Black Titanium Rings For Her – Metal O-rings are the metallic variations of commonly used elastomeric O-rings. They are typically utilised in stationary sealing applications that are incompatible with all the physical and chemical features of elastomeric O-rings. All these O-rings have high tolerance to radiation in addition to high vacuum, and are usually employed for flanged programs. Ideally, metal O-rings are put in both open and closed grooves and axial pressure is applied between two parallel surfaces. Furthermore, grooves that maintain the O-rings are designed to be vertical to the direction of the fluid flow. When placed between surfaces and compressed to a predetermined height, deforms and generates contact between the jointing and sealing faces. Inherently, O-rings’ metallic elasticity displays a affordable deflection and generates maximum sealing contacts during operation to ensure the sealing action. In addition to elastic deflection of the alloy, structural assembles of the O-rings also play a significant part in producing the sealing force. Although most metals may be used for fabricating metal O-rings, the choice of metals must be such that the linear expansion co-efficient of the O-ring metal fluctuates slightly from the linear expansion co-efficient of the alloy(s) of jointing surfaces. Metal O-rings are vulnerable to rusting unlike elastomeric O-rings, and as such, are coated with a suitable material to avoid rusting. This material is softer than the base metal and serves another purpose of negating the effect 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 largely categorized according to their fundamental structural attribute, they are classified as follows:
Strong Metal O-Rings
Strong metal rings are cables of circular profile attached like a ring. These types of O-rings need specific grooves for their effective functionality. This requirement of specific grooves limits the use of strong metal O-rings to certain programs, such as engine cylinder heads. Strong metal rings are usually made in aluminum and appropriate for application in nuclear reactors, for checking radiation leaks. These O-rings can handle pressures of up to 4MPa and temperatures hitting 500°C and are acceptable for moderate pressure and moderate vacuum applications.
Hollow Metal O-Rings
Hollow metal O-rings are structurally more sophisticated in contrast with solid metal O-rings and formed by curved tubes bent into the form of a ring. All these O-rings are sub-classified based on the characteristics of the hollow sector of the ring.
Plain Hollow O-Rings:
These are hollow metal O-rings with nitrogen in atmospheric pressure or vacuum within them. Plain hollow O-rings are employed in low stress or low vacuum applications. Although plain hollow O-rings show similarity in temperature and pressure handling capabilities with solid metal O-rings, they offer considerably superior spring-back and sealing capacities. Generally, plain hollow metal O-rings are manufactured from Inconel 750 and garnished with silver.
Self Energized Hollow O-Rings:
Self-energized hollow O-rings have holes or vents on their surfaces to utilize the system pressure or atmospheric pressure to sealing activity. Based upon the orientation of these grooves, the O-rings are further classified into internally vented O-rings and externally vented O-rings. Internally vented O-rings made of mild steel and garnished with PTFE can withstand pressures of up to 3500 kg/sq cm and temperatures of 600°C. Externally vented O-rings are employed in applications where the outside pressure is higher than the pressure within the seal.
Pressure Filled Hollow Rings:
Pressure stuffed hollow O-rings are altered plain hollow rings using pressurized inert gasses inside them. These O-rings may be utilised in tongue and groove flanges and can handle temperatures from cryogenic temperatures up to 850°C. Pressure filled O-rings are employed in vacuum cleaning applications.
- Metal O-rings can’t be used in highly dynamic sealing applications
- All these O-rings are rendered useless when they are used once because they can’t retain their shape after only use
- Wide tolerances of the groove can’t be adapted by the metal O-rings, especially in larger sizes
- Careful fitting ought to be done in order to avoid their deformation before their seal is tightened.