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U.S. Department of Transportation U.S. Department of Transportation Icon United States Department of Transportation United States Department of Transportation

HL IM Fact Sheet


Improve pipeline safety through:

  • Accelerating the integrity assessment of pipelines in High Consequence Areas (HCAs)
  • Improving integrity management systems within companies
  • Improving the government's role in reviewing the adequacy of integrity management programs and plans
  • Providing increased public assurance in pipeline safety


The initial integrity management rule for hazardous liquid pipelines applied to operators with more than 500 miles of pipeline. It became effective May 29, 2001. A rule change effective February 15, 2002, made the rule applicable to owners of all hazardous liquid pipelines.

Key Features:

  • Provides enhanced protection for defined High Consequence Areas (HCAs) which have been mapped by PHMSA and made available to industry. HCAs include:
    • unusually sensitive environmental areas (defined in 195.6),
    • urbanized areas and other populated places (delineated by the Census Bureau), and
    • commercially-navigable waterways.
  • Hazardous liquid pipeline operators must develop a written Integrity Management Program that includes:
    • Identification of all pipeline segments that could affect an HCA
    • A Baseline Assessment Plan to assure integrity of these segments,
    • A Framework that identifies how each element of the Integrity Management Program will be implemented.

      Operators subject to the initial rule were required to complete the identification of segments that could affect HCAs by December 31, 2001, and prepare the Baseline Assessment Plan and Framework by March 31, 2002. Operators who own or operate less than 500 miles of jurisdictional pipeline were required to identify segments by November 18, 2002, and complete the Baseline Assessment Plan and Framework by February 18, 2003.

  • The Baseline Assessment Plan must:
    • identify all pipeline segments that could affect HCAs,
    • specify the integrity assessment method or methods for each segment that could affect an HCA (acceptable methods include, internal inspection, pressure testing, ECDA, or other technology that the operator demonstrates can provide an equivalent understanding of pipe condition),
    • provide a schedule for assessment of each segment, and
    • explain the technical basis for integrity assessment method(s) selection and risk factors used in scheduling the assessments.
  • All baseline assessments for pipeline subject to the initial rule (called category 1 pipelines) must be completed by March 31, 2008. At least half of the line pipe affecting HCAs must be assessed by September 30, 2004. The corresponding dates for pipeline added by the revised rule (called category 2) are February 17, 2009, and August 16, 2005, respectively. An operator may use an assessment conducted prior to the effective date of the rule (after January 1, 1996, for category 1 pipelines and after December 18, 1996, for category 2 pipelines) to satisfy the baseline assessment requirement.
  • HCA boundaries will change over time (e.g., population expands, additional environmental data is obtained, etc.). Any new HCAs must be incorporated into the Baseline Assessment Plan within one year of the identification of the new area. Integrity assessments for segments that could affect these new HCAs must be completed within five years.
  • An operator's Integrity Management Program must include the following elements:
    • a process for determining which pipeline segments could affect an HCA,
    • a Baseline Assessment Plan,
    • a process for continual integrity assessment and evaluation,
    • an analytical process that integrates all available information about pipeline integrity and the consequences of a failure,
    • repair criteria to address issues identified by the integrity assessment method and data analysis,
    • a process to identify and evaluate preventive and mitigative measures to protect HCAs,
    • methods to measure the integrity management program's effectiveness, and
    • a process for review of integrity assessment results and data analysis by a qualified individual.

      Each of these areas must be addressed in the Framework.

  • An operator must perform periodic integrity assessments (i.e., continual integrity evaluation and assessment) on line segments that could affect HCAs at intervals not to exceed 5 years.
    • The risk represented by the segment should be used to establish the appropriate assessment interval within the 5-year period. PHMSA has produced guidance for pipeline operators to consider when evaluating and determining inspection reassessment intervals.
    • Operators may extend the intervals to more than 5 years if a reliable engineering evaluation and other external monitoring activities show the pipe to be in good condition, or if a new integrity assessment technology the operator plans to use is not readily available.
  • The rule requires that certain defects identified through internal inspection be repaired within defined time limits. These are:
    Immediate repair:
    • metal loss greater than 80 percent of nominal wall thickness,
    • calculated burst pressure less than maximum operating pressure at anomaly,
    • top dent with any indication of metal loss, cracking, or stress riser,
    • Any anomaly judged to require immediate attention.

      60-day repair:

    • top dent greater than 3 percent of nominal pipe diameter (greater than 0.25 inches for pipe less than 12 inches in diameter),
    • Bottom dent with any indication of metal loss, cracking or stress riser.

      180-day repair:

    • dent greater than 2 percent of nominal pipe diameter (greater than 0.25 inches for pipe less than 12 inches in diameter) that affects pipe curvature at a girth weld or longitudinal seam,
    • top dent greater than 2 percent of pipe diameter (0.25 inches for 12 inches in diameter and smaller),
    • bottom dent greater than 6 percent of pipe diameter,
    • calculated operating pressure less than maximum operating pressure at anomaly,
    • area of general corrosion with predicted metal loss greater than 50 percent of nominal wall thickness,
    • predicted metal loss greater than 50 percent of nominal wall thickness at a crossing of another pipe, in an area of widespread circumferential corrosion, or in an area that could affect a girth weld,
    • potential crack that on excavation is shown to be a crack,
    • corrosion of or along a longitudinal seam weld,
    • gouge or groove greater than 12.5 percent of nominal wall thickness.
  • In evaluating the integrity of the line, the operator must integrate all available information, including at a minimum:
    • the potential for excavation or outside force damage, considering potential new development along the line,
    • information about the potential impacts of a release on the HCA (e.g., drinking water intake),
    • data gathered from the integrity assessments required by this rule, and
    • cathodic protection surveys, patrolling, and other maintenance and surveillance activities.
  • Operators must conduct risk analyses for the line segments that could affect HCAs. These analyses should identify and evaluate the need for additional preventive and mitigative actions to protect HCAs. Such measures might include:
    • damage prevention best practices,
    • enhanced cathodic protection monitoring,
    • reduced inspection intervals,
    • enhanced training,
    • conducting drills with local emergency responders, and
    • other management controls

      Operators must explicitly evaluate the need for Emergency Flow Restricting Devices and enhancements to Leak Detection Systems to protect HCAs.

  • An operator's integrity management program must include methods to measure the program's effectiveness in assessing and evaluating integrity, and in protecting high consequence areas.

A written integrity management program and records to support the analyses and decisions made for each of the program elements must be retained by the operator and will be reviewed by PHMSA during inspections.