Offshore Container Manufacturing: How We Build an Offshore Container That Passes Its Tests First Time

An offshore container is not a shipping container with a certificate. An offshore container is a lifting appliance that also carries cargo, and we build the offshore container to that standard. Our offshore container drawings start with the lift, and every offshore container we deliver leaves the yard with the offshore container test record in hand. This is how an offshore container gets built.

An offshore container moves between a vessel and an installation, and the offshore container is lifted every time. That duty is what separates an offshore container from ordinary freight equipment, and why the offshore container is certified. An offshore container is rated to a maximum gross mass of about twenty-five tonnes in our standard offshore container range. An offshore container has to survive a significant wave height of six metres. Salt spray, low temperature and green water all attack the offshore container coating on the offshore container. An offshore container is class certified, and an uncertified offshore container does not go offshore. The offshore container also needs lifting gear that cannot detach accidentally from the offshore container. We design the offshore container around those four facts, and the offshore container drawing reflects them. A box that meets freight rules is still not an offshore container, and we never sell one as an offshore container. So every offshore container starts from the offshore container service case. That case is written down before the offshore container is priced.

Plate thickness on an offshore container is a minimum, and we treat it as the floor for every offshore container. We hold corner posts and bottom rails of the offshore container at six millimetres or more. Other main structure on the offshore container stays at four millimetres or more. Secondary members of the offshore container go no thinner than two millimetres anywhere on the offshore container. A thinner offshore container passes a drawing check and fails an offshore container survey. Design temperature for an offshore container is minus twenty degrees, or zero for an offshore container in mild waters. We confirm the steel grade of the offshore container against that temperature before the offshore container is cut. The offshore container must also resist a thirty degree tilt in any direction without overturning. That tilt case changes the centre-of-gravity assumptions we hold inside the offshore container, and the offshore container layout follows. Nothing structural on an offshore container is sized by habit, and no offshore container leaves with a thin panel.

We weld the offshore container as a continuous load path, not as a series of panels. Full penetration welds run through the offshore container top rail, bottom rail and corner post. A partial penetration weld in an offshore container creates a crack starter in the offshore container frame. The offshore container has no secondary weld that is allowed to be cosmetic. We qualify the welding procedure for the offshore container before the offshore container is built. Welders on an offshore container are qualified for the position they work in on that offshore container. We control heat input on the offshore container to keep distortion out of the offshore container frame. A twisted offshore container cannot be corrected by grinding the offshore container after the fact. Every offshore container weld is visually inspected, and critical offshore container welds are tested further. We photograph the offshore container weld map, and the offshore container file keeps it. That file is what the offshore container surveyor opens first, before the offshore container is looked at.

The pad eye is the most stressed fitting on an offshore container. We weld every offshore container pad eye with full penetration. Hot spot stress at the hole edge of the offshore container pad eye is held to twice yield or less. A four-leg set is calculated as a three-leg set, because an offshore container lift is never perfectly even. The sling angle on an offshore container stays at forty-five degrees or steeper. Every shackle on an offshore container has a breaking force of at least five times its working load. Bolted pins and cotter pins close the offshore container lifting gear, so nothing on the offshore container walks loose. Lifting gear for an offshore container is re-tested every forty-eight months. That test is a non-destructive inspection plus a proof pull at two and a half times the working load of the offshore container. We record the gear serial against the offshore container, so the offshore container stays traceable.

An offshore container is proved before the offshore container is released. The first test loads the offshore container with 2.5R-T distributed evenly. All pad eyes lift together, and the loaded offshore container hangs for five minutes. We measure beam deflection on the offshore container against span over three hundred. The offshore container must come back with no permanent set and no crack. The second test lifts the offshore container on two diagonal pad eyes only, loaded to 1.5R-T. That case is how we prove the offshore container for asymmetric handling. The third test drops the offshore container from at least fifty millimetres at one metre per second. Minor repairable deformation is acceptable on the offshore container; structural failure is not. Weathertightness is checked on ten per cent of an offshore container batch by water spray, and the rest by light. Every offshore container in the batch still gets the full offshore container lift test. We keep the offshore container test charts with the offshore container, not in a folder at the office.

Certification of an offshore container starts before the first offshore container is built. The works gets approval, then the offshore container type gets approval, then each offshore container is inspected. A surveyor looks at every offshore container at the gate, not at a sample. After delivery, the offshore container is surveyed once a year, and the offshore container surveyor signs it off. Pad eye inspection on the offshore container repeats at forty-eight months. A major repair to an offshore container triggers a temporary inspection and a full retest. That last rule is why we keep the offshore container weld records for the life of the offshore container. An offshore container without records is an offshore container that cannot be repaired economically. We hand over an offshore container file with the offshore container, and the offshore container owner keeps it. The file is part of the offshore container, not an optional extra. Buyers who lose that file lose the value of the offshore container. A surveyor who cannot find the offshore container history will survey the offshore container harder.

An offshore container carries permanent marks that cannot be painted over. The offshore container number is at least seventy-five millimetres on the face. The same number is at least three hundred millimetres on the top of the offshore container. Maximum gross mass, tare mass and net load all appear on the offshore container. Safety marks on an offshore container cover overheight, forklift handling and thermite reaction risk. The class emblem and the inspection stamp sit at the door end of the offshore container. The data plate of an offshore container records the builder, the design approval and the inspection history. We check every mark on the offshore container before the offshore container is loaded. A missing mark stops an offshore container at the quay, and the offshore container misses its sailing. That is why marking is a production step for the offshore container, not a stencil job after the offshore container is finished. Our painter signs the offshore container mark sheet before the offshore container is released.

We build offshore containers for four rough families of work, and each offshore container leaves with its own lifting case. Offshore oil and gas takes offshore containers for tools, equipment and chemicals. Offshore wind takes offshore containers for spare parts and maintenance gear. Marine engineering takes offshore containers for survey equipment and construction material. Hazardous cargo moves in an offshore container built as a tank or a cylinder frame. Each of those duties changes the inside of the offshore container and the fittings outside the offshore container. A tank offshore container carries baffles and a relief arrangement. A frame offshore container carries a protection net across the top of the offshore container. An open-top offshore container gets drainage at the base of the offshore container. Nothing on the outside of an offshore container protrudes, so nothing snags during an offshore container lift. The top of an offshore container is treated for grip, because people walk on the offshore container. Every offshore container coating is a heavy-duty system, not a decorative finish.

LongTeng Industrial builds offshore containers and custom container projects as an OEM and ODM offshore container manufacturer, from design review through fabrication, testing and delivery. Send us the duty your offshore container will see, and we will quote the offshore container against it.