Subsea clamp design and installation: Tools and techniques

Subsea clamps have multiple functions involving securing, restraining, and connecting subsea equipment, structures, and pipelines. In the splash zone, they shield and stabilise equipment and pipelines against wave impact and debris, secure underwater flowlines, protect anti-corrosion coatings and sacrificial anodes, and facilitate maintenance activities without requiring extensive operations.

At OceanTech, we offer a wide range of services to cater to our clients' diverse needs, including subsea clamp/guide design, repairs, modifications and installations. These projects thrive on careful strategic planning, the use of specialised robotic tools, proven rigging techniques, and rigorous testing at our Subsea Test Center in Trondheim.

Careful project planning

Planning is crucial to ensure the safety, efficiency, and success of any splash zone project. Here are some key considerations that are typically addressed in the planning phase:

• Pre-installation inspections. Pre-installation inspections play a pivotal role in the planning phase of subsea clamp installations. They help ensure that the installation process proceeds smoothly, safely, and in compliance with regulatory standards.
• Environmental conditions. The conditions in the splash zone can vary significantly across different oceans. Understanding and assessing specific factors such as wave patterns, temperature, and potential for extreme weather events inform the design and installation approach.
• Material selection. The clamp material must be able to withstand a harsh marine environment, and maintain structural integrity over time. When selecting materials, a corrosion risk assessment that considers exposure to seawater, temperature fluctuations, and mechanical stress is typically conducted. 
• Design specifications. In the planning phase, we also develop detailed design specifications for the clamps, including size, load-bearing capacity, and compatibility with the equipment they will secure.
• Regulatory compliance. Compliance with recognised technical standards, environmental regulations, and health and safety regulations, is a critical aspect of any splash zone project.
• Installation methodology. Careful planning of the installation process, including equipment selection, rigging technique, and placement method, ensures project effectiveness and safety. 

OceanTech’s installation methodology does not require divers, remotely operated underwater vehicles (ROVs), or support vessels. Instead, we rely on cutting-edge robotic solutions and topside-deployed access tools. This approach provides exceptional flexibility, effectively overcoming the challenges presented by waves and strong currents. Moreover, it ensures precise alignment and positioning of the clamps, enhancing the accuracy of our installations.

Specialised tools and equipment

Subsea clamp installations typically involve the use of various specialised tools and equipment, including hydraulic torque tools, winches and cranes, alignment and positioning tools, subsea cameras, cutting tools, pneumatic tools, and subsea tooling containers.

OceanTech's splash zone tools and equipment comprise a control unit/cabin/suitcase, a hydraulic power unit (HPU), and a container housing lifting equipment and the splash zone tools themselves:

• Our robotic tools are installed from the platform, and controlled from a purpose-built control unit on the topside of the platform.
• Lifting equipment, such as cranes and winches, is transported offshore within dedicated containers. The choice of lifting equipment is made based on the unique project requirements and prevailing conditions.
• Prior to and during clamp installations, we use specialised tools such as our robotised inspection tools, vertical access tools, manipulator arms, mechanical tools, and diamond wire saws. High-pressure water jet kits can also be employed for cleaning or preparation of surfaces, which may be necessary before attaching the clamps.

Every tool and technique is crafted in-house by our engineering team, boasting extensive field expertise garnered from splash zone projects worldwide. Our tools undergo thorough verification and certification by Det Norske Veritas (DNV), a testament to their reliability in the challenging marine environment. This certification also ensures full compliance with safety standards outlined in the NORSOK standard Z-015. When working on projects beyond the Norwegian continental shelf, we adhere to local requirements and regulations to ensure the highest safety and performance standards are met.

Our Subsea Test Centre plays an important role in refining our tools, conducting full-scale testing to ensure their reliability and effectiveness. This allows us to expedite the deployment of our tools offshore.

Advanced rigging techniques

Selecting the right rigging technique is paramount for the secure and precise installation of clamps onto underwater structures. At OceanTech, we use lightweight tools and equipment, deployed from the platform using specialised rigging methods. This approach eliminates the need for ROVs, divers, or crane vessels to guide the equipment into position.

Central to our installations are our state-of-the-art robotic solutions. Our systems are equipped with manipulator arms and specialised tools, operated remotely to position and secure the clamps. Real-time feedback ensures impeccable alignment. If required, we apply tension or torque to the subsea clamps, guaranteeing their secure fastening.

Throughout the installation process, we maintain vigilant oversight, conducting continuous monitoring and stringent quality control checks to confirm the clamps' integrity and functionality. In cases demanding access to confined underwater spaces, we may enlist the expertise of subcontracted rope access technicians. These skilled professionals employ ropes and specialised gear to navigate and perform rigging tasks with precision. Our trusted strategic partners are renowned for their extensive experience in this field.

Successful OceanTech subsea clamp installations yield a myriad of benefits, including safety, environmental preservation, cost-efficiency, and the overall dependability and efficiency of offshore operations. They stand as an integral facet of asset management and maintenance for offshore operators, making significant contributions to the sustained success of operations.