Sanitary industry
Sealing of pipe connections, fittings and installations, on request to KTW, DVGW, W270, WRAS and others for hygienic standards.
Sealing rings
Crush Seals
SIEGEL Dichtungen manufactures crush seals, compressible sealing rings and flat seals, to drawing or standard, from single parts to series production. Our seals are used in valves and fittings, screw connections, housings, flanges and equipment, and stand out for their dimensionally accurate geometry, suitable Shore hardness and reproducible compression values.
Materials
Various elastomers & TPE
Approvals
KTW-BWGL · WRAS
Manufacturing
Extruded or moulded
Series
Small to large series
Your benefits
Why Crush Seals from SIEGEL
Custom manufacturing
Crush seals made exactly to your specifications and drawings, with surface compression ensuring a reliable seal.
Wide range of materials
NBR, EPDM, CR/Neoprene, PUR, silicone and FKM/Viton, among others: the right solution for every application, and specifically for drinking water on request to KTW-BWGL, EN 16421 (W270), DVGW and WRAS.
Economical and fast
Extruded, punched or moulded, without additional tooling costs and with short delivery times.
Documentation
Test report and inspection certificate, EMPB/PPAP, IMDS, batch traceability to ISO 9001.
Design and advice
We select materials, Shore hardnesses and wall thicknesses to suit the medium, temperature and required compression.
ISO 9001 certified
SIEGEL Dichtungen stands for ISO-certified quality. Automatic 100% inspection on request.
Technical data
Product specifications
Specifications may vary depending on the material option. Contact us for further information or specific requirements.
Material
Various elastomers such as NBR, CR, EPDM, FKM and silicone for reliable sealing, coloured versions can also be produced.
Temperature resistance
Resistant across a wide temperature range from -40 °C to > +200 °C, for use in different environments and countries.
Dimensions
In various diameters and cut thicknesses for screw connections and flanges, to meet different requirements.
Assembly
Quick and easy assembly without special tools, e.g. in a screw connection with different nominal sizes.
Standards and approvals
Available to various drinking water standards and approvals such as KTW-BWGL, DVGW, W270 and WRAS.
Resistance
Materials offering chemical resistance to acids, alkalis, oils and fuels as well as to weathering such as UV and ozone.
Applications
Sanitary industry, construction, building services and more.
Your application
Special requirements for material or standard?
Tell us about your application, for example media, temperature ranges or standards. We recommend the material and the matching manufacturing process and provide samples in advance on request.
Materials & standards
Suitable materials & approvals
Crush Seals are manufactured from the following materials and, on request, designed to meet the relevant standards and approvals. The linked pages provide details on properties, resistances and regulations.
Materials
Standards & approvals
For an overview of all tests, see Standards & approvals.
Process
Manufacturing & processes
More on manufacturing & tolerances
What are crush seals?
Crush seals are compressible sealing elements that create a reliable seal when compressed over a surface or along a line, e.g. between two plane-parallel surfaces, in screw connections or as a washer or housing ring. Depending on their geometry, they are also referred to as compression seals, flat seals, sealing washers, fibre or rubber washers or compression rings.
Typical applications
- Sanitary/heating: valve and appliance screw connections, pump housings, filter bowls
- Mechanical and apparatus engineering: housing covers, measuring instruments, compressors
- Pneumatics/hydraulics: air preparation units, valves, quick-release couplings
- Food/pharmaceuticals: surfaces in contact with media (observe material approvals)
- Electrical/electronics: housing feedthroughs, fire protection requirements possible
Materials and grades
We select materials to suit the medium, temperature and required compression.
| Material | Properties | Temperature range* | Typical applications |
|---|---|---|---|
| NBR (acrylonitrile butadiene) | resistant to oil, grease and fuel | -30 to +100 °C | oil circuits, pneumatics/hydraulics, mechanical engineering |
| EPDM | very good resistance to water and steam, seawater-resistant, weatherproof | -40 to +120 °C | sanitary/heating, drinking water |
| FKM/FPM | excellent resistance to chemicals and temperature | -20 to +200 °C | chemicals, automotive, high temperature |
| Silicone (VMQ) | high temperature resistance, physiologically safe, FDA-compliant | -50 to +200 °C | medical, food, electronics |
| CR/Neoprene | self-extinguishing, classification to UL94 | -30 to +110 °C | mechanical engineering, electrical industry |
*Guide values. Exact limits for each compound or grade on request.
Manufacturing processes
- Punching: economical for high volumes, contours to DIN or drawing
- Water jet cutting: no tooling required, ideal for samples, small series and large diameters
- Moulded articles (transfer moulding/compression moulding): complex geometries possible
- Extrusion: custom diameters can be produced, to DIN 3302-1
- Turning and cutting technology: precision rings made from thermoplastic materials
- Surface treatment and finishing: deburring, grinding and polishing of sealing surfaces, coatings
Standards, approvals and testing
- Drinking water: KTW-BWGL / WRAS (depending on material)
- Gas: e.g. EN 681-1, EN 549, DVGW
- Chemicals/oil: material-specific tests (media and ageing tests)
- Fire protection: UL 94 (V-0/V-1/V-2, 5VA/5VB, HB), depending on the application
- Quality: dimensional and hardness testing (Shore A), compression behaviour, tightness and leakage rate
On request, we supply test certificates, material data sheets, EMPB and IMDS entries, and document batches and traceability to ISO 9001:2015.
Engineering: design and installation
| Parameter | Guide value | Note |
|---|---|---|
| Degree of compression (flat seal) | 10 to 25% | depends on material and hardness, take settling behaviour into account |
| Shore hardness | 40 to 90 A | softer = lower tightening force, harder = more dimensionally stable |
| Surface roughness Ra | 0.8 to 3.2 µm | too smooth = creep, too rough = leakage paths |
| Tightening torque | according to bolts/DN | tighten crosswise, retighten after initial operation |
| Media compatibility | material-specific | oils/fuels vs. water/steam vs. chemicals |
Dimensions, tolerances and delivery forms
- Inner and outer diameters from approx. 5 mm to > 2,000 mm (depending on the process)
- Thicknesses typically 0.5 to 30 mm (elastomer), multi-layer above that
- Tolerances to DIN/ISO or drawing
- Delivery forms: loose, sealed in bags, mounted, stacked, in packaging units
- Marking: on request with batch code, material abbreviation or QA label
Applications
Industries & applications
Building services
Sealing and insulation of sanitary installations, heating and air-conditioning systems, minimising energy losses and ensuring a reliable seal.
Mechanical and plant engineering
Used in sealing systems, connections and electrical assemblies, providing reliable protection against dust, dirt and media, also as buffers.
Hydraulics and pneumatics
For the smooth operation of valves, cylinders, pistons, shafts and fittings.
Food and beverage industry
The highest hygiene standards, and our elastomer and plastic seals play an essential role in meeting them.
Medical technology
Precision, hygiene and reliability for highly sensitive, sometimes life-sustaining applications.
Electrical industry
Insulation and sealing of components, control cabinets, connectors and cable glands, including strain relief, kink protection and protection against moisture, also as EMC seals on request.
Drinking water
On request to KTW-BWGL (EPDM blue), EN 16421 (W270), WRAS and KIWA for drinking water applications.
FAQ
Frequently asked questions
What is the difference between crush seals and O-rings?
Crush seals are compressed across their surface (washers and flat seals), whereas O-rings seal in defined installation spaces (groove) by radial or axial compression.
Which media are possible?
Water and drinking water (EPDM), oils and fuels (NBR/FKM), chemicals (FKM), steam (EPDM/silicone). We check your application individually.
Can the seals meet UL 94 or KTW-BWGL?
Yes, with suitable compounds and verified testing for each requirement and thickness.
Product range
Related products
Cooperation
The right Crush Seals for your application?
Tell us about your application, for example media, temperature ranges or standards. We recommend the material and the matching manufacturing process and provide samples in advance on request.