1. Definition of Offshore Containers
Offshore containers are transportation equipment used in the offshore oil platform environment, with a total weight generally less than 25 tons (as defined by DNV).
They are always carried by lifting appliances fixed on the lifting lugs.

2. Types of Offshore Containers
(1) Offshore transport containers, including general containers, open-top containers, tanks, bulk cargo containers and special containers.
(2) Service offshore containers for offshore oil platform projects, mostly used as temporary equipment, including laboratories, workshops, warehouses, power workshops, control consoles and cable boxes (if there is electrical equipment inside the offshore container, it must be safety-certified for electrical appliances).
(3) Waste skips.

3. Special Requirements for Offshore Containers
(1) Offshore containers are always handled by lifting lugs, and general containers cannot meet their transportation requirements.
(2) The strength of offshore containers should be able to withstand the impact of operating in the marine environment with a wave height of 6 meters.
(3) The design temperature (TD) of offshore containers is lower than -20 °C, so the impact requirements for steel plates of different thicknesses are as follows:
For t ≤ 12mm: impact temperature TD + 10;
For 12mm < t ≤ 25mm: impact temperature TD - 20.
(4) When the total weight is greater than 1 ton, the thickness of the main structure on the outside of the corner posts and bottom beams shall not be less than 6 mm, and that of other main structures shall not be less than 4 mm. (The main structure refers to the structure that transfers the load to the hook, including at least the upper and lower side beams, the upper and lower end beams, corner posts, lifting lugs and other structures considered necessary.)
(5) The thickness of the metal plates of the secondary structure shall not be less than 2 mm. (The secondary structure refers to the structure that is not used for designing and calculating strength and stiffness, including doors, walls, roofs, stiffeners, waves, internal bolt points and tank protection structures.)
(6) Special test requirements:
a) Airbag tests at both ends are 0.6P.
b) For 4 lifting lugs, the internal load is 2.5R - T.
c) For 2 lifting lugs, the internal load is 1.5R - T.
d) Vertical impact test, with an internal load of 1.0P, the container tilted at 5 degrees, but the highest and lowest points shall not exceed 400 mm, and the bottom can be padded with a thickness not exceeding 50 mm. Operation method 1 (drop method): quickly release from a position at least 50 mm high (the end at 50 mm high may be the weak end). Operation method 2 (lowering method): the constant speed of lowering shall not be less than 1.5 m/s.
(7) The materials of each part on the main structure must be traceable.
(8) The welding process of the main structure must be certified in accordance with the requirements of ISO 15624. Samples used for the welding process must undergo bending, tensile, -10 °C impact, weld bead hardness testing, weld bead X-ray film inspection, weld bead magnetic particle inspection and weld bead macro-metallographic examination.
(9) Welders who weld the main structure must be certified according to EN 287-1. The weld samples of welders must be bent and inspected with pearlite flakes.
(10) The weld bead of the main structure should pass 100% magnetic particle inspection or dye penetrant inspection (meeting the requirements of Class 1 standards). If possible, 20% of the weld beads should undergo ultrasonic inspection (meeting the requirements of Class 2 standards) (the minimum detection thickness is 8 mm), 10% of the weld beads should undergo X-ray film inspection (meeting the requirements of Class 1 standards), and 100% of the lifting lugs should undergo ultrasonic inspection (meeting the requirements of Class 2 standards).