External can-seam checks and seam teardown provide different information. External examination observes visible closure condition; teardown reveals features assessed through the approved destructive examination method. One should not be presented as a complete substitute for the other.
Use the actual can-and-end supplier specifications and the proposed can seamer instructions. The FDA container-closure inspection guide provides technical context, while the factory needs methods and criteria appropriate to its own format.
Identify the format and sample
Retain can and end references, seamer identity, relevant head or station identification and the sampling time. An isolated measurement with no format or machine reference is difficult to use for investigation.
| Examination | Information sought | Record needed |
|---|---|---|
| External check | Visible defects and container condition | Location and sample identity |
| Teardown | Defined internal seam measurements | Method, instrument and result |
| Specification review | Comparison with actual requirements | Current can-and-end limits |
| Response | Product and equipment action | Authorized decision and follow-up |
Use the agreed measurement method
The method determines how measurements are obtained and interpreted. Identify instruments, preparation and recording requirements in the approved procedure. Do not apply dimensional limits copied from an unrelated container or a general article.
Keep individual results visible rather than reporting only an average that conceals a concerning observation. Where a finding is uncertain, retain the sample and seek qualified review.
Connect findings to a controlled response
The double-seam defect guide helps organize investigation questions. It should not be read as an instruction to adjust rolls or tooling without the manufacturer's procedures and competent authorization.
Define who reviews findings, controls potentially affected product and authorizes further operation. A setup change and a product disposition decision require separate evidence.
Keep routine checks distinct from qualification
A format-qualification record supports a defined machine, tooling and packaging combination. Routine inspection records show what was observed during operation. Keep both connected, and review the scope when containers, ends or tooling change.
The objective is an interpretable closure-control file, not a blanket statement that a visual check or one passing teardown proves every can acceptable.
Frequently Asked Questions
Can a good-looking seam fail an internal assessment?
Are seam dimensions universal across cans?
Should one unexpected result be averaged away?
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