Case Study: SEPCO EXP Bearing Isolator in a Cement Plant Gearbox

Introduction

Cement plants operate in some of the most demanding industrial environments, characterized by high levels of abrasive dust, extreme temperatures, and continuous heavy-duty operations. Gearboxes in these facilities are critical components that must withstand constant exposure to contaminants, which can lead to lubricant degradation and bearing failures. This case study details the successful implementation of the SEPCO EXP Bearing Isolator on a gearbox in a cement plant, based on operational data from Spring 2019 to February 2026—a period of approximately seven years.

The Challenge

Prior to installing the SEPCO EXP, the cement plant relied on traditional lip seals for the gearbox. These seals proved inadequate for the harsh conditions, resulting in:

• Severe oil loss: The plant lost a full 55-gallon drum of oil every 10 days, leading to frequent refills and increased operational costs.
• Frequent maintenance: Lip seals required replacement every 3 months due to wear and failure.
• Failed interventions: Over a dozen contractors were brought in to address the issue, attempting methods such as coating the shaft beneath the lip seal to reduce friction and improve sealing. None of these efforts yielded lasting results.

In cement production, fine particulate matter like cement dust and silica can infiltrate bearing housings, contaminating lubricants and accelerating wear. Studies indicate that contamination accounts for 52% of bearing failures, with lubrication-related issues contributing to 63% overall. This environment exemplifies why standard contact seals like lip seals often fail prematurely, as they wear against the shaft and allow ingress of abrasives.

The Solution: SEPCO EXP Bearing Isolator

In Spring 2019, the plant installed the SEPCO EXP Bearing Isolator as a replacement for the failing lip seals. The EXP is designed specifically for rotating equipment in harsh industrial applications, such as gearboxes in mining and cement operations.

Technical Overview

The SEPCO EXP Bearing Isolator is a hybrid, non-contact seal that merges proven labyrinth technology with advanced expeller technology. Unlike traditional lip seals, which rely on physical contact and degrade over time, the EXP operates without contacting the shaft, eliminating wear and providing a permanent sealing solution.

Design and Components:

• Dual Expeller System: Features two expellers that generate centrifugal force to propel contaminants away from the bearing housing.
• Vertical Internal Chambers: Double vertically oriented chambers create a labyrinth path, statically forming an effective barrier against ingress.
• Coalescing O-Rings: Two static O-rings break down vapors, mists, or steam, directing them to the expeller chamber for expulsion.
• Angled Oil Drainback: Collects and returns migrating lubricant to the housing, preventing leakage.
• Expeller Chamber and Discharge Port: Dynamically expels contaminants during operation.

The isolator can be split for easy installation without disassembling equipment. For gearbox applications, variants like the EXP-GB provide a positive seal ideal for flooded lubrication conditions.

Materials:

• Housing: Bronze or stainless steel for corrosion resistance in abrasive environments.
• O-Rings: Viton (standard) or custom materials for chemical compatibility.

Specifications:

• Operating Conditions: Handles high RPM, axial movement up to specified tolerances (e.g., total indicator reading for shaft and bore), temperatures in °F/°C, and various lubrication types (oil, grease, oil mist, or circulating systems).
• Mounting Options: Standard press-fit, flange-mounted (EXP-FL), pillow block (EXP-PB), or gearbox-specific (EXP-GB).

• Certifications: ISO 9001:2015 compliant.

How It Works: 

During shaft rotation, centrifugal force adds energy to incoming contaminants (e.g., dust or moisture), deflecting them through the vertical chambers and out via the discharge port. Statically, the labyrinth design and O-rings prevent vapor ingress. This non-contact mechanism ensures no shaft wear, while retaining 100% of the lubricant and excluding external pollutants.

Below is a cross-section view illustrating the EXP’s internal structure in a bearing housing:

This design is particularly effective in cement plants, where abrasive particles would quickly degrade contact seals.

Results

Since installation in Spring 2019, the SEPCO EXP has delivered exceptional performance in one of the harshest environments imaginable:

• Zero Leaks: No oil leakage reported over seven years.

• Minimal Maintenance: The plant has required minimal oil changes, with no EXP isolator replacements.

• Longevity: The unit remains operational without degradation, far surpassing the 3-month lifespan of lip seals.

The success was so profound that when the plant sought to install another EXP on a similar gearbox, extensive archival research—described as “paleontology work”—was needed to locate the original part number, highlighting the rarity of replacements.

Quantitatively, this eliminated the previous oil loss rate (equivalent to over 2,000 gallons per year) and reduced maintenance downtime. Overall, the EXP maximized bearing life by addressing contamination, the leading failure mode, and significantly cut costs on lubricants, labor, and equipment failures.

Conclusion

The SEPCO EXP Bearing Isolator transformed gearbox reliability in this cement plant, turning a chronic maintenance headache into a set-it-and-forget-it solution. By leveraging non-contact centrifugal expulsion and labyrinth sealing, it outperformed traditional lip seals and other attempted fixes, delivering seven years of leak-free operation. This case underscores the value of advanced bearing protection in harsh industries, offering substantial savings in oil consumption, maintenance, and downtime while extending equipment lifespan. For similar applications, the EXP represents a proven, cost-effective upgrade.