Furmanite A corrosion-damaged fuel line on the North West Shelf Venture’s Cossack Pioneer FPSO was permanently repaired and strengthened in-situ recently, avoiding the need for costly cutting and replacement, thanks to advanced composite repair technology from Furmanite, the specialist technical services company geared to maximising asset uptime.
An NDT inspection on the 170m, 7 inch diameter low pressure fuel line found it to have been weakened by external corrosion, which had caused wall thinning to a number of areas of the pipe, pitting, and through-wall defects including holes up to 20mm diameter, which needed repair.
The work was scheduled to take place during a planned shutdown, but cutting and replacing the damaged sections would involve logistical issues and welding, which would in turn have required the line to be drained, at significant cost and disruption. Composite repairs, however, involve no hotwork or pre-fabrication, and are typically carried out on-line, while operation continues uninterrupted.
Furmanite’s repairs in this instance were designed for a 20 year lifespan, against a design pressure of 1200 kpa and temperature of 105°C. Just 9mm thickness of epoxy resin-impregnated carbon fibre applied in a layering process around the pipe provided a repair ten times stronger than steel at less than a quarter the density, and restored full structural strength and pressure integrity to the four damaged sections of line.
Moreover, because the carbon fibre and epoxy resin composites used do not oxidise as metals do, the repair is non-corroding, and will prevent further external corrosion occurring.
Furmanite WA business manager Martin Hurst explains that the work was completed at night, as the heat affected the curing time. “Our technicians were mobilised to site quickly, with the repair work progressing in conjunction with the NDT being carried out on the pipe, and engineering designs, installation procedures and QA provided from our head office as the job proceeded.”
He adds: “This example is typical of the service we’re able to offer – with the ability to repair and strengthen pipes and pipelines, tanks and vessels using our advanced composites technology, permanently, and usually while operation continues (although even when carried out during shutdowns, the benefits of avoiding welding bring valuable cost savings). And unlike many composites solutions, our repairs cater not only for hoop load (restoring pressure integrity) but also axial load to restore structural strength, providing full rehabilitation without disruption.”
Sarah Manwaring-White, Keep in Touch Ltd,
Tel: +44 (0)1451 844 488
Email: sarah_mw@keepintouch.co.uk
Issued on behalf of Furmanite Australia
www.furmanite.com