All You Need to Know About Gasket Material & Mechanical Seal

Gaskets provide for "less-than-perfect" mating surfaces on machine parts by filling imperfections. Gaskets are often made by cutting sheet materials. Given the possible economic and safety consequences of malfunctioning or leaky gaskets, the appropriate gasket material must be chosen for the application.

Properties of Gasket Material

Gaskets are often constructed from a flat material, such as paper, rubber, silicone, metal, cork, felt, neoprene, nitrile rubber, fiberglass, polytetrafluoroethylene (PTFE or Teflon), or a plastic polymer (such as polychlorotrifluoroethylene).

The capacity to sustain large compressive loads is one of the most desirable qualities of an effective gasket in industrial applications for compressed fiber gasket material. Bolts exerting compression in the 14 MPa (2000 psi) range or greater are used in the majority of industrial gasket applications. Numerous generalizations allow for improved gasket performance. "The greater compressive stress imposed on the gasket, the longer it will endure," is one of the more tried and true.

Design:

Gaskets are available in a variety of designs based on industrial purpose, budget, chemical interaction, and physical factors.

Sheet Gasket: Sheet gaskets can be created by punching the desired form out of a sheet of flat, thin material. Sheet gaskets are quick and inexpensive to manufacture and may be made from many materials, including fibrous materials and matted graphite (and in the past - compressed asbestos). Based on the inertness of the material utilized, these gaskets may meet a variety of chemical requirements.

Non-asbestos gasket sheet is long-lasting, multi-material, and thick. Mineral, carbon, or synthetic rubbers such as EPDM, Nitrile, Neoprene, Natural, and SBR Insertion are examples of materials. Each has distinct qualities appropriate for varied uses. Sheet gaskets are used in applications that involve acids, corrosive chemicals, steam, or mild caustics. Flexibility and excellent recovery minimize breaking during sheet gasket installation.

Spiral-Wound Gasket: They are made up of a combination of metallic and filler components. The gasket is typically made of a metal (often carbon-rich or stainless steel) looped outwards in a circular spiral (other forms are conceivable), with the filler material (typically flexible graphite) wound in the same fashion but beginning on the other side. As a result, alternating layers of filler and metal are formed. The metal provides structural support while the filler substance functions as the sealing element in these gaskets.

These gaskets have shown to be dependable in the majority of applications and allow for lower clamping forces than solid gaskets but at a greater cost.

Double-Jacketed Material: Another combination of filler material and metallic components is double-jacketed gaskets. In this application, a metal tube with "C"-shaped ends are used, with an extra piece fabricated to fit within the "C," making the tube thickest at the meeting places. Between the shell and the piece, the filler is injected. When used, the compressed gasket has more metal at the two tips where contact is made (due to shell/piece interaction), and these two points carry the weight of closing the process. Because all that is required is a shell and a piece, these gaskets may be produced from nearly any material that can be formed into a sheet and then filled.

Fishbone Gasket: They are interchangeable with Kammprofile and Spiral wound gaskets. They are both completely CNC machines made of identical materials, but the design of the gaskets has eliminated any inherent flaws. In storage or at the factory, fishbone gaskets do not unravel. The rounded corners do not harm the flange. The additional "Stop Step" avoids the Fishbone gaskets from being unduly compressed/crushed, which is frequently caused by high torque tactics during plant start-up. The gasket's bones stay ductile and adjust to heat cycling and system pressure spikes, resulting in a long-lasting and dependable flange seal that beats all other gaskets of its kind.

Soft Cut Gasket: It is made of a soft (flexible) sheet material that may easily adapt to surface imperfections even when the bolt stress is modest. Soft gaskets are utilized in heat exchangers, compressors, bonnet valves, and pipe flanges.

Ring Type Joint Gasket (RTJ Seal): It is high integrity, high-temperature, the high-pressure seal used in the oil industry, oilfield drilling, pressure vessel connections, pipelines, valves, and other applications.The axial compressive force causes the ring packing (RTJ) to move in an uneven flow in the groove of the deformed sealing flange. Colored seal (RTJ seal) has a tiny load area, resulting in high surface pressure between the sealing surface and the groove, poor maintenance qualities, and is not suited for reuse.

Kammprofile Gasket: Kammprofile gaskets (also known as Camprofile) are utilized in many older seals because of their flexibility and dependability. Kammprofiles are made up of a strong corrugated core and a flexible covering layer. This configuration provides for very high compression and a very tight seal along the gasket's ridges. Because the graphite often fails rather than the metal core, Kammprofile can be repaired during periods of inactivity. For most applications, Kammprofile has a high initial cost, but this is offset by its extended life and greater dependability.

Solid Material Gasket: The concept of solid material is to employ metals that cannot be punched out of sheets yet are still inexpensive to create. These gaskets have a far greater degree of quality control than sheet gaskets and can resist significantly higher temperatures and pressures. The main disadvantage is that a solid metal must be highly compressed to become flush with the flange head and avoid leaking. Because metals are largely utilized, material selection is more challenging, and process contamination and oxidation are hazards. Another disadvantage is that the metal used must be softer than the flange to prevent the flange from warping and thereby preventing subsequent gasket sealing. Nonetheless, these gaskets have found a niche in the industry.

Improvement in Gasket Material

Many gaskets include small enhancements that improve or imply acceptable operation conditions:

An inner compression ring is a popular enhancement. A compression ring increases flange compression while preventing gasket failure. The consequences of a compression ring are limited, and they are normally only utilized when the traditional design fails frequently.

An outer guiding ring is a popular modification. A guiding ring facilitates installation and acts as a mild compression inhibitor. In some alkylation applications, they can be adjusted on Double Jacketed gaskets to indicate when the first seal has failed using an inner lining system and alkylation paint.

Mechanical Seal

What is Mechanical Seal?

A mechanical seal is a device that aids in the connection of systems or mechanisms by preventing leakage (for example, in a pumping system), containing pressure, or excluding contaminants. A seal's efficacy is determined by adhesion in the case of sealants and compression in the case of gaskets. Pump seals are used in a variety of sectors, including chemicals, water supply, paper manufacture, food processing, and many more.

Types of Mechanical Seal

In process equipment, three types of mechanical seals are used:

Cartridge

Component

Air

Cartridge Mechanical Seal:A cartridge-mounted, end-face mechanical seal is a self-contained device including the sealing components—a gland, sleeve, and hardware. A cartridge seal enables the manufacturer to preassemble and pre-set the device. Installation and maintenance are easier because the manufacturer handles these chores. Depending on the use, cartridges may be supplied with one or two seals.

Component Mechanical Seal: End-face mechanical seals are made up of a rotating part and a stationary seat that is mounted in a gland or housing. Installation and maintenance are more difficult than cartridge seals since they are not pre-set. These require professional technicians who can install and calibrate them effectively.

Air Mechanical Seal: Air seals are curvaceous biases that are designed to seal spinning shafts without touching them. These seals are most generally used in dry grease paint or slurry operations. They use small volumes of air or inert gas to guard against product loss, adulterants, and impurities. To establish positive pressure and an effective seal, this air is strangled.

Components of Seal

Most mechanical seals are made up of five parts:

Rotating Primary Face- The rotating main face is attached to the shaft and rotates with it, sealing against the stationary primary sealing element.

Stationary primary face - A stationary face attached to the stationary housing of a pump, mixer, or another piece of equipment through which the rotating shaft travels and seals against the rotating primary sealing element.

Mechanical loading devices - These devices bias the major sealing parts into contact to commence sealing. A single spring, numerous springs, wave springs, or metal bellows can be used.

Secondary seals, static and/ordynamic - A seal between the mechanical seal components and the equipment shaft and housing that compensates for shaft movement that might harm the seal faces.

Drive Mechanisms- Set screws and drive pins are two kinds of drive mechanisms that are utilized to rotate the rotating primary seal face.