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Bridge Type Seal Without Groove: FlipTop® Optima Flip-Off Design

Bridge Type Seal Without Groove | FlipTop® Optima | Autofits

The bridge type seal without groove is a FlipTop® Optima flip-off design in the plain crown profile: an AA8011 aluminium shell crimped over the rubber stopper, topped with a polypropylene button held by tapered aluminium bridges that shear cleanly when the button is flipped, with no added groove feature on the crown. It is the simplest profile in the Optima design set, the classic flip-off cap seen on most injectable vials.

This page gives packaging engineers, formulators and sourcing managers the design explanation, how it differs from the other Optima designs, the sizes and controlled dimensions, materials, quality position, applications and ordering. For the full range, see the FlipTop® Optima product page.

Key takeaways

  • The bridge type without groove is the plain-profile FlipTop® Optima design: a flip-off button connected by tapered aluminium bridges, with no added groove feature on the crown.
  • It opens identically to the grooved bridge type; the groove there is a forming feature that aids a clean crimp and clean button release, and the sealing principle is the same in both.
  • Offered across the Optima size range: 13, 20, 28, 32 and 34 mm, matched to vial necks per ISO 8362-1.
  • Maximum opening force: 30 N (13 mm), 35 N (20 and 28 mm), 65 N (32 mm); the 34 mm value is available on request.
  • Materials: AA8011 aluminium with epoxy lacquer and a polypropylene button moulded in-house on Toyo machines.
  • Made under ISO 15378, ISO 9001 and ISO 14001 with a Drug Master File, assembled in an ISO Class 8 cleanroom, 100% camera inspected.

What is a bridge type seal without groove?

A bridge type seal is the standard flip-off construction: the polypropylene button sits over a central aluminium disc connected to the shell by narrow tapered bridges. Flipping the button up shears the bridges, the button and central disc come away, and a small central area of the rubber stopper is exposed for the needle. The rest of the aluminium stays crimped under the vial neck flange, keeping the stopper compressed against the glass so seal integrity is preserved. The general flip-off action is described on the flip-off seal glossary page.

“Without groove” means the crown carries no groove feature: this is the plain, classic flip-off profile. In the bridge type with groove, a groove is added to the crown as a forming feature that helps the shell seat and crimp cleanly and supports a clean, predictable button release; it does not change the sealing principle or the tamper behaviour. The choice between the two is set by your approved component specification, capping validation and appearance standard. If your incumbent cap is the plain profile, the without-groove version is the like-for-like replacement.

How it differs from the other Optima designs

The Optima top comes in four design variants, all on the same aluminium-plastic construction:

  • Bridge type without groove (this page): tapered-bridge flip-off top in the plain crown profile.
  • Bridge type with groove: the same tapered-bridge top with a groove feature that aids a clean crimp and clean button release.
  • Button type: carries intrinsic tamper evidence, with a 12-stem flower formed under the button disc so the opened state is visibly distinct.
  • Flower type: the petalled top variant within the Optima range.

For the tamper-evident construction, see the button type.

Sizes and specifications

The bridge type without groove follows the controlled Optima dimensions for each neck size, taken from the Autofits engineering drawings. Opening force varies with the number of bridges in the design.

Size Inner Ø alu seal (D1, mm) Outer Ø disc (D2, mm) Total seal height (mm) Alu thickness (mm) Bridges Max opening force (N) Standard packing (per box)
13 mm 13.36 (min) 14.99 (max) 7.62–8.38 0.16–0.20 6 taper 30 15,000 (5,000 × 3 bags)
20 mm 20.22 (min) 23.14 (max) 9.02–9.91 0.16–0.20 6 taper 35 6,000 (2,000 × 2)
28 mm 27.60–28.20 30.10–31.10 11.06–12.06 0.17–0.23 8 35 3,000 (1,500 × 2)
32 mm 32.10–32.90 35.50–36.50 14.30–15.50 0.21–0.25 12 taper 65 1,400 (700 × 2)
34 mm 33.60–34.00 35.50–36.50 15.00–16.00 0.20–0.25 8 taper available on request available on request

The standard shipper box is 420 × 270 × 320 mm; Tyvek bagging is available as an alternative to standard polybag packing. Disc height and inner aluminium height for 13 mm are 2.90–3.30 mm and 6.15–6.40 mm; for 20 mm, 3.20–3.60 mm and 7.37–7.62 mm; for 28 mm, inner aluminium height is 8.70–9.30 mm. Remaining per-size heights are available on request. Per-size detail pages: 13mm, 20mm, 28mm, 32mm and 34mm.

Finishes are glossy, matte, embossed or printed, in a wide range of colours, matte or glossy, customised to requirement; the plain profile suits printed and embossed branding particularly well. Colour coding options are covered on the colours page.

Materials and quality

The shell is AA8011 aluminium alloy (EN 15088:2005, EN 10204 3.1 certification, tested to BS EN 485-2:2008; REACH and RoHS compliant) with an epoxy lacquer coating to 21 CFR 175.300, which may be pigmented for colour. The button is polypropylene to IS 10910 / IS 10909 and FDA 21 CFR 177.1520, moulded in-house on Japanese Toyo injection-moulding machines. Heavy metals (chrome-VI, cadmium, mercury, lead) are held to a maximum 100 ppm total, and components are BSE/TSE-free per EMEA/410/01 rev. 3.

Components are washed on a fully automated line to control particulates, assembled in an ISO Class 8 cleanroom, and every seal passes 100% high-speed camera inspection before packing. 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 Autofits Packaging Pvt. Ltd. 75,000 sq ft facility in Nashik, India. The design follows ISO 8362-6 for aluminium-plastics combination caps; the quality system is described under ISO 15378. AQL: critical nil, major not more than 2.5%, minor not more than 4%, tailorable to customer specification.

Applications

The plain bridge type is the default flip-off closure for routine injectable and parenteral vials: liquid injectables, vaccines, biologics, lyophilised products, diluents and larger-volume parenterals in the 28 to 34 mm sizes. It suits products that rely on colour coding to differentiate strengths and presentations. Where the closure itself must carry intrinsic tamper evidence, specify the button type instead. Browse comparable closures on the by-size index.

Forms of supply and ordering

The seal ships Regular (non-sterile), Ready-to-Use (RTU: assembled in the ISO Class 8 cleanroom, double-lacquered aluminium, washed to control particulates, then gamma irradiated or ETO sterilized, supplied double-bagged for aseptic areas) and Ready-to-Sterilize (RTS). Shelf life is 3.5 years before capping for non-irradiated seals (plus 5 years after capping) and 2 years before capping for RTU.

To order, contact Autofits with your size, the plain bridge design, finish, colour reference and required form of supply. Minimum order quantities and lead times are available on request.

Frequently asked questions

What is a bridge type seal without groove?

It is a FlipTop® Optima flip-off seal with the standard tapered-bridge button top on the plain crown profile, with no added groove feature. Flipping the button shears the bridges and exposes a central injection point while the aluminium stays crimped on the vial.

What is the difference between with-groove and without-groove bridge seals?

The groove. The grooved version adds a forming groove to the crown that helps the shell seat and crimp cleanly and supports a clean button release; the without-groove version is the plain classic profile. The flip-off mechanism, materials and tamper behaviour are the same design family; choose the profile your component specification and capping validation call for.

What sizes does the plain bridge type come in?

It is offered across the Optima range: 13, 20, 28, 32 and 34 mm neck sizes, matched to the vial finish and stopper of the same nominal diameter. Vial necks follow ISO 8362-1.

What is the opening force of a bridge type seal?

Maximum opening force is 30 N for 13 mm, 35 N for 20 mm and 28 mm, and 65 N for 32 mm; the force varies with the number of bridges in the design. The 34 mm value is available on request.

Does the bridge type give tamper evidence?

Any flip-off seal shows it has been opened once the button is flipped and the bridges are sheared, but the bridge type does not carry the intrinsic tamper-evidence feature. That belongs to the button type, which forms a 12-stem flower under the button disc.

Is the plain bridge type available sterilized?

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

Related reading

Sources

  • Autofits FlipTop Seals dossier and engineering drawings (working/spec-sheets/)
  • ISO: ISO 8362-6:2010, Caps made of aluminium-plastics combinations for injection vials (https://www.iso.org/standard/45641.html)

*Last updated: 2026-07-06. This page is general technical and product information, not regulatory or compliance advice; confirm current standard editions and your own specification with Autofits and the issuing bodies.*

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