For Shallow Water areas, BARDOT Group focused on developing stabilization engineering methodology and solutions for Cable to ensure the on-bottom stability on the seabed and at crossing locations.
BARDOT Group developed an advanced engineering methodology to ensure line stability on-bottom and at crossing location.
For on-bottom stability, and in order to reach the relative stability of the line, the below steps are followed:
- Global screening to identify unstable section of exposed line
- For each unstable section a first required spacing will be assessed using DNV RP F109 Generalized approach and accounting for Ballast modules characteristics (additional submerged weight & equivalent hydrodynamic diameter)
- For the most unstable sections, and to reduce the quantity of Ballast modules, as per DNV recommendation, we use our calibrated 3D Finite Element Models with different level of embedment (10, 20 & 30%). The maximum tension and minimum curvature are extracted and checked against line properties or with line manufacturer to ensure suitability
For crossing locations, the use of the DNV generalized method could lead to an underestimate of lateral movements of the line with potential influence on resulting tension build up, fatigue damage and potential underestimate of crossing dimensions. Therefore, the below methodology is followed:
- Analytical Stability Screening of all the crossings. Absolute stability analysis comparing available lateral resistance at crossing with wave and current hydrodynamic loads
- 3D Dynamic Analysis to assess the line cumulated displacement, build-up of tension and resulting curvatures under 3 hour storm event (wave/current RP Combination of 10/100 Years or 100/10 years as per DNV RP F109).
BARDOT Ballast Modules are internationally patented (Patent Ref. FR2015/050053) as its represents an innovation for stability of lines in shallow waters. The design is adapted to each project (route, line characteristics, Meteocean data and other relevant inputs).
The Ballast Modules can be made of steel or lead and are composed of 2 or 3 elements fastened together on the line requiring additional weight.
To protect them from corrosion, the steel modules are painted and equipped with sacrificial anodes, the lead modules are inert and do not require protection.
Anti-sliding pads made of qualified rubber ensure immobilization and prevent any slippage.
The manufacturing, testing and packing are done as close as possible to the final delivery location.
In some areas (crossing, corals barrier, etc.) stabilization and additional protection of the subsea line is required. Our heavy BARDUCT® provides a high level of resistance to abrasion and impact as well as an additional submerged weight (5 to 150+ kg/m) to increase lateral and vertical stability. It is an industry standard fully qualified for 40+ years service life in seawater with no need for periodic maintenance.
The half shells are linked together with a hinge and tightened using standard Anti corrosion alloy banding (Inconel, Super Duplex, or as per project specification). Bands are located in grooves which ensure a smooth passage through the machinery/chute and eliminate the need to measure spacing between straps. The design includes a male/female connection at extremities to ensure a continuous coverage.
Installation of our solutions is safe, fast and very robust.
Here below are a few inputs for your analysis:
- Installation time of Ballast modules: Laying rate + 45 seconds per ballasts
- Installation time of 10 linear meter of Heavy BARDUCT®: 6 minutes.
Our solutions are cost effective compared to other solutions, mainly because installation time and mobilization costs are saved.