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Frequently asked questions

What are the advantages of modular cranes?

The main advantage of a modular crane, fixed to a platform, vs a crane on a floating vessel are:

  1. Precision lifting
  2. Cost efficiency

Lifting vessels and barge cranes have well-known uses and advantages in the offshore industry and are suitably employed where required. However there are many cases where a lift boat or barge crane will not be suited for the situation at hand, either for technical reasons or for cost reasons or both. Firstly, our crane being secured to the platform structure mitigates dynamic issues (harsh weather & sea condition) and provides safe static lifting on deck. Secondly, Thunder Cranes offers significant cost savings versus using more expensive barge cranes and other floating vessels.

Why would we need a modular crane when there is an existing platform crane?

  • When the existing platform crane is not functioning.
  • When the existing platform crane is de-rated and a higher lifting capacity is required.
  • When the existing platform crane is out of reach from the object lift.
  • When there are no platform cranes onboard and well intervention/facility engineering work needs to be carried out.
  • When the object lift requires a second crane for a tandem lift.

Can you rig up a crane when there is no existing lifting capability on an offshore structure?

Yes. Our cranes packages are specifically designed to enable our crew to perform “Self-Lifting”. Put simply, we start with our A-frame jib which allows us to lift components of our smallest crane. Once the smallest crane is ready, it allows us to pick up components of a larger crane, and so on.

Our platform has limited space, can we still get a Thunder Crane on board?

Most likely, yes. We can determine this either through review of detailed plans or a site inspection. Clients are often surprised to find that we can fit in our cranes just about anywhere.

How quick can we get a Thunder Crane rigged up on our platform?

On average a Thunder Crane can be rigged up within 12-18 working hours including the load test.

What secures the crane to the offshore platform?

Our cranes are designed to be installed on almost all offshore platform configurations by either clamping, bolting or welding. Clamping is the preferred method since it is faster and avoids hotworks. We can safely secure cranes to a platform’s skid and main structure beams by using a clamp and stud-bolt system. This allows our cranes to be positioned quickly and efficiently, without affecting ongoing platform operations. Furthermore our clamping system allows for easy repositioning with minimal disruption to our lifting productivity.

What is the maximum load these cranes can lift?

We have a range of stiff-leg and pedestal cranes with a lifting capacity ranging from 2 to 60 metric tons. Lifting capacity onboard depends on several factors:

  1. The distance from the crane at which the load is lifted which affects the angle of the boom.
  2. The sea conditions when lifting from supply boat.
  3. The type of structure upon which the crane is mounted.

Are your cranes API compliant?

Yes. All our cranes are built in accordance with API 2C specification which is the Specification for Offshore Pedestal Mounted Cranes. All our cranes are operated and maintained in accordance with API RP 2D.

How often are your cranes inspected and tested?

Our cranes undergo a full API annual inspection with dynamic load test (via water bag or dead weights) every single time one of our cranes is rigged up. In some cases this may be up to 30 times a year.

In what types of oilfield service projects are your portable cranes most commonly applied?

  • Platform Upgrades
  • Platform Crane Changeout
  • Installation and Removal of Production Modules (Compressor Installations, Valve changeout)
  • Rigless Platform Decommissioning Support
  • Services on Craneless Platforms
  • Rigless Plug & Abandonment Support
  • Coiled Tubing Unit Support
  • Hydraulic Work Over/Snubbing Support
  • Wireline/E-line & Slick line Unit Support
  • Rigless Conductor Installations

Can we work your crew and equipment on a 24hr operation?

Yes. Thunder Cranes provides all the operational, management, engineering and maintenance support needed to operate our cranes on a 24 hour basis.

Can we use our own crew to work on a Thunder Crane?

No. Modular, self-lifting cranes are a highly specialised service requiring experienced personnel. We have the most competent and experienced personnel in our field and our crews are led by seasoned superintendents each with more than 10 years of experience.

What information do you need from us before conducting a site inspection?

  1. Framing Drawing – main deck or deck we plan to install the crane
  2. Elevation Drawing
  3. Main Deck Layout
  4. Client’s equipment list c/w weight and dimension and layout if any

Following the site inspection our engineering team will provide a complete report on how our cranes will be rigged up, its radius reach, its load capability and how it will be secured on the offshore structure/platform. We will also provide the reaction forces from the crane for our clients to check their offshore structure/platform integrity.

What is a dynamic lift?

Offshore lifting jobs generally involve lifting to and from offshore supply vessels and therefore all such lifts are exposed to dynamic effects due to variations in hoisting speeds, crane and vessel motions, object movements etc.

The dynamic effects will be influenced by environmental conditions such as the wave height and wind speeds, as well as rigging arrangements, stiffness of crane-boom and wire, weight of lifted object, and the lifting procedure itself. In the case subsea lifts, once an object is lowered subsea it will pick up additional forces from hydrodynamic action.

All of these factors must be identified and given due consideration when making SWL calculations, designing lifting plans and safe operating procedures.

What is the difference between Dynamic Default Method vs General Method?

In accordance with API 2C, three methods are given for calculating the dynamic forces acting on a crane in a specified sea-state. The methods are:

  1. Vessel Specific
  2. General
  3. Default Dynamic

The Vessel Specific Method is only normally used by cranes on vessels or floating platforms, whereas on fixed platforms crane ratings are determined by the General Method or Default Dynamic Method (with restrictions as explained below).

Default Dynamic method is only allowed for fixed platforms in areas with mild sea and wind conditions and shall only be used in situations where the supply vessel position is maintained constant relative to the platform (such as for a platform-tethered supply vessel).

Is a Thunder Crane Approved for Personnel Lifting or Manriding?

Thunder Cranes’ pedestal crane models can be used for personnel lifting and manriding. However, for the stiff-leg crane models, manriding is not currently provided due to the boom configuration limitation.

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