C-lok is a simple diverless subsea structural connector that is activated using a single hot stab operation from a standard 3,000 psi Workclass ROV. The device is offered in three basic capacities. The C-lok 900 offers the highest load connector capacity, the C-lok 300 mid range and the C-lok 150 the lighter duty applications. The patented C-lok technology   for all three is  described in the C-lok 900 product notes.

The C-lok Connector provides robust and reliable resistance in all 6 degrees of freedom.

This system is operable at any water depth and  may be activated  at any pile penetration depth so pile refusal is of no concern.

This permanent connection is available over the full range of API standard diameters and well beyond.  C-lok may be released permitting equipment/structure recovery and then redeployed and re-activated at any stage.

C-lok is available in a wide variety of capacities to suit the application and operated using standard ROV interface in both ROT and ROV ‘Fly to Place’ formats.

The C-lok is a field proven  Lloyds Register of Shipping approved design.


C-lok is the general purpose connector for all subsea tube to tube structural applications. Equally suited for  multi-pile (post driven)  and monopile (pre and post driven) arrangements. It is also ideal for attachment of subsea structural modules where release and recovery of the module is either a planned or contingency event.

C-lok is a fully adaptable and patented clamp connector  that not only offers the widest range of fully diverless ROV based applications  but is also available in a diver assisted alternative.

Conventional oil and gas subsea structures  have submerged self weight in the region of 50 Te to 150 Te. Allowing for  typical  operational and environmental loads the  maximum pile loads for a four pile structure will often range from 30 Te to 80 Te and for  extreme environmental loads and fishing interaction may increase to 100 Te. For a nominal operational capacity of between 100 Te and 120 Te the C-lok 150 is available.  For more onerously loaded subsea structures  the C-lok 300 is available. For the highest loaded structures or for typical monopile connections the C-lok 900 is typically recommended.

The key advantages of the diverless C-lok 150 is its ability to guarantee full  engagement at any water depth and at any depth of pile penetration regardless of soil type or characteristics. This version of C-lok has been  developed  to suit the light duty range of applications and structure sizes whilst using the compact ‘fly to place‘ tool.  The C-lok 150 is similar to the mid range C-lok 300 but avoids the need for a heavy duty internal collar and pad. The C-lok 150 utilises a section of pile sleeve as the pad and enjoys significant fabrication cost saving as a result.

Key features and advantages
  • Diverless
  • Quick, engagement complete in less than 5 minutes
  • Releasable, allowing disengagement and re-engagement  in less than 15 minutes
  • Fully caters for pile refusal ensuring connection regardless of pile penetration achieved
  • Single tool  may be used repeatedly for a wide range of pile sizes
  • Operates at any water depth
  • C-lok Connector has full qualification testing and is a  field proven LRS approved design
  • Operated by a standard Workclass ROV (Class III) without specialist ROV tooling
  • Common ‘Fly to Place’ tool (60 kg) available for C-lok 300 and C-lok 150 versions
  • Suitable for full range of API pile sizes and fabrication tolerances
  • Allows repetitive use of the hydraulic tool with a full redundancy
  • All hydraulic  equipment is recovered to surface using a simple vertical lift
  • Suitable for  impact or vibrohammer and suction piles
  • C-lok unit may be integrated into the main structure fabrication sequence at any stage
  • The connector is able to accommodate a wide range of seabed inclinations
  • No additional deck space required
  • Tools preset on the C-lok (PCU) avoiding need for separate  tool deployment
  • Tools self centering using self-weight and may be recovered by a simple lift off
  • Allows full FAT testing in the shop along with load tests if required
  • Permanent works all  carbon steel – with full dedicated CP anodes
  • Resists all load types (6 DOF) including  torsion.
  • Ideal for pre-piling post piling, multiple and monopile foundations
  • Range of  RRU tool capacities available  (C-lok 300, C-lok 750, C-lok 900)
  • Lloyds Register Approved Design
Outline offshore procedure

The following procedure is based on a post installed pile for a conventional multi-pile subsea structure foundation:

  • Lower  structure with ‘Fly to Place’ tools pre-mounted and land on seabed
  • If levelling operation required see Subsea Structure Levelling product details
  • Lower pile and penetrate through pile sleeve allowing pile to self penetrate into seabed
  • Remove dummy hotstab and placed into dummy receptacle
  • Stab hotstab into  receptacle
  • Deliver ROV supply (max 3000 PSI)
  • Confirm  required analogue pressure reading on C-lok tool interface (typically 18,500 PSI)
  • Insert Locking Pin actuator and rotate clockwise noting number of turns
  • Open valve to relieve cylinder pressure
  • Insert Locking Pin actuator into Cylinder Release Pin and rotate anti-clockwise two turns
  • Lift off ‘Fly to Place ‘ tool  and recover to vessel
  • Repeat above procedure for each pile

Units are fabricated, adjusted and machined prior to leaving the workshop. Each unit is subject to a complete FAT and optional load tests before shipping

Fabrications and design are carried out under a fully implemented BS EN ISO 9001 approved Quality Management System

All components, including control interface operators are detaile designed in house to ensure a robust offshore and in place performance300_fabrication


BECL provide full FAT and optional Load Test facilities to demonstrate both functional performance and perform hydraulic pressure testing and qualification load testing of the C-lok units300-testing


Design & documentation

Supply Includes a complete project specific documentation pack including:

  • Stand alone C-lok Design Report
  • Optional FE analysis
  • Optional fatigue assessment
  • AFC drawings
  • Handling Procedures
  • Operating procedures
  • FAT and optional Load Test Procedure
  • Fabrication Dossier including material certificates, ITP, Certificate of Conformance, welding, NDE and coating procedures and reports, FAT certificates and dimensional reports.




Video – C-lok 300  ‘Fly to Place’ Tool 

Video – outline offshore procedure.
The C-lok 150  uses an identical offshore procedure and ‘fly to place’ tool to the C-lok 300 but the PRV has been adjusted to suit the de-rated pressure.