Industrial environments and marine vessels rely heavily on the integrity of their penetrations. Whether it is a bulkhead, a concrete wall, or a cabinet, every hole drilled for a cable or pipe is a potential vulnerability. The Roxtec R transit has established itself as a mechanical solution designed to address these vulnerabilities by providing a certified, flexible, and space-efficient seal for round apertures.

The anatomy of the Roxtec R series

The Roxtec R frame is a round sealing solution characterized by a square packing space in its center. This specific design allows for the installation of multiple cables and pipes within a single round hole, distinguishing it from traditional cable glands that typically handle only one cable per entry.

At its core, the R frame is a compression-based system. It consists of a circular metal frame—available in materials such as galvanized mild steel or AISI 316 stainless steel—and an integrated compression mechanism. Unlike rectangular frames that require a separate wedge or compression unit, the R frame incorporates the expansion bolt system directly into its structure. When the bolts are tightened, the frame compresses the internal sealing modules against the cables and the surrounding sleeve or aperture, creating a tight, certified barrier.

Multidiameter technology: The heart of flexibility

The most significant technical advantage of the Roxtec R system is the Multidiameter™ technology. Each sealing module placed inside the frame features removable layers of EPDM rubber. This allows a single module to adapt to a wide range of cable or pipe diameters simply by peeling away layers until a perfect fit is achieved.

In practical terms, this adaptability reduces the need for extensive site surveys. Engineers do not need to know the exact external diameter of every cable down to the millimeter before ordering parts. A standard set of modules can cover most common cable sizes, which simplifies inventory management and reduces the risk of installation delays due to incorrect component sizing.

Certified protection levels and industry standards

When evaluating a sealing system, the certifications it carries are the most reliable indicators of its performance. The Roxtec R frame is tested against various hazards to ensure operational reliability in high-stakes environments.

Fire resistance

The system is frequently used in marine and offshore applications where fire containment is critical. It is certified for A-class and H-class fire ratings according to the IMO 2010 FTP Code. In onshore construction, it meets various EN and UL standards for firestop integrity (E and EI ratings). The intumescent properties of the materials help prevent the spread of flames, smoke, and heat for durations typically ranging from 60 to 120 minutes, depending on the specific configuration.

Tightness against water and gas

Operational environments often face the threat of flooding or gas leaks. The Roxtec R series is designed to withstand significant pressure. Under catastrophic conditions, many configurations are rated for up to 2.5 bar for water tightness and 1 bar for gas tightness. For daily use, it provides an IP66/67 or even IP68 rating, ensuring that sensitive electronic equipment inside cabinets or substations remains dry even when the structure is subjected to high-pressure water jets or temporary submersion.

Electromagnetic compatibility (EMC)

For facilities like data centers or naval vessels, electromagnetic interference (EMI) can be as damaging as fire. The R series includes specialized "ES" versions. These frames and modules are designed to provide lightning protection and shield against both conducted and radiated EMI, ensuring that the signal integrity of communication cables is maintained while preventing the entry of unwanted interference.

Solving the retrofit challenge: The openable frame

One of the most persistent issues in facility maintenance is how to seal an existing cable that is already connected at both ends. Cutting and reconnecting a power or data cable is often expensive and risky. The Roxtec R frame offers a specialized "openable" version to solve this exact problem.

This version of the frame can be cut open and wrapped around an existing cable. When combined with an openable sleeve (such as the SLFO/RI), it allows for the installation of a certified seal without any downtime for the equipment. This makes it an ideal choice for renovation projects in hospitals, telecommunication hubs, and process plants where continuous operation is mandatory.

Technical specifications across sizes

The R series comes in several standardized sizes, denoted by the frame's external diameter in millimeters. Common sizes include:

  • R 70 and R 75: Compact frames suitable for small enclosures or single-cable penetrations in tight spaces.
  • R 100: A versatile size often used in telecommunication shelters and electrical cabinets.
  • R 125 and R 150: Standard sizes for medium-density cable transits in bulkheads and floors.
  • R 200: The largest standard round frame, capable of managing a significant number of cables or larger pipes in industrial infrastructure.

Each size provides a specific "packing space" (e.g., 60x60mm for an R 100). Selecting the right size involves calculating the total cross-sectional area of the cables and ensuring they fit within the frame’s square aperture while leaving some capacity for future additions.

Installation best practices

Achieving the rated protection of a Roxtec R seal requires adherence to specific installation protocols. While the system is designed for ease of use, technical precision is necessary.

  1. Aperture Preparation: The hole in the wall or bulkhead must be clean and sized correctly. If the hole is uneven (such as in brickwork), using a sleeve like the SL or SLF series is recommended to provide a smooth, circular surface for the frame to expand against.
  2. Lubrication: Applying Roxtec Lubricant to the internal surfaces of the frame and the modules is not optional. The lubricant reduces friction, allowing the modules to slide into place and ensuring that the compression is distributed evenly across all cables.
  3. Module Arrangement: Cables should be placed in the modules, and modules should be stacked within the frame. It is generally recommended to place larger cables at the bottom and smaller ones toward the top to maintain stability during the compression phase.
  4. Tightening: The expansion bolts should be tightened in a cross-pattern. Most R frames feature a visual indicator or a specific torque requirement to confirm that the seal is fully compressed. Over-tightening can damage the modules, while under-tightening compromises the gas and water tightness.

Strategic applications in modern infrastructure

As we look at the requirements of infrastructure in 2026, the Roxtec R frame fits into several critical sectors that demand long-term reliability.

Renewable Energy

In offshore wind turbines, the R frame is used to seal cables entering the transition piece and the nacelle. Its resistance to salt spray and vibration makes it superior to traditional plastic glands which can degrade under UV exposure and mechanical stress.

Data Centers

Modern data centers require airtight environments to optimize cooling efficiency and protect against fire. The R series provides a gas-tight seal that prevents the leakage of expensive cooling gases and protects server rooms from dust ingress.

Water Treatment and Utilities

Substations and water treatment plants often face the risk of rodent ingress and flooding. The R frame’s robust EPDM construction is a deterrent to pests and can withstand the hydrostatic pressure of a flooded cable trench, preventing water from entering the control building.

Future-proofing and spare capacity

A common mistake in facility design is sealing a penetration so permanently that adding a new cable later requires drilling a new hole. The Roxtec R system is inherently designed for the future. When a transit is first installed, it is common practice to fill a portion of the frame with "solid compensation modules." These modules act as placeholders. When a new cable needs to be added years later, a solid module can be removed and replaced with a Multidiameter™ module, allowing the new cable to pass through the existing frame without compromising the seal’s certification.

Material science: Why EPDM?

The choice of EPDM (Ethylene Propylene Diene Monomer) rubber for the modules is intentional. EPDM is known for its excellent resistance to ozone, UV radiation, and extreme temperatures. In an industrial context, it maintains its elasticity over decades, which is crucial for maintaining a constant compression seal. Unlike standard rubbers that might become brittle or "set" in a specific shape, the Roxtec modules remain pliable enough to be re-installed multiple times during the lifecycle of a facility.

Considerations for selection

Choosing between an R frame and other Roxtec solutions like the RS seal depends on the application. While the RS seal is designed for a single cable or pipe, the R frame is the better choice when you have a cluster of cables. If the opening is already round—perhaps a core-drilled hole in concrete—the R frame is the most efficient way to utilize that space.

Furthermore, the availability of specialized versions, such as the "Ex" rated frames for explosive atmospheres, ensures that the R series can be deployed in hazardous areas like oil refineries or chemical processing plants, where every component must be spark-proof and certified for safety.

Conclusion

The Roxtec R frame is more than just a piece of hardware; it is a calculated engineering solution for a complex problem. By combining the flexibility of Multidiameter modules with the structural integrity of a compressed metal frame, it provides a level of protection that simple foams or glands cannot match. For project managers and engineers, the primary value lies in the peace of mind that comes from using a system that is tested, certified, and ready for the demands of modern industrial environments.