Square Engagement Rings With Diamond Band – Metal O-rings will be the metallic variations of commonly used elastomeric O-rings. They are generally used in static sealing applications that are incompatible with the chemical and physical features of elastomeric O-rings. All these O-rings have high tolerance to radiation as well as high vacuum, and are generally used for flanged applications. Ideally, metal O-rings are placed in both closed and open grooves and axial pressure is applied between two parallel surfaces. What’s more, grooves that maintain the O-rings are designed to be perpendicular to the direction of the fluid flow. When placed between compressed and surfaces to a predetermined height, deforms and generates contact between the jointing and sealing faces. Inherently, O-rings’ metallic elasticity displays a reasonable deflection and generates maximum sealing contacts during surgery to make sure the sealing action. In addition to elastic deflection of the metal, structural builds of the O-rings also play a significant role in creating the sealing force. Even though most metals can be used for manufacturing metal O-rings, the choice of metals must be such that the linear growth co-efficient of the O-ring metal varies slightly from the linear growth co-efficient of the metal(s) of jointing surfaces. Metal O-rings are vulnerable to rust unlike elastomeric O-rings, and therefore, are coated with a suitable material to prevent rusting. This material is softer than the base metal and serves another purpose of preventing the impact of surface abnormalities. The coating materials that are typically used are soft metals, such as silver, and non-metals like PTFE.
Metal O-rings are primarily classified based on their fundamental structural attribute, they are classified as follows:
Solid Metal O-Rings
Solid metallic rings are cables of round profile attached like a ring. These kinds of O-rings need special grooves for their efficient functionality. This requirement of special grooves restricts the use of solid metallic O-rings to specific applications, such as engine cylinder heads. Solid metallic rings are generally made in aluminum and appropriate for use in nuclear reactors, for assessing radiation leaks. These O-rings can handle pressures of around 4MPa and temperatures reaching 500°C and are acceptable for moderate pressure and medium sized vacuum applications.
Hollow Metal O-Rings
Hollow metallic O-rings are structurally more sophisticated in comparison with solid metallic O-rings and shaped by curved tubes bent into the shape of a ring. All these O-rings are sub-classified dependent on the characteristics of the hollow sector of the ring.
These are hollow metallic O-rings with nitrogen at atmospheric pressure or vacuum within them. Plain hollow O-rings are used in low stress or low vacuum applications. Although plain hollow O-rings display similarity in temperature and pressure handling capabilities with solid metallic O-rings, they provide substantially superior spring-back and sealing capabilities. Normally, plain hollow metallic O-rings are manufactured from Inconel 750 and garnished with silver.
Self-energized hollow O-rings have holes or vents in their surfaces to utilize the system pressure or atmospheric pressure to sealing activity. Depending upon the orientation of such grooves, the O-rings are further classified into internally vented O-rings and externally vented O-rings. Internally vented O-rings made of light steel and garnished with PTFE can withstand pressures of around 3500 kg/sq cm and temperatures of 600°C. Externally vented O-rings are used in applications where the external pressure is greater than the pressure within the seal.
Stress stuffed hollow O-rings are altered plain hollow bands with pressurized inert gasses inside them. These O-rings can be used in tongue and groove flanges and will handle temperatures from cryogenic temperatures up to 850°C. Stress filled O-rings are used in vacuum sealing applications.
- Metal O-rings can’t be used in highly dynamic sealing applications
- All these O-rings are rendered useless after they’re used once because they can’t keep their shape after only use
- Broad tolerances of the groove can’t be adapted by the metallic O-rings, particularly in bigger sizes
- Careful fitting should be done to prevent their deformation until their seal is tightened.