O-Ring Cord: Flexible Sealing for Any Size

Introduction to O-Ring Cord Stock

O-ring cord, also known as extruded cord stock or spliced O-ring material, is a continuously extruded elastomer profile with a circular cross-section that can be cut to any length and joined to form O-rings of virtually any diameter. This versatile sealing product solves one of the most common challenges in industrial maintenance and equipment design: the need for O-rings in sizes that are not available as standard molded parts or that would be prohibitively expensive to manufacture as custom-molded components. With O-ring cord stock and proper splicing techniques, seals can be fabricated on-site to fit any groove diameter from a few centimeters to several meters.

O-ring cord is an essential product for maintenance workshops, field service operations, and equipment manufacturers who need the flexibility to produce seals in non-standard sizes without the lead time and tooling cost of custom-molded O-rings. Understanding the available cord materials, cross-section sizes, and splicing methods enables maintenance teams to create reliable seals for any application quickly and cost-effectively.

Cord Stock Materials

O-ring cord is available in the same range of elastomer materials as standard molded O-rings, allowing material selection based on the specific application requirements:

NBR (Nitrile) Cord

NBR cord is the most commonly stocked material, providing excellent resistance to petroleum-based oils, hydraulic fluids, and fuels. Standard NBR cord in 70 Shore A hardness is suitable for general industrial, hydraulic, and pneumatic applications. Temperature range from -30 to +120 degrees Celsius. NBR cord is the default choice for most industrial maintenance applications.

FKM (Viton) Cord

FKM cord provides superior chemical and high-temperature resistance for demanding applications. Suitable for chemical processing, fuel systems, and high-temperature environments up to 200 degrees Celsius. FKM cord is more expensive than NBR but essential for applications where standard nitrile cannot meet the chemical or temperature requirements.

EPDM Cord

EPDM cord is the preferred choice for water, steam, and outdoor applications where UV and ozone resistance is required. EPDM cord is widely used in water treatment, food processing, and HVAC applications. Temperature range from -50 to +150 degrees Celsius.

Silicone (VMQ) Cord

Silicone cord offers the widest temperature range (-60 to +230 degrees Celsius) and is available in FDA-compliant grades for food and pharmaceutical applications. Silicone cord is also used for high-temperature oven and kiln door seals and other applications requiring extreme temperature flexibility.

Additional Materials

• Neoprene (CR): General-purpose cord with moderate oil and weather resistance
• Polyurethane (PU): High wear resistance cord for abrasive environments
• HNBR: Enhanced temperature and chemical resistance for automotive and oil/gas applications
• FFKM: Premium chemical resistance cord for critical sealing in semiconductor and chemical processing

Cross-Section Sizes

O-ring cord is manufactured in a comprehensive range of cross-section diameters to match standard O-ring groove dimensions. Common cross-section sizes include:

• 1.0 mm, 1.5 mm, 1.78 mm (equivalent to AS568 -0XX series)
• 2.0 mm, 2.5 mm, 2.62 mm (equivalent to AS568 -1XX series)
• 3.0 mm, 3.53 mm (equivalent to AS568 -2XX series)
• 4.0 mm, 4.76 mm (equivalent to AS568 -3XX series)
• 5.0 mm, 5.33 mm, 5.7 mm
• 6.0 mm, 6.99 mm (equivalent to AS568 -4XX series)
• 7.0 mm, 8.0 mm, 8.4 mm
• 10.0 mm, 12.0 mm, 15.0 mm and larger

Cord cross-section tolerances are typically wider than molded O-ring tolerances, which should be considered when calculating gland fill and squeeze percentages. Standard cord tolerances are approximately plus or minus 0.15mm for cross-sections up to 4mm and plus or minus 0.20mm for larger cross-sections.

Splicing Methods

Vulcanized (Hot) Splicing

Vulcanized splicing creates the strongest and most reliable joint by chemically bonding the cord ends using heat, pressure, and a vulcanizing agent. The cord ends are cut at a precise angle (typically 45 degrees), coated with vulcanizing cement, and joined in a heated splice mold. The heat and pressure vulcanize the joint, creating a bond that approaches the strength of the parent material. Vulcanized splices are recommended for dynamic applications, high-pressure sealing, and any application where joint reliability is critical.

Adhesive (Cold) Splicing

Adhesive splicing uses cyanoacrylate (super glue) or specialty rubber adhesive to join cord ends without heat. The cord ends are cut at an angle, adhesive is applied, and the ends are pressed together and held until the adhesive cures. Cold splicing is faster and simpler than vulcanized splicing but produces a weaker joint that is suitable only for static, low-pressure applications. Cold-spliced joints should not be used for dynamic sealing or pressures above 500 psi.

Splice Kits

Complete splice kits are available that include cutting guides, angle-cutting fixtures, vulcanizing cement, and splice molds for producing professional-quality spliced O-rings. These kits enable maintenance personnel to produce reliable spliced O-rings in the field or workshop without specialized training or equipment. Kits are typically available for specific cross-section size ranges and include detailed instructions for the splicing process.

Applications for O-Ring Cord

O-ring cord stock is invaluable for a wide range of sealing applications:

• Large-diameter seals: Manhole covers, tank lids, heat exchanger heads, and large flange connections
• Non-standard sizes: Custom equipment, legacy machinery, and imported equipment with non-standard groove dimensions
• Emergency maintenance: Producing replacement seals on-site when standard molded O-rings are not available
• Prototype development: Creating test seals for new equipment designs before committing to molded O-ring tooling
• Low-volume requirements: Applications where the quantity needed does not justify custom mold tooling
• Adjustable sealing: Applications where the seal diameter may need to be modified for different configurations

Tereefek Solutions: O-Ring Cord Stock Supplier

Tereefek Solutions maintains extensive inventory of O-ring cord stock in NBR, FKM, EPDM, silicone, and other materials across all standard cross-section sizes. We supply cord by the meter or in full-length rolls, along with complete splice kits and accessories for producing professional-quality spliced O-rings. Our technical team can assist with material selection, cross-section sizing, and splicing technique guidance to ensure you achieve reliable sealing results from cord stock O-rings. Whether you need a few meters of cord for a maintenance repair or production quantities for ongoing manufacturing, Tereefek Solutions is your cord stock supply partner. Contact us for pricing, availability, and technical support.