Top Considerations for Converting Existing Pipelines to CO₂

Original Design Basis + Future State (Gas or Liquid)

When considering using an existing pipeline for CO₂ service there are things that need to be considered.  Understanding the operational history and design basis of the existing pipeline is critical in your project development.  The next step is to determine what the future state requires from an immediate and final throughput to meet your shippers needs.  With these two pieces of information you can now begin the process of reviewing the existing pipeline data and developing a risk profile to match your future state to meet the shippers demands.  You then must evaluate the potential threats and determine an appropriate mitigation plan to address those threats.  A set of questions for the current and historical assets and operations are listed and then a set of questions regarding the future CO₂ desired state are listed separately.

Information Collection from Existing Operation and Assets

• Records established documenting physical pipeline characteristics and attributes, including diameter, wall thickness, seam type, and grade (e.g., yield strength, ultimate tensile strength, or pressure rating for valves and flanges, etc.), must be maintained that meet the requirements of traceable, verifiable, and complete. Charpy v-notch toughness values that are needed to meet the requirements of the fracture mechanics requirements?
• Material certificates of equipment on the pipeline (valves sites, pump stations, scraper launching and receiving sites. Etc.) that will be used to develop and implement the establishment and documentation of the ANSI rating or pressure rating?
• Pipeline coatings and corrosion control activities and any identified deficiencies such as CIS, IC, EC, SCC or shorted casings?
• Results of most recent Depth of Cover Survey (DOC)?
• KMZ of existing pipeline with current High Consequence Areas (HCA) (Part 195 or Part 192 pipelines) or Class Location Study results (for Part 192 pipelines)?
• History of type of pipeline service of pipeline which includes previous and current service?
• Current MAOP or MOP of pipeline including limiting factors?
• Current pipeline regulating agency?
• Provide complete leak history of pipeline which will provide data for the identification of current and potential threats?
• The maintenance history of the pipeline (including records required by current regulator) will be used for the determination of “Fit for Service” status of the existing pipeline in the desired CO₂ service?
• Current Integrity Management Program (IMP) and results of required assessments and subsequent repairs?  Also include current pressure test of pipeline?

  Development of Desired Design and Operation to meet CO₂ Project Demands

• Is the required desired future state of the CO₂ expected to be gas or liquid?
• Chemical Assay of CO₂ product including impurities to be transported will be used for compatibility with existing metallurgy and soft materials (gasket material, valve seals, etc.)?
• Desired throughput of CO₂ (MTA (million tons per annum)) that will be used for development of hydraulics and required pressures?
• Pressure requirements at both the origin and end of the existing pipeline?
• Will pressure generation through pumps or compression be provided at either the origin or the termination of the existing pipeline?
• Most of the above information will be used in the calculation of possible Fracture Propagation calculations for both Liquid and Gaseous CO₂ and potential use of crack arrestors for crack propagation caused by CO₂.
• Most of the above information will be used in the creation of the Dispersion Analysis which is used in the spill modeling for the development of the Threat Mitigation Strategy.

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The PCS^® team has +15 years of experience in CO₂ transmission infrastructure and decades of engineering, design and project management of pipeline installations and conversions.