Subsea Pipeline Unblocked On-Line

Collapsed Liner Removed Quickly and Easily

The 4km x 16” subsea pipeline between a small North Sea offshore installation and its land based storage depot had become blocked with wax and a stuck pig causing major disruption for the operator. Tube Tech’s successfully removed the blockages using only two access points.

The Challenge

  • 4km subsea pipeline – half located underwater and half on land.
  • Pipeline horizontal with slight gradient of 22.5 degrees then 22.5 degree levelling out horizontal.
  • Pig used by previous contractor had become stuck in the pipe.
  • Unknown volume of wax like deposits behind or in front of pig along entire length of 16 inch I.D.pipeline.
  • Two access locations used to avoid using divers due to a 12 knot rip tide.

Solution

Tube Tech were able to mobilise urgently, unblock the pipeline and remove the deposit by using:
  • Tube Tech ‘hot tapped’ into a non-pressurised system and removed the stuck pig by a bespoke “drilling” method.
  • Once pig removed the remainder of the line was cleaned to production standard using a variety of cleaning heads to suit heavy scale and other fouling characteristics.
  • The pipeline was inspected before, during and after the cleaning process.
  • Actual cleaning time was 1 week.
Tube Tech technicians were also able to retrieve lodged pig in the final 30m of the pipeline.

Tube Tech Comment

Mike Watson, Technical Director: “Most definitely one of our biggest challenges to date. The Client’s only alternative was to lay a new pipeline. Substantial 6 figure sums per day where being lost while the sub sea pipeline was out of action. Due to the criticality, this particular customer invested in developing this bespoke solution which took approximately 3 months to develop and once the go-ahead was given we were able to respond in a timely manner with appropriate pipeline cleaning techniques to solve what appeared to be an ‘impossible challenge.”

Images and videos associated with this project are available via Tube Tech International
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