Subsea pipelines

Subsea pipelines

One of the important segments of Company business in the sphere of oil and gas industry facilities construction is subsea pipelines construction (trunklines and infield process pipelines).

Engineering personnel of CNGS Engineering has many years of proven experience in pipelines construction in many countries including Ukraine, Russia, Turkmenistan, Romania, Yemen, Vietnam, Cuba.

CNGS Engineering manufacturing facilities allow to perform the following scope of works during subsea pipelines construction:

  • fabrication of transported assembled pipeline sections;
  • pipelines heat insulation and heat tracing;
  • pipelines laying onto sea bed, ballasting; free spans correction;
  • installation of pipe spools and risers, connection to onshore facilities and offshore fixed platforms process equipment;
  • pipelines testing; cavity cleaning, gauging and drying;
  • installation of cathodic protection facilities;
  • preparation and execution of commissioning works;
  • arrangement of subsea trenches including landfall arrangement at shore line area;
  • precommissioning survey of subsea pipelines routes and pipelines post-laying survey;
  • reconnection of pipelines and replacement of existing pipelines sections (including operating pipelines).

Various methods of subsea pipelines transportation and installation are used by Company during subsea pipelines construction:

  • Traditional laying method using pipe-lay barges.
    • Company employs available pipe laying spreads having a wide range of partnership agreements.
    • A mobile pipe welding complex is also installed on Company`s own TB6000 transportation and installation barge, if required.
  • Subsea pipelines construction method using afloat towed sections and “free submergence” installation method.
    • In spite of its conservativism and novelty this installation method provides unprecedented opportunities in subsea pipelines construction in unaccusable regions, at shallow water, in areas with no infrastructure for other construction methods.
    • Thereby a cost of such pipeline is much lower with the same level of quality, reliability and construction duration.
    • The method has no equivalents in application during repair or modification of pipeline systems at offshore fields.