Mono Pile Cleaning Solution

Case Study

Project Details

Client:

MPI Offshore

Location:

Thanet Wind Farm, UK

Equipment:

Specialised Marine Growth Removal (MGR) Tool

Average Pile Cleaning Time:

Less than 90 minutes

Background

When installing a wind turbine, a delay of more than a few days between mono pile installation, transition piece placement and grouting operations can be costly as marine growth and other surface debris can often quickly appear on the mono pile surface. As surface cleanliness of the pile is critical for effective grouting, all loose debris and marine growth needs to be removed quickly and effectively to prevent any costly grout removal after installation.

Project Description

Proserv Offshore was approached by MPI to develop a solution that would speed up the pile cleaning process and avoid possible costly maintenance. Pile cleaning using a diving team is time consuming and costly so it was necessary to develop a solution that was fast, effective, reliable and with ease of deployment and recovery. Furthermore, it was requested that the solution require minimal human intervention and could also be adjustable for a range of different pile diameters.

The Solution

Proserv Offshore designed, developed, manufactured and tested a Marine Growth Removal "MGR" tool. This specialized solution is deployed from a support vessel and located directly upon the open pile. The surface of the pile is then prepared by lowering a hydraulically controlled cleaning sub frame down the pile; utilizing high pressure water jets mounted on a track, a full 360 ° by 450mm wide path is cleaned around the pile.

Once the carriage has completed a full rotation around the track, the support fabrication is lowered to the next position and the surface preparation process is repeated in the opposite direction. This process continues until all the transition area has been prepared to the required standard. Once complete, the rotations are ceased and the lowered fabrication is pulled back up the pile to its secured transport position within the top located fixture. The whole tool can then be lifted and placed back onto the deck of the support vessel ready for the next pile deployment.

The functions of the tool including the circular track speed, jet rotation and jet pressure are all fully adjustable and controlled by the operator on board the deployment vessel. The hydraulic power, high pressure water and electrical power to the observation camera system are supplied via an umbilical. All support equipment including the high pressure, high volume jetting pump is located on the support vessel.

Results

Using the Marine Growth Removal tool, a pile of 4.7 meters in diameter can be completely prepared to a depth of 8 meters in less than 2 hours. Considering it would take a diving team over 30 hours to achieve the same result, this is a significant time saving for our customers.

Conclusion

The Marine Growth Removal tool has been supplied to many major industry leading contractors within the European offshore renewable energy sector, producing excellent results every time.

A summary of the benefits of the MGR tool include:

A complete 360-degree surface clean in under 90 minutes.
Prevents costly maintenance work after installation.
Suits a variety of pile diameters and can be used in a full range of water depths.
Environmentally friendly diverless technology that is operated remotely from the surface.
Easy and quick to deploy with minimal human intervention required.
Variable operating pressures up to 2500 bar (36,00psi) with flow rates up to 200 lpm (55 gpm) if required.