OFF-SHORE RELIABILITY DATABASE (OREDA)

For many years Norwegian and foreign oil companies have been collaborating with SINTEF Industrial Management, Dept. of Safety and Reliability and consultants in the collection of data on maintenance, reliability and safety of offshore installations. Used in conjunction with specially developed software, these data provide a basis for the preparation of reliability analyses. Such analyses simplify the job of selecting the "best" technical solutions and have led to significant savings in the development and operation of platforms.

Reliability is a decisive aspect of equipment installed on offshore installations. Equipment faults alone, or in comination with other factors, have been the cause of a number of accidents. Low oil prices and tighter profit margins mean that the cost of shutdowns is of greater importance.

In the early 80s a number of oil companies operating in the North Sea and the Adriatic started a collaborative project. The idea was to survey the reliability of important equipment under 'real life' operational conditions. The project, which was given the acronym OREDA (Offshore REliability DAta), has been carried out in five phases until the end of 1999, and is continued in a sixth phase until end of 2001. SINTEF Industrial Management, Dept. of Safety and Reliability has been a member of the project since it began, and has been project manager since 1992. The figure shows the tree main goals of OREDA project.

Application

OREDA is a unique data source on failure rates, failure mode distribution and repair times for equipment used in the offshore industri. Such data are necessary for reliability as well as risk analyses.
Possible applications are:

  • Reliability, Availability and Maintainability (RAM) analyses
  • Regularity studies.
  • Risk analyses.
  • Planning and scheduling of maintenance, inspection and testing.
  • Cost benefit studies.
  • Selection of alternative system designs.

The system covers a wide range of components and systems:

  • MACHINERY
    • Compressors
    • Gas turbines
    • Pumps
  • ELECTRIC EQUIPMENT
    • Electric generators
  • MECHANICAL EQUIPMENT
    • Heat exchangers
    • Vessels
  • CONTROL AND SAFETY EQUIPMENT
    • Control Logic Units
    • Fire and Gas Detectors
    • Process sensors
    • Valves
  • SUBSEA EQUIPMENT
    • Control Systems
    • Well Completions

The data in the data base represent the North Sea (Norwegian and UK sector) and the Adriatic Sea. Data have been collected for altogether 7,629 equipment units. The data represent a total observation period of 22,373 years, and 11,154 failures have been recorded.

The data are presented in data sheets for various functions, applications, capacities, fluides, sizes etc. of the equipment. An example of such a data sheet is shown below:

Taxonomy no
1.1.1.1.1
Item
Machinery
Compressors
Centrifugal
Electric Motor Driven
(100-1000) kW

Population

Installations

Aggregated time in service (106 hours)

No of demands

5

2

Calendar time *
0.1248

Operational time
0.0832

 

Failure mode

No of

Failure rate (per 106 hours).

Active

Repair (manhours)

 

fail.

Lower

Mean

Upper

SD

MLE

rep.hrs

Min

Mean

Max

Critical 23*
23
1.31
2.02
217.71
471.18
827.93
1806.90
304.49
665.33
184.33
276.36
10.0 0.5 24.3 186.3
Failed to start 1*
1
0.94
0.29
8.42
17.10
22.20
61.58
7.02
22.41
8.01
12.02
- 13.0 13.0 13.0
Fail while running 14*
14
0.97
1.28
132.09
285.42
499.13
1093.54
183.39
402.61
112.20
168.22
10.0 0.5 24.0 186.3
Unknown 1*
1
0.94
0.29
8.42
17.10
22.20
61.58
7.02
22.41
8.01
12.02
- 11.4 11.4 11.4
Vibration 7*
7
0.71
0.70
65.50
140.94
243.34
538.64
89.14
198.24
56.10
84.11
- 0.5 28.5 117.5
Degraded 6*
6
0.67
0.62
55.99
120.30
206.78
459.35
75.67
169.04
48.09
72.09
- 9.7 27.4 75.4
Other 6*
6
0.67
0.62
55.99
120.30
206.78
459.35
75.67
169.04
48.09
72.09
- 9.7 27.4 75.4
Incipient 29*
29
1.54
2.51
274.78
595.01
1047.12
2282.45
385.22
840.47
232.42
348.45
4.1 2.0 16.2 173.6
External leakage 4*
4
0.60
0.46
36.96
79.02
133.63
300.70
48.67
110.60
32.06
48.06
2.5 3.0 21.3 51.7
Overheated 1*
1
0.94
0.29
8.42
17.10
22.20
61.58
7.02
22.41
8.01
12.02
- 173.6 173.6 173.6
Other 21*
21
1.23
1.85
198.68
429.90
754.87
1648.38
277.58
606.95
168.30
252.33
4.4 2.0 9.0 62.3
Overhaul 1*
1
0.94
0.29
8.42
17.10
22.20
61.58
7.02
22.41
8.01
12.02
2.0 3.0 3.0 3.0
Vibration 2*
2
0.54
0.32
17.94
37.74
60.26
141.78
21.46
52.04
16.03
24.03
- 4.9 9.4 14.0
All modes 58*
58
2.64
4.90
550.66
1193.57
2106.50
4580.93
775.38
1686.97
464.83
696.91
4.4 0.5 20.6 186.3
Comments

OREDA also includes the following facilities:

  • Maintainable Item versus Failure Mode
  • Failure Descriptor/Cause versus Failure Mode

This information is valuable when conducting a Failure Mode and Effect Analys (FMEA). The FMEA analysis is further a major part of a reliability centred maintenance (RCM) analysis.

Maintainable Item versus Failure Mode

In OREDA each equipment class (e.g. compressors) is broken down in a three-level hierarchy:

  • Level one - equipment unit (e.g. compressor)
  • Level two - subunit (e.g. lubrication system)
  • Level three - maintainable item (e.g. bearing)

Maintainable item/level is defined as 'an item that contribute a part, or an assembly of parts, that is normally the lowest indenture level during maintenance'. In the Maintainable Item versus Failure Mode table the relative (percentage) contribution from each maintainable item to the total failure rate is given in total and relted to the failure modes.

Maintainable item versus failure mode
Item:
Compressors

  EXL FTS FWR HGF LGF OHE OTH OVH UNK VIB Sum
Actuating device 0.21 0.37 0.26 0.00 0.16 0.05 2.40 0.05 0.05 0.05 3.60
Agitator 0.05 0.00 0.00 0.00 0.00 0.00 0.05 0.00 0.00 0.05 0.16
Auxiliaries, el. Motor 0.05 0.05 0.00 0.00 0.00 0.00 0.05 0.00 0.00 0.00 0.16
Bearing 0.05 0.00 0.10 0.00 0.00 0.00 0.16 0.00 0.00 0.00 0.31
Casing 0.21 0.00 0.00 0.00 0.00 0.00 0.05 0.02 0.00 0.00 0.28
Control unit 0.16 1.46 2.07 0.05 0.37 0.16 5.90 0.05 0.10 0.05 10.37
Cooler or Heater 0.21 0.05 0.00 0.00 0.00 0.03 0.42 0.05 0.05 0.05 0.86
Cooling system 0.37 0.05 0.00 0.00 0.00 0.05 0.89 0.05 0.00 0.00 1.41
Coupling 0.16 0.00 0.00 0.00 0.00 0.00 0.05 0.00 0.00 0.21 0.42
Cylinder liner (RE only) 0.37 0.00 0.00 0.00 0.00 0.00 0.16 0.00 0.00 0.00 0.52
El. motor 0.05 0.05 0.16 0.00 0.05 0.05 0.73 0.00 0.05 0.05 1.20
Filter 0.21 0.00 0.00 0.00 0.00 0.26 4.07 0.05 0.00 0.05 4.65
Gearbox 0.16 0.00 0.05 0.00 0.00 0.00 0.23 0.05 0.00 0.37 0.86
Heater 0.00 0.00 0.00 0.00 0.00 0.00 0.16 0.00 0.00 0.00 0.16
: . . . . . . . . . . .
Total 15.09 5.69 9.66 0.21 2.04 2.04 58.80 2.24 1.51 2.72 100.0

Failure Descriptor/Cause versus Failure Mode

In the OREDA database a "failure descriptor"-field is available. The information in this field describes the apparent or observed failure cause. In the Failure cause versus Failure Mode table the relative (percentage) contribution from each failure cause to the total failure rate is given; in sum and related to the failure modes.

Failure descriptor versus failure mode
Item:
Compressors

  EXL FTS FWR HGF LGF OHE OTH OVH UNK VIB Sum
Abnormal process deviation 0.00 0.00 1.31 0.00 0.00 0.21 0.63 0.00 0.00 0.00 2.14
Blockage/plugged 0.00 0.26 0.37 0.00 0.16 0.31 3.60 0.10 0.00 0.10 4.91
Contamination 0.00 0.00 0.00 0.00 0.00 0.00 1.51 0.00 0.05 0.00 1.57
Control failure 0.00 0.52 0.78 0.05 0.16 0.00 2.77 0.00 0.05 0.00 4.33
Degraded performance 0.05 0.00 0.21 0.00 0.00 0.37 1.31 0.05 0.05 0.00 2.04
Design errors 0.05 0.00 0.05 0.00 0.00 0.00 0.84 0.00 0.00 0.00 0.94
Design/operator rel. causes 0.00 0.00 0.05 0.00 0.00 0.00 0.42 0.00 0.00 0.00 0.47
Earth fault 0.00 0.05 0.00 0.00 0.00 0.00 0.57 0.00 0.00 0.00 0.63
Electrical f. - general 0.00 0.31 0.21 0.00 0.00 0.05 1.15 0.00 0.16 0.00 1.88
External causes - general 0.00 0.00 0.00 0.00 0.00 0.00 0.42 0.00 0.00 0.00 0.42
F.s related to operation 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.05 0.00 0.05
Faulty operation 0.00 0.10 0.05 0.05 0.05 0.21 0.89 0.05 0.10 0.00 1.51
Faulty signal/indicat/alarm 0.00 0.57 1.46 0.00 0.05 0.05 11.54 0.10 0.31 0.05 14.15
Instrument f. - general 0.00 0.26 0.47 0.00 0.00 0.00 3.08 0.31 0.16 0.00 4.28
Leakage 1.78 0.05 0.21 0.00 0.31 0.10 4.23 0.10 0.05 0.00 6.84
Material damage 0.84 0.05 0.47 0.00 0.00 0.21 1.72 0.05 0.00 0.10 3.45
Material deterioration 5.95 0.16 0.84 0.05 0.26 0.00 4.13 0.52 0.16 0.31 12.38
Material f. - general 0.84 0.00 0.00 0.00 0.00 0.00 0.47 0.00 0.00 0.00 1.31
Mechanical defect 5.07 0.94 0.52 0.05 0.73 0.16 3.03 0.42 0.00 0.16 11.07
Mechanical f. - general 0.00 0.05 0.05 0.00 0.00 0.10 1.46 0.16 0.00 0.05 1.88
Misc. external influences 0.00 0.05 0.00 0.00 0.00 0.00 0.31 0.00 0.00 0.00 0.37
Miscellaneous causes 0.00 0.00 0.00 0.00 0.00 0.00 0.47 0.00 0.00 0.00 0.47
No power/voltage 0.00 0.05 0.10 0.00 0.00 0.00 0.26 0.00 0.05 0.00 0.47
: . . . . . . . . . . .
Total 15.09 5.69 9.66 0.21 2.04 2.04 58.80 2.25 1.51 2.72 100.0

 

Bibliography

Reliability data collected and processed in the OREDA project has been published in generic form in three Reliability Data Handbooks; 1984 (1st edition), 1992 (2nd edition) and recently in 1997 (3rd edition). The Handbooks contain reliability data on offshore equipment compiled in a form that can easily be used for various safety, reliability and maintenance analyses. The '97 edition of the OREDA Handbook include data from phase III of the OREDA project, and covers the period 1990 - 92. The data are compiled in a similar manner as the former two Handbooks, but include also data on a more detailed level typically for use in maintenance analyses (e.g. RCM).