Also called Container corner fittings, ISO corner castings
Corner castings are the eight cast steel fittings, one at each top and bottom corner of a shipping container, that give the box its only structural connection points for lifting, stacking, and locking down. Every crane hook, spreader bar, twist lock, and lashing chain that touches a container grabs one of these eight fittings, never the steel skin. They are welded into the corner posts and hold the oval holes that make handling equipment interchangeable across the whole shipping industry.
Eight. That is the whole count on a standard container, one welded into the top of each corner post and one into the bottom. Nothing bigger, nothing smaller, and nothing added for a longer or wider box, because the number is set by the ISO standard the whole shipping industry builds to.
What changes from that fixed number is how the castings get used. A container sitting still in a yard never calls on them at all; the box just rests on its base. The moment a crane, a chassis, or a stack of other containers gets involved, every ounce of that load routes through these eight points, and the walls and roof carry none of it.
Each casting has an oval opening on its top, bottom, or side face. A spreader bar's twist lock drops into the top openings to lift the box by crane. A chassis lock rises into the bottom openings to pin the container to a truck trailer. When boxes are stacked, a twist lock sits between the bottom castings of the upper container and the top castings of the one underneath, so the stack locks together as a single unit rather than four loose boxes.
Because the openings and spacing are standardized, any genuine ISO container, whatever the manufacturer or build year, accepts the same lifting and locking gear. That is the entire point of the standard: a crane operator in Norfolk and one in Woodlawn are working with the same eight points on every box.
A used cargo-worthy container can have plenty of surface rust and dents in its corrugated panels and still be structurally sound, because those panels were never load-bearing. The castings are a different story. A cracked weld, a deformed opening, or a casting that has been bent out of true is a real structural flaw, since it is one of only eight points holding the box together under load.
That is part of why a walk-around before delivery matters on a used unit: the corner castings are worth a close look, not just the paint.
Walk our Woodlawn yard and we will show you exactly how the fittings work.
Same-day reply. We'll send a real number, a real delivery window, and any photos we need to confirm fit.
You'll hear back from us today (or first thing tomorrow if it's late). For anything urgent, call (276) 237-6144.