Oil Riser Change-out – Flexible DBB Isolation & Services

Maintenance & Modifications
Brunei, South China Sea
Project manager
Peter Bjørnsen
Project type
Maintenance and modification

Project description

Riser repairs involve replacing some sections of the risers and possibly replacing some whole riser sections/segments over sea level. This work entails cutting and welding operations.  


IK Topside has significant experience in this field, together with specially designed flexible plugs for double block and bleed (DBB) weld isolating and cold cutting of the depressurised risers. A DBB barrier is essential when performing hot work operations on hydrocarbon process pipelines.


Tool specifications for riser change-out operations:  

  • Double block & bleed function/facility 
  • All materials are tolerant to hydrocarbon process systems 
  • Maximum operation pressure: 60°C 
  • To hold a minimum differential pressure of 1 bar 
  • Double block seal verification pressure, maximum 3 bar 
  • Plug annulus can be filled and monitored with water or gas 
  • Operating temperature: -10°C to +60°C (+90°C intermittent) 
  • Flexible connection between isolation barriers 
  • Plug must navigate through miter joints and piggable bends