20mm Tear-Off Seal for Pharmaceutical Vials

The 20mm tear-off seal is the highest-volume size in the all-aluminium tear-off range: a one-piece AA8011 shell crimped over the rubber stopper, with a perforated top torn completely away at point of use and no plastic component anywhere on the part. Inner aluminium diameter is 20.00 to 20.60 mm with a 9.70 to 10.50 mm perforation, total seal height 7.40 to 8.00 mm, aluminium gauge 0.16 to 0.20 mm, two bridges and a maximum opening force of 35 N.

This page gives the 20 mm dimensions, materials, quality position, forms of supply and applications. For the opening mechanism and the rest of the family, see the tear-off seal range.

Key takeaways

The 20 mm tear-off seal is all aluminium (AA8011) with no polypropylene disc, which places it under ISO 8362-3 rather than the aluminium-plastics combination standard.
Inner Ø 20.00–20.60 mm, perforation Ø 9.70–10.50 mm, total height 7.40–8.00 mm, gauge 0.16–0.20 mm, two bridges.
The defined perforation diameter is what gives a clean, repeatable tear initiation at this size.
Maximum opening force 35 N; standard packing 6,000 per box (2,000 in each of two bags), shipper 420 × 270 × 320 mm.
Supplied Regular, Ready-to-Use (gamma or ETO sterilized) or Ready-to-Sterilize, double-bagged for aseptic areas.
Produced under ISO 15378:2017 GMP with 100% high-speed camera inspection and AQL critical nil.

What is a 20mm tear-off seal?

A 20mm tear-off seal is the all-metal closure for a 20 mm neck vial: a deep-drawn aluminium shell whose skirt rolls under the neck flange during capping to compress the rubber stopper against the glass, and whose top face carries a 9.70 to 10.50 mm perforation so the metal can be torn away by hand.

The aluminium is not the sterile barrier. The barrier is the stopper held in compression by the crimped skirt, and the crimp survives opening. The perforation defines the tear path, so the metal separates along a controlled circle rather than ragged across the face. When the top comes off the stopper is fully exposed, which is the practical difference from a flip-off seal that reveals only a small central injection point.

The 20 mm neck is the most widely used finish for injectable vials, so this is the size most tear-off enquiries land on. Match the seal to a 20 mm vial finish and a 20 mm stopper of the same nominal diameter; vial necks follow ISO 8362-1. The distinction from the aluminium-plastic FlipTop® range is construction: nothing here is moulded, no disc to rivet, no assembly step.

Specifications and sizing

Controlled dimensions for the 20 mm tear-off seal, from the Autofits engineering drawings, with opening force and packing from the product dossier. The standard shipper box is 420 × 270 × 320 mm.

Property	Value
Nominal size	20 mm
Inner Ø aluminium (D1)	20.00–20.60 mm
Perforation Ø (D2)	9.70–10.50 mm
Total seal height	7.40–8.00 mm
Aluminium thickness	0.16–0.20 mm
Bridges	2
Max opening force	35 N
Standard packing (per box)	6,000 (2,000 × 2 bags)
Construction	One-piece aluminium, no plastic disc
Material	AA8011 aluminium with epoxy lacquer
Standard finish	Double-side silver lacquer

Tyvek bagging is offered as an alternative to the standard polybag. Comparable 20 mm closures across the families are indexed on the 20 mm by-size page; the other two tear-off formats are the 13mm tear-off seal and the 32mm tear-off seal.

Materials and quality

The shell is AA8011 aluminium alloy, conforming to EN 15088:2005 with EN 10204-3.1 certification and mechanical testing to BS EN 485-2:2008, and is REACH and RoHS compliant. The coating is an epoxy lacquer conforming to 21 CFR 175.300, silver on both sides as standard and pigmentable for colour identification in a wide range of colours, matte or glossy, customised to requirement. Heavy metals (chromium-VI, cadmium, mercury, lead) are held to a maximum 100 ppm total, and the materials carry a BSE/TSE-free declaration to EMEA/410/01 rev. 3.

The 0.16 to 0.20 mm gauge is the same aluminium thickness used on the 20 mm aluminium-plastic seals, so the crimping profile on an existing 20 mm line is familiar territory. Seals pass through fully automated washing, then 100% high-speed camera inspection. Production runs under ISO 15378:2017 GMP with ISO 9001:2015 and ISO 14001:2015 certification, a Drug Master File (DMF 18100) and CFDA registration, at the 75,000 sq ft Nashik facility. AQL is critical nil, major not more than 2.5%, minor not more than 4%. The full certification set is on the quality page.

Forms of supply

The 20 mm tear-off seal ships Regular (clean, bulk-packed, for washing and sterilization in house), Ready-to-Use (washed and assembled in an ISO Class 8 cleanroom, gamma or ETO sterilized, double-bagged for aseptic areas) and Ready-to-Sterilize. Shelf life is 3.5 years before capping for non-irradiated seals, plus 5 years after capping, and 2 years before capping for Ready-to-Use. Minimum order quantities, lead times and pricing are available on request.

Applications

The 20 mm tear-off seal covers routine injectable and parenteral vials where a plastic-free closure is preferred or where the stopper has to be fully exposed after opening. Typical categories are IV diluent presentations drawn in bulk, veterinary multidose formats, and research reagent vials where the stopper may be removed entirely. It is also the usual swap for a line already running 20 mm aluminium-plastic seals that wants to drop the plastic component without changing the vial finish. For the wider catalogue, see the full product range.

Frequently asked questions

What are the dimensions of a 20mm tear-off seal?

The Autofits 20 mm tear-off seal has an inner aluminium diameter of 20.00 to 20.60 mm, a perforation diameter of 9.70 to 10.50 mm, a total seal height of 7.40 to 8.00 mm and an aluminium thickness of 0.16 to 0.20 mm, with two bridges.

What is the opening force of a 20mm tear-off seal?

The maximum opening force is 35 N. Opening force varies with the number of bridges and the tear area, so the 13 mm size opens at 30 N and the 32 mm size at 65 N.

How many 20mm tear-off seals are in a box?

Standard packing is 6,000 seals per box, supplied as 2,000 in each of two bags, in a 420 by 270 by 320 mm shipper. Tyvek bagging is available as an alternative.

What does the perforation diameter do?

The perforation is the scored circle across the top face that defines where the metal separates. At 9.70 to 10.50 mm on the 20 mm seal it gives a clean, repeatable tear initiation.

Does a 20mm tear-off seal contain plastic?

No. It is made entirely from AA8011 aluminium with an epoxy lacquer coating. There is no polypropylene disc and no plastic button. Closures with a moulded plastic top sit in the separate aluminium-plastic FlipTop range.

Can the 20mm tear-off seal be supplied sterile?

Yes. It is offered Ready-to-Use, washed and assembled in an ISO Class 8 cleanroom, sterilized by gamma irradiation or ETO and double-bagged for aseptic filling. Ready-to-Sterilize and Regular forms are also available.

Sources

Autofits engineering drawings and FlipTop Seals dossier (working/spec-sheets/)
ISO 8362-3, Aluminium caps for injection vials (https://www.iso.org/standard/33804.html)
ISO 8362-1, Injection vials made of glass tubing (https://www.iso.org/standard/74398.html)
ISO 15378, Primary packaging materials for medicinal products (https://www.iso.org/standard/70729.html)
US FDA: 21 CFR 175.300, Resinous and polymeric coatings (https://www.ecfr.gov/current/title-21/part-175)

*Last updated: 2026-08-18. This page is general technical and product information, not regulatory or compliance advice. All dimensions are nominal drawing values; confirm current standard editions, your vial finish and your specification with the Autofits technical team before ordering.*