Certain project call for the provision of structure levelling. This is often the case where difficult seabed conditions or unacceptable gradients are anticipated. Where piling is required the levelling operation should ideally be carried out prior to piling. Some alternative levelling/piling systems try to resolve this by piling first then levelling. This technique is problematic as the piles are driven at the initial inclination and subsequent levelling is unsuccessful due to racking resistance.

The C-lok levelling system avoids this problem by a three stage operation that first levels the structure followed by pile driving and finally locking onto the piles. This failsafe technique is carried out seamlessly in a single installation sequence.


At the heart of the operation is the unique field proven LRS approved C-lok connector system that is able to clamp the levelled structure onto the driven piles. The levelling operation uses a simple double acting hydraulic cylinder to raise the low end of the structure to within tolerance then a HD threaded locking pins are used to maintain level whilst the permanent C-lok connector is actuated. Thereafter the structure is maintained level and all load is passed through the C-lok into the driven piles. The C-lok has the key advantages of allowing a full strength connection regardless of pile penetration achieved and the unique advantage of allowing a later release and subsequent re-engagement of the connector if required.

The C-lok connector comes in a large range of capacities ranging from the ROT based C-lok 900 to the ‘fly- to-place’ lightweight C-Lok 300 or C-lok 150. The levelling tools are ‘fly to place’ and are interchangeable. These standard tools are available from BECL and use the identical field proven control and ROV interface system. The tools are fully retrievable and replaceable providing generous redundancy.

Key features & benefits

• Diverless
• Permanent engagement in less than 5 minutes
• Ensures mudline anchorage and heading regardless of pile penetration
• Where pile is successfully driven to target depth no further operations required
• Releasable – allowing disengagement and re-engagement , if required, in less than 15 minutes
• Allows single pile, connector and tool to be used repeatedly for a wide range of application
• 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 hydraulic tools
• All hydraulic equipment is recovered to surface using a simple vertical lift
• Design allows unit to be integrated into the main structure fabrication sequence at any stage
• System uses common C-lok tool and interface for a wide range of C-lok sizes
• System uses common levelling tool and interface for wide range of duties

The use of multiple retrievable tools for both levelling and C-lok operations:
i) Minimises vessel time by pre-mounting each tool on the structure prior to overboarding
ii) Provides generous tool redundancy
iii) Eliminates environmental impact due to long term loss of hydraulic fluid
v) Decouples delivery of the Hydraulic Tools from structure fabrication schedule

The outline offshore procedure for levelling is typical for all structures. In this example a jacket template structure levelling/locking operation is described::
• Mount C-lok Tools (3 No.) and Levelling Tools (3 No.) on structure
• Deploy structure to mudline and recover rigging
• Determine ‘low’ levelling foundation pad
• Use levelling tool to raise structure to within level tolerance using bullseye for reference
• Engage Levelling Pin
• Repeat process on remaining two levelling foundation pads as necessary
• Engage first C-lok connector to pile
• Repeat process on remaining two C-lok connectors
• Recover C-lok tools and levelling tools to surface


Video – outline offshore procedure