Pipemaking advance to cut pipeline costs. (glass fiber and plastic coatings on steel pipeline manufactured in sections, Design Unique System)(Brief Article)

A new method of making plastic-coated steel pipeline sections promises a 10% reduction in installed costs of risers, pipelines, and flowlines for sour wells.

This is the claim of Design Unique System (DUS) developer Avesta Sheffield AS, Oslo, which acquired North Sea application rights from Swedish engineer Dag Thulin, who invented and patented DUS.

Sten-Goran Johansson, Avesta's DUS project leader, said, "The typical temperature in North Sea wells is getting higher, pressures are getting higher, and oil is getting more aggressive.

"Titanium components are expensive, and carbon steel can't withstand such tough operating conditions, yet the market requires cost-efficient solutions. We have bought the exclusive right to a cheap and efficient solution."

With Thulin's technique, a length of steel pipe is wrapped in layers of glass fiber sheeting, between which small diameter tubes are laid lengthwise for injection of plastic resin.

Resin is pumped down the injection tubes as they are being withdrawn from the fiber glass wrapping. The resin suffuses evenly through the glass fiber to create a reinforced outer coating for the pipe, which is then cured.

A DUS pipe length consists of a 1-30 m, 6-40 in. pipeline section made of any of a number of types of steel coated in fiber-reinforced plastic.