Metal O-Rings & Metal C-Rings
Stainless steel, Inconel and Monel seals for cryogenic, high-temperature, vacuum and high-pressure applications.
Overview
Metal O-Ring Types
Solid Metal O-Rings
A solid metal ring compressed between flange faces. Highest pressure capacity and simplest form; limited elastic recovery.
Best for: High-pressure flanges, heat exchangers, reactor vessels
Hollow Metal O-Rings
A metal tube formed into a ring and flattened at the seal interface. The hollow section provides spring-back and lower seating load than solid rings.
Best for: Vacuum chambers, bolted covers, applications needing lower bolt preload
Metal C-Rings Seals
A C-shaped metal seal that opens under compression, providing high spring-back and excellent pressure-energized sealing.
Best for: Cryogenic, thermal cycling, high-pressure bolted joints
Metal E-Ring Seals
An E-shaped profile with multiple sealing lips. Provides redundant sealing lines and very low leak rates in UHV and aerospace systems.
Best for: Ultra-high vacuum, semiconductor, critical aerospace seals
Materials & Alloys
| Material | Properties | Best For |
|---|---|---|
| 316L Stainless Steel | −250°C to +550°C; excellent corrosion resistance; lower cost | General chemical, marine, food and pharmaceutical |
| Inconel 718 | −270°C to +800°C; oxidation and creep resistant; high strength | Aerospace, turbine exhaust, nuclear, high-temperature process |
| Monel 400 / K-500 | −200°C to +540°C; seawater and acid resistant; non-galling | Marine, chemical processing, sour gas |
Sizing & Specification
Metal o rings are made to drawing or groove specification. Provide inner diameter, cross-section or tube OD, flange class, operating pressure and temperature.
Standard Profiles
- • Solid round
- • Hollow round
- • C-ring
- • E-ring
Common Alloys
- • 316L SS
- • Inconel 718
- • Monel 400
- • Titanium (select)
Plating Options
- • Silver
- • Gold
- • PTFE
- • None
Metal O-Ring vs Elastomer O-Ring
Metal seals solve the cases where rubber and PTFE cannot survive.
| Feature | Metal O-Ring | Elastomer O-Ring |
|---|---|---|
| Temperature range | −270°C to +800°C | −60°C to +325°C typical |
| Pressure capability | Very high; pressure-energized designs | Up to ~200 bar with backup rings |
| Chemical resistance | Near-universal (alloy dependent) | Material dependent |
| Elastic recovery | Limited; designed spring-back | Excellent |
| Surface finish | Ra ≤ 0.8 µm typical | Ra 0.8–3.2 µm typical |
| Best for | Cryo, UHV, high heat, radiation | Hydraulics, fuel, water, general industrial |
Applications
Aerospace & Propulsion
Turbine seals, cryogenic fuel lines, rocket engine joints
Semiconductor
UHV chambers, plasma processing, wafer handling systems
Nuclear & Energy
Reactor pressure vessel covers, heat exchanger flanges
Cryogenics
LNG transfer flanges, dewar seals, superconducting systems
Frequently Asked Questions
What is a metal o ring?
A metal o ring is an all-metal static seal made from solid, hollow or C-shaped metal. It seals by elastic deflection between two flat mating surfaces and is used where elastomers cannot survive extreme temperature, vacuum or chemicals.
What are metal o rings used for?
Metal o rings are used in aerospace propulsion, semiconductor vacuum chambers, nuclear reactors, cryogenic systems, high-temperature exhaust and any application beyond elastomer temperature or chemical limits.
What is a metal c-ring seal?
A metal c-ring seal is a C-shaped metal seal that opens under flange compression. The design provides spring-back and pressure-energized sealing, making it ideal for cryogenic and thermal-cycling applications.
Can metal o rings replace rubber o rings?
Only with a joint redesign. Metal seals need higher bolt preload, smoother surface finish and a groove designed for metal deflection. They are not drop-in replacements for elastomer O-rings.
What materials are metal o rings made from?
Common alloys are 316L stainless steel, Inconel 718 and Monel 400 or K-500. Plating options include silver, gold and PTFE to reduce seating load and prevent galling.
What temperature can metal o rings handle?
Depending on alloy, metal o rings operate from −270°C to over +800°C. Inconel 718 covers the highest temperatures; 316L is suitable up to about +550°C.
Are hollow metal o rings better than solid?
Hollow metal o rings need lower bolt preload than solid rings and provide better spring-back, but solid rings handle the highest pressures. The best choice depends on pressure, flange stiffness and assembly load limits.
How do I order custom metal o rings?
Provide inner diameter, cross-section or tube size, alloy, plating, operating pressure, temperature and media. We quote from drawing or groove specification, typically within 24–48 hours.