Integrity Management: A risk-based approach to improving pipeline safety
Objectives of Integrity Management
Pipeline safety regulations include requirements for operators of hazardous liquid and natural and other gas transmission and distribution pipelines to develop and implement comprehensive integrity management programs. These integrity management (IM) regulations are codified in Title 49 of the Code of Federal Regulations (CFR) Part 195, § 195.452 for hazardous liquid pipelines, Part 192, Subpart O for gas transmission pipelines, and Part 192, Subpart P for gas distribution pipelines.
Due to the physical and operational similarities between hazardous liquid pipelines and gas transmission pipelines, the IM regulations applicable to each of these types of pipelines have many similarities, and they share the same four basic objectives:
- To perform integrity assessments of pipelines in locations where a pipeline leak or failure could have significant adverse consequences (referred to as High Consequence Areas or HCAs).
- To improve operator management, analytical, and operational processes to manage pipeline integrity.
- To increase government’s role in the oversight of operator integrity management programs and activities.
- To improve public confidence in pipeline safety.
High Consequence Areas
While there are differences between the IM regulations for hazardous liquid and gas transmission pipelines, the basic requirements are very similar. Both sets of regulations require operators to identify locations along their pipelines where a leak or failure could affect an HCA. The regulations specify what conditions constitute an HCA for each type of pipeline. For hazardous liquid pipelines, HCAs are defined in § 195.450 and include:
- Urban areas and other populated areas as designated by the U.S. Census Bureau.
- Commercially navigable waterways.
- Drinking water and ecological resources that are unusually sensitive to a pipeline failure.
For gas transmission pipelines, an HCA is based on identified sites and the population density near the pipeline. The specific definition of an HCA is in § 192.905.
Operators are also required to monitor conditions along their pipelines, and identify new HCAs when changes occur, such as population expansion near the pipeline rights-of-way. These changes in HCAs oftentimes then also prompt corresponding changes in operators’ integrity management plans.
Integrity Management Program Elements
Both the hazardous liquid and gas transmission pipeline integrity management regulations (HL IM and GT IM, respectively) require operators to develop and implement a comprehensive integrity management program for their pipeline facilities. An integrity management program is a set of safety management, operations, maintenance, evaluation, and assessment processes that are implemented in an integrated and rigorous manner to ensure operators provide enhanced protection for HCAs. While the regulations provide some flexibility for an operator to develop a program best suited for its pipeline system(s) and operations, there are certain required features – called “program elements” – which each integrity management program must incorporate. The core integrity management program elements include:
- Identifying all locations where a pipeline leak or failure could affect an HCA.
- Performing integrity assessments using in-line inspection (ILI) tools (also referred to as “smart pigs”), pressure testing, direct assessment, or other technology that can provide an equivalent understanding of the condition of the pipeline or pipeline facility.
- Integrating the integrity assessment results with other relevant information to improve the operator’s understanding of the pipeline’s condition.
- Repairing pipeline defects identified through the integrated analysis of the integrity assessment results.
- Conducting a risk analysis to identify the most significant pipeline threats in segments that could affect HCAs. Examples of pipeline threats include corrosion, excavation-induced damage, natural force damage, material defects, and operator errors.
- Identifying additional measures to address the most significant pipeline threats. These measures include actions to prevent releases and mitigate the consequences of releases that go beyond repairing the defects discovered through integrity assessment.
- Regularly evaluating all information about the pipeline and its location-specific integrity threats to determine when future integrity assessments should be performed and what methods should be selected to conduct those assessments. PHMSA has produced guidance for pipeline operators to consider when evaluating and determining inspection reassessment intervals.
- Periodically evaluating the effectiveness of the integrity management program and identifying improvements to enhance the effectiveness of the program.
Integrity Management Program Requirements
The integrity management program includes requirements to identify the specific integrity assessment and reassessment method(s) for each pipeline segment that could affect an HCA. These methods must be based on the identification of the most significant integrity threats for the specific segment. The IM program includes a schedule indicating when reassessments of each segment will be performed. Operators must document the technical bases for the integrity assessment methods they select and the risk analysis performed to establish the schedule.
Operators must conduct periodic integrity assessments on pipeline segments that could affect HCAs. The frequency of reassessment depends on the risk presented by each segment. Risk is determined based on many factors, including the pipe condition as ascertained from integrity assessments; leak, failure, and operating history; pipeline design features; operating and maintenance practices; and, factors external to the pipeline such as population density, ecological resources, or the presence of drinking water sources. The HL and GT IM regulations provide time limits within which these future reassessments must be performed. PHMSA has produced guidance for pipeline operators to consider when evaluating and determining integrity reassessment intervals.
The regulations also establish deadlines by which certain potentially serious defects identified by the integrity assessments must be repaired. Both the HL and GT IM regulations identify certain defects which must be repaired immediately after they have been identified. For example, if inline inspection results identify a dent in the pipe that has any indication of metal loss, the operator must immediately reduce the operating pressure or shut down the pipeline until the defect is repaired.
The Value of a Risk Analysis Approach
Although integrity assessment and repairing of identified pipe defects are a very important part of the regulations, integrity assessments are not capable of addressing all known pipeline threats. Comprehensive and systematic risk analysis is a valuable tool to help operators identify and determine the significance of previously unrecognized threats. Through rigorous analysis of all available data, pipeline operators are required to identify and evaluate all potential threats of pipeline failure and the risks that they pose. Operators must also identify and implement additional preventive and/or mitigative measures to address the most significant threats identified by the risk analysis. These measures would be dependent on the nature of the threat and the specifics of the operator’s pipeline system and its operation. Some examples include: enhancing damage prevention programs; improving corrosion control monitoring; enhancing control center operator training; improving leak detection system capability; conducting enhanced or more frequent emergency drills with local emergency responders; and, installing remotely operated valves to expedite the isolation of a leak or failure when one is discovered.
Accountability and Continual Program Improvement
PHMSA expects operators to refine and improve their integrity management programs in an ongoing fashion. The HL and GT IM regulations specify that operators must periodically evaluate the effectiveness of their integrity management program activities and processes. Program improvements could come from lessons learned following failures or leaks; internal audits of the program; and, the introduction of new technologies. As part of their program effectiveness evaluation, operators are required to identify specific performance measures that reflect program effectiveness. Those measures, and their associated metrics, are reviewed by PHMSA as part of its inspection of operators.
Integrity Management for Gas Distribution Pipelines
Integrity management for gas distribution pipelines (sometimes referred to as DIMP, for Distribution Integrity Management Program) contains some of the same elements as the integrity management regulations for hazardous liquid and gas transmission pipelines, but there are significant differences. Many integrity management program concepts applicable for hazardous liquid and gas transmission pipelines must be applied quite differently in urban settings where distribution pipelines typically are located. More information regarding these differences and the elements that constitute the gas distribution integrity management regulations are contained within the DIMP pages.
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