Pipeline (Effluent) Unblocked in Four Days

Jetting pressure and water volumes matched to pipeline deposit

Summary

A Netherlands facility of this global oil company was experiencing problems with an effluent pipeline which had become almost completely blocked over time. There were only four days available to clean the pipeline and local contractors couldn’t commit to better than 7-8. Even though the pipe was made of glass-reinforced epoxy (GRE), which placed strict limitations on how it could be jetted if damage to the pipe and rubber cup seals was to be avoided, Tube Tech was able to carry out a thorough clean within the four day limit.

Challenge

• The plant is a joint oil refinery/chemicals manufacturing site and one of the largest such complexes in the Netherlands.
• At this location, the company manufactures lower olefins, methyl tertiary butyl ether (MTBE), chemical solvents, hydrocarbon solvents, brake fluids and polyols.
• Aneffluent pipeline had become progressively more blocked with waste from several different companies and processes that feed into it.
• The 400 metre pipeline was made of glass-reinforced epoxy for chemical resistance, which meant that water-jetting pressures would have to be limited to avoid damaging it.
• The pipeline also had rubber cup expansion joint seals, which would be damaged if jetting was carried out in the wrong direction.
• Being able to work in one direction only would apply extra pressure to the cleaning contractor and the time limit.
• Local and other international contractors had been asked to clean the pipeline, but were all quoting 7-8 days when only 4 days were available, due to the considerable cost of downtime.

Solution

• For cleaning, the pipeline was opened at both ends and the expansion bend removed, so the sections to be cleaned were 200 metres long.
• The proposed combined mechanical and water-jetting system, based on a special rotating head with a helical cleaning pattern to ensure even coverage and avoid ‘tramlining’ the pipe, was trialled on a mock-up rig at Tube Tech’s operations centre.
• The relatively low pressure required a high volume of water to be used – between 60 and 90 gallons per minute.
• Five different systems were actually taken to site, to ensure that the most effective option could be used.
• The system variants allowed different combinations of pressure jets, hoses, reels, pumps, collapsible pigs and ancillary equipment.
• Pressures higher than 250Bar/3,500psi could not be used if damage to pipe and seals was to be avoided. In addition, the pipeline could only be jetted in one direction, so as not to damage the rubber cup seals.
• The first 50mm of deposit surface had the consistency of a hard, crisp, dried chalk, but underneath were chunks of lightly-hardened, clay-like material that washed away readily.
• Careful matching of the jetting pressure and volumes to the deposit ensured that the clean was carried out successfully within the stipulated four days.
• Tube Tech also carried out simultaneous inspection during the cleaning process to confirm that the necessary standard was being achieved.
• Thanks to careful planning and preparation, damage to the pipeline was successfully kept to an absolute minimum. The 90° bends at the expansion section received minor internal surface abrasion and these were patch-reinforced from the outside as a precaution.

Client Comment

The Site Manager observed: “After several local and international cleaning specialists told us the pipeline clean could not possibly be done within our 4-day time limit, we were worried that it was not going to be possible to get the job done properly. When Tube Tech told us they would research a solution that could clean the pipeline in four days or less, we wondered how and why they could claim this when no-one else could. Having seen the mock-up of our pipeline Tube Tech put together to test the system they were proposing to use, we were reassured that they could deliver on their claims. The actual results speak for themselves: the pipeline was cleaned within the time limit and to a far higher standard than we have ever seen before.”

Tube Tech Comment

Mike Watson, Technical Director: “With only four days to complete such a delicate job – one that our competitors reckoned could not be done in less than eight, we had to be sure that we had the right tools for the job, which is why we took several previously-trialled alternative solutions with us to Holland. As in the past, planning the job with a scale mock-up at our UK HQ definitely paid off on this occasion as well.”