Aluminium Crimp Seals Explained - Adelphi Healthcare Packaging

16 Jun.,2025

 

Aluminium Crimp Seals Explained - Adelphi Healthcare Packaging

A seal with a plastic Flip Off button that must be removed to expose the injection site.

Flip Off (FOT) seals are used most commonly to package parenteral drugs where it is important that the vial contents remain sterile and secure.

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The Flip Off button covers the stopper and helps to keep it clean prior to use. When removed a central section of the stopper is exposed ready for needle insertion. The aluminium skirt remains in place to secure the stopper, maintaining sterility of the vial contents.

A seal with a plastic button attached to help facilitate the activation and complete removal of the seal from the container

Flip Tear Up seals can be easily removed from the vial, allowing removal of the stopper and access to the vial contents.

Flip Tear Up seals are used for non-injectables and where needle extraction is not required. They might be used in topical, oral or ophthalmic applications.

They are available in 13mm, 20mm and 32mm sizes.

A seal with a bridged Tear Out tab protecting the target area that must be removed to expose the injection site

Centre Tear seals are used most commonly to seal vials containing a parenteral drug. A central section of the seal can be lifted out in order to expose a central section of the stopper beneath allowing for needle insertion.

An all-aluminium seal with Tear Out tab that allows the complete removal of the closure prior to use

Complete Tear Seals can be fully removed from the vial by hand, allowing access to the vial contents. This solution would suit products that do not require sterility or extraction by needle. Complete Tear Seals might be used to seal vials containing diagnostic solutions, topical or oral products.

Manual crimping tongs are used in cases where automated or semi-automated crimping equipment isn’t warranted, for example in research laboratories and small-scale pharmaceutical manufacturing, such as for gene therapies. They can also be used inside an isolator for small-scale aseptic fill and finish operations.

It is important to ensure you have the correct crimping tongs for the type of crimp seal you are using.

You can find out more and purchase hand crimping tongs from Adelphi company, Adelphi Manufacturing here: Hand Crimping Tongs

Seals: Secondary Components for Drug Product Packages - West

Aluminum Seals with Plastic Buttons

Aluminum seals with plastic buttons, such as West Flip-Off® Seals (FOS) and

 West Flip-Off Tear Off Seals (FOTOS) allow for one-handed opening. Available color-coding on buttons enhances drug identification and market differentiation.1 They provide tamper evidence (i.e., once the button is removed, it cannot be re-attached properly). Additionally, West seals are specially manufactured with a tapered aluminum shell design; there is no risk of exposed sharp edges, and concomitant risk of injury, due to bridge lift-up after button is removed. They are most commonly used for injectable drug products.

Between FOS and FOTOS, FOS are more commonly used for injectable drug products. FOTOS are used usually for special applications where there is a need for complete removal of the seal and stopper to access the vial content.

Flip-Off® Seal Mechanisms: Bridge Versus Controlled Score

A key feature of both FOS and FOTOS is a bridge, which is a small connecting strip of aluminum that secures the plastic button to the aluminum shell. The bridge breaks when the plastic button is removed. Another approach to removing a plastic button is called controlled score. This comprises a design such that the seal is indented to a prescribed thickness. The indented area is where the fracture will occur when the plastic button is removed. This concept is similar to a soda can opening.

BridgesControlled Score 

West recommends use of bridges, instead of the controlled score approach. Bridges are more forgiving in the crimping process and have lower variation in removal force, as compared to inflexible controlled scores. Seals with bridges offer advantages with modern machines which exert eccentric force to the seal during crimping, i.e., those that use roller or rail-based technology. A controlled score seal could partially break during such crimping.

FOS Button Designs

Smooth TopFlip-Off ® Matte Top Flush Button

 Typically not
recommended

 Traditional Standard;
Not sold in the US
market Recommended

Commonly used for 
narrow vial 
applications

Among FOS button designs, Matte-Top is recommended. It is less prone to scratches and scuffing, and better suited to camera inspection (less glare).FOS with a logo embossed can be used in all regions, except for the US market. It is not permitted per USP General Chapter <1> Injections and Implanted Drug Products (Parenterals) - Product Quality Tests. Details on this regulation are discussed in section titled Spectra™ FOS.

Want more information on Aluminium Flip Off Seal Manufacturer? Feel free to contact us.

Spectra™ FOS

An optional add-on technology for FOS is Spectra™ FOS technology. Spectra™ FOS technology is West’s proprietary method for placing messages on a FOS – to provide point-of-use instructions, product authentication, and counterfeiting deterrence. It comprises printing and/or applying in-mold text on the plastic button and/or printing on the aluminum shell.2

It is noted that all drug products offered in the US must meet the requirements in Chapter <1> regarding labeling. According to Chapter <1>, only cautionary statements intended to prevent imminent life-threatening situations are permitted to appear on the top circle area of the ferrule (i.e., aluminum shell) and the plastic cap (i.e., button). Additionally, the cautionary statements should be printed in a contrasting color and should be clearly visible under ordinary conditions of use.

Seal Grades

West has developed Flip-Off® seals in different product grades to address different fill-finish and regulatory requirements2:

  1. Standard FOS: for consistent, reliable crimping outside controlled environments
  2. Flip-Off® Plus (FO Plus) seals: for clean crimping under grade A air supply
  3. Flip-Off® Clean, Certified, Sterilized (FOCCS) seals: for aseptic crimping inside grade A environments

Standard FOS (except ready-to-use irradiated, RUI) are supplied as assembled without any further processing; they do not come with any cleanliness specification. On the other hand, FO Plus seals and FOCCS seals are certified for pre-sterilization bioburden, to meet the guidelines of the latest European Medicines Agency (EMA) Good Manufacturing Practice (GMP) Annex1 – Manufacture of Sterile Medicinal Products (more guideline details are provided below). This is achieved by measures to control cleanliness in manufacturing, such as specified gowning and sanitization of assembly equipment contact surfaces.

EMA GMP Annex1 Manufacture of Sterile Medicinal Products”3

Some key features are:

  • Clause 80: The bioburden should be monitored before sterilization. There should be working limits on contamination immediately before sterilization, which are related to the efficiency of the method to be used. Bioburden assay should be performed on each batch for both aseptically filled product and terminally sterilized products…
  • Clause 120: Vial capping can be undertaken as an aseptic process using sterilized caps or as a clean process outside the aseptic core. Where this latter approach is adopted, … stoppered vials should be protected with a Grade A air supply until the cap has been crimped.

This guideline applies to manufacturing in Europe and to companies that want to export to Europe.

For FOCCS seals, manufacturing cleanliness control is further enhanced by processing and surface treatment measures, which include washing of the plastic buttons and applying an additional silicone coating to the aluminum shells prior to assembly with the washed buttons. These allow the FOCCS seals to have further reduced bioburden levels and visible particle levels respectively. For more details about FOCCS seals and FO Plus seals, please see the report by West scientists: TR /158: West Flip-Off® Seals for Aseptic and Clean Crimping Processes. 

West neither washes assembled seals, nor recommends washing. This is because there is a risk of the aluminum shells deforming, especially for larger seals. Moreover, the seals may undergo stress by collision or abrasion during the washing process, which may result in formation of particles, so particle levels may be potentially higher after washing.4

The three product grades are offered as gamma-sterilized or ready-for-sterilization:

*RUI: ready-to-use irradiated

West performs sterilization by gamma irradiation, instead of steam, to avoid the possibility of excess condensate being trapped under the seal buttons, which would then require further drying.

The plastic buttons used for gamma-irradiated sterilized seals are made of gamma-stable polypropylene (PP) resin, instead of standard PP resin, which may discolor and become brittle following gamma irradiation. If irradiation is required, gamma-stable buttons may be specified.

Follow up reading

The Knowledge Center contains a wealth of information on seals. An easy read is our Flip-Off® Seals Product Technical Overview, and background on colors and color terminology can be found here.For more discussion about seal types and recommendations, please contact the West Technical Customer Support Team or visit the West Knowledge Center.

Note: Lined seals are not discussed within this blog as they are not a secondary component and do come in direct contact with drug products.

Flip-Off, Flip Off Tear Off and Spectra are trademarks and registered trademarks of West Pharmaceutical Services, Inc., in the United States and other jurisdictions.

References:

If you want to learn more, please visit our website Eurohead Caps.