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Failure Analysis of GE-F9 Gas
Turbine Journal Bearings(Research Note)
Principle of Corrosion | Postgraduate Corrosion | 2011
Alfonsius B J Haslim
0806331355
Introduction: Jahromi, Goudarzi, & Nazarboland. (2008) [1]
Abstract– This paper presents a failure analysis of journal
bearings used in GE-F9 gas turbines. Detailed studies
including visual examination, optical microscopy, scanning
electron microscopy, XRD and oil analysis were performed to
determine the root causes of failure. Based on the results, it
was determined that fretting, sulfur attack and fatigue were
the main causes of failure.
Keywords– Journal bearing, bearing failure, fretting, sulfur
attack, fatigue.
Presentation Content’s
Introduction
Summary
Basic Theory
Study Case
Experimental & Discussion
BASIC THEORY
PART II
Fretting Corrosion
Fretting corrosion (a
corrosion phenomenon)
is a combined wear and
corrosion process in which
material is removed from
contacting surfaces. Occur
between two material
under load and is restricted
to very small amplitude
oscillations [2-4].http://corrosion.ksc.nasa.gov/i
mages/fret4.jpg
http://www.iahcsmm.org/Recertifica
tion/LessonPlans/images/CIS211pi
cs/exampleOfFrettingCorrosion.jpg
Recognizing Freeting Corrosion
Figure – Weight loss of mild steel
versus mild steel by freeting corrosion
[5].
Figure – Schematic of the fretting
process (form local surface dislocation
and deep pits) [3].
Example [3]
Prevention Fretting Corrosion [3-4]
1. Use of Lubricants, Surface
Treatments (Phospating), & Coating.
2. Increase the hardness of surfaces.
3. Decrease bearing loads on mating
surfaces.
4. Use of barriers to limit ingress of a
corrosive environment to mating
surfaces.
5. Restricting the degree of movement.
6. Selecting materials and combinations
that are less susceptible to fretting
corrosion (Table 4).
Sulfur Attack (Sulfidation)
Sulfidation is a reaction of a
metal or alloy with some form
of sulfur to produce a sulfur
compound that forms on or
under the surface of a metal or
a alloy [6].
Sulfur is one of the most common corrosive
contaminants in high temperature (2100 to
2200 F in excess air) industrial environment.
When combustion takes place with excess
air to ensure complete combustion of fuel
for generating heat in many industrial
processes, sulfur in the fuel reacts with
oxygen to form SO2 and SO3 [7-9].•Reducing Environment:
H2S
•Oxidizing
Environments: SO2
(Much Less Corrosive)
Some Application of Sulfidation
1. Calcining of mineral and chemical
feedstock [10].
2. Petrochemical Processing [11].
3. Fossil-fired boilers [11].
4. Petroleum Refining [12].
5. Coal Gasification [13-14].
6. Waste Incineration [15-16].
7. Fluidized-bed coal combustion [17-19].
http://newsimg.bbc.co.uk/media/images/4
1230000/gif/_41230096_mass_burn_inf4
16.gif
http://www.lawrencepumps.com/imag
es/PetroleumRefining.jpg
Some Cases
(Sulfidation) [7]
STUDY CASE
PART III
Journal and Bearing [1]
Failure analysis of GE-F9 gas turbine bearings having dimensional
characteristics given in Table 1 was the objective of this investigation. Therefore, in
the present case, samples of failed bimetal journal bearing were subjected to
detailed metallurgical investigations. Depending on environment temperature
(winter and summer) and cooling condition, the temperature of the lubricating
oil was between 70 to 90 °C.
Visual Examination [1]
Fretting
a) Damaged (Darkened regions). b) normal wear
EXPERIMENTAL &
DISCUSSION
PART IV
Chemical Composition of the bearing alloy [1]
Atomic adsorption Spectrometer
(http://elchem.kaist.ac.kr/vt/chem
ed/spec/atomic/graphics/aa.jpg)
Corresponds to ASTM B-23-
alloy 2.
Optical Microscopy and hardness measurements [1]
Matrix: 25.2 Cuboids: 77.2 Needles: 89.3
Microhardness Hv Results:
Scanning electron Microscope and XRD [1]
Containing Cu2S
The sulfide was formed by the action of sulfur acids in the lubricating oil on the
copper in the bearing material. The decomposition of sulfur compounds in the
lubricating oil usually occurs when moisture is present in the oil and when the
operating temperature is high and exceeds a normal condition. In the present
case, the frictional heat due to the oscillation of the bearing in the housing
bore has stimulated a sulfur attack.
Scanning electron Microscope and XRD [1]
Scanning electron Microscope and XRD [1]
Additives are chemical agents added to lubricating oil to improve oil
properties. Oxidation inhibitors (phenolics and dithiophosphate)
and rust inhibitors (organic acids and sodium petroleum
sulfonate) are among the additives which are extensively used in
gas turbine lubricating oil. In contrast to phenolics and organic acids,
dithiophosphate and sodium petroleum sulfonate include sulfur.
It is clear that a sulfur attack can be prevented by using sulfur-
free additives.
Oil Evaluation [1]
The results shown in Table 3 indicate that there was no problem
with the oil in the normal operating condition. The result values
have been compared with the recommended values mentioned
in the manufacturer’s instructions.
SUMMARY
PART V
Summary
Reference
1. S. A. J. Jahromi, M. M. Goudarzi, & A. Nazarboland. (2008). “Research
Note” Failure analysis of GE-F9 Gas Turbine Journal Bearings. Iranian
Journal of Science & Technology, Transaction B, Engineering. Vol. 32,
no. 81, pp. 61-66.
2. R. W. Revie, & H. H. Uhlig. (2008). Corrosion and Corrosion Control,
an Introduction to Corrosion Science and Engineering, 4th ed. Canada:
John Wiley & Sons, Inc.
3. J. R. Davis. (2000). Corrosion, understanding the basics. USA: ASM
International.
4. A. Groysman. (2010). Corrosion for Everybody. Springer Science +
Business Media.
5. I-Ming Feng, & H. H. Uhlig. (1954). Fretting Corrosion of mild steel in
air and in nitrogen. Journal of Applied Mechanics. (Published by
ASME). Vol. 21, pp. 395.
6. C. Grosenick. (2011). High Temperature turbine blade corrosion.
Aircraft Maintenance Technology.
7. G. Y. Lai. (2007). High Temperature Corrosion and Materials
Application. USA: ASM International.
Reference
8. P. A. Schweitzer. (2010). Fundamental of Corrosion: Mechanism,
Causes, & Prevention Methods. USA: CRC Taylor & Francis Group.
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Practice. New York: Marcel Dekker, Inc.
10.G. Y. Lai. (1985). Journal of Metallurgy. Vol. 41, pp. 14.
11.G.L. Swales, in Behavior of High Temperature Alloys in Aggressive
Environments, I. Kirman et al., Ed., Proc. Petten International
Conference, Oct 15–18, 1979, The Metals Society, London, 1980, p 45.
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14.K.J. Barton, V.L. Hill, and R. Yurkewycz, in The Properties and
Performance of Materials in the Coal Gasification Environments, V.L.
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15.S.K. Srivastave, G.Y. Lai, and D.E. Fluck, Paper No. 398, Corrosion/87,
NACE, 1987.
16.J.A. Harris, W.G. Lipscomb, and G.D. Smith, Paper No. 402,
Corrosion/87, NACE, 1987.
Reference
17. J. Stringer, in High Temperature Corrosion, R.A. Rapp, Ed.,
Conference Proceedings (San Diego, CA) March 2–6, 1981, NACE,
1981, p 389.
18. A.J. Minchener, D.M. Lloyd, and P.T. Sutcliffe, “Materials Evaluation for
Fluidized Bed Combustion Systems,” CS- 3511, Final Report to EPRI
on Research Project RP979-11, Electric Power Research Institute, Palo
Alto, CA, 1984.
19. J. Stringer, Paper No. 90, Corrosion/86, NACE, 1986.