Types of Seals and Gaskets: A Complete Guide to Materials, Functions, and Industrial Applications

In industrial machinery, automotive manufacturing, petrochemicals, engineering, and energy systems, seals and gaskets are mission critical parts. From fluid containment to mechanical integrity, these components prevent leaks, minimize friction, and support safety in high pressure or corrosive environments.

Founded in 1968, Sun Rubber designs and manufactures rubber seals and gaskets for global customers. This guide explains the main types of seals and gaskets, common materials, and how to select the right product for your application.

Seals vs. Gaskets: What Is the Difference

Seals are used where at least one component moves, such as a rotating shaft. They must retain fluids or gases while tolerating friction and wear. Gaskets are used between two static surfaces. They create a compressive barrier that prevents leakage when flanges or plates are bolted together. Both are essential to keep systems efficient, clean, and reliable.

Common Types of Seals and Where They are Used

1. O Rings

O rings are circular elastomer rings used in both static and dynamic sealing. They are cost effective, easy to install, and compatible with many fluids and temperatures.

• Materials: NBR, EPDM, Viton, Silicone, CR.
• Applications: pumps, hydraulic cylinders, compressors, valves, fuel systems.

Sun Rubber provides custom sizes and tooling that follow common standards such as AS568 and ISO 3601.

2. Oil Seals or Shaft Seals

Oil seals retain lubricants around rotating shafts and keep contaminants out. They are used in engines, gearboxes, motors, and automotive powertrains.

• Materials: NBR and Viton with metal reinforcement and spring elements.
• Key benefit: stable dynamic sealing under high speed, pressure, and temperature.

3. Mechanical Seals

Mechanical seals create tight interfaces between a rotating shaft and a stationary housing, most often in pumps.

• Materials: carbon, ceramic, silicon carbide, metal springs, and rubber secondary seals.
• Applications: chemical pumps, water systems, food processing equipment.

4. Custom Molded Seals

When geometry is complex or service conditions are extreme, custom molded seals are the best route. Sun Rubber supports compression and injection molding as well as CNC tooling for prototypes and rapid scale up.

Common Types of Gaskets and Where They are Used

1. Rubber Gaskets

Rubber gaskets provide flexibility, resilience, and broad chemical compatibility.

• Materials: NBR, EPDM, CR, Silicone, Viton.
• Applications: pipes, flanges, fuel tanks, HVAC, household appliances.

Sun Rubber offers press molded and die cut gaskets. For small batches, die cutting can replace a metal mold to reduce cost, noting that hydraulic molding provides higher dimensional accuracy.

2. Compressed Fiber Gaskets

These gaskets blend fibers with rubber and are selected for high temperature and chemical resistance.

• Applications: boilers, pipelines, flanges in oil and gas.
• Typical temperature: up to about 400 C depending on grade.

3. Metal Gaskets

Used under extreme pressure, heat, or aggressive media.

• Types: spiral wound, ring type joint, corrugated metal.
• Applications: petrochemical plants, offshore rigs, power and nuclear systems.

4. Sponge and Foam Gaskets

Best for low pressure sealing, moisture control, cushioning, and vibration absorption.

• Materials: EPDM foam, neoprene foam, polyurethane foam.
• Applications: electronics enclosures, automotive interiors, packaging.

Key Materials for Seals and Gaskets

The material determines performance, life, and cost. Select based on media, pressure, motion, temperature, and environment.

Material	Characteristics	Resistant To	Typical Applications
NBR (Nitrile Rubber)	Good oil and fuel resistance, balanced cost and performance	Petroleum based fluids	Oil seals, O rings, fuel systems
EPDM (Ethylene Propylene)	Excellent weather, ozone, and steam resistance	Acids, outdoor exposure, hot water and steam	Water systems, HVAC gaskets, automotive cooling
Viton or FKM	High temperature and chemical resistance	Fuels, solvents, synthetic oils	Automotive, aerospace, petrochemical
Silicone	Very wide temperature range and good flexibility	Oxidation, ozone, UV	Food grade and medical seals, low temperature service
CR or Neoprene	Good aging, weather, and flame resistance	Refrigerants, moderate oils	Electrical systems, refrigeration, enclosures

Sun Rubber provides material consulting to match temperature range, media compatibility, mechanical load, and regulatory needs such as ISO, RoHS, and FDA where applicable.

How to Choose the Right Seal or Gasket

1. Temperature: confirm minimum and maximum service temperatures.
2. Media: identify oils, fuels, gases, acids, water, or steam in contact.
3. Pressure and Motion: static vs dynamic, shaft speed, compression set limits.
4. Standards: confirm industry or customer specifications and test methods.
5. Manufacturing: choose molded, die cut, extruded, or bonded construction.
6. Cost and Quantity: plan for prototypes and scale up to mass production.

Why Industrial Buyers Choose Sun Rubber

With more than 50 years of manufacturing experience, Sun Rubber is a solutions partner, not only a parts supplier. We offer in house mold design, custom compounding, ISO based quality control, small batch prototyping, scalable mass production, and a commitment to sustainable development through recycled rubber initiatives. If you need standard or custom seals and gaskets, our team can help specify the right material and geometry for your project. We support OEM and ODM, custom sizes and materials, and global export.