In the asphalt industry, selecting the appropriate sealing components is just as important as maintaining equipment reliability. In this case study, Hi-Tech Seals introduced Viton™ O-rings, offering a sealing solution engineered for the customer’s unique application to help reduce downtime and costly maintenance.
Viton™ is a high-performance fluorocarbon (FKM) compound known for its exceptional resistance to heat, fluids, and aggressive chemicals while maintaining outstanding physical properties even in the most demanding environments.
Customer Profile
The customer is an industry-leading company that specializes in mix design and manufacture of asphalt emulsions for construction, roadway, and municipal maintenance industries.
Application
Hi-Tech Seals was consulted by the customer regarding a critical issue affecting a key piece of their production equipment, the centrifugal pump. The pump is used in transferring asphalt throughout the production process.
During peak season, production runs 24 hours a day and 7 days a week. The pump’s service life is between 2.5 to 3 weeks. At this point, asphalt may breach the pump’s internal stator, leading to equipment failure.
Such a breakdown could result in one to two days for transporting parts, followed by two to three days of equipment overhauling, and approximately $20,000 in repair costs per occurrence, excluding any associated profit losses.
Sealing Challenges
Upon reviewing the application, the issue appeared to have originated from failed fluorocarbon (FKM) O-rings located in various ports of the pump. During the coking process, the seals experienced heavy compression set (the cross-section became triangle shaped), became hardened, cracked, and extremely brittle. Temperatures consistently reached 325°F (163°C) internally, and the pumping pressure was maintained at 50 psi.
Hi-Tech Seals’ Solution
For further analysis, the customer submitted the failed seal samples to our engineering lab. After a thorough examination, we ruled out temperature and pressure as the primary causes of failure. This is because FKM’s temperature range exceeds the pump’s operating temperature. The pump’s operating pressure was also too low to cause a compression set or deterioration of this magnitude. We then changed our focus to chemical compatibility in conjunction with heat and pressure.
Asphalt is comprised of a mixture of the following components:
- Bitumen
- Stoddard Solvent
- Fatty Acids
- Styrene
- Butadiene
- Water
- Aggregate
- Petroleum-based Binder
FKM is rated as having excellent compatibility with each component, except when directly exposed to water. Based on this assessment, we concluded that the original O-rings’ failure was due to their composition, specifically being a sub-quality elastomer with low fluorine content. The immediate solution was to replace the affected seals with our Viton™ O-rings.
The Results
After implementing Viton™ O-rings, an end-of-season maintenance and evaluation confirmed that Viton™ exceeded the performance and service life of the original FKM O-rings exponentially, with no instances of failure observed. Viton™ O-rings exhibited only a minor compression set, minimal increase in hardness, and negligible bypass. As a result, the pump performed reliably and uninterrupted throughout the season.