What is an Offshore Steel Structure?
Offshore steel structures serve as essential infrastructures for the exploration and extraction of offshore oil and natural gas reserves. The surge in global oil prices in 2008 prompted a rise in offshore structure projects. An offshore structure is a hybrid of steel structure design, harbor design, and construction.
The initial offshore structures were constructed using wood, with the earliest known offshore oil drilling structure established in 1887 near Santa Barbara, California. This structure was a basic wooden wharf equipped with a drilling ring for vertical wells into the seabed. Subsequent developments included more complex projects supported by timber piers, such as those in Caddo Lake, Louisiana (1911), and Maracaibo, Venezuela (1927). Eventually, researchers realized that the lifetime of these early projects in lakes and oceans was limited due to the attack of marine organisms.
There are various applications of offshore structures such as Offshore Vessels, Drilling Platforms (bridges, booms, decks, living quarters, process skids), Ro-ro Ramps, Headstocks, Pontoon, Dolphin, Gangway, and Subsea Structures.
The offshore vessel serves operational purposes such as oil exploration and construction work on the high seas. It provides not only exploration and drilling of oil but also the provision of necessary supplies to excavation and construction units located on the high seas.
There are four main groups of offshore vessels:
Oil exploration and drilling vessels.
Offshore support vessels
Offshore production vessels
Construction/special purpose vessels.
In offshore structures, there are complex installations used in the extraction of oil and gas from the earth’s crust.
Some of the components are:
Bridges – these are the pathways of personnel and equipment for transferring materials and facilitating communication between different parts of the offshore installation. There are interfaces such as electrical, instrumentation, and piping interfaces from one platform to another
Booms – these are used for oil spill response operations to contain and deflect oil away from sensitive areas. It can also be part of lifting and handling systems
Decks – this is the flat surface area at the top of the structure where most of the facilities are located. Here is the drilling area, processing facilities, and living quarters.
Living quarters – this is where the crew lives. There are sleeping quarters, dining areas, recreational facilities, and sometimes there are also medical facilities.
Process skids – these are pre-assembled units that have a process system or part of a process system. They are often used in the oil and gas industry for easier and lighter installation and operation. It can include systems for oil-gas separation, water treatment, chemical injection, etc.
The RoRo, short for roll-on/roll-off – are the vessels used to carry wheeled cargo such as cars, trucks, and heavy machinery that are taken out and put in using their own wheels or platform vehicle. The RoRo ship, often called RoRo ramps, is designed to accommodate the weight and dimension of the various vehicles.
The design of RoRo ramps follows a specific code of practice such as the British Standard BS 6349-8:2007, which provides guidelines for RoRo ramps. It generally consists of a metal gangway with dimensions suitable for each case. It is joined to the ground and driven by a mechanism that allows it to reach a suitable contact position with the boat. Some challenges faced by engineers in making this are the harsh marine environment, so regular maintenance of these and corrosion-resistant materials is needed to ensure the longevity of the ramps.
Headstocks refer to the concrete structure at the top of a set of sheet piles that hold them together. They must be robust enough to withstand the harsh marine environment and dynamic loads imposed by waves, wind, and currents.
The pontoon-type offshore structures, also known as Very Large Floating Surfaces (VLFSs), are artificial islands used for multiple purposes, including floating airports, bridges, breakwaters, piers and docks, storage facilities (oil and natural gas), wind and solar power plants, and even habitation. Its basic element is a box structure, resting on the water surface intended for deployment in calm waters such as a cove, lagoon, or harbor. It is supported by buoyancy on the sea surface. Steel-concrete composite materials can be used to build this floating structure. Safety and strength requirements, operating conditions, etc. must be considered. The pontoon offshore structure uses a mooring system to keep it in position. These systems use a combination of heavy anchor chains and wire ropes attached to anchors at the seabed.
In the context of offshore structures, the dolphin is a group of pilings arrayed together to serve various purposes. It acts as a protective hardpoint along the dock, waterway, or shore, as it is the point of stabilization of the dock, bridge, or similar structures, as a mooring point and base of navigational aids. It usually contains several piles driven into the seabed or riverbed, connected above the water level to provide a platform or fixing point. Dolphins are also used to protect against possible ship impacts. One notable example of the use of a dolphin is to protect the Sunshine Skyway Bridge across the mouth of Tampa Bay.
The gangway is a specially designed access system that can provide workers with safe and stable access to offshore installations. It connects the vessel or platform to the shore or another vessel, allowing safe access for personnel, equipment, and supplies. They are designed to counteract the ship’s multidimensional swing motions and keep the transfer object steady. One of the successful projects was the dynamic model of an offshore gangway under dynamic load presented in the Journal of Marine Science and Engineering. There was a thorough examination of the equation to carry out the mathematical model that was verified by joint simulation.
Subsea structures are underwater constructions installed on the seabed for the foundation, support, and protection of subsea oil and gas processing equipment. The design and analysis of these involve structural analysis, piping, and finite element analysis. In a case study, inventors used remotely operated vehicles (ROVs) to retrofit subsea infrastructure in 450-foot water depths offshore Trinidad and Tobago. All installations have complicated computations documented for analysis.
All of these have a history or origin that has now led to various innovations. ESC Steel Structure is one of the companies that make it possible to create such projects that can withstand the harsh marine environment. In fact, we are both ready and experienced in compliance with international standards such as DNV, NACE, ISO, ANSI, ASME, BS, ASTM, and AWS standards. They also have various projects that prove the robust materials and installation they have completed.
ESC Steel Structures is a global leader specializing in heavy offshore structure fabrication, serving various industries including general marine, offshore renewables, and oil & gas. The company’s core group of engineers collectively offers a wealth of knowledge and experience, delivering high-value steel structures with excellent and professional service. Their applications span offshore vessels, drilling platforms, Ro-ro ramps, and subsea structures, showcasing their versatility and adaptability.
Using ESC Steel Structures’ materials in offshore structure fabrication offers several benefits. Their materials are known for their high strength and durability, making them ideal for offshore structures that need to endure harsh environments. ESC Steel Structures’ materials are resistant to corrosion, crucial considering that offshore structures are constantly exposed to saltwater. Using their materials can lead to significant cost savings in terms of maintenance and repair costs, contributing to the economic viability of offshore structures.
Learn more about ESC Steel Structures, visit our website at escsteelstructures.ph. We offer a wide range of products and services, including Bailey Bridge, Bridge Structures, Pre-engineered Buildings, Port & Offshore Structures, Offshore Platforms, Pressure Vessels, Steel Bridges, Mining Excavation, Steel Towers, Rail Infrastructures, and others. For consultation and project discussion, you can reach us at +632 8526 8839 or via email at philippines@escpile.com
Recognition is due for the dedication and tireless efforts of our team. The unwavering commitment to excellence has played a vital role in successfully securing and executing our projects, showcasing our combined expertise.
ESC’s reputation is built on excellence and commitment in providing high-quality, efficient, and cost-effective solutions. We can provide competitive prices by adhering to engineering innovations and advance technologies that enhance safety and product quality, reduce unnecessary operational costs, and create added value to our products and services.
The industry’s outputs are utilized by both commercial and industrial enterprises, such as electronics, steel sections manufacturing, and shipbuilding, among others. Hence, the industry’s demand for steel production has extremely increased throughout the years.
Manufacturers/suppliers having innovative tools and equipment are likely to finish the production projects without any delays, increasing efficiency and quality for low costs.
One of the criteria that qualifies a metal fabricator is its capability to design and formulate engineering solutions for different project specifics. A metal fabricator should be able to work with drawings, translate drawings and specifications to shop drawings, and design a project from scratch if necessary including undertaking field investigation works.
300,000 mT Annual fabrication capacity in total more than 15 factories
With ESC’s well-established facilities in United Arab Emirates and China, and its vast global sales and logistics network, the Company has been providing structural steel fabrications around the world for more than 30 years. Our track record in different continents and regions demonstrates a hard-earned success and recognition as characterized by a wide variety of project types and magnitudes – from small components to large structures. Some of our accomplishments are as follows:
Structural steel can create a huge reduction in the overall cost by the accumulation of savings in logistics, construction time, equipment cost, labor cost, and material cost.
Structural steel building can be 30% lighter than conventional building when properly designed and constructed. This is a factor that can greatly reduce the costs of foundation works and the overall degree of construction difficulties.
