Nine ways a cage goes out of square
A composite IBC stacks on its cage, so a frame that will not sit square is a container that cannot do its main job. Here is every way we see it happen, and which ones a jig fixes.
- Sheet
- 09
- Revision
- 2026-10
- Scale
- 1:1
- Drawn at
- Peoria IL
Everything a steel cage does, it does by being square. Load transfers through the corner posts; stacking depends on posts aligning; racking depends on the base sitting flat. Three-eighths of an inch of diagonal error across the base is where we stop calling it cosmetic.
Forklift strike on a corner post
The classic. A dent and a lean, usually at the entry side. Repairable, and the giveaway is paint transfer from a fork tine.
Frozen bottle pushing outward
A bottle that froze full expands into the cage. The frame bows at mid-height, evenly, on two sides. Repairable, but the bottle never is.
Bottle-on-bottle stacking
Load bypasses the posts and goes through the polyethylene. The lower cage racks and twists. Repairable; the lower bottle is not.
Strapped without corner boards
A strap tightened directly across tube at a corner pulls the joint. Often shows as a popped weld rather than a bow. Repairable.
Mixed-height stacking
A 330 on top of a 275 puts load between posts rather than on them. Slow, progressive racking over weeks. Repairable early, not late.
Lifting by the cage top rail
Someone slung it from the top instead of forking it from the base. Pulls the top frame out of plane. Usually repairable.
Ice-jacking under the pallet
Water freezes under one runner over a winter and lifts a corner. The frame twists to follow. Repairable, and often the pallet needs re-decking too.
Perforating rust at the base rails
Years on bare ground, moisture wicking up. This is the one that is not repairable — there is no metal left to straighten.
Bad previous repair
A weld laid over a crack without cutting back, or a post heated and bent cold. Sometimes recoverable, often not worth the hours.
How we check it, in forty seconds
- Set it on known-flat concrete and look at all four pallet corners. A rock means twist.
- Measure both base diagonals. More than three-eighths of an inch of difference and it goes to the jig.
- Sight down each corner post from the top. Bows show up against a straight line far better than against a tape.
- Press a thumb on each weld at the base and mid-rails. A weld that moves is a weld that has cracked under the paint.
- Set a second empty cage on top. If the posts do not land on posts, nothing above it ever will either.
“If it will not stack, it is not a tote. It is a tank with a fence around it.”
— Rebottling bench
Prevention, which is free
- Empties three high, posts aligned, same height containers only.
- Filled containers two high and only if the units are rated; one high in transit, always.
- Corner boards wherever a strap crosses tube. They cost cents and they prevent the most common repairable damage we see.
- Store on concrete or asphalt, not on bare ground. Base-rail rust is the one cage failure with no repair path.
- Fork from the base, lift from the base, never sling from the top rail.
- If a container rocks on flat ground, take it out of the stack now rather than after it has racked the two under it.
Cage sound, bottle finished?
That is a rebottle: roughly 60% of the container by weight reused and about half the cost of replacement.