Pharmaceutical vial aluminium seal (crimp seal and flip-off cap)

01

Fit the seal to vial and stopper, crimp it and choose the opening

US patent 6,382,442 (Plastic closure for vials and other medical containers) describes the conventional vial: an open end with a radial rim, a reduced-diameter neck and an elastomeric stopper whose planar rim overlies the vial rim, secured by a thin malleable aluminium cap. The cap's tubular portion surrounds the stopper and vial rims, an annular portion overlies the stopper, and its free end is crimped radially into the neck beneath the rim; because aluminium is malleable it accommodates the build-up of dimensional tolerances of the stopper and vial rim, which are set by ISO standards. [1]

The patent explains that closed aluminium caps torn open by a pre-slit tab create sharp edges that can cut gloves or the user and metal particles that can contaminate the drug; adding a plastic flip-off cap riveted to a central opening, which tears out a serrated ring when flipped off, reduces but does not remove these problems, and aluminium dust is still created when the collar is formed, crimped and the flip-off cap removed. [1]

Editorial note: give the supplier the vial neck finish and stopper drawing, and ask for crimp trials on your capping machine with the seal's inner diameter, skirt height and aluminium thickness, plus its particle and cleanliness controls.

Give the supplier the vial size and neck finish, stopper type and drawing, seal type (plain, flip-off, tear-off), aluminium alloy and thickness, button colour, printing on skirt or top, capping machine and crimp settings, sterilisation or washing needs, cleanliness and particle limits, packaging and lot documentation.

02

Print and colour the seal within labelling rules

West Pharmaceutical Services explains that the revised USP General Chapter <1> Injections, Labeling on Ferrules and Cap Overseals, effective 1 December 2013, limits what may be printed on the top surface of cap overseals and ferrules (aluminium shells) securing injectable drug vials sold in the United States. Only cautionary statements, meant to prevent an imminent life-threatening situation, may appear on the top (circle) surface, printed in a contrasting colour and clearly visible; identifying numbers or letters such as code numbers, lot numbers, company names, logos or product names may appear on the side (skirt) but not on the top. [2]

Editorial note: agree with the drug owner which statements, if any, appear on the top of the seal, and place lot or code marks on the skirt; ask the seal supplier for its printing capability and colour options.

03

Specify the flip-off force window

West Pharmaceutical Services' note on Flip-Off seal cap removal testing explains that in an aluminium–plastic combination seal the plastic cap is moulded into the aluminium, and flipping it off breaks the thin aluminium bridges holding the centre disc (six bridges on its 13 mm and 20 mm seals), exposing the stopper; the broken bridges cannot be re-attached, which gives tamper evidence. [3]

The note lists conditions that can change the flip-off force after crimping: stopper bulging under the crimp, shrinkage of the metal seal in cryogenic storage, and simulated transport conditioning to ASTM D4169-22. Seals are factory-tested against ISO and/or YBB flip-off force specifications, but crimped and conditioned vials may need to show they still meet a minimum force so that caps do not come off in transport or storage. West validated its test with surrogate samples because the test destroys the sample. [3]

Editorial calculation: for a 20 mm seal the acceptance window under the Chinese standard is 6–35 N, a ratio of about 1 to 6; for a 13 mm seal it is 6–25 N.

State the standard (ISO 8362-6 or YBB 00372003-2015), the force window, whether testing is on loose seals or on crimped, conditioned vials, and any cryogenic or transport conditioning.

04

Choose cap type, size, colour and supply format

Datwyler, which makes both vial stoppers and aluminium caps, describes the cap's job as securing the stopper against the vial finish and protecting the closure through processing, transport, storage and use, with the stopper forming the primary seal. Its cap range covers standard and PrimeCaps™ flip-off caps, total tear-off caps, centre tear-off caps and aluminium hole caps, in 13 mm, 20 mm and 32 mm formats for serum, lyophilisation and infusion vials. It lists 40 standard plastic colours and 5 standard aluminium colours, with inkjet printing, embossing and debossing on selected products. [4]

Components are offered ready-for-sterilisation (RFS), ready-to-use (RTU) or in Rapid Transfer Port (RTP) bags, with steam or gamma sterilisation options, and Datwyler states that they are made at eight sites in Europe, North America and Asia. For its PrimeCaps™, offered in selected 13 mm and 20 mm formats, it describes a centre-gated disc, rounded edges, a controlled opening-force design and a precision skirt edge intended for feeding, seating, crimping and inspection on high-speed lines. Datwyler states that cap selection should account for vial and stopper dimensions, crimping parameters, fill-finish equipment and opening performance, and that the drug manufacturer remains responsible for qualifying the components. [4]

Editorial note: printing options on the cap must still respect the USP <1> rule that only cautionary statements go on the top surface, with lot and code marks on the skirt; agree the flip-off force window against the ISO 8362-6 and YBB values above before choosing a design. [2] [3] [4]

05

Aluminium skirt, top, flip-off button, tear-off ring and skirt markings

06

Inner diameter, aluminium thickness, skirt height and tolerance for a vial seal order

Thickness and tolerance rows decide whether the crimp takes up the ISO tolerance build-up of stopper and vial rim that the patent describes, so ask for both on the seal drawing. [1]

07

Send the vial, stopper and labelling data together

Paste it into your enquiry below or into an email to a maker, then replace every bracket.

Vial: [size; neck finish]
Stopper: [type; drawing]
Seal: [plain; flip-off; tear-off]
Material: [alloy; thickness]
Printing: [top cautionary statement; skirt marks]
Capping: [machine; crimp settings]
Cleanliness: [particles; washing]
Packaging: [bags; documentation]

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