Gaskets Vs Seals
It is a widespread misperception that gaskets and seals are interchangeable. Applications for gaskets and seals are different and distinct.
The main purpose of a gasket is to create a static seal between two flat surfaces (flanges). Seals are mainly used in dynamic applications like rotating shafts, pumps, and engines.
What exactly is a Gasket?
- Gasket materials are chosen for their properties and ability to withstand a variety of environments, such as chemical, alkaline or acid resistance, extreme temperatures, and pressure.
- A gasket needs to be sufficiently compressed to create an entire barrier that will result in a seal that is pressure-tight and safeguard the contents inside the seal for it to function.
- In the case of a gasket or O’Ring, the effectiveness of a static seal is determined by compression.
How are gaskets manufactured?
- Gaskets can be manufactured from many diverse products including treated Non-asbestos (Aramid fiber) (Vegetable Fiber), A wide range of Elastomers (Cork and Rubber), Graphite, PTFE, and Open or closed cell sponge when a highly compressible gasket is required.
- Gaskets are cut from the Gasket Sheets into various shapes to fit the components for which they are required.
Where can gaskets be used?
- When fusing two asymmetrical surfaces together, gaskets are the perfect solution for filling deformities.
- They must be made from a material that is easily deformed and can fill in any irregularities because a gasket will fill the space between these two surfaces.
- The gasket must be able to withstand the process’s temperature and pressure, as well as be chemically compatible with its surroundings.
When do you need to change or replace gaskets?
- A new gasket should be used every time any equipment is disassembled and then reassembled.
Which industries make use of gaskets?
- Many industries, including oil and gas, pulp and paper, electric production, and transportation, require gaskets.
Gaskets are cut flat shaped from environmentally suitable material which is compressed between surfaces to maintain a seal. For this reason, every Gasket makes a Seal but every Seal is not a Gasket. Most Gasket materials are slightly flexible, have good compression set (bounce back ability) and allow for slight movement of the surfaces that they are secured between.
Seals are a Broader Category that Includes O’Rings, Valve Stem Seals Rotary Seals and Mechanical Seals. Seals are most commonly used between engine parts, pumps, and shafts that rotate rather than those that are completely static. This type of seal is generally a moulded or machined product.
All about O’Ring Seals
- O’Ring Seals are seals that are ring-shaped with a round cross-section, they have basically moulded rubber rings used as seals.
- O-rings are among the most widely used seals in machinery and equipment, as they are, easy to produce, reliable, and easy to fit.
- O’Ring seals are special as these are seals that can be used in both static and dynamic applications.
- O’Ring seals are designed to sit within the groove or housing between two components, the compression of the O-ring creates a fluid-tight seal capable of withstanding extreme temperatures and pressures.
- The effectiveness of a dynamic seal is dependent on adhesion in the case of the Sealant
All about Rotary Element Seals (Dynamic seals)
- A selection of the styles OF Rotary Element Seals are Radial shaft seals [Lip Seals],- Cartridge seals -Mechanical Seals- Labyrinth seals,- Axial shaft seals, and Valve Stem Seals,
- Radial shaft seals [Lip Seals], Most of these seals are made of an outer ring that is metal and nests over an inner surface that is often made of rubber. Two angles combine to form the point contact that creates the seal, with the air side angle often being less than the oil side angle. The seal will flow wetter the shallower the slope on the oil side of the seal.
- On a rotating shaft, a mechanical seal is a device that keeps fluids in and impurities out. The most common kinds of contamination are moisture, water, and dry materials such as dust, sand, dirt, or particulates generated during manufacturing. The Seal prevents the fluid moving through say a centrifugal pump, from leaking. These seals would be located in the stuffing box or seal chamber.
- A mechanical seal called a labyrinth provides a winding path to help stop leaks.
When should a seal be changed?
- Ideally it is best to change a seal is every time the machine is up for servicing.
Allow the professionals at kemtron.ie to assist you in locating the ideal gasket or seal for your project.