Natural Gas Systems Integrity
At Enbridge, we manage the integrity of our natural gas systems by identifying, assessing and mitigating the risk of a natural gas release, particularly as it relates to design, construction, operation and structural integrity. To supplement our normal maintenance practices, we have developed an Integrity Assessment and Risk Management Plan for our natural gas systems in higher populated areas. This plan evaluates the probability of a failure on a pipeline system and the consequences of such a failure.
The risk assessment component of the integrity management (IM) plan describes the method of computing risk and identifies the likelihood of failure and consequence of failure variables.
|Risk = Likelihood of Failure X Consequence of Failure
Likelihood of failure factors considered in our plan include:
- External corrosion.
- Internal corrosion.
- Third-party damage.
- Pipe design and materials.
- Potential for ground movement.
- System operations.
These failure factors are each examined through analysis of these variables:
- Environment – conditions that exert some influence on a pipeline.
- Design – conditions associated with the pipeline that cannot be easily changed.
- Integrity monitoring – non-destructive testing or inspection performance data.
- Rehabilitation – performance testing or the disposition of inspection results.
Individual impact on environment, business and/or the population and the total impact are consequence of failure factors used to help us evaluate the potential impact of a pipeline release. Our consequence of failure analysis considers the sensitivity of the impacted variable as well as the type of product released and the volume.
Using accepted scientific techniques and formulas, the likelihood and consequence of failure variables are used to identify and prioritize pipeline failure risks. This analysis helps us to address the most significant risks first to protect the public and the environment — and to systematically plan our maintenance and testing activities.
The integrity assessment component of the integrity management (IM) plan describes the methods we use to assess the structural integrity of our natural gas systems, which include pipelines, tanks, pressure vessels and station piping.
The methods of assessment may include:
- Tools that inspect for any corrosion, dents, cracks, etc.
- Water-pressure (hydrostatic) testing.
- Direct assessment, a multi-step process to evaluate the integrity of a pipeline and which typically involves systematically exposing underground pipes through excavation and examining the pipe for any potential problems.
The type of assessment method that is selected is based on a thorough engineering evaluation. We seek to achieve the highest degree of structural integrity with an emphasis on safeguarding the public and environment while minimizing the impact of the assessment on natural gas customers and operations.
The risk mitigation component of the integrity management (IM) plan describes programs that we use to reduce the risk of a release by decreasing the likelihood of a pipeline failure or the consequence of a pipeline failure, or both.
Preventive measures begin with the design and construction of our pipelines and facilities. These measures include design specifications, selection of suitable construction materials, development and selection of welding procedures, pipe coatings and cathodic protection systems. Other measures help to ensure the proper design, installation, operation and maintenance of internal and external corrosion prevention systems.
Additionally, manufacturing controls are used to promote high-quality installation of the pipeline and facilities and to limit operating stress.
We have a comprehensive preventive maintenance program to inspect, maintain and test facilities. We check and adjust our cathodic protection system, we routinely test our valves to verify they are operating correctly and we calibrate electronic components.
We also monitor the pipeline 24 hours a day, 365 days a year from our control center and through regular aircraft and/or ground patrols that keep tabs on activity near our pipeline. Our gathering pipelines are monitored during operation as some do not operate around the clock.
To prevent external damage to our pipeline from excavators, we participate in local One Call programs and their “Call Before You Dig” initiatives. When we determine that anyone is planning to dig on or near our pipelines, our specially trained field personnel mark the location of the pipeline and monitor any digging that occurs near our pipe.
These are just a few of our normal operations and maintenance practices. As our neighbor you, too, can help by calling us or your local law enforcement agency if you see any unauthorized digging along our pipeline or unauthorized personnel in our facilities.
The performance measures component of the integrity management (IM) plan describes how our natural gas integrity assessment and risk management plan is evaluated and determines if improved safety has been achieved.
Performance measures include:
- Process or activity measures – leak prevention or mitigation activities.
- Operational measures –system response to our integrity management efforts.
- Direct integrity measures – lagging and leading indicators of integrity management performance.
Management of Change
The management of change component of the integrity management (IM) plan identifies and considers the impact of change to the pipeline systems and their integrity. The management of change process tracks:
- The reason for change.
- The authority for approving changes.
- An analysis of the implications associated with a change.
- Acquisition of required permits.
- Communication of the change, time limitations and qualification of staff.
A geographic information system (GIS) is used to manage pipeline data and facilitate the management of change process.
A communications component of the integrity management (IM) plan helps us apprise appropriate company personnel, jurisdictional authorities and the public about our pipeline integrity management efforts. Communications with affected public, emergency agencies and public officials regarding our IM plans in high consequence areas are carried out according to a written plan. Specific information regarding IM plans is included with our outreach along our pipeline system, and interested parties are invited to this website for an overview.
The quality control component of the integrity management (IM) plan tracks how well we are meeting the requirements of our IM plan. Requirements of this plan include documentation, implementation and maintenance.