Conical Silicone Plugs – Rubber Stopper Sealing End Caps for Pipe & Tube (1.5–16mm)

The size format is A×B×C where A = small end outer diameter, B = large end outer diameter, and C = plug height/length. Measure the inner diameter of your pipe or hole opening. Choose a plug whose small end (A) fits inside the opening and whose large end (B) is wider than the opening so it seats firmly.

For example, a 4.5×8.5×16mm plug fits openings typically between 4.5mm and 8.5mm (approx. 3/16" to 11/32"). If your opening is 6mm ID, the 4.5×8.5×16mm or 6×10×19mm would generally be appropriate — size up for a tighter, more secure seal.

These plugs are made from silicone rubber, which is flexible, chemically inert, and heat-resistant. Silicone typically withstands temperatures from approximately -60°C to +200°C (-76°F to +392°F), making them suitable for use near heat sources, powder coat ovens, and engine bays. For applications at the extremes of this range, we recommend confirming suitability before use.

Yes. Silicone rubber is generally resistant to UV exposure, moisture, rain, and mild chemicals, making these plugs suitable for outdoor installations, marine environments, and wet conditions. For prolonged immersion or exposure to aggressive solvents or acids, please confirm chemical compatibility before use.

These are compression-fit plugs — they do not have threads and are not designed to engage NPT, BSP, or metric pipe threads. They seal by wedging into the bore opening via their tapered conical shape. They are compatible with any round opening whose inner diameter falls within the plug's A–B size range, regardless of thread standard.

These plugs are designed for sealing, masking, and protection rather than high-pressure containment. They are generally suitable for low-pressure applications such as dust and moisture exclusion, powder coat masking, and storage sealing. For specific pressure ratings relevant to your application, please contact us to confirm suitability.

Both colors are made from the same silicone rubber material and offer the same performance. Clear plugs are useful when you need to visually inspect the sealed area without removing the plug. Black plugs provide a more finished, professional appearance and are generally better at blocking UV light for long-term outdoor use.

Yes. Silicone rubber is durable and elastic — these plugs can typically be removed and reinserted multiple times without losing their sealing ability, as long as they are not cut, torn, or exposed to conditions beyond their material limits. This makes them significantly more economical than single-use foam or paper masking plugs for repeated use in production environments.

If you work with a variety of bore sizes, consider the 54-piece assorted set (18 Types) which includes one plug of each size in both Clear and Black. This is a practical option for shops, toolboxes, and maintenance kits where you need coverage across the full 1.5mm–16mm range without ordering individual sizes separately.