. The source inventory includes casing-bolt heating equipment and dedicated sockets/wrenches; casing and rotor lifting beams, slings, eyebolts and guides; hydraulic jacks; torque/tension equipment; dial indicators and stands; outside, inside and depth micrometers; vernier and depth calipers; precision and frame levels; feeler and wedge gauges; cleaning and grinding tools; welding equipment; chain blocks; electrical leads and protective devices; and tools for the turning gear and generator-bearing work. Check identification, capacity, condition, calibration where applicable, and inspection status before use. A tool list is a readiness check, not permission to use equipment outside its rating or approved lifting plan.
Review work scope, sequence, schedule, materials and spare parts for omissions. Check that measuring instruments are suitable and their accuracy is adequate for the specified measurements. Confirm system and site conditions, lighting, power, water, air, fire protection, housekeeping, barricades, floor protection, access and communications. Verify the plant-approved isolation, permits, zero-energy state and release for maintenance. The source includes machine-temperature and depressurization checks before casing work; apply the actual unit's approved values and isolation procedure.
Before dismantling, mark component orientation and matched parts, prepare clean and protected storage, arrange tagged containers for fasteners and small parts, and establish measurement sheets. Identify hold points, witness points, responsible inspectors and the person authorized to approve deviations or additional work. Protect machined joints, shaft journals, blades, sealing teeth, instrument wiring and open oil/steam passages from impact, dirt and moisture.
3. Disassembly sequence and handling controls
Remove external casing attachments and insulation/covering as planned. Disconnect instrumentation and electrical leads through the responsible disciplines and identify each connection for restoration. Remove high-, intermediate- and low-pressure steam connections and crossover sections in the approved order; cap or cover open flanges and passages immediately. Remove casing-joint fasteners and locating pins using the specified heating and release method. If a fastener binds, stop and follow the approved engineering repair route; do not compensate with an unapproved extension or forced lift.
Before lifting a casing, appoint one lift director, inspect the crane, hooks, rigging, lifting points and dedicated tools, and confirm that every connection has been released. Lift evenly under the approved lift plan. Monitor separation and rotor movement; stop if components bind, move unexpectedly or show contact. Do not force a casing apart with unapproved wedges or pry bars. Support and secure removed casings and internal assemblies so joint faces and locating features are not damaged.
Disassemble high- and intermediate-pressure inner casings, diaphragm carriers, balance pistons and internal seals in the documented order. For low-pressure sections, record accessible exhaust-hood and last-stage blade clearances before disturbing the relevant parts where the approved procedure requires it. Remove internal sections with their lifting points and supports; retain orientation marks and matched hardware. Complete the specified pre-lift records before rotor removal, including flow-path clearances, coupling position/center, rotor runout or eccentricity, rotor lift/centerline readings, shaft-journal bridge readings and seal/oil-deflector gaps.
Rotor lifting requires the approved dedicated rigging, adequate support and a controlled path through seals and stationary blades. Confirm coupling separation and bearing/thrust-component status. Keep personnel clear of suspended loads, prevent rotor swing and contact, and never leave a rotor suspended unattended. Lower it onto prepared supports that protect journals, thrust surfaces, coupling faces and sealing features. Record support locations and preservation condition.
4. Cleaning, examination and dimensional records
Clean components using methods compatible with their materials and surfaces. Keep foreign material out of oil passages, steam passages, drain lines and instrument connections. Establish component identity before cleaning or examination so each finding remains traceable. Record the as-found condition before repair: deposits, rubs, erosion, corrosion, cracks, looseness, distortion, missing material, fretting, damaged threads, leakage paths and contact patterns.
Inspect casing halves, internal casings, diaphragm/nozzle assemblies, balance pistons, seal carriers, steam-chest/nozzle areas, extraction connections, drains and welds. Examine joint faces, guide slots, locating pins, fits and support/contact areas for scoring, pull-up, oxidation, deformation or fretting. Where a suspected crack or material defect is found, use the examination method required by the approved procedure and refer disposition to the responsible engineering authority. Check specified bolts and studs for condition, thread damage, hardness or non-destructive examination where required by the unit documents; record replacements and material traceability.
Measure casing level and horizontal-joint gaps, casing half alignment, support/cat-paw and sliding-key conditions, locating-pin and fastener clearances, diaphragm and seal fits, flow-path clearances, and relevant axial/radial positions. Use the procedure's prescribed measurement locations and record instrument IDs, datum, temperature where required, as-found/as-left values and units. Repeat doubtful or inconsistent readings; preserve raw readings rather than recording only a pass/fail result. Do not use generic limits.
5. Rotor, blades, seals and steam-path components
Examine rotor surfaces, journals, thrust faces, coupling fits and balance features. Record runout/eccentricity at the designated sections, rotor lift or centerline, shaft-journal dimensions, taper and out-of-roundness, and blade/impeller positions where required. Check blades and attachments for cracks, looseness, rubbing, deposits, erosion, deformation and damaged locking features. Compare findings with the unit's records and design criteria; an observed symptom alone does not define a repair.
Inspect gland seals, shaft sleeves, labyrinth teeth, diaphragm seals, balance-piston seals and oil deflectors as distinct components. Record location and segment identity, clearances, contact or rub evidence, damage and fit with mating parts. Do not confuse a shaft sleeve with a stationary gland-seal segment. Any refurbishment, blending, welding, replacement or geometry change requires an approved repair instruction and defined inspection/acceptance method. Keep replacement-part identification tied to the drawing and revision.
During rotor cleaning, protect blade edges, shrouds, seal teeth and precision surfaces. The original procedure describes special precautions for deposits and cleaning methods; select the method only under the current approved work instruction and material compatibility review. After cleaning, verify that passages and features are free of residue and reinspect any area previously obscured.
6. Journal bearings, thrust bearing and oil deflectors
Before bearing disassembly, identify and protect vibration/temperature probes and leads; record oil-deflector gaps and bearing condition. Mark bearing halves, pads, shims, locating rings and oil connections. Drain and disconnect supply, return and jacking-oil lines as applicable, then cap every opening against contamination. Remove bearing parts with the specified support and lifting method; do not allow pads or precision surfaces to fall or be mixed.
Clean and examine white-metal bearing surfaces, contact patterns, wipe, scoring, cracks, corrosion, embedded material, local separation and evidence of overheating. Use the inspection method required by the unit documents. Record pad identity and orientation. Measure side and top clearances, bearing crush/tightness, shaft-journal dimensions and bridge/shaft-lift readings using the specified locations and methods. Retain each reading and compare it only with the applicable machine-specific criteria. Adjustments to shims, scraping, repair or replacement need recorded engineering disposition.
For the thrust bearing, preserve working and non-working pad identity and position. Inspect pad contact marks, surface condition, locating ring and housing, oil-seal ring and adjustment elements. Record the original positions/heights of adjustment screws and shims before removal. On assembly, return identified parts to their positions, restore connections and instrument leads without pinching, and verify thrust clearance and relevant oil-seal gaps to the unit requirements. Record final readings and acceptance.
Inspect oil deflectors and bearing-housing baffles for fit, joint alignment, deformation, rubbing, damage and correct orientation of oil-return features. Measure and record their clearances at the specified points. Confirm the housing is clean, oil passages are open, and all temporary plugs, cloths and foreign materials are removed before closing.
7. Sliding keys, supports, turning gear and auxiliaries
Inspect accessible sliding keys and support arrangements for freedom of movement, wear, galling, sticking, damaged surfaces and correct marking. Clean before dismantling; record as-found positions and clearances. Measure all designated gaps and verify against the manufacturer's unit-specific criteria. Repair or replace only through an approved disposition. Refit parts to their marked positions and orientation; use the specified lubricant and amount. Protect the finished sliding surfaces against dirt and keep records of final movement and clearance.
Inspect turning-gear gears, worm/wheel, shafts, bearings, lubrication, seals, base and associated chain or drive arrangements. Record tooth and bearing condition, backlash or axial/radial movement where specified, and any abnormal wear. Check engagement, turning function and associated interlocks in the approved test sequence. Inspect oil-injection equipment, piping, valves and connections as included in the work package; keep cleanliness and system restoration records.
8. Reassembly, casing closure and alignment
Do not begin final assembly until internal components have passed inspection, repairs are approved, required measurements are complete, records are reviewed and acceptance hold points released. Confirm casing internals, rotor, bearings, seals, fasteners and temporary protections are clean and complete. Check that assembly conditions and records required by the procedure are satisfied, including casing defect findings, casing level/joint fit, rotor lift/runout, flow-path and seal clearances, bearing/oil-deflector records, thrust clearances, preliminary alignment and applicable bolt inspection reports.
Reinstall components in the approved sequence, maintaining orientation marks and matched sets. Use specified bolt materials, heating/tightening method, sequence and documented values; do not infer tightening data from a similar unit. Confirm locating pins, joints, support contacts, sliding keys and seals are correctly seated. Measure clearance at the prescribed assembly stages; if a result is unexpected, stop and resolve it before the next closure step. Use the approved joint compound or sealant only where specified and keep it out of passages.
Align the turbine shaft train and coupling using the approved datum, instruments, temperature/cold-alignment conditions, correction factors and acceptance criteria. Record readings at each coupling/position and all corrections. Coordinate casing load distribution/support adjustments with shaft-train alignment where required by the source procedure. Verify coupling fit and fastener installation using the approved instructions. Restore external piping, drains, instrumentation, electrical connections, lagging and guards only after the relevant inspection release.
9. Generator journal and seal-bearing work
Handle generator journal bearings and seal bearings as a separately controlled scope even when they share the outage. Record the unit and bearing identity, as-found oil and seal conditions, clearances, contact marks, insulation/electrical observations and instrument status. Protect rotor journals, seal surfaces and generator internal cleanliness. Keep mechanical and electrical specialists coordinated at the coupling and bearing interfaces.
Inspect bearing shells/pads, seal rings and associated parts for wear, rubbing, deposits, damage, deformation and fit. Measure the designated clearances and dimensions using the specific generator drawings and procedure. Reassemble with the correct matched components, documented orientation, clean oil passages and restored instrumentation. Where the procedure requires a generator pressure/air test or other verification, use the approved test medium, boundary, pressure, duration, safety controls and acceptance criteria from the current unit documents. Record leakage/pressure results and any corrective action. Do not substitute a guessed test value.
10. Tests, handover and acceptance
Complete the specified rotor dynamic-balance test, shaft-center/alignment checks, generator pressure test, insulation or other electrical tests, turning-gear checks, instrument checks and system restoration only where included in the approved scope. Each test needs a defined configuration, calibrated instrument, acceptance basis, responsible witness and signed result. A test being performed is not proof of acceptance; retain the result and the approval.
Close out the work pack with: equipment and component identity; current drawing/procedure revisions; pre- and post-repair measurements; inspection and non-destructive examination records; material/part traceability; approved repair dispositions; bolt examination and tightening records; clearance, bearing, rotor and alignment sheets; generator test reports; instrument and auxiliary restoration checks; open items/deviations; and the authorized return-to-service release. Identify any limitation or follow-up action explicitly.
Field-ready review checklist
Correct unit identity, approved procedure, drawings and acceptance criteria are available at the worksite.
Scope, interfaces, sequence, permits, isolations, lifts, tools, consumables and spares are ready.
Measurement points, instrument IDs, record sheets, hold points and approving roles are agreed.
Every removed component remains identified, oriented, protected and traceable.
As-found findings and readings are recorded before repair or adjustment.
Unexpected damage, doubtful measurements or proposed deviations are stopped, documented and approved before proceeding.
Assembly and testing are released against equipment-specific criteria, with signed records and open actions handed over.