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Pipeline Repair

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ABC Company ABC Chemical Complex Engineering Specification Pipeline Repair PURPOSE Provides repair guidelines on above ground and buried pipelines. – PowerPoint PPT presentation

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Title: Pipeline Repair


1
Pipeline Repair
  • ABC Company
  • ABC Chemical Complex
  • Engineering Specification

2
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.

3
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

4
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

5
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.

6
  • 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

7
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.

8
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

9
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.

10
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.

11
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.

12
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.

13
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.

14
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.

15
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.

16
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.

17
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.

18
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.
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