Another method for the installation of flexible and rigid subsea pipelines is by Reel-lay. Long pipe segments are welded, tested and coated onshore and then spooled onto a large, usually vertically oriented pipe reel, in one continuous length. Once the Reel-lay vessel is in position, the pipe is unspooled, straightened and then lowered to the seabed as the vessel moves forward.
The major advantages of Reel-lay are the high production rate as well as the controlled welding and inspection conditions onshore. These advantages make Reel-lay an extremely efficient method for the installation of pipelines in all waters. To make Reel-lay efficient, a spool base is required nearby the Reel-lay vessel to reduce transit time to and from the pipe installation location. We can deliver complex Reel-lay systems including main and piggy-back reels, traction and storage winches, tensioners, drives and supporting cranes.
An example of Huisman’s innovative drive is the development of modular skidding Reel-lay systems. This type of system can carry several reels with pipe on deck, which can be lifted onboard the vessel using her own main crane and can then be skidded over deck rails to unspool over the ramp. With this setup it is possible to exchange the empty reels with full reels, without the pipelay vessel needing to shuttle between the pipelay location and the spool base. This results in a more efficient use of the pipelay vessel and a higher effective lay rate. Reel-lay can be easily combined with Flex-lay capabilities.
- Suitable for shallow to ultra-deep waters;
- Very high production rate;
- Pipe welding in non-critical vessel time (onshore);
- Dedicated spool base required for pipe preparation;
- Diameter of the pipe is restricted by the size of the reel;
- Not suitable for installation of concrete coated pipe;
- Used for pipelines with thermal outer coatings or inner linings;
- Due to the plastic bending less suitable for fatigue sensitive pipes