Inflatable Pipe Plugs and Sealing Cushions for Wastewater Systems

Inflatable pipe plugs and sealing cushions are indispensable tools across a wide range of applications. They are used whenever sewers, pipelines or drainage inlets need to be temporarily sealed or blocked off. This may be during new pipe installations, inspections, repairs, rehabilitation works, or even in emergency and rescue operations. The fields of application for inflatable plugs are equally diverse – including road and civil engineering, sewer rehabilitation, industrial maintenance, water utilities, fire services and other emergency organisations.

Compared to mechanical shut-off devices, pneumatic pipe plugs and sealing cushions offer the advantage of being lightweight and easy to handle. Thanks to their low weight and compact size when deflated, they can generally be transported through standard manholes and deployed directly at the site of operation without difficulty.

In addition to standard sealing plugs used solely for isolation purposes, testing technology is also frequently employed. These are designed not only to block flow, but also to perform leak or pressure tests (using air or water) on newly installed or rehabilitated pipelines and sewers, in accordance with standards such as DIN EN 1610. Testing plugs are equipped with a bypass, allowing water or air to be introduced into or released from the isolated pipe section during tightness testing.

What’s the Difference Between Inflatable Pipe Plugs and Sealing Cushions?

The German Occupational Safety and Health Authority defines the difference between pipe plugs and sealing cushions in its guideline BGI 802 “Safety Guidelines for the Use of Temporary Pipe Sealing Devices” as follows:

• Inflatable pipe plugs are sealing devices made from stretchable materials that can be filled with air or liquid, with or without a through-passage for air or water.
• Sealing cushions are sealing devices made from non-stretchable materials that can be filled with air or liquid, again with or without a through-passage.

The distinction lies in their mode of operation: inflatable plugs expand like a balloon when filled with air, whereas sealing cushions do not stretch – they behave more like a flat, empty sack (often conical-cylindrical in shape) that unfolds and presses firmly against the pipe walls when inflated.

The main disadvantage of inflatable plugs compared to sealing cushions is that they must always be secured with an anti-expulsion safety device. Due to their elasticity, even a slight pressure loss can cause them to collapse and be forced out of the pipe by water pressure. Sealing cushions, on the other hand, maintain full surface contact with the pipe wall even when pressure drops slightly, minimising the risk of displacement thanks to their more rigid structure.

Which Pipe Profiles Are Suitable for Inflatable Plugs and Sealing Cushions?

Conventional inflatable pipe plugs expand only in diameter when inflated, making them suitable exclusively for sealing and testing circular pipes and sewers.

In contrast, depending on their design, sealing cushions can also be used in a wide range of non-circular profiles – such as egg-shaped, kite, mouth or kidney-shaped cross-sections. Flat sealing cushions are also commonly used for large-area sealing applications.

At MOWOTAS, we offer a wide selection of high-quality, durable barrier technology for a variety of pipe shapes – available in numerous designs and for almost any pipe diameter.

Need a Custom Solution or Have Technical Questions?

We're happy to help – whether you need a bespoke product or have technical questions about inflatable pipe plugs and sealing cushions.

Simply get in touch with us via our contact form orsend us an email at: info@mowotas.com

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Author: Elisabeth Pietraß
You can find out more about the author of this article by visiting her LinkedIn profile.