The item in question is a liquid bulk container known as a “Flexitank. It is a container specifically designed for the transport of fluids with a capacity of 22,000 Liters and is intended for repeated use. It consists of an inner liner made of polyethylene sheeting and an outer fabric woven of polypropylene strip (less than 5mm in width) and coated on the inside of the fabric with polypropylene plastic which is visible to the naked eye. The Flexitank is equipped with steel braces and supports enabling it to be secured to a transporting conveyance. The steel supports consist of horizontal bars of square tubing 2” x 2” and vertical bars of steel flat bar with a width of 2” and a thickness of 3/8”. The steel supports form walls around the liquid filled tank which facilitate handling and securing to the transporting conveyance.
[1] Please importantly note that only the relevant portion of the related is displayed above. You may refer to the said customs ruling for the entire ruling explanation.
[1]. https://rulings.cbp.gov/ruling/N063921