Carbon Graphite and Silicon Carbide for Marine Sealing Systems
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Datum: 27. August 2026
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CarSIK-CT: Greater Reliability for Marine Sealing Systems
The seal ring made of reaction-bonded silicon carbide can be split without compromising its sealing effect and installed around the shaft from the outside. Embedded graphite also provides reliable emergency-running properties – ideal for demanding applications in the marine industry.
Bulkhead seals, stern tube seals, and submarine seals must perform reliably over long periods of operation. Wear, temperature, and exposure to different media place high demands on both the material and the component.
Schunk supports manufacturers of marine sealing systems with materials expertise and precision-manufactured seal rings made of carbon graphite and silicon carbide. Different material grades and designs are available depending on the application.
What Does the Material Need to Deliver?
Selecting the right material for a marine sealing application depends on several factors. Depending on the operating conditions, wear and media resistance can be just as important as strength, thermal conductivity, or temperature resistance.
Schunk uses materials including carbon graphite and silicon carbide for these applications. Different grades within these material groups provide distinct technical properties.
Material
42Z5
42A
82Z5
82A
FH NT
CarSIK CT
Material group
Carbon graphite
Carbon graphite
Carbon graphite
Carbon graphite
SiSiC
SiSiC+C
Flexural strength [MPa]
60
80
75
90
280
120
Compressive strength [MPa]
210
250
250
350
3,000
650
Thermal conductivity [W/mK]
11
13
8
9
120
120
Temperature resistance, oxidizing [°C]
200
350
200
350
1,380
1,380
The values shown are typical, non-binding values based on experience. Variations in materials and manufacturing should be taken into account.
The comparison highlights the differences between the individual property profiles. Which material is suitable for a particular sealing application therefore depends on the specific operating conditions.
When a Segmented Seal Ring Is the Better Choice
Material selection is only part of the equation. The design of the seal ring also matters, especially when installation conditions make a one-piece ring impractical.
For these applications, Schunk manufactures segmented seal rings. Their multi-part design is particularly suited to installation situations where a one-piece seal ring cannot be used.
Options range from small to very large diameters and from custom-made individual components to series production. This allows both material and design to be selected for the specific application.
From Raw Material to Finished Seal Ring
Technical material properties are only one part of a high-performance component. Manufacturing quality is equally important.
Schunk products are manufactured from raw materials that undergo strictly defined treatment or are selected based on exact specifications. Subsequent manufacturing processes also follow precise technical requirements.
The result is carbon graphite and silicon carbide seal rings designed for high resistance to wear, temperature, and media, as well as long service life. In addition to standardized processes, custom solutions are available for specific applications.
For Bulkhead, Stern Tube, and Submarine Seals
A stern tube seal has different requirements than a bulkhead or submarine seal. Dimensions and installation conditions can also vary considerably.
Depending on the application, different material grades as well as one-piece and segmented seal rings are available. Durable, low-maintenance solutions help provide a high level of process reliability.
Conclusion: Consider Material and Design Together
For marine sealing applications, material properties, component design, and manufacturing quality need to work together. Carbon graphite and silicon carbide offer different property profiles, while one-piece and segmented seal rings address a range of installation conditions.
Schunk combines materials expertise with precision manufacturing, from custom-made individual components to series production and application-specific solutions.
Interested in more information?
Find relevant brochures, technical documents and further information on seal rings made of carbon graphite and silicon carbide for maritime applications.
Learn more about Schunk Carbon Technology’s material and component solutions for seal rings, bearings and sleeves under demanding operating conditions.
CarSIK-CT: Greater Reliability for Marine Sealing Systems
The seal ring made of reaction-bonded silicon carbide can be split without compromising its sealing effect and installed around the shaft from the outside. Embedded graphite also provides reliable emergency-running properties – ideal for demanding applications in the marine industry.
