What is an offshore container?
As defined by the International Maritime Organization, an offshore container is a “portable unit, specially designed for repeated use in the transport of goods or equipment to, from or between fixed and/or floating offshore installations and ships.”
Offshore containers also refer to containers and portable tanks for dangerous goods. There are three categories of offshore containers, as defined by the European Committee for Standardization (CEN):
Offshore containers also refer to containers and portable tanks for dangerous goods. There are three categories of offshore containers, as defined by the European Committee for Standardization (CEN):
Offshore freight containers.
An offshore container built for the transport of goods, which can include general cargo containers, cargo baskets, bulk containers, special containers, boxes and gas cylinder racks.
Offshore portable tanks are also included in this category. These are used to transport dangerous goods used offshore, and must also meet the International Maritime Dangerous Goods code.
An offshore container built for the transport of goods, which can include general cargo containers, cargo baskets, bulk containers, special containers, boxes and gas cylinder racks.
Offshore portable tanks are also included in this category. These are used to transport dangerous goods used offshore, and must also meet the International Maritime Dangerous Goods code.
Offshore service containers.
Custom-built containers for a specific task that are generally temporary. Examples include pressurized container, labs, workshops, power plants and control stations.
Custom-built containers for a specific task that are generally temporary. Examples include pressurized container, labs, workshops, power plants and control stations.
Offshore waste skip
A container that holds waste that can be open or closed.
Offshore containers are also commonly called “skids” in the offshore oil and gas community, as they are often used to transport large components to drilling and production rigs. These can be as simple as frames that hold the contents. The skid, along with its contents, is sometimes referred to as a “skid package.”
A container that holds waste that can be open or closed.
Offshore containers are also commonly called “skids” in the offshore oil and gas community, as they are often used to transport large components to drilling and production rigs. These can be as simple as frames that hold the contents. The skid, along with its contents, is sometimes referred to as a “skid package.”
ISO containers vs. offshore containers
Offshore containers evolved from the common intermodal or ISO shipping container.
“Intermodal” refers to the ability to move the container by different methods without having to unload it at each transfer (ship to rail to truck, for example).
The intermodal came into use in the 1950’s and changed the world of commerce by providing a standard, low-cost method to transport goods internationally. The international Standards Organization published ISO standards for containers between 1968 and 1970, cementing the role of the shipping container in the global economy.
The IMO also studied the safety of containerization in marine transport and in 1972 the International Convention for Safe Containers (CSC) was adopted.
There are, in general, three factors that separate offshore containers from ISO containers:
Exposure to harsh environments. Offshore containers are often left exposed to open seas on the decks of supply vessels, and also loaded to platforms in harsh weather conditions, this also means that the minimum design temperature is normally specified as -20° C and the primary structure requires material of sufficient toughness for -20° C.
Loading and unloading forces. Because many offshore containers cannot be used with typical lifting equipment such as spreader beams, the methods of loading and unloading put different types of pressure on the structures of offshore containers. Offshore containers are supplied with a permanently installed sling set. Most do not have corner castings, and if they do, they are not allowed to be lifted from them.
Non-standard designs. Most offshore containers are built to fit a specific piece of equipment, and as a result do not fit into the categories of ISO containers.
“Intermodal” refers to the ability to move the container by different methods without having to unload it at each transfer (ship to rail to truck, for example).
The intermodal came into use in the 1950’s and changed the world of commerce by providing a standard, low-cost method to transport goods internationally. The international Standards Organization published ISO standards for containers between 1968 and 1970, cementing the role of the shipping container in the global economy.
The IMO also studied the safety of containerization in marine transport and in 1972 the International Convention for Safe Containers (CSC) was adopted.
There are, in general, three factors that separate offshore containers from ISO containers:
Exposure to harsh environments. Offshore containers are often left exposed to open seas on the decks of supply vessels, and also loaded to platforms in harsh weather conditions, this also means that the minimum design temperature is normally specified as -20° C and the primary structure requires material of sufficient toughness for -20° C.
Loading and unloading forces. Because many offshore containers cannot be used with typical lifting equipment such as spreader beams, the methods of loading and unloading put different types of pressure on the structures of offshore containers. Offshore containers are supplied with a permanently installed sling set. Most do not have corner castings, and if they do, they are not allowed to be lifted from them.
Non-standard designs. Most offshore containers are built to fit a specific piece of equipment, and as a result do not fit into the categories of ISO containers.
Offshore container certification process
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Design appraisal
The container’s structural drawings are reviewed according to the standards referenced in IMO MSC/Circ. 860. Details of the materials and strength of the cargo containment structure, as well as the lifting and securing arrangements are appraised. Drawings must show: -- Dimensions and load ratings -- Material specifications -- Details of welding methods and weld sizes -- Details of any other fastening methods -- Details of any special treatment for materials -- Details of sealant materials -- Details of corner fittings and closure mechanisms, together with name(s) of the manufacturer(s) of these parts -- Mandatory marking |
Survey
A qualified surveyor inspects the process to meet code requirements. Inspection programs include: -- Verification and testing of materials -- Welder qualification -- Acceptance of weld procedures -- Acceptance of NDE procedures -- Witness and acceptance of prototype testing -- Verification of identification and marking |
Testing
Type approval of a container involves the construction and testing of a prototype built according to the approved drawings. It must also use the same materials as proposed for normal production. Tests include: -- Four-point lift using all padeyes -- Two-point lift test using opposed padeyes -- A vertical impact test -- A tilt test -- Tanks for dangerous cargoes shall in addition be tested with all the requirements of the IMDG code. |
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