3D Modelling and Stress Analysis for Inert Gas & CAF System

Project Background:

Seagreen Wind Energy Limited (SWEL) has been consented for both the wind farm and offshore transmission elements by Marine Scotland and the relevant local authorities. SWEL will be located approx. 27 km (at its closest point) from the Angus coastline in the East Coast of Scotland.

Power will be collected on one Offshore Substation Platform (OSP) via 66 kV array cables and associated equipment. The main purpose of an OSP is to transfer power from 66 kV to 220 kV using a grid transformer for onward export to the onshore substation.

SWEL intends to develop Offshore Wind farm platform facility and awarded the “SEAGREEN OFFSHORE WIND FARM PROJECT” EPC Contract to M/s Petrofac. In project scope, fire safety for the electrical equipment and components, Inert Gas system (IG System) & Compressed Air Foam System (CAF System) are selected. M/s Petrofac, invited the vendors and awarded the Sub-Contract for EPC of IG and CAF System to M/s TYCO Fire & Security UAE LLC. Design, Engineering and 3D Modelling of Skids and Piping Network for IG & CAF System was performed by Elixir Engineering for TYCO Fire & Security UAE LLC. The piping design was performed under design code of BS EN 13480.

Execution Methodology:

  • Review of P&ID for IG and CAF Systems
  • Review of Process design parameters and conditions
  • Performing IG and CAF demand calculation for each room in 3 tiers
  • Re-Validation of Number of Cylinders required and dimensions
  • Preparation of Piping and Valve Material Specification
  • Performing Pipe wall thickness calculation as per EN-13480 design code.
  • Selection of Pipe fittings as per EN-1092 design practice.
  • Preparation of Line list
  • Review of existing 3D model prepared by Petrofac for Platform arrangement and electrical equipment.
  • Creation of Admin modules in PDMS for Piping components and Skid arrangements
  • Generation of preliminary pipe routing in 3 tiers for both IG and CAF System and ensure the coverage area of Sprinkler arrangements
  • Preparation of Support drawings and Support Schedule
  • Identification of critical piping arrangements for Pipe Stress analysis  
  • Pipe modelling as per provided preliminary GA drawing in Software
  • Definition of fluid and material properties as per project specification.
  • Definition of environmental conditions as per project specification.
  • Definition of External load conditions (Wind load, Wave parameters) as per project design specification. Earthquake or Seismic condition is not applicable for the design condition.
  • Definition of Support type and support details
  • Performing the Stress analysis for various load conditions (Thermal load case, Sustained load case, Hydro load case, Occasional load case and Transportation load case) as per project design specification and Stress analysis basis.
  • Validation of pipe load values in all support locations and node points.
  • Validation of deflection, displacement and Pipe stress values within allowable limit.
  • Skid Nozzle loads are taken into the account while nozzle load allowable check.
  • Finalizing the first anchor point outside of Skid and inside skid, based on the connecting nozzle loads.
  • If stress and deflection limits are exceeded, the analysis will be re-performed for suitable Pipe Support and routing arrangements.
  • If all stress and load values are within the limit, the Stress summary, Restraint summary with Input Echo are extracted and submitted to client.
  • The necessary changes in GA drawing with respect to piping and Pipe support arrangements have updated in 3D modelling.
  • Participation of 3D model review (30%, 60% and 90% model review) and preparation of 3D model review report.
  • Ensure the Clash checking of piping network with other arrangements and constructability point.
  • Piping loads and other components load values are provided to Structural team to check integrity of Structural arrangements.
  • Definition of Piping loads (Axial, Vertical & Friction loads) in all support locations.
  • Definition of other components load on the specified structural locations.
  • Preparation of complete report with Results summary and Software results for Stress analysis.
  • Final Submission of 3D model.
  • Preparation and submission of GA drawings, Isometric drawings and Spool preparation, Primary support schedule and Secondary support schedule and Bulk MTO.
  • Estimation of painting quantity.
  • Providing support and addressing vendor queries during procurement.
  • As-Built 3D model support based on the redline markups.


  • Pipe wall thickness calculation
  • Pipe Material Specification
  • Valve Material Specification
  • Line List
  • Primary Support Schedule
  • Secondary Support Schedule
  • Piping Stress Analysis Report
  • Extracted GA drawing
  • Extracted Piping isometric drawings
  • Extracted Sprinkler coverage drawing
  • Painting Specification
  • Pipe Spool drawings
  • Transportation philosophy
  • Bulk MTO

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