Introduction
Piling installation programs sometimes call for piles to be installed well in advance of use. This may expose the projecting pile section to excessive corrosion and or marine growth.
To resolve this issue BECL have developed a simple diverless field proven solution to protect the exposed pile length until the structure installation campaign has been completed.
The diverless ROV friendly C-lok Pile Cap is a purpose made fitted cap that effectively seals and protects the projecting pile section. The cap contains both dedicated CP anodes to maintain corrosion protection inside and out plus biocide and oxygen scavengers to effectively control marine growth.
The Pile Cap is customised to meet the project requirements and is fully compatible with the C-lok connector. The use of the Pile Cap allows dramatic cost savings whereby a single pile installation campaign may be used to set all the piles for both current and a future staged field development.
Application
The C-lok Pile Cap is a custom made protection sleeve ideal for pre-driven piles deployed in advance of use. The cap offers long term protection from corrosion and marine growth. The units are designed to allow both pre and post installed biocide and oxygen scavenger chemical treatments. The ROV friendly receptacles have seals to receive and contain the chemical sticks and bundles. The fabrications incorporate internal baskets, anodes and perimeter neoprene seals in both ring and patch arrangements to keep the pile in a controlled environment until the caps are removed and the structures deployed. Features also include free flooding features to allow a fully controlled decent, shaped perforated baskets, dosing access panels, metrology transponder supports, ROV friendly lifting points and ROV friendly attachment points for future anode skids.
Outline offshore procedure
The outline procedure is as follows:
- Overboard the pile cap and lower to pre-driven pile
- Align and lower Pile Cap over the pile top and lower under selfweight until cap plate engages with pile top
- Disengage rigging and recover
If it is decided at some point to delay structure installation further then to extend the duration of protection the unit is designed to allow additional chemicals to be added and also attachment of a CP anode sled using an ROV friendly connector.
Prior to the structure installation program the C-lok Pile Caps may be simply lifted off and recovered. The units may be refurbished and reused on another pile. Immediately before structure deployment the external pile surface may be water jetted or brushed or as required using standard ROV attachments.
Key features & benefits
- Diverless
- Allows all piles to be driven in a single campaign
- Ensures protection to projecting pile against corrosion and marine growth
- Engagement under self-weight in minutes
- Dis-engagement by simple vertical lift off
- Custom designed to suit planned exposure period
- Includes seals and chemical baskets
- Design suitable for any pile diameter
- Chemicals may be replenished for duration extensions
- Incorporated ROV friendly future CP skid attachment
- Includes perforations for free flooding waterline stability and mating
- Operated by a standard Workclass ROV (Class III) without specialist ROV tooling
- Field Proven Design
- Operates at any water depth
- Operated by a standard Workclass ROV (Class III) without specialist ROV tooling
- Allows full 360 degree flexibility for heading orientation
