Developing cost-efficient pipeline materials

Improved steel and corrosion performance are among the features of new technologies.
  • Forfatter Subsea 7
  • Fotograf Subsea 7

The selection of higher-specification pipeline materials can significantly improve pipeline performance, but at costs that may critically impact the economic feasibility of field development, especially when the industry focus remains on lowering CAPEX and OPEX.

To address this challenge, Subsea 7 is accelerating its strategic development of cost-efficient pipeline material solutions for the expenditure-constrained oil price environment.

By collaborating with major pipeline manufacturers and acquiring commercial interests in two specialist material developers, Subsea 7 has accelerated the development of a number of high-performance but cost-effective pipeline technologies, including:

  • The use of higher-strength steels (ie. exceeding X65) for pipeline installation in deeper waters
  • Qualifying a new lined pipe product, Glubi®, for improved Reel-Lay corrosion performance
  • Developing polymer-lined pipe and connectors as an economic alternative to CRA clad pipe
  • Adopting lightweight Thermoplastic Composite Pipe (TCP) materials for subsea service
     


Seven Oceans installing Mechanically Lined BuBi pipe. 
 

High performance steels

Using higher strength steel to decrease pipe thickness can contribute to lower material and fabrication costs and significantly reduced installation costs. A recent cost/benefit study for deepwater Steel Lazy Wave Risers (SLWRs) identified a 20% reduction in pipeline weight and an 11% reduction in buoyancy material cost by replacing X65 riser material with higher-strength X80. . Further potential cost savings could be realised by improved efficiencies in both the floater design and better utilisation of the Reel-Lay vessel.

Subsea 7 has recently performed qualification programmes for reelable X80 riser pipe in collaboration with steel tubular manufacturer Vallourec. These confirmed that welding of X80 can be carried out using similar reliable and cost-effective methods as for X65. Subsea 7 can now offer operators pipeline material and fabrication solutions to support the design of offshore risers and flowlines in X80 pipe, including for sour service.

The use of CRA mechanically lined pipe provides a highly cost-efficient alternative to the use of metallurgically clad pipe for many applications requiring improved corrosion performance. Working closely with manufacturer Butting, Subsea 7 has pioneered the Reel-Lay installation of mechanically lined BuBi® pipe which is now well established for production risers and flowlines.

A new lined pipe product, GluBi®, is now being qualified which eliminates the use of internal pressurisation as required for reeling conventional BuBi® pipe. GluBi® includes an adhesive layer between the substrate pipe and the liner which results in an enhanced grip condition which can be maintained during reeling to prevent liner wrinkling. GluBi® technology will enable further cost savings to be realised for reeled pipe.