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There are many causes and contributors to pipeline failures. The U. S. Department of Transportation’s Research and Special Programs Administration, Office of Pipeline Safety (RSPA/OPS) compiles data on pipeline accidents and their causes. (reference 76)
This combined data for 2002-2003 indicate that “outside force” damage contributes to a larger number of pipeline accidents and incidents than any other category of causes, if all accidents involving hazardous liquid, natural gas transmission, and natural gas distribution pipelines are considered together. When hazardous liquid pipeline data is considered separately, corrosion contributes to a higher number of accidents than other categories.
Outside force damage can include the effects of: earth movement, lightning, heavy rains and flood, temperature, high winds, excavation by the operator, excavation by a third party, fire or explosion external to the pipeline, being struck by vehicles not related to excavation, rupture of previously damaged pipe, and vandalism. The data show that for hazardous liquid pipelines and gas transmission pipelines, the largest portion of outside force damage results from excavation damage. This may occur when excavation activity occurring near the pipeline causes an accidental hit on the line. The range of excavation damage runs from damage to the external coating of the pipe, which can lead to accelerated corrosion and the potential for future failure, to cutting directly into the line and causing leaks or, in some cases, catastrophic failure.
Following are tables and graphs based on recent RSPA/OPS statistics, showing the causes of pipeline accidents. Information on OPS Safety Initiatives that address these significant failure causes may be found here.
Reported Cause | Number of Accidents | % of Total Accidents | Barrels Lost | Property Damages | % of Total Damages | Fatalities | Injuries |
Excavation | 40 | 14.7 | 35,075 | $8,987,722 | 12.0 | 0 | 0 |
Natural Forces | 13 | 4.8 | 5,045 | $2,646,447 | 3.5 | 0 | 0 |
Other Outside Force | 12 | 4.4 | 3,068 | $2,062,535 | 2.8 | 0 | 0 |
Materials or Weld Failure | 45 | 16.5 | 42,606 | $30,681,741 | 41.0 | 0 | 0 |
Equipment Failure | 42 | 15.4 | 5,717 | $2,761,068 | 3.7 | 0 | 0 |
Corrosion | 69 | 25.4 | 55,610 | $17,775,629 | 23.8 | 0 | 0 |
Operations | 14 | 5.1 | 8,332 | $817,208 | 1.1 | 0 | 4 |
Other | 37 | 13.6 | 20,022 | $9,059,811 | 12.1 | 1 | 1 |
Total | 272 | 175,475 | $74,792,161 | 1 | 5 |
Notes:
(1) The failure data breakdown by cause may change as OPS receives supplemental information
on accidents.
(2) Sum of numbers in a column may not match given total because of rounding error.
Natural Gas Transmission Pipeline Incident Summary by Cause 1/1/2002 - 12/31/2003
Reported Cause | Number of Incidents | % of Total Incidents | Property Damages | % of Total Damages | Fatalities | Injuries |
| Excavation Damage | 32 | 17.8 | $4,583,379 | 6.9 | 2 | 3 |
| Natural Force Damage | 12 | 6.7 | $8,278,011 | 12.5 | 0 | 0 |
| Other Outside Force Damage | 16 | 8.9 | $4,688,717 | 7.1 | 0 | 3 |
| Corrosion | 46 | 25.6 | $24,273,051 | 36.6 | 0 | 0 |
| Equipment | 12 | 6.7 | $5,337,364 | 8.0 | 0 | 5 |
| Materials | 36 | 20.0 | $12,130,558 | 18.3 | 0 | 0 |
| Operation | 6 | 3.3 | $2,286,455 | 3.4 | 0 | 2 |
| Other | 20 | 11.1 | $4,773,647 | 7.2 | 0 | 0 |
| Total | 180 | $66,351,182 | 2 | 13 |
Note that corrosion (external and internal) is the most common cause of natural gas transmission pipeline incidents in 2002-2003.
Natural Gas Distribution Pipeline Incident Summary by Cause 1/1/2002 - 12/31/2003
Reported Cause | Number of Incidents | % of Total Incidents | Property Damages | % of Total Damages | Fatalities | Injuries |
Construction/Operation | 20 | 8.1 | $3,086,000 | 6.7 | 0 | 16 |
Corrosion | 3 | 1.2 | $60,000 | 0.1 | 2 | 9 |
Outside Force | 153 | 62.2 | $32,334,352 | 70.1 | 6 | 48 |
Other | 70 | 28.5 | $10,617,683 | 23.0 | 13 | 31 |
Total | 246 | $46,098,035 | 21 | 104 |
Note that over 60% of natural gas distribution pipeline incidents were caused by outside force damage in 2002-2003. These incidents can include damage from excavation by the operator or by other parties, as well as damage from natural forces.
