Annular Space Seals: Complete Guide to Selection and Application
Annular space seal (UKP) is a special engineering solution designed for sealing and protecting gaps (annular spaces) that arise during the installation of pipelines, cable lines, and other communications through building structures: foundations, walls, floors, tank bottoms. Its main task is to prevent the penetration of water, gas, steam, groundwater, aggressive liquids, or fire through these technological openings, ensuring the integrity and durability of both the structure itself and the engineering systems passing through it.
1. Purpose and Key Functions
Annular space seal performs a set of protective functions critically important for the safety and reliability of a facility:
- Waterproofing: Creating a watertight barrier preventing pressure and non-pressure water ingress through foundations, basement walls, wastewater treatment plants, swimming pools.
- Gas and Vapor Barrier: Blocking the penetration of radioactive radon, natural gas, chemical vapors, or simply moist air, which is important for energy efficiency and the microclimate of buildings.
- Protection Against Aggressive Environments: Resistance to salt water, acids, alkalis, petroleum products, necessary in industrial enterprises, water treatment facilities, and the oil and gas sector.
- Fire Protection (when using special compounds): Ensuring the required fire resistance rating of the barrier when combustible communications pass through it.
- Mechanical Fixation and Vibration Protection: Fixing the pipe or cable in the opening, preventing displacements that could compromise the seal, as well as protection against abrasion.
2. Construction and Operating Principle
A modern annular space seal is not just a gasket, but a complex multi-layer system. Let’s examine its design using popular solutions as an example.
| Design Element | Material and Purpose | Operating Principle and Key Properties |
| Outer Sealing Shell | High-strength synthetic rubber (EPDM, NBR), thermoplastic elastomers, silicone. | Provides the primary seal between the seal and the opening walls in the structure. Possesses high elasticity, resistance to UV radiation, ozone, and temperature fluctuations. |
| Swelling (Intumescent) Elements | Tapes or cores based on bentonite clay or hydrophilic polymers. | Key active element. Upon contact with water, it increases in volume several times (up to 400%), creating powerful radial pressure and hermetically filling all micro-voids and irregularities around the pipe. |
| Mechanical Fixing Elements | Steel tension clamps (straps) with screw tensioners, compression flanges. | Provide primary and permanent mechanical fixation of the seal on the pipe and in the opening. Allow adjustment of the compression force. |
| Inner Sealing Rings (Lips) | Special profile rubber, often with spring rings. | Create multi-level sealing directly on the pipe surface or cable sheath, compensating for its irregularities and ensuring tightness even with minor displacements. |
| Fire-Resistant Filler (for fire-resistant UKP) | Fire-resistant mats, pastes, or intumescent tapes that expand when heated. | Expands during a fire, hermetically sealing the opening and providing a fire resistance rating (e.g., EI 90 or EI 120). |
The operating principle is based on a combination of mechanical compression and the chemical activity of swelling elements, guaranteeing long-term and reliable sealing even in dynamic conditions (vibration, building settlement).
3. Types of Seals and Their Application
The choice of a specific type of annular space seal depends on the task at hand, the type of communication, and operating conditions.
| Seal Type (using GERDA systems as an example) | Design Features | Typical Applications |
| Seal for Pipelines (ZUKP) | It is a split coupling with an outer sealing shell, inner sealing lips, and tension clamps. Often equipped with swelling elements. | Sealing entries of water supply, sewage, process pipes through foundations and basement walls, clean and waste water tanks, dams, tunnels. |
| Seal for Cable Penetrations | Can be modular (from individual segments) or in the form of an elastic membrane with a set of plugs for different diameters. Aimed at sealing bundles of cables. | Protecting cable entries into buildings from the ground, sealing penetrations through walls of technical rooms where it is important to prevent leaks or gas spread. |
| Universal Membrane Systems | Elastic sheet membrane made of EPDM or PVC, which is installed on the structure before the introduction of communications. Passages are created by cutting holes and installing sealed sleeves. | Comprehensive waterproofing of foundation slabs and walls at the new construction stage, when the exact location of future entries is unknown. |
| Combined Fire and Water Seals | Combine elements of a fire-resistant cable penetration (fire-resistant filler) and a waterproofing annular space seal (swelling elements, sealed gaskets). | Through penetrations in walls and ceilings of basements, parking garages, where protection against both fire (EI) and groundwater is required simultaneously. |
4. Advantages of Modern Systems (using GERDA ZUKP as an example)
The use of system solutions, such as GERDA ZUKP seals, offers significant advantages over traditional methods (caulking with cement, pouring sealant):
- Absolute Tightness: Achieved through a multi-level sealing system and the activity of swelling elements, effective even in the presence of cracks in the structure.
- Compensation for Displacements and Vibrations: Elastic materials and design allow minor axial and radial displacements of pipes without loss of tightness, which is important during building settlement or equipment operation.
- Ease and Speed of Installation: Seals come ready-made; installation does not require special tools or qualifications (compared to welding waterproofing elements).
- Durability: Materials are resistant to aging, corrosion, and biological damage; service life is comparable to the service life of the structure itself.
- Versatility: A single type of solution can be used for pipes made of different materials (steel, cast iron, HDPE, PVC) and different diameters (due to the range of models).
- Maintainability: If necessary to replace or add a pipe, the seal can be dismantled and reinstalled.
5. Applications
- Civil and Industrial Construction: Waterproofing entries of engineering systems into basement floors, technical subfloors, elevator shafts.
- Water Supply and Sanitation: Sealing pipe penetrations through the walls of clean water tanks, settling tanks, sewage collectors, pumping stations.
- Transport Infrastructure: Tunnels (road, railway, subway) requiring protection against pressure groundwater.
- Energy and Oil & Gas Sector: Sealing entries at facilities where aggressive environments are present or special reliability is required.
- Special Structures: Dams, embankments, underground storage, swimming pools, wastewater treatment plants.
6. Installation: Key Stages and Rules
- Preparing the Opening and Pipe: The opening in the structure must be even, cleaned of dust, dirt, and sharp edges. The pipe surface in the sealing area must be clean and dry.
- Pre-assembly: The seal (if it is split) is put onto the pipe before it is finally placed into its design position.
- Positioning: The pipe with the seal elements installed is placed into the opening so that the seal is located strictly in the middle of the wall thickness (or according to the instructions).
- Tightening the Tension Clamps: The clamps are tightened with the recommended torque (usually with a torque wrench) to create uniform initial pressure around the entire perimeter.
- Activation of Swelling Elements (if present): After installation, the sealing area is moistened to initiate the swelling process of the bentonite or polymers.
- Inspection: A visual check of the correct installation is carried out and, if necessary, a leak test is performed.
7. Conclusion
Annular space seal is a modern, effective, and durable solution for ensuring the tightness of building structures at points where engineering communications pass through. It solves a set of tasks: from basic waterproofing to protection against aggressive environments and fire.
Choosing a proven system, such as GERDA UKP, guarantees reliability that meets the strict requirements of modern building codes. Proper installation, carried out according to the instructions, ensures the protection of the facility throughout its entire life cycle, preventing costly repairs associated with leaks and damage.
You can explore the range of solutions in the annular space seals section.
