ISO 8362-3: Aluminium Caps for Injection Vials Explained

ISO 8362-3 is the international standard that specifies the plain aluminium caps used to seal injection vials, defining their forms, dimensions, and requirements. These are the all-aluminium caps that crimp over the rubber stopper and the vial neck to hold the stopper compressed against the glass. It is Part 3 of the ISO 8362 series, “Injection containers and accessories.” The current edition is ISO 8362-3:2001. The standard ensures the cap is dimensionally compatible with the vials and closures covered by the other parts of the series.

This guide explains what ISO 8362-3 covers, how a plain aluminium cap works, how it fits the ISO 8362 series, and how it differs from the aluminium-plastic combination caps.

Key takeaways

ISO 8362-3 specifies the plain aluminium caps for injection vials: their forms, dimensions, and requirements.
It is Part 3 of the ISO 8362 series; the current edition is ISO 8362-3:2001.
A plain aluminium cap is the all-metal seal that crimps over the rubber stopper, without the moulded plastic top of a combination cap.
ISO 8362-3 ensures the cap fits the vials of ISO 8362-1 and the closures of ISO 8362-2.
The aluminium-plastics combination caps (flip-off seals) are covered separately by ISO 8362-6 and ISO 8362-7.
The cap holds the stopper compressed against the glass, which is what maintains the container closure system seal.

What is ISO 8362-3?

ISO 8362-3 is the part of the ISO 8362 series that defines the plain aluminium caps used to seal injection vials: the all-metal seals that crimp over the stopper. It is published by the International Organization for Standardization (ISO), and the current edition is ISO 8362-3:2001.

A plain aluminium cap is the simplest seal in the series: a thin formed aluminium shell that covers the top of the vial and extends down as a skirt around the neck, with no moulded plastic top. During capping its lower edge is rolled under the vial neck flange, compressing the rubber stopper to form the seal. Tear-off and tear-down aluminium seals are practical examples of all-aluminium caps, opened by tearing the metal away rather than flipping a plastic button. ISO 8362-3 standardises the forms and dimensions of these caps so a cap from one manufacturer fits a vial and stopper conforming to the corresponding parts of the series.

What ISO 8362-3 covers

ISO 8362-3 covers the types, shapes, and dimensions of plain aluminium caps for injection vials, with the requirements those caps must meet. In broad terms it standardises:

Cap forms and dimensions. The geometry of the aluminium shell, dimensioned so the cap fits over the seated stopper and crimps under the vial neck flange.
Size designations. Caps sized to the common vial neck finishes (for example 13 mm and 20 mm) so they pair with the corresponding vials and closures.
Requirements. Material and construction requirements for the aluminium cap.

The standard exists so the cap fits and crimps reliably. A cap conforming to ISO 8362-3 seats over a stopper conforming to ISO 8362-2 in a vial conforming to ISO 8362-1, and crimps cleanly on a capping line.

How a plain aluminium cap seals a vial

A plain aluminium cap seals a vial the same way any vial seal does: by being crimped over the stopper so the stopper stays compressed against the glass. The capping head presses the cap down while rollers fold the lower edge of the aluminium skirt under the vial neck flange. The result is a permanent mechanical clamp: the stopper is held under compression, its sealing surfaces stay pressed against the glass, and the cap can no longer be lifted by hand.

What a plain aluminium cap lacks is the moulded plastic flip top of a combination cap. It is opened by tearing the aluminium (as with a tear-off seal or tear-down seal) rather than by flipping a plastic button. The sealing function is identical; the difference is the opening method and the absence of the colour-codeable plastic surface.

How ISO 8362-3 fits the ISO 8362 series

ISO 8362-3 is one of three cap parts in the series, covering the all-aluminium caps, while Parts 6 and 7 cover the aluminium-plastic combination caps. Each part of the series addresses a different component, all dimensioned to be compatible.

Part	Scope
ISO 8362-1	Injection vials made of glass tubing
ISO 8362-2	Closures for injection vials
ISO 8362-3	Aluminium caps for injection vials
ISO 8362-5	Freeze drying closures for injection vials
ISO 8362-6	Caps made of aluminium-plastics combinations
ISO 8362-7	Aluminium-plastics combination caps without overlapping plastics part

All three cap parts (3, 6, and 7) crimp over the closure of Part 2 in the vial of Part 1. The difference is construction: Part 3 is all aluminium, while Parts 6 and 7 add a moulded plastic top. Because the components are dimensioned to match, a cap conforming to ISO 8362-3 pairs with vials and closures conforming to the corresponding parts.

How this works in practice at Autofits

Autofits manufactures all-aluminium caps as well as aluminium-plastic combination seals. The all-aluminium products include tear-off seals and tear-down seals, opened by tearing the metal, alongside aluminium pilfer-proof (ROPP) caps. The combination seals, covered by ISO 8362-6 and 8362-7, include the FlipTop Optima range. The full set is on the products page. Whether all-aluminium or combination, the cap crimps over the stopper and the vial neck to hold the stopper compressed against the glass. Production runs under an ISO 15378:2017 quality system, alongside ISO 9001:2015 and ISO 14001:2015 certification and a Drug Master File, in a 75,000 sq ft Nashik facility with an ISO Class 8 cleanroom and high-speed visual inspection for dimensional control. The full certification set is on the quality page.

Frequently asked questions

What does ISO 8362-3 cover?

ISO 8362-3 specifies the plain aluminium caps for injection vials: the all-metal seals that crimp over the rubber stopper, without the moulded plastic top of a combination cap. It is Part 3 of the ISO 8362 series and standardises the caps’ forms, dimensions, and requirements so they are compatible with the vials and closures covered by the other parts.

What is the current edition of ISO 8362-3?

The current edition is ISO 8362-3:2001. ISO standards are reviewed periodically, so confirm the current edition and its requirements directly with ISO before relying on any specific clause.

What is the difference between a plain aluminium cap and a combination cap?

A plain aluminium cap (ISO 8362-3) is all metal and is opened by tearing the aluminium, as with a tear-off or tear-down seal. An aluminium-plastics combination cap (ISO 8362-6 or 8362-7) adds a moulded plastic top that flips or lifts away while the aluminium stays crimped, and gives a colour-codeable surface. Both crimp over the stopper to seal the vial.

Is a tear-off seal an ISO 8362-3 cap?

A tear-off seal is an all-aluminium cap opened by tearing the metal top away, which is the kind of plain aluminium cap ISO 8362-3 covers. The exact requirements that apply to a specific design should be checked against the current ISO 8362-3 text, since the standard sets the forms and dimensions for these caps.

How does ISO 8362-3 relate to the vial and stopper?

ISO 8362-3 standardises the aluminium cap so that it fits the vial of ISO 8362-1 and crimps over the stopper of ISO 8362-2. The three components are dimensioned to be compatible, so a cap conforming to Part 3 seats over a conforming stopper in a conforming vial and crimps cleanly to hold the seal.

Sources

ISO: ISO 8362-3:2001, Injection containers and accessories, Part 3: Aluminium caps for injection vials (https://www.iso.org/standard/33804.html)
ISO: ISO 8362-2:2024, Injection containers and accessories, Part 2: Closures for injection vials (https://www.iso.org/standard/87251.html)
ISO: ISO 8362-6:2010, Injection containers and accessories, Part 6: Caps made of aluminium-plastics combinations for injection vials (https://www.iso.org/standard/52806.html)

*Last updated: 2026-06-18. This article is general technical information, not regulatory or compliance advice; confirm current standard editions and requirements with ISO.*