Multi-Diameter Pigging Feasibility Study


During Concept Development, Client was investigating the feasibility of a 24-inch Steel Catenary Riser (SCR) system on a semi-submersible compression platform. The 24-inch SCR presented an opportunity for topsides intelligent pig launching as opposed to subsea launching. This would result in a significant reduction in technical, health and safety risk, and reduction in cost for in-line inspections act.

Atteris was engaged to investigate current and near-future multi-diameter ILI capabilities to determine the likelihood of achieving “industry-standard” inspection results for such a large diameter step change.

Work Performed by Atteris

The scope included:

  • Estimates of wall thicknesses for the future riser system.
  • Identification and assessment of ILI tools currently available to the industry.
  • Assessment of technical feasibility and status of each inspection technology, as it applies to a 24 to 34-inch pipe diameter change.
  • Recommend a multi-diameter ILI tool for a 24 to 34-inch system that can be qualified in the near term with high confidence.


Atteris identified and assessed a range of inline inspection technologies which enabled client to progress its concept for a 24 to 34-inch multi-diameter riser / pipeline system. The work proved feasibility that the system would be inspectable and thus reduced development costs could be realised.