CO2 pipeline transportation is becoming increasingly important as the following schemes worldwide are moving from pilot to demonstration phases:
- Enhanced Hydrocarbon Recovery (EHR),
- Carbon Capture and Storage (CCS),
- Exploitation of Natural Gas Fields rich in CO2
In particular the important safety and risk discriminators emerging in pipelines transporting anthropogenic CO2 service are:
- effect of contaminants & impurities,
- volume transported that forces the use of larger diameter pipelines,
- longer distances with several crossing of high-consequence areas.
All these factors have a dramatic impact on fracture propagation arrest in case of pipeline failure caused by longitudinal occurring defects.
The most catastrophic type of pipeline failure is running fractures (Brittle or Ductile), potentially involving rapid “unzip” of the pipeline up to several hundred meters length, causing the release of large fluid amount in a short time span. For Natural Gas there’s a long lasting experience and consolidated Know How; the method named “Battelle Two Curve” (BTC) was the first developed to express the criterion for long shear running fracture propagation in terms of fluid decompression wave velocity and crack propagation velocity.
It’s well known the susceptibility to long running shear fracture of any pipeline transportation system involving gases, dense phase fluids, two phase fluids or high vapor pressure liquids as Carbon Dioxide.
In this context was born, SARCO2, an RFCS project with the support of EPRG and DNV GL. The project was aimed at contributing to the pipeline design, from the long-term integrity. This paper deals with the full scale testing campaign on CO2 pipeline fracture propagation prevention programme; it involves EN 10208-2 L450 24” outside diameter, 12.5-13.7 mm wall thickness pipes, with upper shelf Charpy V-notch impact energy (toughness) up to a maximum of 320 J coming from different metallurgic routes and the use of composite crack arrestors.