SRP has developed a number of large diameter flange designs for high pressure riser applications, including shallow water jack-up and deepwater dry-tree drilling risers.

We offer riser optimised designs with enhanced bending capacity and sealing performance in dynamically loaded applications based on:

  • API Spec 6A.
  • Compact Flanges (NORSOK L-005).
  • Customer specification.

All our designs are designed and independently verified to comply with the requirements of API RP 2RD or ISO 13628-7 in terms of material utilisation limits and sealing capacity.

Our proprietary flange designs have seen extensive use in the North Sea since 2008 in different drilling risers in applications to 15,000psi working pressure.

Through our experience in developing and running high pressure riser systems in the North Sea with our sister company Claxton, we can offer a number of design features for faster running and reliable make-up. Typical features include:

  • Full 3D finite element analysis (FEA).
  • Fatigue qualification testing and FEA correlation.
  • Fastener and bolt tensioning designs for easy spidering and faster rig floor handling.
  • Internal handling grooves for remotely operated running tool.
  • A range of metal sealing options based on industry standard and wellhead bore seals.

We can supply flanged riser joints in fully forged and fabricated joints. For details on our riser joint construction experience, please refer to the project services page.


  • Shallow water subsea wellhead jack up drilling
  • Dry tree systems, including tension leg platform (TLP) drilling risers


  • High reliability: our flanges feature replaceable metal bore seals, high make-up accuracy and enhanced fatigue life for maximum reliability in surface BOP drilling.
  • Optimised solution for your application: whether you want a weight saving slim flange or a workhorse with the fewest bolts, we can offer the right riser flange for your application.
  • Lowest lifecycle cost: with comparable capital costs to other large diameter mechanical connectors, our flanges offer significantly lower lifecycle cost, owing to repairable seal faces and replaceable seals and fasteners.