p–ISSN: 2723 - 6609 e-ISSN: 2745-5254
Vol. 5, No. 11, November 2024 http://jist.publikasiindonesia.id/
Indonesian Journal of Social Technology, Vol. 5, No. 11, November 2024 4790
Cause Analysis and Preventive Measures for Deterioration
of Steam Turbine Lubricating Oil
Rikki Martin1*, Liu Guoqing2
PT. DSSP Power Kendari, Indonesia
Email: [email protected]1*, [email protected]2
*Correspondence
ABSTRACT
Keywords: lubricating
oil, deterioration, particle
size, water content,
impurities, preventive
measures.
Lubricating the oil system of the steam turbine in the power
plant is an important part of maintaining the normal
operation of a steam turbine. The quality of oil directly
affects the safe and stable operation of steam turbines. If the
oil quality deteriorates, it is very easy to cause major
accidents such as wear of steam turbine bearings, jamming
of the speed control system, and even burning of bearings,
failure of steam turbine speed control system leading to
overspeed. This research method uses a literature review.
In the operation of the power plant, it is common for
lubricating oil to exceed the standard particle size and water
content, and there are many reasons for this. This article
analyzes the causes of lubricating oil deterioration and
explains more specific preventive measures. Conclusion
Deterioration in oil quality and excessive particle size can
easily lead to serious consequences. Therefore, it must be
controlled from the inspection of new oil entering the
factory, sampling and testing, and monitoring of the
operation stage, to improve the maintenance process.
Introduction
The function of the steam turbine lubricating oil system is to provide lubrication for
the support bearings, thrust bearings, and turning devices of the steam turbine generator,
to supply spare oil for the hydrogen sealing system, and to supply pressure oil for the
overspeed release device of the operating machinery of some models (Tang & Wu, 2011).
In the case of oil quality deterioration, the particle size and water content exceed the
standard, which leads to the wear of the bearing and rotor in serious cases, which is the
main reason threatening the safe operation of the steam turbine generator set and the
service life of the equipment (Hildreth & Tymvios, 2016). When the particle size and
water content exceed the standard during the operation of the power plant, the oil filtering
measures are taken immediately. Although it can ensure the continuous operation of the
system, the cause of the oil quality deterioration is unknown, resulting in a serious waste
of resources due to long-term oil filtering. Taking certain effective measures in the storage
Vol. 5, No. 11, November 2024 http://jist.publikasiindonesia.id/
Indonesian Journal of Social Technology, Vol. 5, No. 11, November 2024 4790
Cause Analysis and Preventive Measures for Deterioration
of Steam Turbine Lubricating Oil
Rikki Martin1*, Liu Guoqing2
PT. DSSP Power Kendari, Indonesia
Email: [email protected]1*, [email protected]2
*Correspondence
ABSTRACT
Keywords: lubricating
oil, deterioration, particle
size, water content,
impurities, preventive
measures.
Lubricating the oil system of the steam turbine in the power
plant is an important part of maintaining the normal
operation of a steam turbine. The quality of oil directly
affects the safe and stable operation of steam turbines. If the
oil quality deteriorates, it is very easy to cause major
accidents such as wear of steam turbine bearings, jamming
of the speed control system, and even burning of bearings,
failure of steam turbine speed control system leading to
overspeed. This research method uses a literature review.
In the operation of the power plant, it is common for
lubricating oil to exceed the standard particle size and water
content, and there are many reasons for this. This article
analyzes the causes of lubricating oil deterioration and
explains more specific preventive measures. Conclusion
Deterioration in oil quality and excessive particle size can
easily lead to serious consequences. Therefore, it must be
controlled from the inspection of new oil entering the
factory, sampling and testing, and monitoring of the
operation stage, to improve the maintenance process.
Introduction
The function of the steam turbine lubricating oil system is to provide lubrication for
the support bearings, thrust bearings, and turning devices of the steam turbine generator,
to supply spare oil for the hydrogen sealing system, and to supply pressure oil for the
overspeed release device of the operating machinery of some models (Tang & Wu, 2011).
In the case of oil quality deterioration, the particle size and water content exceed the
standard, which leads to the wear of the bearing and rotor in serious cases, which is the
main reason threatening the safe operation of the steam turbine generator set and the
service life of the equipment (Hildreth & Tymvios, 2016). When the particle size and
water content exceed the standard during the operation of the power plant, the oil filtering
measures are taken immediately. Although it can ensure the continuous operation of the
system, the cause of the oil quality deterioration is unknown, resulting in a serious waste
of resources due to long-term oil filtering. Taking certain effective measures in the storage
Cause Analysis and Preventive Measures for Deterioration of Steam Turbine Lubricating Oil
Indonesian Journal of Social Technology, Vol. 5, No. 11, November 2024 4791
of new oil at the factory, sampling and testing, operating conditions, maintenance quality,
and oil replenishment rate will greatly reduce the phenomenon of oil quality deterioration
during the operation of the oil system (Chowdhury et al., 2021).
Most steam turbine lubricating oils are made of highly refined paraffin-based
mineral oils compounded with antioxidants and rust inhibitors. Depending on the quality
grade, there may also be a small amount of other additives, such as metal passivation,
extreme pressure additives, and defoamers. Steam turbine lubricating oils are mainly used
to lubricate and cool bearings and gears. (Gulfam & Zhang, 2019).
New steam turbine lubricating oil should have good oxidation resistance and
provide adequate rust resistance, demulsibility, and anti-foaming properties while
inhibiting the formation of sludge and varnish deposits. Factors that affect the service life
of turbine lubricating oil include system design and type, system pre-operation
conditions, original oil quality, system operating conditions, oil contamination, oil
replenishment rate, and oil handling and storage conditions.
Recent studies have investigated various analyses and preventive actions for
the deterioration of steam turbine lubricating oil. Li et al. (2022) Studied and
demonstrated that high-temperature and high-stress conditions accelerate the degradation
of turbine oils, leading to significant changes in their chemical and physical properties.
Understanding these mechanisms is crucial for improving the durability and reliability of
turbine systems. Xu, Wang, Liang, Lv, & Chen, (2024) Explained that oxidation is a
predominant factor affecting the properties of turbine oils. Our review highlights that
oxidation leads to increased acidity, viscosity changes, and formation of sludge, which
ultimately compromise the oil's performance and longevity. Liu et al., (2016) Mentioned
that spectroscopic techniques such as FTIR are invaluable for assessing turbine oil
degradation. These methods provide detailed insights into the chemical changes occurring
in the oil, including oxidation and additive depletion.
Gao & Liu, (2021) Explained that contamination and degradation of turbine oils in
power generation systems can lead to operational inefficiencies and increased
maintenance costs. Our study emphasizes the need for regular monitoring to mitigate
these issues. Zhou et al., (2023) Mentioned that thermal stress has a profound impact on
turbine oil stability. Our findings reveal that elevated temperatures accelerate oil
degradation, necessitating enhanced oil formulations or improved cooling systems.
(Zhang et al., 2021) Investigated that water contamination significantly affects turbine oil
performance. Our research indicates that even small amounts of water can lead to
accelerated degradation, reduced lubrication effectiveness, and increased risk of
corrosion.
Sun et al (2016) Advanced monitoring techniques are essential for maintaining
turbine oil quality. Our review covers various methods, including spectral analysis and
particle counting, to ensure that oil remains within optimal performance parameters.
Wang et al., (2023) High-performance liquid chromatography (HPLC) provides a detailed
Indonesian Journal of Social Technology, Vol. 5, No. 11, November 2024 4791
of new oil at the factory, sampling and testing, operating conditions, maintenance quality,
and oil replenishment rate will greatly reduce the phenomenon of oil quality deterioration
during the operation of the oil system (Chowdhury et al., 2021).
Most steam turbine lubricating oils are made of highly refined paraffin-based
mineral oils compounded with antioxidants and rust inhibitors. Depending on the quality
grade, there may also be a small amount of other additives, such as metal passivation,
extreme pressure additives, and defoamers. Steam turbine lubricating oils are mainly used
to lubricate and cool bearings and gears. (Gulfam & Zhang, 2019).
New steam turbine lubricating oil should have good oxidation resistance and
provide adequate rust resistance, demulsibility, and anti-foaming properties while
inhibiting the formation of sludge and varnish deposits. Factors that affect the service life
of turbine lubricating oil include system design and type, system pre-operation
conditions, original oil quality, system operating conditions, oil contamination, oil
replenishment rate, and oil handling and storage conditions.
Recent studies have investigated various analyses and preventive actions for
the deterioration of steam turbine lubricating oil. Li et al. (2022) Studied and
demonstrated that high-temperature and high-stress conditions accelerate the degradation
of turbine oils, leading to significant changes in their chemical and physical properties.
Understanding these mechanisms is crucial for improving the durability and reliability of
turbine systems. Xu, Wang, Liang, Lv, & Chen, (2024) Explained that oxidation is a
predominant factor affecting the properties of turbine oils. Our review highlights that
oxidation leads to increased acidity, viscosity changes, and formation of sludge, which
ultimately compromise the oil's performance and longevity. Liu et al., (2016) Mentioned
that spectroscopic techniques such as FTIR are invaluable for assessing turbine oil
degradation. These methods provide detailed insights into the chemical changes occurring
in the oil, including oxidation and additive depletion.
Gao & Liu, (2021) Explained that contamination and degradation of turbine oils in
power generation systems can lead to operational inefficiencies and increased
maintenance costs. Our study emphasizes the need for regular monitoring to mitigate
these issues. Zhou et al., (2023) Mentioned that thermal stress has a profound impact on
turbine oil stability. Our findings reveal that elevated temperatures accelerate oil
degradation, necessitating enhanced oil formulations or improved cooling systems.
(Zhang et al., 2021) Investigated that water contamination significantly affects turbine oil
performance. Our research indicates that even small amounts of water can lead to
accelerated degradation, reduced lubrication effectiveness, and increased risk of
corrosion.
Sun et al (2016) Advanced monitoring techniques are essential for maintaining
turbine oil quality. Our review covers various methods, including spectral analysis and
particle counting, to ensure that oil remains within optimal performance parameters.
Wang et al., (2023) High-performance liquid chromatography (HPLC) provides a detailed
Rikki Martin, Liu Guoqing
Indonesian Journal of Social Technology, Vol. 5, No. 11, November 2024 4792
analysis of turbine oil degradation. This method allows for precise detection of
degradation products and helps in understanding the oil’s degradation pathways.
Method
The study began with a literature review, including an examination of the Dongfang
Turbine manual, international journals, and other relevant sources. Field visits were
conducted to take samples for analysis of quality lube oil turbines. During normal
operation, quality lube oil was inspected. The following steps were taken to complete the
research methodology:
1. Research Location:
This research was conducted at a Thermal Power Plant utilizing the Turbine N56-
8.83/535 Lube oil system. The research site is located at [PT DSSP Power Kendari,
IPP PLTU kendari-3], [Jl. Poros Kdi.- Moramo, Tj. Tiram, Kec. Moramo Utara,
Kabupaten Konawe Selatan, Sulawesi Tenggara 93891], [Indonesia]. This location
was selected due to the issue of lube oil pressure sometimes dropping in the turbine
units, which became the focus of this study.
2. Research Subjects:
The research subjects were Precilia ISO VG 32 of unit 2 in the N56-8.83/535
turbine operating at the power plant. Lube oil in a turbine is crucial for the reliable and
efficient operation of the turbine system, making this the target for analyzing and
resolving this issue.
3. Data Processing Techniques:
a. Data Collection: Oil samples are collected from the equipment at regular intervals
using standardized methods to ensure consistency. Key properties of the oil are
measured, such as viscosity, Total Acid Number (TAN), Total Base Number
(TBN), water content, particulate contamination, wear metals, and oxidation
levels. Instruments like viscometers, spectrometers, and infrared analyzers are
used for this purpose.
b. Data Preprocessing: The measurement data is logged into a database or an oil
analysis management system. This includes details like the sample date,
equipment ID, and environmental conditions. Any outliers or erroneous data
points are identified and corrected or removed. This ensures that the analysis
reflects accurate and reliable data. Data may need to be normalized to account for
varying conditions, such as temperature, which can affect oil properties like
viscosity.
Indonesian Journal of Social Technology, Vol. 5, No. 11, November 2024 4792
analysis of turbine oil degradation. This method allows for precise detection of
degradation products and helps in understanding the oil’s degradation pathways.
Method
The study began with a literature review, including an examination of the Dongfang
Turbine manual, international journals, and other relevant sources. Field visits were
conducted to take samples for analysis of quality lube oil turbines. During normal
operation, quality lube oil was inspected. The following steps were taken to complete the
research methodology:
1. Research Location:
This research was conducted at a Thermal Power Plant utilizing the Turbine N56-
8.83/535 Lube oil system. The research site is located at [PT DSSP Power Kendari,
IPP PLTU kendari-3], [Jl. Poros Kdi.- Moramo, Tj. Tiram, Kec. Moramo Utara,
Kabupaten Konawe Selatan, Sulawesi Tenggara 93891], [Indonesia]. This location
was selected due to the issue of lube oil pressure sometimes dropping in the turbine
units, which became the focus of this study.
2. Research Subjects:
The research subjects were Precilia ISO VG 32 of unit 2 in the N56-8.83/535
turbine operating at the power plant. Lube oil in a turbine is crucial for the reliable and
efficient operation of the turbine system, making this the target for analyzing and
resolving this issue.
3. Data Processing Techniques:
a. Data Collection: Oil samples are collected from the equipment at regular intervals
using standardized methods to ensure consistency. Key properties of the oil are
measured, such as viscosity, Total Acid Number (TAN), Total Base Number
(TBN), water content, particulate contamination, wear metals, and oxidation
levels. Instruments like viscometers, spectrometers, and infrared analyzers are
used for this purpose.
b. Data Preprocessing: The measurement data is logged into a database or an oil
analysis management system. This includes details like the sample date,
equipment ID, and environmental conditions. Any outliers or erroneous data
points are identified and corrected or removed. This ensures that the analysis
reflects accurate and reliable data. Data may need to be normalized to account for
varying conditions, such as temperature, which can affect oil properties like
viscosity.
Cause Analysis and Preventive Measures for Deterioration of Steam Turbine Lubricating Oil
Indonesian Journal of Social Technology, Vol. 5, No. 11, November 2024 4793
c. Data Analysis: Historical data is compared over time to identify trends, such as
gradual increases in wear metals or changes in viscosity. These trends can help
predict potential equipment failures. Relationships between different oil
properties are analyzed. Specific peaks in the spectrum can indicate types of
degradation or contamination. Statistical methods, such as regression analysis, are
used to model the behaviour of the oil over time and under different conditions.
This modelling can help predict future oil conditions and equipment health.
d. Condition Monitoring and Diagnostics: Measured values are compared against
established thresholds or standards. Exceeding certain limits (e.g., high water
content, and low viscosity) may trigger alerts for maintenance actions.
Microscopic or spectroscopic analysis of particles in the oil can reveal wear
patterns and potential sources of wear within the machinery. Predictive algorithms
process the data to forecast when the oil or equipment might reach a critical
condition, enabling maintenance to be scheduled before failures occur.
e. Reporting and Visualization: Analysis results are compiled into reports that
include charts, graphs, and interpretations, providing actionable insights for
maintenance teams. Data visualization tools like dashboards present real-time data
and trends, helping to quickly identify issues and make informed decisions. Based
on the processed data, recommendations are made regarding oil changes,
equipment maintenance, or further investigation.
f. Feedback and Continuous Improvement: The results of the analysis and any
subsequent actions are fed back into the system to improve future analyses. For
instance, if certain trends consistently predict failures, the predictive model can be
refined. Predictive models are updated regularly with new data to enhance their
accuracy and reliability.
4. Research Instruments:
a. Viscometer: Measures the viscosity of the oil, which is crucial for understanding its
lubrication properties.
b. Fourier Transform Infrared (FTIR) Spectrometer: Analyzes the chemical
composition of the oil by identifying specific molecular bonds.
c. Inductively Coupled Plasma (ICP) Spectrometer: Measures the concentration of
wear metals, additives, and contaminants in the oil.
d. Total Acid Number (TAN) and Total Base Number (TBN) Analyzers: TAN
measures the acidity, and TBN measures the alkalinity of the oil.
e. Particle Counter: Counts and sizes of particles suspended in the oil.
Indonesian Journal of Social Technology, Vol. 5, No. 11, November 2024 4793
c. Data Analysis: Historical data is compared over time to identify trends, such as
gradual increases in wear metals or changes in viscosity. These trends can help
predict potential equipment failures. Relationships between different oil
properties are analyzed. Specific peaks in the spectrum can indicate types of
degradation or contamination. Statistical methods, such as regression analysis, are
used to model the behaviour of the oil over time and under different conditions.
This modelling can help predict future oil conditions and equipment health.
d. Condition Monitoring and Diagnostics: Measured values are compared against
established thresholds or standards. Exceeding certain limits (e.g., high water
content, and low viscosity) may trigger alerts for maintenance actions.
Microscopic or spectroscopic analysis of particles in the oil can reveal wear
patterns and potential sources of wear within the machinery. Predictive algorithms
process the data to forecast when the oil or equipment might reach a critical
condition, enabling maintenance to be scheduled before failures occur.
e. Reporting and Visualization: Analysis results are compiled into reports that
include charts, graphs, and interpretations, providing actionable insights for
maintenance teams. Data visualization tools like dashboards present real-time data
and trends, helping to quickly identify issues and make informed decisions. Based
on the processed data, recommendations are made regarding oil changes,
equipment maintenance, or further investigation.
f. Feedback and Continuous Improvement: The results of the analysis and any
subsequent actions are fed back into the system to improve future analyses. For
instance, if certain trends consistently predict failures, the predictive model can be
refined. Predictive models are updated regularly with new data to enhance their
accuracy and reliability.
4. Research Instruments:
a. Viscometer: Measures the viscosity of the oil, which is crucial for understanding its
lubrication properties.
b. Fourier Transform Infrared (FTIR) Spectrometer: Analyzes the chemical
composition of the oil by identifying specific molecular bonds.
c. Inductively Coupled Plasma (ICP) Spectrometer: Measures the concentration of
wear metals, additives, and contaminants in the oil.
d. Total Acid Number (TAN) and Total Base Number (TBN) Analyzers: TAN
measures the acidity, and TBN measures the alkalinity of the oil.
e. Particle Counter: Counts and sizes of particles suspended in the oil.
Rikki Martin, Liu Guoqing
Indonesian Journal of Social Technology, Vol. 5, No. 11, November 2024 4794
f. Karl Fischer Titrator: Measures the water content in the oil.
g. Rotating Disc Electrode (RDE) Spectrometer: Analyzes metal content in used oil.
h. Wear Particle Analyzer (Ferrography): Analyzes the size, shape, and composition
of wear particles in the oil.
i. Flash Point Tester: Determines the temperature at which the oil produces enough
vapour to ignite.
j. Oxidation Stability Tester: Evaluates the oil’s resistance to oxidation.
5. Field Visits and Inspections:
During normal operation, conditions within the oil tank and lube oil were
thoroughly inspected. Inspections were conducted to identify some issues that might
affect the quality of the lube oil system.
Results and Discussion
1. Acceptance of New Oil
When new oil is delivered, it should be inspected and accepted by GB11120. In
addition, the rotating oxygen bomb should also comply with the provisions of Table 1.
Table 1
Quality standards for new turbine oil rotary oxygen bomb
Project Quality Index Experiment Method
Rotating oxygen bomb
(150°)/insolvent refined
mineral oilHydrogenated
mineral oil
> 300
> 1000
SH/T0193
Literature
Study
Site
Inspection
Take
Sample Oil Analysis
Validation Evaluation Result and
Discussion
Indonesian Journal of Social Technology, Vol. 5, No. 11, November 2024 4794
f. Karl Fischer Titrator: Measures the water content in the oil.
g. Rotating Disc Electrode (RDE) Spectrometer: Analyzes metal content in used oil.
h. Wear Particle Analyzer (Ferrography): Analyzes the size, shape, and composition
of wear particles in the oil.
i. Flash Point Tester: Determines the temperature at which the oil produces enough
vapour to ignite.
j. Oxidation Stability Tester: Evaluates the oil’s resistance to oxidation.
5. Field Visits and Inspections:
During normal operation, conditions within the oil tank and lube oil were
thoroughly inspected. Inspections were conducted to identify some issues that might
affect the quality of the lube oil system.
Results and Discussion
1. Acceptance of New Oil
When new oil is delivered, it should be inspected and accepted by GB11120. In
addition, the rotating oxygen bomb should also comply with the provisions of Table 1.
Table 1
Quality standards for new turbine oil rotary oxygen bomb
Project Quality Index Experiment Method
Rotating oxygen bomb
(150°)/insolvent refined
mineral oilHydrogenated
mineral oil
> 300
> 1000
SH/T0193
Literature
Study
Site
Inspection
Take
Sample Oil Analysis
Validation Evaluation Result and
Discussion
Cause Analysis and Preventive Measures for Deterioration of Steam Turbine Lubricating Oil
Indonesian Journal of Social Technology, Vol. 5, No. 11, November 2024 4795
The inspection items shall at least include appearance, colour, kinematic viscosity,
viscosity index, pour point, density, flash point, acid value, moisture, foaming, air release
valve, copper corrosion, liquid phase rust, anti-emulsification, rotating hydrogen bomb
and cleanliness (particle pollution level). At the same time, the test results of oxidation
stability, carrying capacity, and filterability should be obtained from the oil supplier, and
it should be ensured that they meet the requirements of the GB11120 standard.
Ask the oil supplier for information on the type of antioxidants, and test the
antioxidant content according to the test method required by GB/T7596 or ASTMD6971,
and use this as a benchmark value to guide the supervision and addition of antioxidants
during operation.
Acceptance may also be based on relevant international standards or indicators
agreed upon by both parties in the contract. All samples should be inspected immediately
after sampling, and the acceptance test should be completed before the equipment is filled
with oil.
2. Steam turbine lubricating oil operation quality standard
The lubricating oil of the steam turbine in operation shall comply with the
standard of GB/T7596. See Table 2 for details.
Indonesian Journal of Social Technology, Vol. 5, No. 11, November 2024 4795
The inspection items shall at least include appearance, colour, kinematic viscosity,
viscosity index, pour point, density, flash point, acid value, moisture, foaming, air release
valve, copper corrosion, liquid phase rust, anti-emulsification, rotating hydrogen bomb
and cleanliness (particle pollution level). At the same time, the test results of oxidation
stability, carrying capacity, and filterability should be obtained from the oil supplier, and
it should be ensured that they meet the requirements of the GB11120 standard.
Ask the oil supplier for information on the type of antioxidants, and test the
antioxidant content according to the test method required by GB/T7596 or ASTMD6971,
and use this as a benchmark value to guide the supervision and addition of antioxidants
during operation.
Acceptance may also be based on relevant international standards or indicators
agreed upon by both parties in the contract. All samples should be inspected immediately
after sampling, and the acceptance test should be completed before the equipment is filled
with oil.
2. Steam turbine lubricating oil operation quality standard
The lubricating oil of the steam turbine in operation shall comply with the
standard of GB/T7596. See Table 2 for details.
Rikki Martin, Liu Guoqing
Indonesian Journal of Social Technology, Vol. 5, No. 11, November 2024 4796
Table 2
Quality standards of turbine oil in operation
No. Project Quality Index Testing
Method
1 Exterior Transparent, no ㎜≤
impurities or suspended
matter
DL429.1
2 Chroma <5.5 GB/T6540
3 Kinematic viscosity
a/(40℃）mm2/s
3
2
Not more than 5% of the
new oil test value
GB/T265
4 Flashpoint (open cup)℃ >180, and not less than
10℃ higher than the
previous measured value
GB/T3536
5 Particle pollution level <8 DL/T432
6 Acid value (in KOH) / (㎎/g) <0.3 GB/T264
7 Liquid phase corrosion degree
c Rust-free GB/T11143
(Method A)
8 Demulsification c (54℃)/min <30 GB/T7605
9 Moisture c/㎎/L <100 GB/T7600
10 Foaming
property/(foaming
tendency/foaming
quality)
24℃
or
after
24℃
<500/10
<100/10
GB/T12579
93.5
℃
11 Air release valve (50℃)/min <10 SH/T0308
12 Rotating oxygen bomb value
(150℃)/min
Not less than 25% of the
new oil test value, and the
turbine oil ≥ 100
SH/T0193
13 Antioxidant
content/%
T50
Antioxidant
Not less than 25% of the
new oil test value
GB/T7602
Hindered
phenol or
aromatic
amine
antioxidants
ASTMD69
71
Indonesian Journal of Social Technology, Vol. 5, No. 11, November 2024 4796
Table 2
Quality standards of turbine oil in operation
No. Project Quality Index Testing
Method
1 Exterior Transparent, no ㎜≤
impurities or suspended
matter
DL429.1
2 Chroma <5.5 GB/T6540
3 Kinematic viscosity
a/(40℃）mm2/s
3
2
Not more than 5% of the
new oil test value
GB/T265
4 Flashpoint (open cup)℃ >180, and not less than
10℃ higher than the
previous measured value
GB/T3536
5 Particle pollution level <8 DL/T432
6 Acid value (in KOH) / (㎎/g) <0.3 GB/T264
7 Liquid phase corrosion degree
c Rust-free GB/T11143
(Method A)
8 Demulsification c (54℃)/min <30 GB/T7605
9 Moisture c/㎎/L <100 GB/T7600
10 Foaming
property/(foaming
tendency/foaming
quality)
24℃
or
after
24℃
<500/10
<100/10
GB/T12579
93.5
℃
11 Air release valve (50℃)/min <10 SH/T0308
12 Rotating oxygen bomb value
(150℃)/min
Not less than 25% of the
new oil test value, and the
turbine oil ≥ 100
SH/T0193
13 Antioxidant
content/%
T50
Antioxidant
Not less than 25% of the
new oil test value
GB/T7602
Hindered
phenol or
aromatic
amine
antioxidants
ASTMD69
71
Cause Analysis and Preventive Measures for Deterioration of Steam Turbine Lubricating Oil
Indonesian Journal of Social Technology, Vol. 5, No. 11, November 2024 4797
After the turbine oil system is overhauled and before the unit is started, the oil
pollution grade and particle size should not be greater than SAEAS4059F, and the
kinematic viscosity, flash point, acid value, moisture, foaming properties, and anti-
emulsification properties should comply with the requirements of Table 2.
3. Abnormal oil quality of steam turbine during operation and treatment
measures
The oil quality test results should be analyzed according to the quality standards of
the running turbine oil in Table 2. If the oil quality exceeds the standard, the cause should
be found and corresponding treatment measures should be taken. The possible causes and
reference treatment methods of the running turbine oil exceeding the standard are shown
in Table 3.
Table 3
Abnormal oil quality of steam turbine during operation and treatment measures
No. Project Warning limit Abnormal Treatment
measures
1 Exterior
1. Emulsified and
opaque
2. Contains
suspended
particles
3. Contains oil
sludge
1. Oil contains
water or other
liquid pollution
2. Oil impurity
pollution
3. Deep
deterioration of oil
quality
1. Dehydration or
oil change
2. Filtration
3. Invest in an oil
regeneration device
or change the oil
2 Chroma
Rapidly
darkening
Abnormal color
1. Other pollutants
2. Oil impurities
pollution
3. Additive
oxidation
discoloration
1. Invest in an oil
regeneration device
or change the oil
3
Kinematic
viscosity
a/(40℃）
mm2/s
More than 5% of
the new oil value
1. The oil is
contaminated
2. The oil quality
is seriously
deteriorated
3. Add high or
low-viscosity oil
If the viscosity is
low, measure the
flash point and
change the oil if
necessary.
4 Flashpoint
(open)℃
15℃ higher or
lower than new
oil
Oil is
contaminated or
overheated
Find out the cause
and compare it with
other test results to
consider treatment
or oil change.
Indonesian Journal of Social Technology, Vol. 5, No. 11, November 2024 4797
After the turbine oil system is overhauled and before the unit is started, the oil
pollution grade and particle size should not be greater than SAEAS4059F, and the
kinematic viscosity, flash point, acid value, moisture, foaming properties, and anti-
emulsification properties should comply with the requirements of Table 2.
3. Abnormal oil quality of steam turbine during operation and treatment
measures
The oil quality test results should be analyzed according to the quality standards of
the running turbine oil in Table 2. If the oil quality exceeds the standard, the cause should
be found and corresponding treatment measures should be taken. The possible causes and
reference treatment methods of the running turbine oil exceeding the standard are shown
in Table 3.
Table 3
Abnormal oil quality of steam turbine during operation and treatment measures
No. Project Warning limit Abnormal Treatment
measures
1 Exterior
1. Emulsified and
opaque
2. Contains
suspended
particles
3. Contains oil
sludge
1. Oil contains
water or other
liquid pollution
2. Oil impurity
pollution
3. Deep
deterioration of oil
quality
1. Dehydration or
oil change
2. Filtration
3. Invest in an oil
regeneration device
or change the oil
2 Chroma
Rapidly
darkening
Abnormal color
1. Other pollutants
2. Oil impurities
pollution
3. Additive
oxidation
discoloration
1. Invest in an oil
regeneration device
or change the oil
3
Kinematic
viscosity
a/(40℃）
mm2/s
More than 5% of
the new oil value
1. The oil is
contaminated
2. The oil quality
is seriously
deteriorated
3. Add high or
low-viscosity oil
If the viscosity is
low, measure the
flash point and
change the oil if
necessary.
4 Flashpoint
(open)℃
15℃ higher or
lower than new
oil
Oil is
contaminated or
overheated
Find out the cause
and compare it with
other test results to
consider treatment
or oil change.
Rikki Martin, Liu Guoqing
Indonesian Journal of Social Technology, Vol. 5, No. 11, November 2024 4798
No. Project Warning limit Abnormal Treatment
measures
5
Particle
pollution
level
>8
1. Particles are
introduced during
oil replenishment
2. Dust and
impurities enter
the system
3. Parts in the
system are worn
or corroded
4. The precision
filter is not put
into operation or
fails 5. Particles
are generated by
oil ageing
Identify the source
of particles and
check and start the
precision device
cleaning oil system.
6
Acid value
(in KOH) /
(㎎/g)
The added value
exceeds that of
new oil by more
than 0.1
1. High oil
temperature or
local overheating
2. Antioxidant
depletion
3. Oil
contamination and
oil quality
deterioration
1. Take measures to
control oil
temperature and
eliminate local
overheating
2. Add antioxidant
3. Put into oil
regeneration device
4. Change oil when
necessary based on
the results of
rotating oxygen
bomb
7
Liquid
phase
corrosion
degree c
There is rust Rust inhibitor
depleted Add rust inhibitor
8
Demulsifica
tion c
(54℃)/min
>30 Oil contamination
or deterioration
Put into oil
regeneration device
or change oil
9 Moisture c/
㎎/L >100
1. Oil cooler
drainage leakage
2. The oil seal is
not tight
3. The oil tank is
not
Check the
demulsification
degree, use the
filtering equipment
to remove water,
and pay attention to
the system
conditions to
eliminate defects.
Indonesian Journal of Social Technology, Vol. 5, No. 11, November 2024 4798
No. Project Warning limit Abnormal Treatment
measures
5
Particle
pollution
level
>8
1. Particles are
introduced during
oil replenishment
2. Dust and
impurities enter
the system
3. Parts in the
system are worn
or corroded
4. The precision
filter is not put
into operation or
fails 5. Particles
are generated by
oil ageing
Identify the source
of particles and
check and start the
precision device
cleaning oil system.
6
Acid value
(in KOH) /
(㎎/g)
The added value
exceeds that of
new oil by more
than 0.1
1. High oil
temperature or
local overheating
2. Antioxidant
depletion
3. Oil
contamination and
oil quality
deterioration
1. Take measures to
control oil
temperature and
eliminate local
overheating
2. Add antioxidant
3. Put into oil
regeneration device
4. Change oil when
necessary based on
the results of
rotating oxygen
bomb
7
Liquid
phase
corrosion
degree c
There is rust Rust inhibitor
depleted Add rust inhibitor
8
Demulsifica
tion c
(54℃)/min
>30 Oil contamination
or deterioration
Put into oil
regeneration device
or change oil
9 Moisture c/
㎎/L >100
1. Oil cooler
drainage leakage
2. The oil seal is
not tight
3. The oil tank is
not
Check the
demulsification
degree, use the
filtering equipment
to remove water,
and pay attention to
the system
conditions to
eliminate defects.
Cause Analysis and Preventive Measures for Deterioration of Steam Turbine Lubricating Oil
Indonesian Journal of Social Technology, Vol. 5, No. 11, November 2024 4799
No. Project Warning limit Abnormal Treatment
measures
10
Foaming
property/(fo
aming
tendency/fo
aming
quality)
24℃
and
after
24℃
Tendency
>500
Stability
>10
1. Oil aging
2. Defoamer
disappears
3. Oil is
contaminated
1. Put into oil
regeneration device
2. Add defoamer 3.
Change oil if
necessary93.5
℃
Tendency
>500
Stability
>10
11
Air release
valve
(50℃)/min
>10 Oil contamination
or deterioration
Change oil when
necessary
12
Rotating
oxygen
bomb value
(150℃)/min
Not less than
25% of the new
oil test value, and
the turbine oil ≥
100
Antioxidant
depletion
Oil ageing
Add
antioxidants
Regeneration
and oil change
when necessary
13
Antioxidant
content/%
T50
Antioxidant
Hinder
ed phenol or
aromatic
amine
antioxidants
Less than 25% of
the new oil value
1.
Antioxidant
depletion
2. Incorrect
oil filling
1. Add
antioxidants
2. Check other
items and change
oil if necessary
4. Analysis of causes of particle size exceeding the standard during operation
a) Contaminants left over from the manufacturing and equipment process of oil
system components, such as unpolished processing burrs on equipment
pipelines, uncleaned sand used for sandblasting at dead corners, welding slag
generated by welding pipelines and workpieces, dust on the inner wall of
pipelines, and sealants on the dividing surface of the bearing box and flange
joints, etc. These contaminants were not effectively removed during the
installation and oil flushing stages. Although the oil quality test was qualified
when the whole set was started for the first time, with the change in the unit's
operating conditions, the flow rate and temperature of the lubricating oil
changed, and various impurities originally attached to the equipment and
pipelines would be washed away and enter the oil system, causing intermittent
oil quality failure.
Indonesian Journal of Social Technology, Vol. 5, No. 11, November 2024 4799
No. Project Warning limit Abnormal Treatment
measures
10
Foaming
property/(fo
aming
tendency/fo
aming
quality)
24℃
and
after
24℃
Tendency
>500
Stability
>10
1. Oil aging
2. Defoamer
disappears
3. Oil is
contaminated
1. Put into oil
regeneration device
2. Add defoamer 3.
Change oil if
necessary93.5
℃
Tendency
>500
Stability
>10
11
Air release
valve
(50℃)/min
>10 Oil contamination
or deterioration
Change oil when
necessary
12
Rotating
oxygen
bomb value
(150℃)/min
Not less than
25% of the new
oil test value, and
the turbine oil ≥
100
Antioxidant
depletion
Oil ageing
Add
antioxidants
Regeneration
and oil change
when necessary
13
Antioxidant
content/%
T50
Antioxidant
Hinder
ed phenol or
aromatic
amine
antioxidants
Less than 25% of
the new oil value
1.
Antioxidant
depletion
2. Incorrect
oil filling
1. Add
antioxidants
2. Check other
items and change
oil if necessary
4. Analysis of causes of particle size exceeding the standard during operation
a) Contaminants left over from the manufacturing and equipment process of oil
system components, such as unpolished processing burrs on equipment
pipelines, uncleaned sand used for sandblasting at dead corners, welding slag
generated by welding pipelines and workpieces, dust on the inner wall of
pipelines, and sealants on the dividing surface of the bearing box and flange
joints, etc. These contaminants were not effectively removed during the
installation and oil flushing stages. Although the oil quality test was qualified
when the whole set was started for the first time, with the change in the unit's
operating conditions, the flow rate and temperature of the lubricating oil
changed, and various impurities originally attached to the equipment and
pipelines would be washed away and enter the oil system, causing intermittent
oil quality failure.
Rikki Martin, Liu Guoqing
Indonesian Journal of Social Technology, Vol. 5, No. 11, November 2024 4800
b) Impurities enter the system with air at places where the oil system is not tightly
sealed. Since the oil system generates oil smoke during operation, the exhaust
fan is always in operation, and the bearing box and the oil return system are
under negative pressure. If the seal is not tight, impurities will be sucked into the
system with air, causing oil pollution. Due to the negative pressure of the system,
dust, insulation cotton, and other impurities will inevitably enter the gap at the
oil baffle of the bearing box. This requires that the sanitary environment in the
main plant should be maintained after the oil system is put into operation,
especially in the insulation stage of the later stage of the project, when the unit
is overhauled, there is a lot of insulation and sanitation cleaning work. If
conditions permit, the exhaust fan can be temporarily stopped.
c) Oil pollution caused by normal or abnormal wear of the oil pump and various
speed regulating parts. Check at the bottom of the oil tank or the bottom of the
bearing box. If newer metal residues are found, it can be concluded that the
equipment running parts have abnormal wear. If the bottom inspection is mostly
impurities such as sludge, the probability of abnormal wear is small.
d) The clearance of the steam turbine shaft seal exceeds the standard. The clearance
adjustment during installation does not meet the design requirements or the shaft
seal teeth are worn during operation, resulting in large steam leakage from the
steam seal system, which leaks into the bearing box and causes oil
emulsification.
5. Preventive measures to prevent particle size from exceeding the standard
a) Clean the impurities inside the equipment.
Bearing boxes, oil tanks, oil coolers, and other equipment, there are residual
weld skin and slag in the internal dead corners of the welds, or residual sand, burrs,
gaskets, etc. during casting; during operation, impurities in the pipeline
accumulate at the bottom of the oil tank and the dead corners of the bearing seat.
The measures are taken:
1) After the equipment arrives, it should be carefully inspected and any defective
or impurity-attached parts should be cleaned and polished.
2) During the oil flushing process, the oil tank, bearing box, and other equipment
should be cleaned in stages, which can not only help shorten the oil flushing
time but also prevent impurities from remaining and causing wear on the
equipment during operation.
3) For equipment such as oil coolers, jacking oil devices, sealing oil
components, etc. that are difficult to dismantle on site but must be oil flushed,
they should be oil flushed only after the system pipelines and other equipment
have been flushed and qualified to prevent internal contamination.
4) The filter elements in all parts used in the oil flushing process should be
replaced after the oil flushing is completed.
5) The sealant used for the centre dividing the surface of the bearing seat and the
temporary oil flushing system restoration should be prevented from excessive
Indonesian Journal of Social Technology, Vol. 5, No. 11, November 2024 4800
b) Impurities enter the system with air at places where the oil system is not tightly
sealed. Since the oil system generates oil smoke during operation, the exhaust
fan is always in operation, and the bearing box and the oil return system are
under negative pressure. If the seal is not tight, impurities will be sucked into the
system with air, causing oil pollution. Due to the negative pressure of the system,
dust, insulation cotton, and other impurities will inevitably enter the gap at the
oil baffle of the bearing box. This requires that the sanitary environment in the
main plant should be maintained after the oil system is put into operation,
especially in the insulation stage of the later stage of the project, when the unit
is overhauled, there is a lot of insulation and sanitation cleaning work. If
conditions permit, the exhaust fan can be temporarily stopped.
c) Oil pollution caused by normal or abnormal wear of the oil pump and various
speed regulating parts. Check at the bottom of the oil tank or the bottom of the
bearing box. If newer metal residues are found, it can be concluded that the
equipment running parts have abnormal wear. If the bottom inspection is mostly
impurities such as sludge, the probability of abnormal wear is small.
d) The clearance of the steam turbine shaft seal exceeds the standard. The clearance
adjustment during installation does not meet the design requirements or the shaft
seal teeth are worn during operation, resulting in large steam leakage from the
steam seal system, which leaks into the bearing box and causes oil
emulsification.
5. Preventive measures to prevent particle size from exceeding the standard
a) Clean the impurities inside the equipment.
Bearing boxes, oil tanks, oil coolers, and other equipment, there are residual
weld skin and slag in the internal dead corners of the welds, or residual sand, burrs,
gaskets, etc. during casting; during operation, impurities in the pipeline
accumulate at the bottom of the oil tank and the dead corners of the bearing seat.
The measures are taken:
1) After the equipment arrives, it should be carefully inspected and any defective
or impurity-attached parts should be cleaned and polished.
2) During the oil flushing process, the oil tank, bearing box, and other equipment
should be cleaned in stages, which can not only help shorten the oil flushing
time but also prevent impurities from remaining and causing wear on the
equipment during operation.
3) For equipment such as oil coolers, jacking oil devices, sealing oil
components, etc. that are difficult to dismantle on site but must be oil flushed,
they should be oil flushed only after the system pipelines and other equipment
have been flushed and qualified to prevent internal contamination.
4) The filter elements in all parts used in the oil flushing process should be
replaced after the oil flushing is completed.
5) The sealant used for the centre dividing the surface of the bearing seat and the
temporary oil flushing system restoration should be prevented from excessive
Cause Analysis and Preventive Measures for Deterioration of Steam Turbine Lubricating Oil
Indonesian Journal of Social Technology, Vol. 5, No. 11, November 2024 4801
use, as it is easy to remain on the internal joint surface of the equipment and
be washed by oil for a long time, resulting in oil pollution and sludge.
b) The oil system equipment is not sealed tightly.
The oil return system will draw impurities from the air into the system due
to the slight negative pressure, causing the lubricating oil particle size to exceed
the standard. During the installation process, reliable sealing measures should be
taken at the following parts, such as applying Loctite 587 sealant, using flange
gaskets with better-sealing properties, and rechecking whether the flange bolts are
tightened in place.
1) The oil return flanges, manholes, oil pumps, exhaust fans oil tank connection
flanges, breathing holes, etc. above the oil level of the main engine oil tank.
2) The dividing surface, observation window, inspection hole, and the joint
surface with the oil return pipe flange of each bearing box.
3) Inspection flanges, manholes and observation windows of generator end
covers, oil return expansion tanks, float tanks, and other equipment.
4) The return oil filter and return oil observation window of the return oil pipeline.
c) Lubricating oil water content exceeds the standard
Excessive water content will cause oil emulsification. The main reason is
that the clearance of the bearing seal exceeds the standard or the seal pressure is
adjusted too high, steam enters the bearing box, and water enters the oil.
Therefore, during operation, the following points should be noted:
1) The end seal clearance of each bearing shell should be checked carefully to
ensure that the clearance is adjusted to the lower and middle limits of the design
range.
2) Before operation, the shaft seal piping system should be inspected in detail.
The water spray volume of some units' water spray coolers exceeds the design
value or the nozzles are faulty, and the water is not in a mist shape, which not
only fails to reduce the temperature but also causes more water to enter the
shaft seal, causing water to enter the oil; the shaft seal return steam pipe
installation slope is not enough or the return steam pipe is not smooth, which
can also cause water to accumulate in the shaft seal, causing water to enter the
oil.
3) When putting the shaft seal system into operation before the unit is started up,
the shaft seal pressure should be carefully controlled to prevent water from
entering the oil.
4) If there is an internal leak in the oil cooler, the water pressure will be higher
than the oil pressure when the machine is shut down, which will cause water to
enter the oil. Therefore, a water pressure test should be carried out before
installing the oil cooler to prevent internal leakage.
Indonesian Journal of Social Technology, Vol. 5, No. 11, November 2024 4801
use, as it is easy to remain on the internal joint surface of the equipment and
be washed by oil for a long time, resulting in oil pollution and sludge.
b) The oil system equipment is not sealed tightly.
The oil return system will draw impurities from the air into the system due
to the slight negative pressure, causing the lubricating oil particle size to exceed
the standard. During the installation process, reliable sealing measures should be
taken at the following parts, such as applying Loctite 587 sealant, using flange
gaskets with better-sealing properties, and rechecking whether the flange bolts are
tightened in place.
1) The oil return flanges, manholes, oil pumps, exhaust fans oil tank connection
flanges, breathing holes, etc. above the oil level of the main engine oil tank.
2) The dividing surface, observation window, inspection hole, and the joint
surface with the oil return pipe flange of each bearing box.
3) Inspection flanges, manholes and observation windows of generator end
covers, oil return expansion tanks, float tanks, and other equipment.
4) The return oil filter and return oil observation window of the return oil pipeline.
c) Lubricating oil water content exceeds the standard
Excessive water content will cause oil emulsification. The main reason is
that the clearance of the bearing seal exceeds the standard or the seal pressure is
adjusted too high, steam enters the bearing box, and water enters the oil.
Therefore, during operation, the following points should be noted:
1) The end seal clearance of each bearing shell should be checked carefully to
ensure that the clearance is adjusted to the lower and middle limits of the design
range.
2) Before operation, the shaft seal piping system should be inspected in detail.
The water spray volume of some units' water spray coolers exceeds the design
value or the nozzles are faulty, and the water is not in a mist shape, which not
only fails to reduce the temperature but also causes more water to enter the
shaft seal, causing water to enter the oil; the shaft seal return steam pipe
installation slope is not enough or the return steam pipe is not smooth, which
can also cause water to accumulate in the shaft seal, causing water to enter the
oil.
3) When putting the shaft seal system into operation before the unit is started up,
the shaft seal pressure should be carefully controlled to prevent water from
entering the oil.
4) If there is an internal leak in the oil cooler, the water pressure will be higher
than the oil pressure when the machine is shut down, which will cause water to
enter the oil. Therefore, a water pressure test should be carried out before
installing the oil cooler to prevent internal leakage.
Rikki Martin, Liu Guoqing
Indonesian Journal of Social Technology, Vol. 5, No. 11, November 2024 4802
Conclusion
The steam turbine lubricating oil system is the key to the operation of the unit. The
deterioration of oil quality and the excessive particle size can easily cause serious
consequences. Therefore, it should be controlled from the inspection of new oil entering
the factory, sampling and testing, and monitoring of operation stages, to improve the
maintenance process, ensure the internal cleanliness of the oil system, lay a good
foundation for the smooth operation of the unit, and improve the reliability of the safe
operation of the unit.
Indonesian Journal of Social Technology, Vol. 5, No. 11, November 2024 4802
Conclusion
The steam turbine lubricating oil system is the key to the operation of the unit. The
deterioration of oil quality and the excessive particle size can easily cause serious
consequences. Therefore, it should be controlled from the inspection of new oil entering
the factory, sampling and testing, and monitoring of operation stages, to improve the
maintenance process, ensure the internal cleanliness of the oil system, lay a good
foundation for the smooth operation of the unit, and improve the reliability of the safe
operation of the unit.
Cause Analysis and Preventive Measures for Deterioration of Steam Turbine Lubricating Oil
Indonesian Journal of Social Technology, Vol. 5, No. 11, November 2024 4803
Bibliography
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Indonesian Journal of Social Technology, Vol. 5, No. 11, November 2024 4803
Bibliography
Chowdhury, S. N., Tung, T. T., Ta, Q. T. H., Castro, M., Feller, J. F., Sonkar, S. K., &
Tripathi, K. M. (2021). Upgrading of diesel engine exhaust waste into onion-like
carbon nanoparticles for integrated degradation sensing in nano-biocomposites.
New Journal of Chemistry, 45(7), 3675–3682.
Gao, Z., & Liu, X. (2021). An overview on fault diagnosis, prognosis and resilient control
for wind turbine systems. Processes, 9(2), 300.
Gulfam, R., & Zhang, P. (2019). Power generation and longevity improvement of
renewable energy systems via slippery surfaces–A review. Renewable Energy, 143,
922–938.
Hildreth, J. C., & Tymvios, N. (2016). Preventive Maintenance Criteria. Publication
FHWA/NC/2015-11, North Carolina Department of Transportation.
Liu, Z., Wang, H., Zhang, L., Sun, D., Cheng, L., & Pang, C. (2016). Composition and
degradation of turbine oil sludge. Journal of Thermal Analysis and Calorimetry,
125, 155–162.
Tang, W. H., & Wu, Q. H. (2011). Condition monitoring and assessment of power
transformers using computational intelligence. Springer Science & Business
Media.
Wang, C., Du, C., Shang, J., Zhu, Y., Yao, H., Xu, M., Shan, S., Han, W., Du, Z., & Yang,
Z. (2023). A comprehensive review of the thermal cracking stability of endothermic
hydrocarbon fuels. Journal of Analytical and Applied Pyrolysis, 169, 105867.
Xu, Y., Wang, F., Liang, D., Lv, G., & Chen, C. (2024). A Comprehensive Review of
Waste Wind Turbine Blades in China: Current Status and Resource Utilization.
Journal of Environmental Chemical Engineering, 113077.
Zhang, Q., Zhang, H., Yan, Y., Yan, J., He, J., Li, Z., Shang, W., & Liang, Y. (2021).
Sustainable and clean oilfield development: How access to wind power can make
offshore platforms more sustainable with production stability. Journal of Cleaner
Production, 294, 126225.
Zhou, S., Song, J., Xu, P., He, M., Xu, M., & You, F. (2023). A review of tribology,
characterization and lubricants for water-based drilling fluids. Geoenergy Science
and Engineering, 212074.