Santos GLNG – Roma

Scope: 222km DN630 to DN63 HDPE

Timeline: 2012 - 2013

Mitchell met all the required criteria on this milestone project, significantly through the use of our innovative systems. Mitchell specifically developed ‘over trench welding barges’ for this project that allowed the direct installation of the pipe and tees. All were butt welded on the ‘weld barge’ and laid direct to the trench, removing the need to use large electrofusion couplings, improving safety, quality and productivity.

 

Criteria Included

    • Nil use of Electrofusion Couplings >DN250
    • Single High Pressure Butt Fusion Fast Cool Welding
    • 100% Time of Flight Diffraction NDT testing
    • 100% Pneumatic strength and leak testing
    • 100% GPS weld location and traceability
    • 100% traceability of all materials
    • 100% Welding qualification
    • Native soil screened for bed and pad
    • Marker tape and added tracer wire above the pipe
    • Pull through cleaning of each pipe at welding
    • Pneumatic flushing for pipe cleanliness verification
    • Machine control graded trenching including engineering survey and design by Mitchell
    • Full installation of facilities and tie-ins

Construction Methods

Pipe DN280 to DN630
laybarge style fast fusion weld trailers, welded and laid directly to pre-dug trench including Tees (removing the need for large Electrofusion Couplings)
Pipe DN140 to DN250
using laybarge style fast fusion weld trailers, welded and laid directly to pre-dug trench including Tees
Pipe DN63 to DN125
conventional butt welded direct to ground and lowered to post-dug trench

 

Potable & Oily Water: Below ground HDPE Piping systems

Scope: 14km DN50 to DN400, drain lines at grade up to 5 metres deep

    • Tie in to drain line pits
    • Backfill compaction above 95%
    • 100% Hydrostatic strength and leak testing
    • Bed and Pad with sand material
    • Pig flushing for pipe cleanliness verification

Pipe racks: Above ground HDPE Piping fabrication

Scope: ~2000 joints DN20 to DN400, fabrication spooling of client supplied materials

  • Single High Pressure Butt Fusion Welding
  • 100% Time of Flight Diffraction NDT testing
  • 100% Hydrostatic strength and leak testing
  • 100% Welding qualification
  • 100% traceability of welds and materials