A steel coil is heavy, and every protection decision is a load decision. When coils are stacked on their faces, the face edge of the lower coil carries the weight of the coil above through a narrow rim. A paperboard ring spreads that load along a radial band and keeps steel off steel at the one point where a burr or a dent becomes a quality claim.
Face stacking is where the ring pays
Coils stacked eye to the sky put the full weight of the stack through the face edges. Without an interface, the rim deforms and the wrap loosens; on a coated coil the deformation shows as a bright ring that cannot be hidden.
The ring also separates steel from steel. Two coil faces in contact are a sliding pair under vibration, and the mark that results is the kind of defect a customer photographs.
Specification at a glance
Three numbers matter, and the third is often the one that fails: inner diameter, ring width and board thickness. For steel, the thickness is chosen by stack height and coil weight, and it is worth confirming on a trial rather than assuming.
| Coil | Ring inner diameter | Ring width | Board |
|---|
| Coil, eye to sky | To the coil OD | Wider than strap path | Thicker for stack height |
| Coil, eye to wall | To the coil OD | Covers the rim | Standard |
| Coated coil | To the coil OD | Covers the rim | Clean, dry board |
| Banded with 2 straps | To the coil OD | One wide ring | Spreads between straps |
| Small coil | To the coil OD | Narrow band | Standard |
Strap path and the ring width
Coil strapping crosses the face, so the ring should be at least as wide as the strap path. A narrow ring under a wide strap concentrates the load at the strap edges, which is the opposite of the intent.
Where the coil is banded with several straps, one ring of adequate width is better than several narrow rings, because the ring is also spreading load between the straps.
Moisture, rust and the contact surface
Paper against bare steel in a humid container is a rust risk. Fit the rings dry, keep them wrapped until use, and do not leave a damp ring against a coil face overnight.
Where the coil is oiled or coated, discuss the surface with the supplier. The ring does not need to be special, but it does need to be dry and free of grit.
Questions buyers ask before ordering
Is a paper ring strong enough for a steel coil?
It spreads face contact and separates steel from steel. The pallet or cradle still carries the stack.
What board thickness for a stacked coil?
Chosen by stack height and coil weight, and confirmed on a trial rather than assumed.
How wide should the ring be?
At least as wide as the strap path, and wider where several straps cross the face.
Can it cause rust?
A damp ring against bare steel can. Fit dry rings and keep them wrapped until use.
One wide ring or several narrow ones?
One wide ring, because it also spreads load between strap positions.
Share the drawing or a product sample with mona@hengnicepacking.com and we will confirm feasibility before quoting.
