Steam and Autoclave O-Rings
Peroxide-cured EPDM and steam-resistant FFKM for saturated steam, autoclaves and boiler seals.
Steam sealing is one of the most challenging applications for elastomers. Saturated steam above 120°C causes rapid hydrolysis and degradation in many rubber compounds. Standard NBR hardens and cracks. Standard FKM swells and loses physical properties. For reliable steam service, material selection is critical. Peroxide-cured EPDM is the industry-standard elastomer for saturated steam up to approximately 150°C. It resists hydrolysis, maintains compression set resistance, and performs reliably through thousands of autoclave and SIP cycles. For superheated steam or temperatures exceeding 150°C, steam-resistant FFKM grades are required.
Application Requirements
Recommended Materials
Design Tips
- 1.Always specify peroxide-cured EPDM for steam; sulfur-cured grades fail much faster
- 2.Use 70 Shore A for the best balance of sealing and thermal recovery in steam
- 3.Design grooves with 20-25% compression to compensate for thermal expansion
- 4.Keep groove fill below 80% to allow for swell and thermal expansion
- 5.Avoid NBR and standard FKM in continuous saturated steam service
Common Sizes
| Size | Typical Use |
|---|---|
| Tri-Clamp sanitary seals | 1/2" to 4" for autoclave and bioreactor ports |
| AS568-006 to AS568-050 | small steam valve and instrument seals |
| AS568-110 to AS568-178 | medium boiler and pump seals |
| AS568-210 to AS568-284 | large flange and manway seals |
Frequently Asked Questions
Can EPDM handle 134°C autoclave cycles?
Yes. Peroxide-cured EPDM is the standard material for 121-134°C saturated steam autoclaves and can survive thousands of SIP cycles.
Is FKM good for steam?
Standard FKM has limited steam resistance and is generally not recommended for continuous saturated steam above 120°C. Steam-resistant FFKM grades are a better choice for high-temperature steam.
What is the best O-ring for a steam boiler?
For saturated steam boilers up to 150°C, peroxide-cured EPDM 70 Shore A is the best choice. For superheated steam or temperatures above 150°C, specify steam-resistant FFKM.
How long do steam O-rings last?
In properly designed glands, peroxide-cured EPDM steam seals typically last 3-5 years in industrial service and over 1,000 autoclave cycles in medical/pharmaceutical equipment.