Technology Reference / Primary Packaging & Filling / Aluminum Can Filling & Seaming
Primary Packaging & Filling

Aluminum Can Filling & Seaming

Filling a beverage into an aluminum can and forming the double seam that joins lid to body — the seam is the entire integrity of the package, with no liner backup behind it.

This is the filling and seaming step itself — product into the can and the double seam that closes it.Primary Packaging & Filling Pasteurization or hot-fill treats the beverage around seaming so the sealed can stays stable on the shelf.Thermal Processing & Preservation Once the cans are seamed and coded, they move on to labeling, multipacking, and palletizing.Labeling, Secondary Packaging & Logistics
What it is

The whole package integrity is one rolled seam.

Aluminum can filling and seaming is a high-speed beverage operation that fills product into aluminum cans and forms the hermetic double seam joining the lid (end) to the can body. The seam is the entire integrity of the package. Carbonated products use counter-pressure filling to retain CO₂; the double seam must be dimensionally correct or the can leaks or spoils.

Unlike a capped bottle, there’s no gasket or liner to fall back on — two pieces of aluminum are rolled together into an interlocked seam, and that geometry is the only thing standing between the product and the outside.

The levers are double-seam dimensions (the critical control), fill level, carbonation, seamer setup and maintenance, and the can/end spec. Seam dimensions are measured by routine teardown and scope — there’s no other way to know the seam is sound, because a bad one looks fine from outside.

Cans are rinsed and conveyed, filled (counter-pressure for carbonated) to net content, the lid placed and the double seamer rolls the body flange and lid curl together, seam dimensions checked, then pasteurized or treated if required and packed.

Process flow
1

Cans depalletized, rinsed/inverted, and conveyed

2

Filled (counter-pressure for carbonated; still-fill otherwise) to net content

3

Lid placed; double seamer rolls the body flange and lid curl into the interlocked double seam

4

Seam dimensions checked (seam scope/teardown); fill, CO₂, and coding verified

5

Pasteurized or treated if required; packed

Hermetically seamed filled cans

The leversDouble-seam dimensions (the critical control), fill level, carbonation, seamer setup and maintenance, and can/end spec.
Why it matters

No liner backup — so the seam teardown is the make-or-break control.

The double seam is the hermetic seal, and there’s no liner backup, so seam integrity — measured by routine seam teardown and dimensions — is the make-or-break control for shelf life and safety. A seam out of dimension leaks, admits microbes, or fails under pressure, and none of that is visible without actually tearing a seam down and measuring it.

Fill and carbonation set quality and the pressure the seam has to hold, and the internal can coating’s food-contact compliance matters for acidic products. The discipline is routinely measured seam dimensions against spec, controlled seamer setup and maintenance, monitored fill level and carbonation, an internal coating suited and compliant for the product’s acidity, post-seam leaker and dome inspection, and requalification of any can/end supplier spec change.

21 CFR 174–178 · food-contactGoverns the interior can coating and any component that touches the beverage, so the food-contact surface is cleared for its intended use.
21 CFR 113.60 · double-seam integritySets the container-closure requirements for the sealed can, so the double seam is examined and holds a hermetic seal.
21 CFR 113 · if retortedApplies when a low-acid product is thermally processed in the sealed can, setting the process controls that keep it commercially sterile.
21 CFR 101.7 · net quantityRequires an accurate net-quantity-of-contents declaration, so your fill has to hold the amount stated on the can.

Food-contact coating under 21 CFR 174–178 (retorted low-acid cans add 21 CFR 113); double-seam integrity under 21 CFR 113.60 and net quantity under 21 CFR 101.7 anchor the rest.

How it compares

Why a maker cans — and what they trade.

The can is light, opaque, and fast to chill. Knowing what it was chosen over tells you what the beverage needed.

vs.

PET/glass bottle

Bottles reclose and show product.

The tradeCans are light, opaque (full light barrier), and chill fast, but can’t be resealed.
vs.

Pouch

Pouches are lighter still.

The tradeThey lack the rigidity and the proven hermetic seam of a can.
vs.

Carton (aseptic)

Cartons suit aseptic ambient liquids.

The tradeCans suit carbonated and retort/pasteurized beverages that need pressure resistance.
Where it tends to go wrong

The gaps a reviewer looks for on a can line.

None of these are exotic. They’re the quiet places a seam goes out of spec across many cans — recognizable the moment you’ve run a seamer.

Double-seam dimensions aren’t routinely measured (teardown/scope) — the one critical control left to chance.

Seamer maintenance and setup drift, producing marginal seams across many cans.

Fill level and carbonation aren’t monitored — pressure on the seam, net content.

The internal can coating isn’t suited or compliant for an acidic or aggressive product.

Post-seam handling (dome reverse, leakers) isn’t inspected.

Can/end supplier spec changes aren’t requalified.

If this is your operation

Six things to check against your own records.

Not an audit — a read you can run yourself before anyone else does. Pull a recent seam-teardown log and walk it.

01

Ask how often double-seam dimensions are measured (teardown) and against what spec.

02

Check seamer setup and maintenance records.

03

Review fill-level and carbonation monitoring.

04

Confirm the can coating suits the product’s acidity.

05

Look at leaker/defect inspection after seaming.

06

Verify can/end spec changes were requalified.

Applications

The same seam, across very different beverages.

The product changes — the discipline never does: measure the seam, hold the fill and carbonation, match the coating.

Food & beverage

Carbonated soft drinks & seltzers

Counter-pressure-filled carbonated drinks where the seam holds CO₂ pressure and dimensions are the safety control.

Food & beverage

Beer & hard seltzer

Canned alcohol where seam integrity and (often) tunnel pasteurization carry shelf life.

Supplement / functional

Energy & functional drinks

Functional and energy canned beverages, where fill, carbonation, and coating compatibility govern.

Food & beverage

Coffee, tea & juices

Still and lightly carbonated coffees, teas, and juices, where acidic products demand a compliant internal coating.