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Updated June 2021

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Incident consequence rating
A rating indicating the effect an incident had on the public, land, environment, wildlife, and livestock. The AER has three incident consequence ratings: low, medium, and high. Each rating has a set of criteria associated with it and an incident only needs to meet one criterion in order to be assigned that rating. If an incident meets criteria for different ratings, the highest one is assigned. The AER reviews ratings assigned to all incidents. If the AER determines that a rating assigned by the system does not adequately reflect what happened, the AER may change it. For example, the AER may downgrade an incident from medium to low if a released substance that affected a large area was fresh water (with no additives) and did not cause significant erosion or if a released substance was large in volume, but was completely contained inside a containment structure.

  • High: A rating of high is assigned if at least one of the following criteria is met:
    • Liquid release volume exceeds 200 cubic metres.
    • If hydrogen sulphide (H2S) is released from the pipeline and the public is or has the potential to be affected.
    • Over 1000 square metres have been affected.
    • Flowing water is affected.
    • Wildlife (including waterfowl) or livestock have been injured or killed.
    • Major public impact (e.g., an evacuation is ordered).
    • Moderate public impact (e.g., incident caused a potential hazard that led to public notification) combined with at least one other medium consequence criteria, excluding the liquid release volume.
  • Medium: A rating of medium is assigned if at least one of the following criteria is met:
    • Liquid release volume exceeds 20 cubic metres.
    • Over 100 square metres has been affected.
    • Muskeg or stagnant water has been affected.
    • Wildlife (including waterfowl) or livestock) may be affected.
    • Moderate public impact (e.g., incident caused a potential hazard that led to public notification).
  • Low): A rating of low is assigned if at least one of the following criteria is met:
    • Liquid release volume is less than 20 cubic metres.
    • Cause was a pipeline hit.
    • 100 square metres or less affected.
    • No impact to a water body.
    • No wildlife (including waterfowl and livestock) were affected.
    • Minor to no public impact.

Incident date
The day that the incident happened as reported by the licensee.

Incident location
The legal land description of where the incident happened (e.g., Legal Subdivision 1, Section 77, Township 66, Range 3, West of the 4th Meridian).

Incident ratio
The number of incidents per 1000 kilometres (km) of pipeline length. Usually expressed as a function of time (e.g., 2.5 incidents per 1000 km per year).

Internal protection
The type of internal protection used to prevent corrosion. The most common types include expanded liners, free standing liners, and thin film coating.


Joint type
The method used to join the pipe segments. The most common types are welded, flanged, threaded, mechanical coupling, butt fusion, and bonded.


The holder of a facility, pipeline, or well licence. A licensee bears responsibility for the construction and safe operation of the facility, pipeline, or well. The licensee is also responsible for decommissioning, abandoning, and reclaiming the facility, pipeline, or well.

Liquid release volume
The total volume in cubic metres (m3) of liquid released during a pipeline incident. The released substance can be

  • fresh water (e.g., potable water or surface water),
  • hydrocarbon liquids (e.g., crude oil, condensate, liquid petroleum products, and natural gas liquids),
  • non-fresh water (e.g., produced water), or
  • refined liquids (e.g., lubricants, solvent, diesel fuel, gasoline, heating oil, kerosene, etc.)


Maximum operating pressure
The maximum pressure a pipeline is licensed to operate at.


Nominal pipe size
The outside diameter of a pipeline as a nominal size expressed in inches. Different pipe materials have dimensions that vary from the nominal, thus the AER groups pipeline diameter using ranges extending from below to above the nominal size. Those ranges are expressed below.

Nominal pipe size

Outside diameter


 0 to ≤81


>81 to ≤108


>108 to 134.2


>134.2 to ≤193.7


>193.7 to ≤246.1


>246.1 to ≤298.5


>298.5 to ≤339.8


>339.8 to ≤431.7


>431.7 to ≤533.5


>533.5 to ≤736.5


>736.5 to ≤838.5


>838.5 to ≤939.5




Oil-well effluent
A mixture of unrefined oil, gas, and produced water.


Pipe grade
A grade assigned to pipe and, depending on the type of material, based on pipe material strength, pressure rating, or standard dimensional ratio (calculated by taking the outside pipe diameter and dividing it by the thickness of the pipe wall).

Pipe material
The material the pipeline is made of. The common pipeline materials are steel, aluminum, composite, fibreglass, and polyethylene.

Pipe substance
The substance a pipeline is licensed to transport. If a pipeline is licensed to carry more than one substance, the substance of record is the substance with the highest priority (see table below).





Sour natural gas

Natural gas with >10 moles per kilomole of H2S content


High vapour pressure products

Butane, ethylene, propane, pentanes, liquid ethane


Low vapour pressure products

Condensate, diesel fuel, gasoline, heating oil, hydrocarbons, diluents, kerosene, solvents


Crude oil

Blended crude bitumen, crude oil, synthetic crude oil


Oil -well effluent

A mixture of unrefined oil, gas, and produced water


Natural gas

Methane, natural gas with ≤10 moles per kilomole of hydrogen sulphide


Fuel gas

Fuel gas


Salt water

Produced water


Miscellaneous liquids

Ammonia, caustic, glycol, methanol, polymer, sulphur, carbon dioxide


Miscellaneous gases

Air, ammonia, carbon dioxide, ethane, helium, hydrogen, nitrogen, steam


Fresh water

Potable water, surface water

Pipe type
A pipe's manufacturing standard or product identifier.

Pipeline failure types
Each incident reported to the AER is assigned a category that identifies the main reason an incident occurred. Incidents are first assigned a general failure type, such as internal corrosion or construction deficiency. All of the general failure types, presented below, are then broken down further into more specific causes of failure (cause type) that led to the incident. For example, the incident may be due to internal corrosion, but caused specifically by CO2 corrosion.

  • Construction deficiency: A failure caused by improper construction practices.
  • Damage by others; contact damage: Physical damage (hit, leak, or rupture) to coating or pipe caused during activities related to a ground disturbance. See definition of "contact damage" in the Pipeline Rules.
  • Earth movement: A failure due to external forces applied to the pipeline by earth movement, either as a result of natural events or human activity. Examples are frost heaves, slope movement, flood, earthslide, subsidence, and washouts.
  • External corrosion: A failure caused primarily by corrosion on the outside of the pipe, valve, fitting, flange, or inline coupler. Also includes fretting damage. Note that corrosion can occur even on a coated pipe if the coating is damaged.
  • Internal corrosion: A failure caused predominantly by corrosion inside of the pipe, valve, fitting, flange, or inline coupler.
  • Installation leak: If the incident type is installation leak, then the failure type will also be called "installation leak."
  • Mechanical joint failure: Either a failure on metallic pipelines of mechanical interference joints (e.g., Thru-Kote Welded, Crimp Kote, Sure Lok, Pronto Lock, Zap-Lok, Twin Lok) or a failure on nonmetallic pipelines at mechanical couplings, including crimped metallic connections on spoolable composite pipe. Corrosion at metallic connections on nonmetallic pipeline is reported under the failure type "Corrosion external" or "Corrosion internal."
  • Mechanical pipe damage: A failure caused by damage from mechanical activities to pipelines, risers, or piping that is not related to a ground disturbance and that results in a release (e.g., truck running into a riser, cultivator hitting pipeline while cultivating to a depth of less than 45 centimetres).
  • Miscellaneous: A failure that does not fall under other defined failure causes. May include pipeline erosion from external jetting action from nearby pipeline failures, lightning strikes, vandalism, damage caused by wildlife or livestock, and plastic liner failures that result in a release to the environment through the vent.
  • Miscellaneous joint failure: A failure at a butt-fusion, electrofusion, or other fusion joint on plastic pipe; at a bonded or solvent-welded joint on PVC pipe; at a high-energy joint on aluminum pipe; or at a threaded or bonded joint on fibreglass pipe.
  • Operator error: A failure caused by operator error. Does not include incidents related to ground disturbance, mechanical pipe damage, or pressure test failures. Also does not include incidents where normal operating pressure was increased to maximum operating pressure or slightly below it in order to resolve a problem, such as a stuck pig, because operator error would not be the primary cause of the failure. Such incidents would fall under other failure categories (e.g., external corrosion if it reduced the wall thickness, resulting in a failure when the pressure was increased).
  • Overpressure failure: A failure due to pressure beyond design limits. Situations that may result in overpressure include frozen lines, lack of pressure control or lack of an overpressure protection device, or temperature increase in a shut-in line. Failures as a result of reduced wall thickness due to corrosion are reported under the failure type "Corrosion internal" or "Corrosion external." Leaks from frozen aboveground valves are reported under the failure type "Valve or fitting failure." Overpressure due to the actions of the operator is reported under the failure type "Operator error."
  • Pipe body failure: A failure that occurs in the pipe body due to material flaws, defects, or sensitivity to the operating environment. Examples include stress corrosion cracking, sulphide stress cracking, hydrogen-induced cracking, brittle cracks, running cracks, fatigue cracking, cyclic stress damage, laminations, or separations. Also includes material degradation of nonmetallics.
  • Seam failure: A failure due to a leak or fracture at a long-seam weld or spiral weld. Seam leaks or fractures are rarely due to corrosion but are mechanical failures of a defective manufactured weld.
  • Unknown: A failure where the cause cannot be determined because the pipeline cannot be exposed, recovered, or examined. Only used when the cause is truly unknown and not when the cause is temporarily unknown.
  • Valve or fitting failure: A release associated with packing, gaskets, flanges, fittings, or pigging facility components or failures in the valve body.
  • Weld failure: A failure due to a fracture at a weld or in the heat-affected zone of a weld that is not caused by corrosion. Includes branch, fillet, and circumferential (girth) welds.

Pipeline incident types
All pipeline incidents are grouped into one of the following categories when they are reported.

  • GSPT: Low-consequence release caused by a leak at a gasket, seal, packing gland, or threaded fitting (GSPT) that can be stopped by mechanical adjustments (e.g., tightening of bolts or replacing seals) and that does not indicate a pipeline or valve integrity issue.
  • Hit: Contact damage to a pipeline or its coating during ground disturbance that does not result in the release of a substance. See definition of "ground disturbance" in the Pipeline Act. Note that the following are not considered a hit and do not need to be reported as an incident:
    • minor damage to a pipeline's coating sustained during hand excavation and external cleaning
    • pre-existing damage to the coating that is revealed during the unearthing of the pipeline
  • Installation leak: Release from the equipment at an auxiliary site, such as a compressor, pumping station, tank farm, or meter station that is listed as an installation on the pipeline licence. These incidents are reportable under the Pipeline Act. However, because they do not actually involve a pipeline, the option of viewing incidents according to pipeline specifications such as pipe material, pipe type, or pipeline length is not applicable.
  • Leak: The release of a substance from a pipeline that does not immediately impair the operation of the pipeline.
  • Rupture: An incident where a pipeline breaks or bursts, preventing the pipeline from operating.

Produced water
Water from a wellbore that is produced as a by-product of oil and gas production.


Strike area
An administrative geographical boundary used in relation to potential resource accumulations (e.g., Pembina, Provost, Suffield). For a map of Alberta's strike areas, see Map-94, available on the AER website, > Providing Information > Data and Reports > Maps, Map Viewers, and Shapefiles