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ISO 27913:2024 — CO2 Pipeline Transportation Systems for Carbon Capture and Storage
Comprehensive guide to design, construction, operation, and maintenance of CO2 pipeline systems
1. Overview of ISO 27913:2024
ISO 27913:2024 specifies requirements and recommendations for the design, construction, operation, and maintenance of pipeline transportation systems for carbon dioxide (CO2) streams in carbon capture and storage (CCS) applications. This second edition, published in 2024 with a corrected version in 2025, supersedes the first edition (ISO 27913:2016). The standard applies to onshore and offshore pipelines used for transporting CO2 from capture facilities to storage sites, covering both gaseous and dense-phase transportation.
ISO 27913:2024 has been technically revised with significant updates including impurity level limits capped at 5%, 17 new requirements for pipeline integrity, and expanded guidance on CO2 stream composition examples in Annex A.
The standard is part of the ISO 279xx series developed by ISO/TC 265 (Carbon dioxide capture, transportation, and geological storage). It addresses the unique challenges of CO2 pipeline transport, including the thermodynamic behavior of CO2, corrosion risks, fracture propagation, and the need for specialized safety systems.
2. Key Technical Requirements
2.1 CO2 Stream Specifications and Impurity Control
A critical aspect of ISO 27913:2024 is the strict control of impurity levels in CO2 streams. The standard mandates that the total impurity content shall not exceed 5% by volume. Specific impurities that must be monitored include water (H2O), hydrogen sulfide (H2S), nitrogen (N2), oxygen (O2), methane (CH4), and other hydrocarbons. The presence of water is particularly concerning as it can form carbonic acid, leading to severe internal corrosion. The maximum water content is specified based on the operational phase and pipeline conditions, with the standard requiring continuous monitoring of water content and dew point at custody transfer points.
| Parameter | Requirement | Monitoring Method |
|---|---|---|
| Total impurities | ≤ 5% by volume | Gas chromatography |
| Water content | Below saturation limit | Dew point measurement |
| H2S content | As per pipeline design | Online analyzer |
| O2 content | Limited to avoid corrosion | Paramagnetic sensor |
| Hydrocarbon dew point | Below min. operating temp | GC or chilled mirror |
2.2 Pipeline Design and Fracture Control
CO2 pipelines present unique fracture propagation risks due to the thermodynamic properties of CO2. When a pipeline rupture occurs, the rapid decompression of dense-phase CO2 can create a running ductile fracture that propagates for long distances. ISO 27913:2024 provides detailed methodologies for calculating minimum wall thickness to arrest running ductile fractures, considering both gas-phase and dense-phase operations. The standard references the Battelle Two-Curve Method and requires fracture arrestors at intervals determined by the fracture propagation analysis.
Running ductile fracture is a critical failure mode for CO2 pipelines. The standard requires fracture propagation modeling using validated decompression models specific to CO2, as traditional natural gas models are not applicable due to the unique phase behavior of CO2.
2.3 Materials and Corrosion Management
The standard addresses material selection for CO2 pipeline systems, emphasizing the need for corrosion-resistant materials or adequate corrosion allowances. Internal corrosion management is paramount, with requirements for corrosion monitoring probes, chemical injection facilities (corrosion inhibitors), and periodic in-line inspection using intelligent pigging tools. External corrosion protection follows conventional pipeline practices, including cathodic protection and external coatings.
3. Operational and Safety Considerations
3.1 Venting and Depressurization
One of the most challenging aspects of CO2 pipeline operation is planned or emergency depressurization. The Joule-Thomson effect during CO2 decompression can cause extreme low temperatures, potentially embrittling pipeline steel. ISO 27913:2024 includes specific requirements for vent station design, including heating facilities to prevent low-temperature embrittlement. The standard distinguishes between onshore and offshore vent facilities, with offshore systems requiring additional considerations for marine safety and dispersion modeling.
During rapid depressurization, CO2 temperatures can drop below -78°C (dry ice formation). Pipeline materials and vent system components must be rated for these extreme conditions. The standard requires thermal analysis of the depressurization transient to ensure material ductility is maintained.
3.2 Leak Detection and Monitoring
Continuous leak detection is mandatory for CO2 pipelines. The standard requires multiple complementary methods, including mass balance calculation, pressure monitoring, and acoustic detection where appropriate. Flow modeling for leak detection must account for the compressibility and phase behavior of CO2. Additionally, fugitive emissions from valves, flanges, and other components must be quantified using periodic monitoring with appropriate detection equipment.
3.3 Re-qualification of Existing Pipelines
A significant addition in the 2024 edition is detailed guidance on re-qualifying existing pipelines for CO2 service. Many pipelines originally designed for natural gas or other hydrocarbons are being considered for CO2 transport. The standard requires comprehensive assessment including material verification, fracture propagation analysis, corrosion assessment, and review of historical operating and maintenance records. Re-qualification must demonstrate that the pipeline meets all requirements of the standard for CO2 service.
4. Engineering Design Insights
From an engineering perspective, ISO 27913:2024 emphasizes that CO2 pipeline design cannot simply follow natural gas pipeline codes. The thermodynamic complexity of CO2 near its critical point (31°C, 7.38 MPa) introduces design challenges not encountered in conventional hydrocarbon pipelines. Key insights include:
- Operating pressure should be maintained above the critical pressure to avoid two-phase flow, which complicates pressure drop calculations and increases risk of slug formation.
- Pipeline elevation changes significantly impact pressure profiles due to the high density of dense-phase CO2, requiring detailed hydraulic analysis over topographical profiles.
- Water content limits must be more stringent than for natural gas pipelines due to the enhanced corrosivity of CO2/water mixtures (carbonic acid).
- Depressurization system design must consider the triple point of CO2 to avoid solid CO2 (dry ice) formation that can block vent paths.
Proper implementation of ISO 27913:2024 enables safe and reliable CO2 transportation, which is the critical link between capture and storage in the CCS value chain. The 2024 edition brings significant improvements in impurity management and fracture control.
5. Frequently Asked Questions
Q: Does ISO 27913:2024 apply to all CO2 pipeline sizes?
A: Yes, the standard applies to all CO2 pipeline transportation systems regardless of diameter or length, from small-diameter gathering lines to large-diameter trunk lines.
A: Yes, the standard applies to all CO2 pipeline transportation systems regardless of diameter or length, from small-diameter gathering lines to large-diameter trunk lines.
Q: Can existing natural gas pipelines be converted to CO2 service under this standard?
A: Yes, Clause 11 provides specific requirements for re-qualification of existing pipelines. However, the conversion requires comprehensive technical assessment and may require modifications including new fracture arrestors.
A: Yes, Clause 11 provides specific requirements for re-qualification of existing pipelines. However, the conversion requires comprehensive technical assessment and may require modifications including new fracture arrestors.
Q: What is the maximum allowable operating pressure under ISO 27913?
A: The standard does not prescribe a specific MAOP. The allowable pressure is determined by the design process based on material properties, wall thickness, and applicable national regulations.
A: The standard does not prescribe a specific MAOP. The allowable pressure is determined by the design process based on material properties, wall thickness, and applicable national regulations.
Q: How does the standard address CO2 stream quality variations from different capture technologies?
A: Annex A provides example compositions for CO2 streams from different capture processes (amine-based, oxyfuel, etc.). The standard requires that the CO2 stream specification be established based on the specific capture technology and verified through regular sampling.
A: Annex A provides example compositions for CO2 streams from different capture processes (amine-based, oxyfuel, etc.). The standard requires that the CO2 stream specification be established based on the specific capture technology and verified through regular sampling.
