An Oil And Gas industry Reliability Engineer asked me.: Can you help me while am I doing RCM study on the lubricated components of a turbomachinery?

I replied back with below content:

Can We Do an RCM Study on the Lubricated Components of Turbomachinery?

By Khash

Yes, you absolutely can do an RCM study on the lubricated components of turbomachinery. In fact, for an oil and gas company, this is one of the most valuable areas to apply Reliability-Centered Maintenance because lubrication-related failures can quickly affect production, equipment availability, repair cost, process safety, and environmental risk.

However, the best answer is not simply “do RCM on the bearing” or “do RCM on the oil pump.” For turbomachinery, the correct approach is to study the lubricated component together with its lubrication system, protection system, operating context, and failure consequences. A journal bearing, thrust bearing, gearbox, or control-oil valve does not fail in isolation. It fails because of load, speed, temperature, oil condition, contamination, pressure, flow, vibration, misalignment, process upsets, or protection-system weakness.

A true RCM process should identify asset functions, functional failures, failure modes, failure effects, consequences, and the right maintenance or risk-control policy. SAE JA1011 is the recognized benchmark for deciding whether a process genuinely qualifies as RCM, and the current SAE listing describes JA1011 as a standard for organizations managing physical assets or systems. (SAE International) In oil and gas, ISO 14224 is also highly relevant because it provides a standard basis for collecting reliability and maintenance data in petroleum, natural gas, and petrochemical facilities. (ISO)

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1. Should the RCM Scope Be the Lubricated Component or the Whole Turbomachinery Train?

The practical answer is: both, but at different levels of detail.

For critical turbomachinery, the RCM study should normally be performed at the train or package level, then broken down into sub-systems. For example:

Compressor train RCM boundary:

Compressor
Driver: gas turbine, steam turbine, or electric motor
Gearbox, if installed
Couplings
Journal bearings
Thrust bearings
Seal systems
Lube oil system
Control oil system
Protection and shutdown system
Condition monitoring system
Cooling water or air-cooling interfaces
Oil storage, transfer, sampling, and filtration practices

The lubricated components are then analyzed as a major sub-system inside the RCM. This prevents a common mistake: analyzing the bearing as a mechanical part while ignoring the oil supply, contamination control, standby pump logic, cooler performance, trip functions, and operator response.

API 614 is directly relevant here because it covers lubrication systems, oil-type shaft-sealing systems, oil-control systems, and auxiliaries, including systems serving compressors, gears, pumps, drivers, or complete trains; it excludes dry gas seal systems and fuel systems. (GlobalSpec) API 670 is also important because machinery protection systems cover parameters such as radial shaft vibration, casing vibration, shaft axial position, rotational speed, overspeed, surge detection, and critical machinery temperatures such as bearing metal temperatures. (American Petroleum Institute)

So, if your company is doing a whole-site RCM program, I recommend this structure:

Level 1: Whole asset class RCM

Gas turbines, steam turbines, centrifugal compressors, axial compressors, turboexpanders, critical pumps, and gearboxes.

Level 2: Turbomachinery package RCM

Train-level study covering process function, driver, driven equipment, seals, lube oil, control oil, protection, utilities, and operations.

Level 3: Lubricated-components RCM

Focused study on bearings, gears, couplings, seal oil interfaces, hydraulic/control-oil valves, oil pumps, coolers, filters, reservoir, piping, drains, instruments, and contamination-control practices.

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2. Which Lubricated Parts Should Be Included?

For turbomachinery in oil and gas, the RCM scope should normally include the following lubricated or oil-dependent items:

Area	Components to include in RCM
Bearings	Journal bearings, tilting-pad bearings, sleeve bearings, thrust bearings, rolling-element bearings where applicable
Gear elements	Gear mesh, pinions, bull gears, bearings, spray nozzles, gear oil supply
Couplings	Gear couplings, lubricated flexible couplings, coupling guards and inspection points
Lube oil system	Main oil pump, auxiliary oil pump, emergency oil pump, reservoir, heaters, coolers, filters, strainers, relief valves, pressure-control valves, check valves
Control oil system	Governor valves, trip valves, servo valves, hydraulic actuators, accumulators, fine filters
Seal oil system	Wet seal oil supply, seal oil differential pressure control, degassing, contaminated oil return
Oil cleanliness system	Offline filtration, kidney-loop filtration, centrifuge, purifier, coalescer, breathers, transfer carts
Instrumentation	Pressure, temperature, flow, level, differential pressure, vibration, axial displacement, bearing metal temperature, oil mist or oil condition sensors
Drain and return system	Bearing drains, slope, vents, return headers, reservoir return, foam/aeration control
Oil handling	Storage drums, bulk tanks, transfer hoses, filtration before filling, sampling points, labeling and contamination control

Do not limit the study to the rotating element only. In many cases, the direct failure symptom appears at the bearing, but the root cause is elsewhere: dirty oil, water ingress, wrong viscosity, cooler leakage, filter bypass, failed standby pump, blocked drain, poor oil sampling, wrong top-up oil, or an alarm/trip that did not function when required.

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3. Why Lubricated Components Are Excellent RCM Candidates

Lubricated components are excellent RCM candidates because they have clear functions and measurable degradation indicators. Oil pressure, oil temperature, bearing metal temperature, vibration, particle count, water content, viscosity, acidity, wear metals, and filter differential pressure all give useful information before many failures become serious.

ASTM D4378 is especially relevant to turbine oil programs because it covers effective in-service monitoring of mineral turbine oils in steam, gas, and combined-cycle turbines, including sampling and testing schedules for lubricant condition. (ASTM International | ASTM) ISO 4406:2021 is also useful because it defines a coding method for the level of solid particle contamination in fluids. (ISO)

This means lubricated turbomachinery is well suited for condition-based maintenance, not only fixed-time preventive maintenance. RCM helps decide when to use:

Condition monitoring
Scheduled restoration
Scheduled replacement
Failure-finding tests
Redesign or modification
Operator tasks
Run-to-failure for low-consequence items

The value of RCM is that it prevents both extremes: doing too little maintenance and exposing the plant to risk, or doing too much maintenance and creating unnecessary cost, disturbance, and maintenance-induced failures.

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4. Main Functions to Define in the RCM Study

Before listing failure modes, define the functions. For a turbomachinery lubrication system, typical functions are:

1. Provide clean lubricating oil at the required pressure, flow, viscosity, and temperature to all bearings and gears.
2. Maintain a stable oil film between rotating and stationary surfaces.
3. Remove heat from bearings, gears, and control-oil components.
4. Remove or control contaminants such as particles, water, air, process gas, sludge, and varnish precursors.
5. Supply control oil or hydraulic oil to actuators, trip devices, governors, or control valves.
6. Maintain seal oil pressure or differential pressure where wet seals are used.
7. Provide alarms, shutdowns, and protective actions before damage occurs.
8. Allow safe starting, running, coast-down, turning gear operation, and emergency shutdown.
9. Allow effective sampling, inspection, filtration, draining, and maintenance without introducing contamination.

From these functions, the RCM team defines functional failures. Examples:

Low lube oil pressure
Insufficient oil flow to one bearing
High oil supply temperature
High bearing metal temperature
Oil contamination above target
Water contamination above target
Incorrect oil viscosity
Filter bypass open
Standby oil pump fails to start
Cooler unable to remove heat
Oil foaming or aeration
Drain restriction from bearing housing
Control oil valve sticking
Trip system fails to act on low-low oil pressure
False trip from faulty instrument
Oil leakage causing unsafe conditions
Wrong oil added during top-up

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5. Typical Failure Modes for Lubricated Turbomachinery

A strong RCM study should go beyond generic phrases like “bearing failure.” That is too broad. The study should identify realistic failure modes such as:

Particle contamination causing bearing wear
Water ingress causing corrosion and reduced lubricant performance
Oil oxidation leading to sludge or varnish formation
Wrong oil grade or incompatible oil added
Loss of oil pressure from pump failure
Standby pump unavailable due to hidden electrical or logic fault
Filter blockage causing bypass operation
Cooler fouling causing high oil supply temperature
Cooler tube leak causing water ingress
Relief valve passing or stuck open
Pressure control valve instability
Check valve leakage during pump changeover
Reservoir level too low
Reservoir level too high causing aeration or carryover
Blocked bearing oil feed orifice
Restricted bearing drain
Poor reservoir venting
Foaming due to contamination or wrong additive condition
Oil mist or vapor handling issue
Bearing misalignment
Rotor unbalance causing high dynamic load on bearings
Thrust bearing overload due to process surge or axial force
Control oil servo valve sticking due to varnish
Instrument impulse line blockage
Faulty bearing temperature element
Vibration probe failure or incorrect gap setting
Trip bypass left active after maintenance

These failure modes should be linked to actual site evidence: historical work orders, vibration trends, oil analysis reports, trip logs, bad-actor lists, shutdown reports, OEM bulletins, and operator experience.

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6. Example RCM Worksheet for Lubricated Turbomachinery

Below is a simplified example. Your actual worksheet should include asset tag, operating context, function, functional failure, failure mode, failure effect, consequence category, existing task, proposed task, frequency basis, responsible discipline, and CMMS task text.

Function	Failure mode	Failure effect	Consequence	Suitable RCM task
Supply oil at required pressure	Main oil pump fails	Header pressure drops; standby pump should start	Production loss, possible equipment damage	Online pressure monitoring; standby pump auto-start test; pump health checks; alarm and trip proof testing
Maintain emergency oil supply	Standby pump fails to start on demand	Hidden failure until main pump problem occurs	High-risk hidden failure	Failure-finding test at risk-based interval; verify permissives, power supply, start logic, and discharge pressure
Keep oil clean	Filter plugs and bypass opens	Contaminants reach bearings and control valves	Accelerated wear, servo sticking	Filter differential pressure monitoring; change filters on condition; investigate rapid DP increase
Control oil temperature	Cooler fouling	Oil supply temperature rises; viscosity drops	Bearing distress risk, oil degradation	Trend cooler approach temperature; inspect and clean cooler based on performance
Prevent water contamination	Cooler tube leak	Water enters oil; oil analysis shows rising water	Corrosion, poor demulsibility, reduced lubrication quality	Routine water testing; cooler pressure test; purifier/coalescer use; root-cause investigation
Maintain oil health	Oil oxidation or varnish formation	Sticky control valves, deposits, higher temperatures	Trip risk, control instability	Oil health monitoring; varnish potential testing; filtration or varnish removal where justified
Support rotor loads	Bearing wear or wiping	High vibration, high bearing temperature, possible axial/radial movement	Production loss, repair cost, safety exposure	Vibration monitoring, bearing metal temperature monitoring, oil debris analysis, outage inspection
Maintain thrust control	Thrust bearing overload	Axial displacement increases; thrust temperature rises	Major train damage risk	Axial displacement protection; surge-control verification; process operating envelope review
Remove oil from bearing housing	Drain restriction	Oil level rises locally, foaming or leakage may occur	Bearing temperature increase, leakage	Inspect drain slope and restrictions; verify venting; check return temperature and flow
Protect machine	Low-low oil pressure trip fails	Machine continues running without adequate oil	Severe consequence	Proof test trip function; manage bypasses; validate alarm response and shutdown logic

The important point is that each proposed task must be technically defensible. RCM should not simply say “inspect monthly” unless the inspection can actually detect the failure mode early enough to act.

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7. Oil Analysis Program Inside the RCM Strategy

For lubricated turbomachinery, oil analysis is not just a laboratory activity. It is a core RCM task. The oil analysis program should be designed around failure modes.

Recommended monitoring parameters include:

Failure mode being controlled	Useful oil analysis or field parameter
Particle contamination	ISO particle count, membrane patch, filter debris inspection
Wear	Wear metals, ferrous density, PQ index, analytical ferrography for critical cases
Water ingress	Karl Fischer water test, crackle test for screening, demulsibility trend
Oil oxidation	TAN, FTIR oxidation, viscosity change, RPVOT where applicable
Additive depletion	RULER, elemental additive trend
Varnish potential	MPC, ultracentrifuge rating, patch colorimetry, servo valve symptoms
Wrong oil or mixing	Viscosity, FTIR, elemental fingerprint, additive comparison
Foaming/aeration tendency	Foam test, air release, field observation in reservoir
Cooler leak	Water trend, glycol markers where relevant, pressure test evidence
Dirt ingress during filling	Particle count after top-up, transfer filtration records

ASTM D4378 is a good reference for in-service monitoring of mineral turbine oils in steam, gas, and combined-cycle turbines. (ASTM International | ASTM) ISO 4406:2021 gives a standardized contamination code for solid particles, which is useful for setting cleanliness targets and trending oil cleanliness. (ISO)

A good RCM output should define not only “take oil sample,” but also:

Where to sample
How often to sample
Which bottle and flushing method to use
Which tests to run
Which alarm limits apply
What action is required at alert, alarm, and critical levels
Who reviews the results
How results are linked to work orders
How repeat abnormal results are escalated

The most common weakness in oil analysis programs is not the testing itself. It is the lack of action after abnormal trends appear.

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8. Condition Monitoring Tasks for Lubricated Components

RCM normally favors condition-based maintenance where the failure mode has a detectable warning period. For turbomachinery lubricated parts, useful condition-monitoring tasks include:

Vibration monitoring for journal bearing instability, unbalance, misalignment, looseness, rub, and gear mesh issues
Axial displacement monitoring for thrust bearing and process-load problems
Bearing metal temperature monitoring
Oil supply and return temperature trending
Lube oil pressure and flow trending
Filter differential pressure trending
Oil reservoir level trending
Oil cooler approach temperature trending
Oil analysis and wear debris analysis
Thermography on coolers, motors, pumps, and electrical connections
Ultrasonic checks on valves, leakage, or abnormal flow where applicable
Operator rounds with numeric readings, not only checkmarks

API 670 is relevant when defining protection and monitoring requirements for critical machinery, including vibration, axial position, speed, surge detection, and bearing or motor winding temperatures. (American Petroleum Institute) API standards are widely used in oil and gas, and API describes its standards as consensus-based documents developed through an ANSI-accredited process. (American Petroleum Institute)

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9. Preventive Maintenance Tasks That Usually Survive RCM Review

A proper RCM study often reduces unnecessary time-based work, but some preventive tasks remain valid. For lube oil systems, these often include:

Filter replacement based on differential pressure or condition, not only calendar time
Breather replacement based on saturation or condition
Oil cooler cleaning based on heat-transfer performance
Reservoir inspection during shutdown
Relief valve inspection and testing
Instrument calibration and loop checks
Trip and alarm proof testing
Standby pump test runs
Accumulator pre-charge checks where applicable
Oil purifier or filtration unit service
Inspection of flexible hoses, expansion joints, and small-bore tubing
Inspection of drains, vents, and return lines
Verification of oil transfer equipment cleanliness
Verification of correct oil labeling and storage

The RCM question is not “what PM do we normally do?” The RCM question is: which task is technically effective against a specific failure mode, and is it worth doing compared with the consequence of failure?

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10. Failure-Finding Tasks: Very Important for Lube Oil Protection

Some lube oil failures are hidden. For example, the standby pump may be unavailable, but nobody knows because the main pump is running. The low-low oil pressure trip may have a failed input, but the machine continues operating normally until a real demand occurs.

These are classic RCM failure-finding cases.

Examples of failure-finding tasks:

Start the standby oil pump and verify actual pressure rise
Simulate low oil pressure signal and verify alarm/trip response according to approved procedure
Verify emergency oil pump automatic start
Check UPS or DC supply for emergency lube systems
Test pump changeover logic
Verify filter bypass indication
Verify low reservoir level alarm
Verify high oil temperature alarm
Confirm vibration and axial displacement trip channels are healthy
Review bypassed or inhibited protection channels

These tests should be controlled by approved procedures because they may interact with running critical machinery. The interval should be based on risk, required availability, demand rate, and company functional safety or machinery protection requirements.

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11. When RCM Leads to Redesign Instead of More Maintenance

RCM is not only about adding PM tasks. Sometimes the correct answer is redesign.

Redesign may be justified when you find repeated or high-risk failure modes such as:

No proper oil sampling point
Oil sample taken from dead leg or drain instead of active flow
No offline filtration for critical turbine oil
No desiccant breather in humid or dusty environment
Poor oil storage and transfer practice
Common-cause failure between main and standby oil pumps
Standby pump does not start fast enough
Cooler undersized for summer operation
Filter bypass not alarmed
Bearing drain line too small or poorly sloped
Oil reservoir has poor water separation or air release
No varnish control on sensitive control-oil systems
Obsolete protection system with poor diagnostics
Repeated contamination after maintenance
No clear alarm response procedure for operators

For critical, unspared equipment, redesign can be more effective than repeatedly increasing inspection frequency. IOGP’s 2024 supplementary specification to API 614 is also relevant for special-purpose, unspared equipment in critical service because it addresses lubrication and oil-control systems and auxiliaries as an overlay to API 614. (IOGP)

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12. Recommended RCM Implementation Plan for Your Oil and Gas Company

A strong company-level implementation can follow this sequence.

Step 1: Prioritize assets

Do not start with every machine. Start with critical turbomachinery:

Main gas compressors
Export compressors
Reinjection compressors
Gas turbines
Steam turbines
Turboexpanders
Critical compressor gearboxes
Critical process pumps with high consequence
Machines with repeated bearing, oil, vibration, or trip issues

Use safety, environmental, production, cost, and bad-actor history to rank assets.

Step 2: Build the asset hierarchy

Use a structure compatible with your CMMS and reliability data system:

Plant
Unit
System
Turbomachinery train
Equipment item
Sub-system
Maintainable item
Component

ISO 14224 is useful here because it provides a common reliability and maintenance data language for petroleum, natural gas, and petrochemical equipment. (ISO)

Step 3: Collect technical inputs

Gather:

P&IDs
Lube oil system drawings
Cause-and-effect diagrams
Trip logic
OEM manuals
API datasheets
Oil analysis history
Vibration history
Bearing temperature trends
Failure reports
Work orders
Spare parts usage
Operator logs
Alarm and trip history
Previous RCA reports
MOC records
Inspection reports

Step 4: Conduct the RCM workshop

Include the right people:

Rotating equipment engineer
Reliability engineer
Operations representative
Condition monitoring specialist
Lubrication specialist
Instrument and control engineer
Maintenance supervisor
HSE/process safety representative where needed
OEM or vendor support for complex machines

Step 5: Convert RCM decisions into CMMS tasks

Each task should include:

Asset tag
Failure mode addressed
Task description
Frequency or trigger
Acceptance criteria
Required tools
Responsible discipline
Estimated duration
Safety precautions
Follow-up action if abnormal
Link to procedure or standard

Avoid vague tasks like “check oil system.” Use specific tasks like: “Record lube oil supply pressure, supply temperature, filter DP, reservoir level, and cooler outlet temperature; compare with normal operating band; raise notification if outside limit.”

Step 6: Review and improve

RCM is not a one-time exercise. Review after:

Major trip
Bearing failure
Oil contamination event
Repeated alarms
Shutdown inspection
Oil change or flush
Control valve sticking event
Change in operating mode
Major overhaul
Modification to lube oil system or protection system

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13. Example Maintenance Policy for a Critical Compressor Lube Oil System

This is a practical starting point. Final intervals must be adjusted to your machine criticality, OEM requirements, site history, oil analysis results, and operating regime.

Frequency / trigger	Task
Each shift or daily	Record oil pressure, oil temperature, filter DP, reservoir level, bearing metal temperatures, vibration, abnormal noise, leaks, and active alarms
Weekly	Verify standby pump availability, inspect breather condition, check for water at reservoir drain where safe and applicable
Monthly	Take routine oil sample from live sample point; review viscosity, water, particles, TAN, wear metals, and visual condition
Monthly or risk-based	Test standby pump start and changeover logic if permitted by operating procedure
Quarterly	Review trend report combining oil analysis, vibration, bearing temperature, filter DP, and operating conditions
Quarterly / semiannual	Inspect cooler performance using temperature approach and fouling trend
Semiannual / annual	Conduct detailed oil health testing for critical turbine oils, including oxidation and varnish-related tests where applicable
Shutdown opportunity	Inspect reservoir, strainers, coolers, drains, bearings, coupling, gear teeth, oil nozzles, and instrumentation impulse lines
After abnormal event	Take confirmation oil sample, inspect filters, review vibration and temperature trends, and perform RCA if limits were exceeded
After maintenance opening	Flush or filter as required; confirm cleanliness before startup

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14. Common Mistakes to Avoid

The biggest mistakes in RCM for lubricated turbomachinery are:

Doing the study at component level only and ignoring the oil system
Calling a PM optimization exercise “RCM” without analyzing functions and consequences
Copying OEM maintenance intervals without checking local operating context
Changing oil by calendar time only, with no oil condition basis
Taking oil samples from the wrong location
Receiving oil analysis reports but not creating corrective work orders
Ignoring particle count because viscosity and TAN look acceptable
Ignoring water because the machine has not failed yet
Not testing standby pump auto-start logic
Not managing alarm and trip bypasses
Ignoring filter bypass events
Treating varnish as an oil problem only, not a control-system reliability problem
Not including operators in the RCM workshop
Not linking RCM outputs to CMMS task quality
Failing to review the RCM after real failures or trips

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15. Final Answer

Yes, you can and should do an RCM study on the lubricated components of turbomachinery. But for oil and gas turbomachinery, the best practice is to treat lubricated components as part of a larger system: bearing, oil film, oil supply, oil cleanliness, cooling, control oil, seal oil, protection system, operator response, and operating context.

For a whole-company RCM program, use a tiered approach:

Critical turbomachinery: full RCM
Important rotating equipment: streamlined RCM or FMEA-based PM optimization
Low-criticality lubricated equipment: standard lubrication strategy and condition-based inspections

The highest-value outputs will be:

Clear failure modes for bearings, gears, oil pumps, filters, coolers, valves, and instruments
Oil analysis program linked to failure modes
Vibration and bearing-temperature monitoring linked to actions
Failure-finding tests for standby pumps and trips
Cleanliness and contamination-control strategy
CMMS tasks with clear limits and corrective actions
Redesign recommendations for chronic lubrication weaknesses

In simple terms: RCM on lubricated turbomachinery is not only possible; it is one of the best reliability opportunities in an oil and gas company when done at the correct system boundary.