Oring cord
O-ring cord is a sealing gasket supplied in the form of a continuous cylindrical cord, sold by the meter or by the roll, from which the user cuts and joins the O-ring of the required size on site. It is a practical alternative to prefabricated O-rings when the required size is not available in stock, when the seal has non-standard dimensions, or when a groove with a variable or unconventional length needs to be sealed.
Differences between NBR, FKM, EPDM, and VMQ materials and their compatibility with oils, temperatures, and chemical environments
NBR — the standard material for mineral hydraulic oils, greases, and fuels, operating between -40°C and +120°C. FKM (Viton) — for aggressive fluids and temperatures up to +200°C. EPDM — suitable for hot water, low-pressure steam, and water-based fluids; incompatible with mineral oils. VMQ (silicone) — for extreme temperatures (-60°C / +230°C), with lower mechanical resistance compared to NBR or FKM. You can also find prefabricated O-rings in all these materials in our catalog.
How to choose the section diameter, material, and appropriate hardness depending on the application and working conditions
The section diameter of the cord must correspond to the depth and width of the sealing groove. A cord that is too thick compresses the seal excessively; one that is too thin does not seal. The standard hardness for hydraulic applications is 70 Shore A — a balance between flexibility and resistance to extrusion under pressure. Higher hardness (80-90 Shore A) is chosen for high pressures. Also compare with seal kits for complete overhauls of hydraulic cylinders.
Preparing the O-ring cord: correct cutting, measuring the length, and joining the ends for sealing
The length of the cord is calculated from the inner circumference of the desired ring. Cutting is performed perpendicular to the axis of the cord, with a sharp blade, to obtain a flat joining surface without burrs. The ends are bonded with fast cyanoacrylate adhesive or primer + two-component adhesive for joints subjected to thermal or chemical loads. The joint is allowed to cure completely before installation — an incomplete joint fails under pressure.
How to order the right O-ring cord from the Hydraulic Seals Store catalog
We keep O-ring cord made of NBR, FKM, and other materials in stock, in standard section diameters. We deliver by the meter or by the roll, quickly throughout Romania. Order online from the hydsealstore.ro/category/nur-oring/ catalog or contact the Hydraulic Seals Store team for assistance in choosing the correct material and diameter.
Frequently asked questions
When is O-ring cord more suitable than a standard ring?
O-ring cord is more suitable when the required ring size is not available in stock as a finished product, when the seal has non-standard dimensions, or when a groove with a variable length needs to be sealed. Any inner diameter can be made on site.
How do I choose the correct O-ring cord diameter?
The section diameter of the cord must correspond to the depth of the sealing groove. A cord that is too thick compresses the seal excessively; one that is too thin does not seal. The standard hardness for hydraulic applications is 70 Shore A.
How is the cord cut and bonded to obtain a sealed O-ring?
The cord is cut perpendicular to its axis with a sharp blade. The ends are bonded with cyanoacrylate or two-component adhesive, depending on the load. The joint is allowed to cure completely before installation — an incomplete joint fails under pressure.
Can O-ring cord be ordered by the meter?
Yes. We keep O-ring cord available by the meter or by the roll, in NBR, FKM, and other materials. You can order exactly the required quantity from the hydsealstore.ro/category/nur-oring/ catalog or by contacting our team directly.