Sealing light hydrocarbons such as methane, ethane, propane, and butane presents a unique set of challenges. Their low boiling points mean even small pressure or temperature changes can cause vaporization at the seal faces. Add humidity, and you’re often dealing with icing, rapid wear, and unplanned shutdowns.
The Real-World Challenge
Operators in gas plants, refrigeration units, and petrochemical facilities see the same issues repeatedly:
- Icing in the seal chamber: A few drops of leakage can flash to vapor and freeze. Ice builds around the faces, leading to hang-up and scoring.
- Volatile leakage: Unlike heavier fluids, light hydrocarbons escape easily. What looks like a small leak can quickly become a safety or emissions problem.
- Downtime pressure: Failures in these services usually mean high-consequence repairs, lost production, emergency seal changeouts, and regulatory headaches.
Proven Sealing Approaches
Dual Seals with API Plan 53A
A dual pressurized seal with a Plan 53A support system is the most reliable approach for cold-service hydrocarbons.
- Barrier fluid control: Keeps hydrocarbons out of the seal chamber, preventing flashing and icing.
- Cooling and lubrication: Maintains stable face conditions under cold and variable loads.
- Leak prevention: Provides a secondary safety envelope, critical in volatile hydrocarbon service.
Metal Bellows Seals
When temperature swings are significant or elastomers are unreliable, metal bellows seals are often the best option.
- Elastomer-free flexibility: No O-rings to shrink, harden, or hang up in low temperatures.
- Self-cleaning action: The bellows design uses rotation to shed debris and deposits, extending life in fouling conditions.
Materials That Withstand the Cold
Seal reliability in this service is as much about materials as design:
- Sintered silicon carbide: Resists wear and transfers heat away from the faces.
- Hastelloy®️ and 316 stainless steel: Withstand corrosive byproducts in gas processing streams.
- Perfluoroelastomers: Maintain elasticity where standard elastomers would embrittle.
Results in the Field
Plants that have adopted these approaches report:
- Longer MTBF, with seals lasting years instead of months in propane and ethane service
- Improved safety, with emissions events reduced or eliminated
- Lower lifecycle costs, with less emergency maintenance and fewer unplanned outages
Closing Takeaway
Light hydrocarbons at low temperature leave little margin for sealing errors. Success depends on the right seal type, the right support system, and materials engineered for the cold. Flexaseal designs specifically for these conditions, helping operators run safely, reliably, and with confidence in their equipment.
