Supercritical CO2 Flushing

AFP has teamed up with Ocean Team Scandinavia to offer Supercritical CO2 Flushing for the first time in Australia. The technology is specifically designed for cleaning and unblocking subsea control lines and umbilicals, where conventional flushing methods were unsuccessful.

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Supercritical CO2 equipment for subsea control line flushing, backflushing and unblocking

Cleaning Subsea Control Lines with Supercritical CO2 Flushing

The unique physical properties of the SCCO2 makes it the ideal flushing medium for systems like umbilical’s and control lines. At only 1/10th the viscosity of water, SCCO2 flushing can safely achieve the high turbulent flows required to effectively clean small-bore, subsea lines. SCCO2 offers:

  • Excellent contaminant carry capacity (comparable to oil)
  • Cleans to AS4059 Class 3 (ISO 4407 12/9)
  • Overcome flow restrictions in the line
  • Nontoxic, environmentally safe and recyclable
  • Kills bacteria
  • Leaves no residue, no cross contamination with control fluid

As the search for resources moves into deeper and more remote waters, the use of longer umbilical and control lines continues to become more common. Conventional flushing with water-glycol/oil are the current standard for cleaning these systems and a turbulent flushing flow is mandatory for cleaning effectively. However, the challenge lies in maintaining turbulent flow all the way through the line. For subsea control lines and umbilicals, this may require a pressure drop that is more than 30,000 PSI due to the viscosity of the flushing medium and small bore size. This kind of pressure drop exceeds the maximum test operational pressure, which most pipe systems are designed to withstand.

Back-flushing and Unblocking

Another application for SCCO2 flushing technology involves unblocking built up grease/wax in single line and closed loop control lines. The technology exploits SCCO2’s unique surface tension and solvent properties to disperse the blockage using a soda pop type effect.