Cygnus Project Dimensional Control

Cygnus Gas Field Development

Heerema Fabrications Hartlepool yard in the United Kingdom was chosen by GDF SUEZ E&P UK for the fabrication and commissioning of four topsides for the Cygnus gas field development on the UK Southern North Sea.

The total scope of the Cygnus project for execution at the Heerema Fabrication Hartlepool yard represented approximately 10,500 tons fabrication work and consisted of the 3,900 tons Process & Utilities (PU) module, two bridges of 200 tons and 250 tons and a 250 tons flare, a 1,600 tons Wellhead module and a 1,500 tons Compression module which was installed onto the PU module, all destined for the Cygnus Alpha three bridge-linked complex. Fabrication work of the remote Cygnus Bravo development consisted of the 2,800 tonne Wellhead module.

Fabrication of the Cygnus Alpha Wellhead topsides started in December 2012 and was completed around March 2014.  The fabrication of the Cygnus Alpha Processing & Utilities module was followed by the commencement of fabrication in June 2013 of the Cygnus Alpha Processing & Utilities module, bridges and flare as well as the Cygnus Bravo Wellhead topsides, all of which were completed in April 2015.

The Cygnus gas field consists of four platforms and produced first gas production towards the end of 2015. Cygnus Alpha, a three-platform bridge-linked complex and Cygnus Bravo, a not normally manned installation is located in the UK’s Southern North Sea approximately 150 km north-east of Easington in a water depth of 23 meters. The produced gas is exported via the ETS to Bacton. The field is operated by GDF SUEZ, with partners Centrica and Bayerngas.

RSL were chosen by Heerema Fabrication Group at their Hartlepool facility, to provide full Dimensional Control and survey services throughout the project.

 RSL were involved with HFG at the Project Tender Stage all the way through to completion. Upon following the project award HFG in conjunction with RSL prepared a Dimensional Control Procedure for each Jacket and topside fabrication.

The procedure contained:

  1. Responsibilities
  2. Pre and post survey points
  3. Calibration Information
  4. Tolerances
  5. Equipment
  6. Specialist measurement i.e., flatness surveys
  7. Relevant Project & national standards


The procedure was agreed with the Heerema QC, Construction & Production and these procedures were always referenced on the ITP.

RSL provided Dimensional control and survey assistance throughout the full project. Dimensional control survey teams from RSL worked across all shifts to ensure that Heerema had 100%-Dimensional control cover to assist the Heerema project and fabrication teams.

Project Reel

Project Details

Client: Hartlepool Heerema
Project Start Date: 03/12/2012
Project Completion Date: 10/03/2014

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