Mooring Anchor arrangements involve a wide variety of water depths, soil conditions and anchor loading. These key variables require careful assessment to ensure a successful mooring anchorage.
The simple diverless ROV friendly C-lok Mooring Anchor takes advantage of the unique field proven LRS approved C-lok releasable connector. The C-lok fallows full adjustment of the anchorage to suit achieved pile penetration or required heading and is able to generate the widest wide range of resistance using the same pile.
The use of driven piles for mooring line anchors is a traditional technique that is reliable and low cost. More recently suction anchors and to a lesser extent gravity bases have been used although the cost of fabrication, installation and handling these large structures is a major consideration. Common to all piling solution is the concern regarding reliability of soil data and the key issue of pile penetration and potential for pile refusal or failure to achieve target penetration.
Suction anchors are often considered suitable for soft and medium clays and silts and is a common deepwater solution where soils permit. Suction Anchor penetration failures occur where granular or gravel soils permit free running seawater flow around the skirt perimeter and is also problematic where clays overlay either granular or cementitious soils. Failure to drive to target penetration is often a sign of soils being more competent than survey predictions. Although the pile performance in refusal conditions may be adequate there will inevitably be concern should the anchorage elevation sit proud of the mudline. .
The diverless C-lok provides the simple solution to these concerns by allowing for a full capacity and aligned mudline connection regardless of penetration achieved. This is made possible by allowing the connector to pass freely down the outside of the pile to the mudline whilst providing free orientation adjustment to the desired heading. A simple ROV operated engagement operation is then carried out to fix the connector. The C-lok is designed to cater for the full range of fabricated pile sizes and accommodates API 2B pile fabrication tolerances. The C-lok mooring anchor system ensures a trouble free operation regardless of soil type. Should the pile need to be re-located at some point in the future the C-lok Mooring Anchor may be released and re-used.
The unique C-lok Mooring anchor assures the mooring line is attached at the mudline regardless of pile penetration and allows full rotational alignment(heading) prior to connector engagement. Additionally in the event that the Mooring Line Anchor requires release and recovery the connection may be disengaged and re-engaged as required
Key features and advantages
- Ensures mudline anchorage and heading regardless of pile penetration
- Where pile is successfully driven to target depth no further operations required
- Disengagement and re-engagement , if required, in less than 15 minutes
- Pile is driven with C-lok connector attached
- Allows single pile, connector and tool to be used repeatedly for a wide range of application
- Allows simultaneous attachment of the layaway line
- Operates at any water depth
- C-lok Connector is qualification tested and is afield proven and LRS approved design
- Operated by a standard Workclass ROV (Class III) without specialist ROV tooling
- Uses simple field proven ‘fly to place’ tool (65 kg)
- Caters for full range of API pile sizes and fabrication tolerances
- Allows full 360 degree heading orientation
- Equally suitable for both vibrohammer, impact hammer or suction pile
- Fully caters for pile refusal
- Provides a full strength and fast anchor connection irrespective of water depth or soil type
- Includes dedicated CP anodes
- Allows repetitive use of the single hydraulic tool with a spare tool for redundancy
- All hydraulic equipment is recovered to surface using a simple vertical lift
Outline procedure (vibrohammer)
- Overboard the vibrohammer with pile attached and lower to the seabed
- Allow pile to self penetrates.
- Activate the vibrohammer and drive to either full penetration or refusal.
If the pile achieves target penetration and is within heading tolerance then the deployment of the C-lok Anchor and mooring line may commence. Should the pile refuse then depending on assessment either leave penetration as is or deploy an impact hammer to continue the drive.
- Deploy the C-lok with ‘fly to place’ hydraulic tool mated and dock with pile top
- Lower the C-lok anchor to the mudline and orientate to suit required heading
- Engage C-lok
- Remove C-lok tool and recover to vessel
- Apply Mooring Line Tension