Pipeline Repair

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Pipeline Repair

• ABC Company
• ABC Chemical Complex
• Engineering Specification

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Pipeline Repair

• PURPOSE
• Provides repair guidelines on above ground and
  buried pipelines.
• GENERAL
• When a pipeline is determined to be leaking, an
  immediate temporary repair will be made to insure
  public safety, minimize damage to property, and
  avoid damage to the environment.

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Pipeline Repairs

• REFERENCES
• API 1104
• Welding of Pipelines and Related Facilities
• API 1107
• Pipeline Maintenance Welding Practices
• ASME B31.8
• Gas Transmission and Distribution Piping Systems
• ASME B31.4
• Liquid Transportation Systems for Hazardous
  Chemicals and Hydrocarbons

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Pipeline Repair

• DEFINITIONS
• CGI Combustible Gas Indicator
• HVL Highly Volatile Liquid
• LEL Lower Explosion Level
• MAOP Maximum Allowable Operating Pressure
• MSDS Material Safety Data Sheet

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Pipeline Repair

• Consult MSDS for the pipeline product during a
  pipeline repair. Determine personal protective
  equipment specific to the chemical and request
  from person in charge of the repair.
• The following table summarizes the minimum
  required safety equipment for pipeline repairs.

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• Material or Chemical
• Ethylene
• Hydrogen
• VCM Vapors
• VCM Liquids
• Kerosene
• Ethylene Dichloride
• Natural Gas

• Safety Equipment
• Fire extinguisher
• Combustible Gas Ind.
• Fire Retard. Clothing
• Eye goggles
• Ear plugs
• Full or air face mask
• Slicker suits and boots
• Non-Sparking Tools

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Pipeline Repair

• Check for gas presence prior to welding in or
  around an area containing flammable gas or
  liquids.
• Maintenance craftsman have the final authority
  for work to be performed.
• Post warning signs at the entrances of the
  right-of-way during repair work.

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Pipeline Repair

• PROCEDURE
• Leak Repairs
• Leak Classification
• Pinpointing the Leak - Aboveground Gas and HVL
• Pinpointing the Leak - Underground Gas and HVL
• Excavation
• Precautions
• Preliminary Failure Analysis
• Initial Leak Arrest

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Pipeline Repair

• Methods of Repair - Corroded Areas
• Repair, if possible, by cutting out a cylindrical
  pipe section and replacing it with a pipe of
  equal or greater design strength.
• Do not weld on hydrogen or ethylene pipelines
  before shutdown/purging operations are complete.
• Acceptable repairs on a pipeline during
  operation
• Weld a nipple over a small leak and install
  fitting.
• Install a leak clamp over a corrosion pit.
• Use a patch with rounded corners for pipe with
  lt40K SMYS.
• Repair with full encirclement welded split sleeve.

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Pipeline Repair

• Leak Repair - Cracks or Tears
• Replace a cylindrical section containing the
  crack or tear with an equivalent pipe section.
• Reduce the pressure to 20SMYS equivalent or less
  if the line cannot be removed from service.
• Determine the pipe condition by visual and NDE
  methods.
• Stop welding or heating operations on the pipe.
• Drill the ends of the crack and test by NDE
• Repair with a full encirclement welded split
  sleeve.
• Request Unit Manager approval to return to
  service.

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Pipeline Repair

• Leak Repair - Gouges, Grooves, and Dents
• Repair by cutting out a section of the pipeline
  containing the defect and replace with a new
  section of equivalent or higher strength and
  composition.
• Reduce pressure to 20SMYS or less if line cannot
  be removed from service. Use one of the
  following methods for repair
• Install a full encirclement welded split sleeve.
• Repair with installation of a full encirclement
  welded hot tap sleeve providing the entire defect
  can be removed with the hot tap coupon.

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Pipeline Repair

• RECONDITIONING OF PIPE
• Pipelines that cannot be removed from service
• Repair with replacement of an equivalent section.
• Repair cracks in welds by grinding and rewelding.
• Repair small corroded areas by weld metal
  overlay.
• Repair small pitted areas with a welded patch.
• Repair large corroded area with a full
  encirclement welded split sleeve.
• Repair all gouges or grooves deeper than 10 wall
  thickness. Use a full encirclement welded sleeve.

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Pipeline Repair

• Repair dents deeper than 1/4 on pipe to NPS 12
  or more than 2 greater than NPS 12.
• Repair dents that affect the curvature of the
  pipe with removal of a cylindrical section
  containing the defect and replacement with an
  equivalent section.
• Repair dents not meeting the above restrictions
  by filling the dent with a hardenable material
  and installing a full encirclement welded split
  sleeve.

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Pipeline Repair

• Initial Inspection
• Determine soundness of the pipe adjacent to the
  defect prior to work
• Inspect external surface of the pipe by one of
  the following methods
• Inspect exterior of pipe visually aided by a pit
  gage.
• Use magnetic particle inspection if cracking is
  suspected.
• Determine pipe wall thickness with ultrasonic
  testing.
• Use radiographic inspection as required for
  definition.

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Pipeline Repair

• Welding
• Check for hardness on hydrogen lines and maintain
  a hardness equal to or less than BHN 235.
• Welding Procedures
• Perform all weld repairs by Company employees
  using Company Welding Procedure Specification
  (WPS) 1.2.
• Perform all weld repairs by Contract employees
  using Company-approved welding procedures
  provided by the Contractor.

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Pipeline Repair

• Welder Qualifications
• Use Company welding procedure for qualification
  of Company employees to make weld repairs.
• Use Contractor welding procedure (Company
  approved) for qualification of Contract employees
  to make repairs.
• Burn through control
• Burn through during welding is not expected when
  welding parameters do not exceed 20 volts and 100
  amperes, if the remaining wall thickness is
  greater than 0.320 inches (See ASME/ANSI B31.8,
  paragraph 851.43f). Welding performed outside
  these limits must be approved by the Plant
  Engineer.

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Pipeline Repair

• Coating Repair
• Repair pipe coating damaged during pipeline
  repair activities in accordance with the original
  coating manufacturers recommendations.
• Hydrotest pipe replacement sections to 1.5 times
  MAOP prior to installation. Hold for one hour.
• Test all field welds with 100 NDE coverage using
  the best method for the weld configuration.
• Grade and repair weld defects in accordance with
  API 1104 and API 1107 requirements.

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Pipeline Repair

• Documentation
• Include the location of the leak, location class,
  grade of the leak, and action taken when writing
  leak reports.
• Add repair reports to the original equipment
  file, the inspection file, and the DOT
  coordinators file.
• The DOT Coordinator shall determine if the leak
  is classified as an incident that requires
  reporting to the regulatory authorities.