This recent Thunder Cranes project on an FPSO in offshore Vietnam is a great example of the effectiveness of our solutions when dealing with unusually challenging offshore projects. Prior to contacting Thunder Cranes, the client had searched for solutions since 2022, but the other methods they looked at were not feasible or cost-effective.


Case Summary

Our client – a Vietnam based offshore production company and FPSO operator – contacted Thunder Cranes for a lifting solution on an FPSO and gave us an opportunity to showcase our modular offshore lifting solutions for the first time in Vietnam.

The clients’ objective was to replace/changeout 2x units of gas lift after coolers (GL AC).  The coolers were located outside of the reach of the FPSO cranes at the fore of the vessel, approximately 9m above the main deck.

The client explored usual options in the tendering stage – such as hiring a barge crane or a lift vessel. Thunder Cranes presented our innovative modular approach and it became the obvious solution from the viewpoint of cost, efficiency, safety, and time savings.

The project called for expert and detailed planning due to the cooler unit weights – approximately 6.5 tons – as well as their challenging location on the FPSO. However, Thunder Cranes’ unique self-lifting crane packages and experienced crews enable us to provide cost-effective lifting solutions via modular cranes in challenging scenarios.

An extensive site survey enabled our project team to create a detailed proposal and lifting plan for a multi-step lifting solution involving the skidding, self-lifting, rigging and repositioning of 2 modular cranes – the TC05 and the TC20.

TC20 lifting a 5.5 ton GL AC unit on an FPSO in Vietnam

Challenges & Solutions

Challenge #1 – Skidding and transferring crane components and auxiliary equipment across long distances from initial laydown area to the final rig up location. This challenge required using a variety of customised trolleys, pallet trucks, and skidding rails to move equipment.

Challenge #2 – No existing lifting support systems in the work area to lift crane components and equipment to the top deck, and to assist crane rig up.  This challenge required designing a customised self-erecting system with scaffolding, A-frame jib, and TC05 to rig up the TC20 at the intended work location.

Challenge #3 – Limited space for manoeuvring equipment and rigging up cranes, especially crane boom sections. This challenge required dismantling and temporary removal of certain FPSO deck structures.

Thunder Cranes plans and implements rigging, skidding and self-erecting methods to overcome challenging rig up scenarios


Our process starts with a thorough assessment of the client’s lifting requirements, platform drawings, general specifications, and project timelines. A site visit is then conducted to verify that an appropriate and practical solution can be proposed.

Our proposal and quotation come with a Site Visit Report to clearly communicate the proposed method with drawings and photos.

After the proposal is given the green light, we begin the detailed planning stage where we collaborate with the client to customize elements of the project in terms of materials, equipment, 3rd party services, utilities, scaffolding, etc.  Customization can include any platform modifications if needed, or any re-positioning, or removal of elements from the main deck of the platform.

Furthermore, our modular crane configuration is customized to meet specific needs with regards to the tied down method, boom reach radius, zone rating, or any other safety or environmental considerations.

In the next step an engineering work pack is submitted to the client addressing the specific scope of work and lifting requirements, featuring detailed considerations from the site visit, with comprehensive rig up and lifting plans, customized layout and positioning drawings, as well as reaction force calculations needed to conduct a structural analysis.

Pre-mobilization planning includes risk assessment/hazard identification, and alignment sessions are conducted for offshore personnel to ensure safe and efficient operation of the modular cranes.

Depending on the project location, the preparation and deployment of the modular cranes and auxiliary equipment might begin months ahead to ensure cranes are at the load out port and ready to be transported to the offshore site and assembled according to the pre-planned schedule and project configuration.


  • Load out from port and sailing to FPSO via supply boat.
  • Offload TC Modular Crane components from supply boat by FPSO Crane to FPSO laydown area.
  • Transfer TC Modular Crane components to Final Location by pallets jacks and skidding systems.
  • Erect scaffolding to lift A-Frame Jib at Cooler Deck Level.
  • Lift TC05 components to Cooler Deck Level.
  • Rig up TC05 and load testing.
  • Lift TC20 components to Cooler Deck Level using TC05 and skid TC20 components to final position.
  • Rig up TC20 with TC05 as the rig up crane, and load testing TC20.
  • Lift old GL AC Cooler no.1 with TC20 to supply boat.
  • Lift new GL AC Cooler for installation on FPSO.
  • Reposition TC20, and load testing.
  • Lift old GL AC Cooler no.2 to supply boat.
  • Lift new GL AC Cooler for installation on FPSO.
  • Rig down and transfer all equipment back to the FPSO main deck laydown area for backload to supply vessel and demob.


The total project timeline from load out to demob was only 28 days and we were able to demobilize several days ahead of the original plan. Most importantly the planned shutdown period was reduced, providing additional cost savings to the client.


In the post job analysis, our client remarked that they were not previously aware of our solutions and that in prior years they had been presented with methods by other service providers which were deemed either not feasible or not cost effective.

Thanks to the planning and cooperation from all parties, and our customised Thunder Cranes modular solution, our client was able to complete their project ahead of schedule and within budget.

  • Lifting Solution for GL AC on FPSO
  • Limited Space on FPSO
  • Heaviest Lift of 6.5MT
  • Complex Self Erecting
Our Service
  • TC20 modular rental crane
  • TC05 rig up assist crane
  • Crane Operators
  • Detailed Planning & Preparation
  • Cost Effective
  • Safe Operation
  • Timely Execution
  • Offshore Vietnam