Subsea 7 Mezzanine Decks

March 2021

Structural Steelwork & Fabrication

Dales Marine were contracted to fabricate 2 no. ROV Mezzanine Decks for installation on two separate offshore support vessels heading to Brazil. The client looked to increase available deck space along with solving an issue with high bulwarks and over boarding activities.


  • 43te (per assembly) of Universal Column, European Steel Beam Sections, PFC and Profiled Plates supplied
  • IPE 500 sections purchased and supplied from Continent to meet client’s specifications
  • Mezzanine Deck was floored out using GRP grating panels – approx. 460m² (per deck)


  • Dales used their workshop in Grangemouth due to Aberdeen’s high workload at time
  • Mezzanine was designed to be fabricated in 6 individual modules
  • Total dimensions for completed mezzanine deck was 25.8m long x 18.2m wide
  • Fabrication of the first vessel was completed and continued with second build
  • Workshop was capable of taking 2 modules at a time with rotation outside when completed and NDT inspected
  • All welding connections were full penetration with 50% UT Inspection required
  • Full NDT inspection with load test of lift points


  • Dale’s scope included the preparation and painting of the modules prior delivery to vessel
  • Using our highly skilled ship painters along with qualified paint inspector we paint-ed all twelve modules onsite
  • Steel was purchased pre-blasted and shop primed prior to fabrication. Minimal damage was done during fabrication to the coating
  • Mechanically cleaned all weld areas, scars and damaged areas and proceeded with priming. Strip coated all welds and proceeded to paint to manufactures and clients specification
  • All onsite connections were masked off and left primed to save preparation time onsite


  • Utilising three arctic trucks with wide load notification and police escort we shipped the first mezzanine deck assembly to our Leith base for mobilisation.
  • The second mezzanine deck had the same requirements but was sent to our Aber-deen facility to be mobilised during dry docking.

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