Quickflange used for Underground Firewater System


The repair scope had the following specifications:

Structure Underground firewater system
Line Media Water
Design Pressure 1,809kPag
ANSI Rating CI#150
Design Temperature 60 °C
Design Code ASME B16.5
Schedule / Wall thickness (WT) 7.04mm to 8.38mm
Material and Grade A53GR B
Flange materials/specification A105N (Quickflange material)
Geometory Connections for new spool - underground
Orientation 3 x horizontal and 1 x vertical



An underground firewater system required a connection spool to be inserted. The location was within a live gas plant so required a no hot work approach. Four flanges, two at DN200, one at DN250 and one at DN300 were required to be installed, with associated onsite machining to be provided.


  • 8”, 10” and 12” flanges specified and tested through DNV approved process
  • Onsite machining tooling and technicians provided in one mobilization of a crew of 2
  • Flexibility to fit within larger site crew, helping out with all tasks associated with the job to optimize the job schedule


  • No hot work
  • Flexibility in the methodology to address latent conditions and residual stresses in the pipework
  • Short time on site, 5 days with 2 technicians to complete 4 flange installations.
  • ​​​​​​​No welding preparation, inspection or habitat requirements

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