Split Oil Seals & Open-Type Shaft Seals

Install or replace rotary shaft seals without removing the shaft, bearing or coupling

Overview

Split oil seals—also called open-type oil seals, segmented shaft seals or clamped rotary seals—are designed for equipment where removing the shaft to install a one-piece seal is impractical or prohibitively expensive. The seal body is split along one side or hinged so it can be opened, wrapped around the shaft and closed in the housing bore. Once installed, the joint is locked by an internal tongue-and-groove or interlocking rib that restores circumferential sealing integrity. Split seals are widely used on large pumps, mixers, turbines, gearboxes, paper machine rolls and mining equipment. The primary advantage of a split oil seal is maintenance access. In a conventional solid seal replacement, the shaft, pulley, coupling and sometimes bearings must be removed to slide a new seal into place. A split seal reduces this downtime from hours or days to minutes. The trade-off is a slightly more complex design and higher unit cost compared to a standard TG4 seal, but the total cost of ownership is often far lower when downtime, labor and lost production are included. Our split seals are available in two main constructions. All-rubber split seals use a flexible NBR or FKM body without a metal case, making them highly conformable and easy to install in worn or non-standard housings. Metal-cased split seals combine a segmented steel shell with a rubber sealing lip for applications requiring higher structural rigidity, pressure retention and dimensional stability. Both designs use a garter spring or internal energizer to maintain lip-to-shaft contact after assembly. Split seals rely on precise joint design to prevent leakage at the split line. We use interlocking profiles, adhesive bonding at the joint or clamping bands depending on the pressure, speed and size. For critical services, we recommend sending a housing drawing and operating conditions so our engineering team can recommend the appropriate joint style and material hardness.

Split Oil Seal Types

All-Rubber Split Oil Seals

Flexible NBR or FKM split seal without a metal case. Conforms to worn housings and installs quickly around the shaft by hand or with simple tools.

Best for: Large pumps, mixers, low-speed shafts, worn bores

Metal-Cased Split Oil Seals

Segmented steel outer shell with a rubber lip and garter spring. Provides the dimensional stability of a TG4 seal with the installation convenience of a split design.

Best for: High-speed shafts, pressurized housings, precise bore fits

Heavy-Duty Split Seals

Reinforced construction with multiple locking segments and high-modulus elastomer for mining, pulp and paper, and marine propulsion shafts.

Best for: Abrasive environments, large diameters, high runout tolerance

Custom Split Seal Assemblies

Designed from shaft and housing drawings with split location, clamping method and lip geometry optimized for the application.

Best for: Obsolete OEM parts, special shaft diameters, unique envelope constraints

Materials

Material	Properties	Best For
NBR	-40°C to +120°C; excellent mineral oil and water-glycol resistance; flexible for easy installation	General industrial, pumps, mixers, gearboxes
FKM	-20°C to +200°C; resistant to synthetic oils, fuels, heat and chemicals	High-temperature and chemical service
HNBR	-40°C to +150°C; improved abrasion, ozone and sour-gas resistance	Oilfield, mining and outdoor equipment

Sizing

Split oil seals are custom-made to the shaft diameter, bore diameter and width of the existing housing. Because they must open and close around the shaft, the split line geometry and clamping method are as important as the nominal dimensions. Provide a housing drawing or sample seal for accurate quotation.

Standard Split Seal Range

• Shaft diameters typically 50 mm and larger
• Custom OD and width per housing
• NBR and FKM standard; HNBR optional

Custom Split Seals

• Manufactured from drawing or sample
• Special joint profiles and clamping bands
• MOQ from 1 piece

Frequently Asked Questions

Do split oil seals leak at the joint?

A properly designed split seal does not leak at the joint under normal operating conditions. The joint uses an interlocking profile, clamping band or adhesive to restore circumferential sealing. For high-pressure or high-speed applications, metal-cased designs with precision joints are recommended.

When should I choose a split seal over a standard TG4 seal?

Choose a split seal when the cost of removing the shaft exceeds the cost premium of the split seal. Common scenarios include large pumps, turbines, paper machine rolls, gearboxes with tight assemblies and any equipment where shaft removal requires crane rental or major disassembly.

Can split seals be used on high-speed shafts?

Yes, metal-cased split seals are suitable for moderate to high speeds when the joint is well-clamped and balanced. All-rubber split seals are generally limited to lower speeds because their flexibility can cause distortion at high centrifugal forces.

What information do you need to quote a split seal?

Provide shaft diameter, bore diameter, width, operating speed, temperature, sealed fluid, pressure and whether the housing is accessible for clamping. A drawing or photo of the existing seal and housing is ideal.

Are split seals reusable?

Split seals are typically designed for one installation cycle. Reusing a split seal risks joint leakage because the locking features may not seat as tightly the second time. Keep spare split seals in stock for planned maintenance.

What is the lead time for custom split seals?

Standard split seals in common NBR compounds ship in 10–20 business days. Custom sizes, FKM or HNBR compounds and special joint designs require 15–25 business days. Rush service is available for critical shutdowns.