An overview of the methods outlined in ASTM D7718. Topic to be presented to attendees at the OilDoc2015 Conference held in Rosenheim, Bavaria, Germany on January 29, 2015.

2. Lubricant Sampling
• Oil analysis using valves and gravity
• Drop tube sampling
• Retrofit sampling mini-mess
• Importance of sample location
• Drop tube point of
sample uncertain
Image from Noria Corporation

3. Grease Sampling
• Historically during disassembly following failure
• Using “popsicle stick”, screwdriver, cable ties
• Samples only available near access points, ports
• “Grab Sample” has similar limitations to “Drop
Tube Sampling”
• ASTM Grease subcommittee initiates working
group to develop sampling standard, 2009
• Projects initiated in USA and Denmark to test
effectiveness of grease sampling in 2010, 2012

4. Motor Operated Valves (MOV)
• EPRI method using
plastic tubing at gears
• Grease removed and
visually inspected
• Kits made utilizing
known consistency
greases for comparison
to obtained sample
• Questionable samples;
very subjective analysis
Photos: Bolt, et. al. Machinery Lubrication Magazine. May 2003

5. Grease sampling devices
• Maintain purge function with little/no backpressure
when threaded into machine
• Can be attached to T-handle for precise sample location
adjacent to internal gears
• Design to optimize the analysis process

6. Sampling Techniques
• MOV Gearbox
1 2 3 4 5
• Electric Motor Bearing
1 2 3 4 5
• Pillow Block Bearing
1 2 3 4

7. Sampler Effectiveness

8. MOV Test Stand-EPRI Project
•Actuators filled with in-service grease
•Cycled forward and backward
•Produced video of grease flow
•Data on consistency of wear levels

9. Wear monitoring
• Hall effect sensor counts total ferrous debris
level of sample, not the variable amount
through the body of grease
Method Average
Standard
Deviation
Relative Standard
Deviation
fdM+ 277 ppm 7 2.53
DR- 205 46 22.44
RDE 57 ppm 16 28.07
Method Average
Standard
Deviation
Relative Standard
Deviation
fdM+ 277 ppm 7 2.53
DR- 205 46 22.44
RDE 57 ppm 16 28.07

10. Wear Evaluation

11. Wind Turbine Lubricant Monitoring
11

12. Wind Turbine grease sampling and analysis
• 2-year project conducted with DONG Energy and
Vattenfall, two largest offshore wind operators in the
world
• Dr. Kim Esbensen, internationally recognized expert in
Theory of Sampling (TOS), Denmark
• Rich Wurzbach, MRG Labs, inventor of Grease Thief
• Systematic evaluation of grease heterogeneity, sampling
methodology, and analysis validity and repeatability for
wind turbine main bearings in on-shore and off-shore
applications
• Results published at OilDoc, LUBMAT, and AWEA
Richard Wurzbach– OilDoc Conference 2015

13. Wind Main Bearing Sampling
• Grease flow dependent on
temperature, bearing
movement
• Grease Thief & T-handle
used to capture flowing
grease
• Revised T-handle developed
for Denmark Off-shore Wind
Research Project
13

14. ASTM Standard Development
• Incorporation of grease sampling research
• Inclusion of historical methods for sampling
with considerations and limitations
• Failed component sampling, care in obtaining
sample or multiple samples
• Use of tubing, adequacy of suction alone,
possibility of peripheral grease sampling
• Inclusion of new technologies for active and
passive sampling
Richard Wurzbach– OilDoc Conference 2015

15. Scope and Terminology (ASTM D7718)
• Inservice grease samples, various components
• Requirements for multiple samples
• “Passive” and “Active” sampling
• “Actuate” to take core samples
• Hazards and Cautions
Active Grease-Sampling Device (shown as Fig. 1 in ASTM D7718)Passive Grease-Sampling Device (shown as Fig. 3 in ASTM D7718)

16. General Procedures (ASTM D7718)
• cleanliness of sampling tools
• homogeneity of samples
• uniformity and design of the sampling devices
• operator training and knowledge of equipment
being
• shipping considerations and sample labelling
• containers and protective sleeves to prevent
leakage and co-mixing of samples

17. Active Sampling
• Introducing a device to the surface or inside of a
machine
• “Stinger probe” allows for the positioning of the
device adjacent to target surface
• Use of an extending handle to reach set depth
within machine
• Use of tubing to extract sample, possibly with
suction
• Use of spatula or soft tool to extract from
accessible surface (pillow block, open gear)

18. Active Sampling
• T-handle Coring with active
or passive sampler
• Spatula and syringe on
pillow block
• Syringe and tubine on
slewing bearing
“Taking a sample” from Rothe Erde “Grease Sampling Set” instructions

19. Passive Sampling
• Threaded or attached to machine
• Normal or initiated purging of reservoir displaces
into sampler
• Must have provision for proper purge;
overgreasing must be
avoided
• Sample prevents
contamination from
surroundings during
purge

20. Failure Analysis
• Proper handling of
specimen
• Separation of external
dirt/debris
• Removal of shields and seals
• Extraction of grease sample;
need for multiple samples
• Correlation to observed
conditions, history and
metallurgy

21. Cautions and Concerns
• Use of plastic tubing may not properly suction
all representative grease, point of sampling may
vary, as in oil “drop-tube” sampling
• Samples must be taken from “live-zone” in the
machine, understanding of flow dynamics
important
• Sample must be properly labeled and protected
during shipment
• Quantity must be sufficient for required tests

22. Acceptance and Use
• D7718 is basis for AWEA Recommended Practices for
wind turbine sampling
– 812 Grease Sampling - Main Bearing
– 813 Grease Sampling - Generator Bearing
– 814 Grease Sampling - Pitch Bearing
– 815 Grease Analysis
• Used by largest operators in Danish Offshore Wind
industry
• Published by US Nuclear Industry in “Effective Grease
Practices” NMAC Guideline
• Analysis utilized by labs in Europe, Asia, North America
• Sampling kits used on six continents around the globe

23. Next Steps
• Development of ASTM Standard for Grease Analysis
– Integrated Tester section of ASTM with a balloted Work Item
–Currently in Interlaboratory Study (ILS) in US labs for precision statement
– Laboratories in Asia, Europe and North America to participate in
development of methods
• Development of “Slim” version of sampler to access rail
locomotive wheel bearings, wind bearings
• Mini-lab development for “In-Sampler” Analysis, including
ferrous debris, colorimetry
• Real-time particle counting in grease processed between two
samplers
• Major lubricant manufacturers worldwide utilizing for support of
customer base

24. Analysis Techniques
Sample is received. fdM+ is run Die extrusion is performed and substrate is made
Two strips are used to make
a dilution to run RDE/ICP.
One Strip is used
for FT-IR.
One Strip is Dissolved in Green
RULER solution to run RULER.
24

25. Die Extrusion Analyzer

26. Grease Consistency – Back Bearings in a USA
Wind Farm: Outliers in Yellow

27. Optical Spectroscopy
•Optical spectroscopy quantifies the appearance of grease
•Grease aging, contaminants, mixtures, chemometrics
27

28. FdM Wear Levels across Wind Farm
28

29. 3-D Sampling, OEM repair shop

30. 3-D sampling

31. Trends of moisture in bearings
0
100
200
300
400
500
600
700
800
900
Moisture,ppm
314 Front
314 Rear
319 Front
319 Rear
Grease type: SKF LGWM1
• Thickener: Li
• Base oil: Mineral oil
• Viscosity @ 40C: 200 cSt
• NLGI-class: 1

32. Wear levels in Robot fleet-comparison