Weibull Database

Weibull databases require considerable use of engineering judgment for meaningful application of the facts stored in database format. Do not apply the data blindly without understanding the specific situation, as this database is solely intended for educational purposes.

Data, described in this database, are very general. The facts are broad as is usually found in engineering references. Typical values are given for a specific case which may not be applicable for each condition envisioned by the end user of the database as exceptions always exist. Therefore you are the sole responsible individual for use of this table--Barringer & Associates, Inc. assumes no liability for your use/misuse of these tables in any manner either obvious or implied.

Item

Beta Values

Eta Values

 

(Weibull Shape Factor)

(Weibull Characteristic Life--hours)

Low

Typical

High

Low

Typical

High

Components

 

 

 

My engineering judgment does not support the range of a few values shown in published databases

Ball bearing

0.7

1.3

3.5

14,000

40,000

250,000

Roller bearings

0.7

1.3

3.5

9,000

50,000

125,000

Sleeve bearing

0.7

1

3

10,000

50,000

143,000

Belts, drive

0.5

1.2

2.8

9,000

30,000

91,000

Bellows, hydraulic

0.5

1.3

3

14,000

50,000

100,000

Bolts

0.5

3

10

125,000

300,000

100,000,000

Clutches, friction

0.5

1.4

3

67,000

100,000

500,000

Clutches, magnetic

0.8

1

1.6

100,000

150,000

333,000

Couplings

0.8

2

6

25,000

75,000

333,000

Couplings, gear

0.8

2.5

4

25,000

75,000

1,250,000

Cylinders, hydraulic

1

2

3.8

9,000,000

900,000

200,000,000

Diaphragm, metal

0.5

3

6

50,000

65,000

500,000

Diaphragm, rubber

0.5

1.1

1.4

50,000

60,000

300,000

Gaskets, hydraulics

0.5

1.1

1.4

700,000

75,000

3,300,000

Filter, oil

0.5

1.1

1.4

20,000

25,000

125,000

Gears

0.5

2

6

33,000

75,000

500,000

Impellers, pumps

0.5

2.5

6

125,000

150,000

1,400,000

Joints, mechanical

0.5

1.2

6

1,400,000

150,000

10,000,000

Knife edges, fulcrum

0.5

1

6

1,700,000

2,000,000

16,700,000

Liner, recip. comp. cyl.

0.5

1.8

3

20,000

50,000

300,000

Nuts

0.5

1.1

1.4

14,000

50,000

500,000

"O"-rings, elastomeric

0.5

1.1

1.4

5,000

20,000

33,000

Packings, recip. comp. rod

0.5

1.1

1.4

5,000

20,000

33,000

Pins

0.5

1.4

5

17,000

50,000

170,000

Pivots

0.5

1.4

5

300,000

400,000

1,400,000

Pistons, engines

0.5

1.4

3

20,000

75,000

170,000

Pumps, lubricators

0.5

1.1

1.4

13,000

50,000

125,000

Seals, mechanical

0.8

1.4

4

3,000

25,000

50,000

Shafts, cent. pumps

0.8

1.2

3

50,000

50,000

300,000

Springs

0.5

1.1

3

14,000

25,000

5,000,000

Vibration mounts

0.5

1.1

2.2

17,000

50,000

200,000

Wear rings, cent. pumps

0.5

1.1

4

10,000

50,000

90,000

Valves, recip comp.

0.5

1.4

4

3,000

40,000

80,000

 

 

 

 

 

 

 

Machinery Equipment

 

 

 

 

 

 

Circuit breakers

0.5

1.5

3

67,000

100,000

1,400,000

Compressors, centrifugal

0.5

1.9

3

20,000

60,000

120,000

Compressor blades

0.5

2.5

3

400,000

800,000

1,500,000

Compressor vanes

0.5

3

4

500,000

1,000,000

2,000,000

Diaphgram couplings

0.5

2

4

125,000

300,000

600,000

Gas turb. comp. blades/vanes

1.2

2.5

6.6

10,000

250,000

300,000

Gas turb. blades/vanes

0.9

1.6

2.7

10,000

125,000

160,000

Motors, AC

0.5

1.2

3

1,000

100,000

200,000

Motors, DC

0.5

1.2

3

100

50,000

100,000

Pumps, centrifugal

0.5

1.2

3

1,000

35,000

125,000

Steam turbines

0.5

1.7

3

11,000

65,000

170,000

Steam turbine blades

0.5

2.5

3

400,000

800,000

1,500,000

Steam turbine vanes

0.5

3

3

500,000

900,000

1,800,000

Transformers

0.5

1.1

3

14,000

200,000

14,200,000

 

 

 

 

 

 

 

Instrumentation

 

 

 

 

 

 

Controllers, pneumatic

0.5

1.1

2

1,000

25,000

1,000,000

Controllers, solid state

0.5

0.7

1.1

20,000

100,000

200,000

Control valves

0.5

1

2

14,000

100,000

333,000

Motorized valves

0.5

1.1

3

17,000

25,000

1,000,000

Solenoid valves

0.5

1.1

3

50,000

75,000

1,000,000

Transducers

0.5

1

3

11,000

20,000

90,000

Transmitters

0.5

1

2

100,000

150,000

1,100,000

Temperature indicators

0.5

1

2

140,000

150,000

3,300,000

Pressure indicators

0.5

1.2

3

110,000

125,000

3,300,000

Flow instrumentation

0.5

1

3

100,000

125,000

10,000,000

Level instrumentation

0.5

1

3

14,000

25,000

500,000

Electro-mechanical parts

0.5

1

3

13,000

25,000

1,000,000

 

 

 

 

 

 

 

Static Equipment

 

 

 

 

 

 

Boilers, condensers

0.5

1.2

3

11,000

50,000

3,300,000

Pressure vessels

0.5

1.5

6

1,250,000

2,000,000

33,000,000

Filters, strainers

0.5

1

3

5,000,000

5,000,000

200,000,000

Check valves

0.5

1

3

100,000

100,000

1,250,000

Relief valves

0.5

1

3

100,000

100,000

1,000,000

 

 

 

 

 

 

 

Service Liquids

 

 

 

 

 

 

Coolants

0.5

1.1

2

11,000

15,000

33,000

Lubricants, screw compr.

0.5

1.1

3

11,000

15,000

40,000

Lube oils, mineral

0.5

1.1

3

3,000

10,000

25,000

Lube oils, synthetic

0.5

1.1

3

33,000

50,000

250,000

Greases

0.5

1.1

3

7,000

10,000

33,000

 


You'll recognize the form of the above table from Appendix A of the reference: Bloch, Heinz P. and Fred K. Geitner, 1994, Practical Machinery Management for Process Plants, Volume 2: Machinery Failure Analysis and Troubleshooting, 2nd Edition, Gulf Publishing Company, Houston, TX. If you're interested in machinery life, you'll find this book (and others written by Block and Geiter) worthy of adding to your library for good maintenance practices and good solid advice on plant equipment.

Bloch and Geitner's Appendix A is given in failures per million hours. Information from Appendix A has been interpreted and converted into ages-to-failure as shown under the low/high values by Barringer & Associates, Inc. along with estimates of typical Weibull values. Bloch and Geitner also give additional failure rates in their 1994 book: An Introduction To Machinery Reliability Assesment, 2nd Edition, Table 4.3. This book is also published by Gulf Publishing Company in Houston, TX.

Bloch and Geitner also list Weibull shape factors in Table 7-2 of the above reference. You will find many of their values are different than listed above (remember you can always think of different applications and situations which result in different Weibull values for shape factors and characteristic life!!--be carefull when you use the data!!). The issue is not which Weibull value is right or wrong--the issue is to understand your conditions so you select the correct value for your operations based on your experience and your operating conditions. Frequently we find the same equipment in use in similar applications within large companies will display significantly different Weibull values because of the way it is installed, maintained, and operated--so don't be surprised by different Weibull values.

You can communicate with: Heinz P. Bloch, P.E. in West Des Moines, IA by e-mail at     hpbloch@mchsi.com and Fred K. Geitner, P.Eng. in Brights Grove, Ontario, CANADA by e-mail at     fgeitner@compuserve.com.

Other information for this database was developed from details supplied verbally by David P. Weber. Dave is a gas turbine reliability expert and author of papers in fuzzy logic for solving reliability problems. He has an extensive Weibull database information on gas turbines and other equipment. You can contact Dave at Phone: 513-697-0852 or FAX: 513-697-0860 and     e-mail.   Also consider use of Dave Weber's Weibul db software. Weibull db uses data from the above database and displays probability plots, hazard plots, and Monte Carlo variations of the above information in an Excel spreadsheet--cost for the software is US$70 plus shipping and handling.

This database is intended for educational purposes only. Barringer & Associates, Inc. clearly is not responsible (neither obvious liability or implied liability) for how you use this database. If you are not personally responsible for knowledgeable use of the details in this database, then don't use it.

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Last revised 11/19/2008
This database may be revised at any time to correct values or to reinterpret operating conditions.