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  > 1. Heave Compensated Gangways
  > 2. Design of Marine and Offshore Structures
  > 3. Marine Operations
 
 
1. Heave Compensated Gangways  
 

The diesel engine powered hydraulic operated telescopic personnel walkway(called Gangway herein) is designed to be used to transfer personnel between a support vessel and a fixed platform.

 

Principal Dimensions

  Walkway Width 1.2m
  Maximum Extended Length 34.5m
  Mean Operation Length 29.5m
  Complete Retracted Length 24.5m
  Normal Operation Area 29.5m+ / -3.0m
  First Alarm Area 29.5m+ / -3.0 - 3.8m
  Second Alarm Area 29.5m+ / -3.8 - 4.6m
  Emergency Lift off Limits 29.5m+ / -4.6m
 

(Measured from centre of pedestal to end of Landing area).

   

The walkway is connected to the vessel by lifting the walkway from the park position and utilising the electro-hydraulic controls, manoeuvring the walkway so that the free end is placed on the fixed structure. Once landing has been completed, the walkway automatically enters free-floating mode.

The Gangway is self-sufficient in all its operations and is able to self-stow while not in use or in emergency conditions.

 

Main operating condition, walkway supported at both ends

  Load on walkway 3 kN/m2
  Wind 25 m/s
     
Emergency situation with walkway supported at one end only
  Load on walkway 1.5 kN/m2
  Wind

50 m/s

     
The walkway has three movement planes, slewing, luffing and telescoping. It is designed when connected between support vessel and fixed platform to remove the relative movements between the two installations.
 

The gangway will be able to do the following motions namely

  Slewing 270 or 360 degrees (TBD)
  Luffing +24 deg to -16.5 deg
  Telescoping 10m end to end
     

The walkway assembly consists of three primary components; these being the steel pedestal support structure, the rotating turret complete with A-Frame and hydraulic cylinders, and the telescoping bridge section (will be of Aluminium construction). The telescopic bridge section comprises a number of sub assemblies: one fixed outer bridge section, one telescoping inner bridge section, landing cone/shock absorber and access stairs assembly.

Once the walkway is in contact with the fixed installation (a shock absorber is located at the end of the bridge section and provides, within the landing cone the interface between the walkway and the fixed installation), the hydraulic system is automatically free-coupled and the walkway will follow the relative motion of the vessel and platform.

 

The walkway os designed to be in compliance with the following rules and certifying bodies

CNR UNI
NMD Draft 5
AWS D1-1
ASTM

AISC

RINA
Lloyd’s Register of Shipping
DnV – Rules for the Construction and Classification of Offshore Mobile Units
CEI
CETOP
   
 
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2. Design of Marine And Offshore Structures  
 

The naval architects and structural engineers at Rabutec Engineering and its consultants Engineers have many years experience in the design and analysis of marine structures.  We have been involved in a wide variety of design projects from offshore structures to super yachts and designing complete vessels to third party verification.

Our marine engineering division is a small company specialising in design and analysis of fixed and floating structures and for marine operations in the offshore industry.  Our size means we do not have large company overheads and we are flexible enough to set up a project team to meet the requirements of our client.  We have further design and analysis turnover rates (say a crane formation design and analysis takes 2 weeks including drafting).

Our engineers have come from design companies such as ST Marine and Sembawang and fabrication yards such as Daewoo and Keppel.  Accordingly they have the required understanding to produce designs that are easy to fabricate whilst minimising materials and fabrication time and meeting the requirement of the approving body.

We own core software products including Autodesk Inventor Professional, NASTRAN and AutoHydro Pro and specialist software (such as ANSYS for jacket and jack-up structural analysis).  We prepare all drawings using Autodesk Inventor and can issue drawings and reports in PDF format.

Our engineers have worked on projects in many different parts of the world including Australia, Middle East, and South East Asia.  We can save time and costs for our clients by using the appropriate national and international standards used in these areas for design work and speeding up the approval and fabrication phases.

 

Services offered include

Vessel and offshore design to Classification Society rules such as ABS, LR, DNV, BV.
Steelwork design to national rules such as BS5950, NS3472, ASME, NORSOK.
Design modifications for tanker to FSO/FPSO conversions.
Buckling checks for stiffened panels, rings and curved shells to codes such as DNV 30.2, BV.
Drawings both 3D and 2D modelling and drafting for structure.
Piping schematics design and layouts for Ships’ piping systems, Cargo systems etc.
Electrical Single line diagrams, Load Analyses, Cable tray layouts etc.
   
 

Recent experience

Preparation of installation procedure and operations manual update for a jack up rig loaded with an offshore heavy lift crane
Global Analysis of a Jack up rig.
Design of seafastenings structure for jacket.
Design of crane pedestals and support structure for an offshore support vessel.
Design and analysis of a 100m long Crane boom and design drawings for the same in 3D.
SPS compliance review for an offshore support vessel.
Design and Analysis of structures including helideck, Flare tower, and module supports for a dynamically positioned FPSO on a site specific criterion.
 
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3. Marine Operations  
 

The engineers at Rabutec have many years experience of the marine operations undertaken during the installation, maintenance and decommissioning of Ships and offshore facilities

By employing naval architects, structural engineers, mariners and marine engineers, we are able to provide a complete service to the client, undertaking all the required engineering and marine operations planning to produce a comprehensive operation manual.

Our engineers have an excellent working knowledge of relevant design codes and maritime regulations.  This knowledge enables us to assist clients by advising on decisions such as selecting the appropriate marine philosophy for the operations.

Rabutec Engineering uses the industry standard softwares to design according to the needs as required for each project.  By selecting the most appropriate method for each job, we provide value for money by performing the minimum engineering required to satisfy the approving body.  We use the hydrostatics program AutoHydro Pro, the hydrodynamic analysis program, ANSYS AQWA (Diffraction based) and the riser/moorings program ORCAFLEX (leased on order) where required.  For structural analysis we use the finite element analysis program NASTRAN from Noran Engineering and ANSYS, and for drafting we use AUTOCAD and Autodesk Inventor Professional. For analysing Structure – wave interactions MetoceanDesign uses Staad.Offshore like for Jacket legs design and Jack-up Rig leg strength verifications on AQWA.

Our capability includes undertaking the engineering required for piping schematics layouts and Electrical single line diagrams.  Accordingly, we can act as to a single contractor as to provide clients with all their marine requirements and new build engineering support.

 

Services offered include

Loadouts calculations.
Lifting analysis for heavy offshore lifting.
Seakeeping and Towroute Analysis.
Calculation of trim and stability of vessels.
Structural Analysis and report preparations.
New Ship/barge Structural designs and drawings.
Production of marine operation manuals.
Piping system designs / modifications concepts and detailed drawings.
Planning and preparation of 2D and 3D layouts for piping.
Electrical Systems design and drawings including cable tray layouts.
Verification of engineering or procedures for marine operations.
   
 

Recent experience

Global Analysis using a beam model of a Jackup rig using Staad.Offshore.
Longitudinal strength of the Hull for Jackup using Staad.Pro.
Special Purpose Ship compliance review and modifications for an offshore maintenance vessel.
Upgrade of Crane - Design and analysis for existing pedestal modifications and adaptor piece.
(Project finished in 15 working days)
Fitment of a Hamann Sewage Treatment plant and associated pipe work – Foundation drawing, schematics and 2D Piping layouts. (Design Project finished within 12 days)
Design and analysis of a Helideck to CAP 437 compliance for a dynamically positioned FPSO.
 
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