Reeling Trials

Key details

  • Verification of reeling installation criteria and design parameters

  • Simultaneous laser and camera measurements are taken along the entire length of a pipe allowing 3-D visualisation

  • Allows development of a reeling finite element model

  • Multiple scans can be used to identify pipe ovality changes throughout the reeling cycles

  • Highly accurate and repeatable tools, accurate to 0.05 mm

  • Localised features and defects can be selected and analysed in detail

  • A number of different report formats are available

Why?

TechnipFMC, Subsea 7 and a small select group of others companies are the masters of bending pipes onto a reel and taking them offshore and laying the pipe. This methodology provides a considerable cost saving as virtually all of the welds are conducted onshore with vastly reduced costs. Typically each spoolbase around the world, for example in Angola, USA, Scotland or Norway will weld together multiple kilometre long strings which are then welded together to construct a multiple kilometre string for laying in a far off location. The reason for the simulated reeling process is to ensure that the design (which is carried out by computer simulation) will meet the specification before the pipes go offshore. By convention, bending a 12 metre long single section of pipe with or without weld(s) simulates sufficienctly well the reeling process to be allow the actual reeling to be accepted.

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Solution

OMS has been involved in measuring the effects of the reeling process inside the test pipes since around 2002. The simulation requires a pipe to be bent against a former of the same radius as the spool on the vessel. Then the pipe is straightened in a simulation of the unreeling process. This process is then repeated again to simulate the reeling of the pipe back onto the vessel should this be required. As the pipe is bent and unbent it will go from being more or less round to an oval shape. When it is straightened it will return to the original shape but some residual ovality will remain. The resulting information provides the pipeline engineer with vital information as to whether the design meets the specification.The solution provided by OMS supercedes any indirect method by measuring the ovality of the pipe inside before, during bending, and after straightening.

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How?

An OMS profiling device is put into the pipe ready for reeling and then moved along the pipe to desired test locations. The following figure illustrates an operator moving the tool within the pipe using push-rods. At each location the tool measures more than 2,000 radial distances at discrete angles. When this information is combined the result is the shape of the pipe.

By undertaking this process at the same location as the pipe is bent and unbent the vital

measurement data can be collected for the design engineer to review. The following figure illustrates a typical unwrapped and exaggerated profile of the pipe during the simulated reeling process.

While as small amount of ovality is good, excessive ovality is not. The end goal is shown in the picture below which shows how pipes of several kilometres long can be reeled onto a vessel for subsequent pipelay.