At the beginning of the 20th century, the spiral wound gasket was made because oil refinery operations were getting harder and harder to do. This kind of gasket is often used with flange surface finishes made with a flange-facing machine. Because of this, we decided to put together this simple overview as an introduction for the machinist who is working on-site.
In the oil, gas, and petrochemical industries, gaskets need to be made to withstand high pressures, high temperatures, and chemicals. Changes in these things, as well as differences in temperature across the flange face and bolt stress relaxation, make it essential for a gasket to be flexible and able to bounce back. We can’t say enough about how important it is for the gasket to be able to adapt to changes.
Spiral Wound Gasket Construction
The spiral wound gasket is made of a v-shaped strip of stainless steel wrapped around in a spiral and a non-metallic filler material, like graphite or PTFE. A solid outer ring is also part of the gasket. This ring is used to center and control compression. This makes it less likely that the material will move because it was tightened too much.
There are spiral wound gaskets with an extra inner ring for the toughest conditions. This keeps the windings, especially the filler, from getting contaminated or damaged by the product going through the pipeline joint.
How to Install Spiral Wound Gaskets
- When putting gaskets on a new flange or replacing an old one, the faces of the flange should be clean and free of dents and scratches. Cross-face scoring is a big worry because it can cause joints to leak.
- The flange surface can be re-machined with a portable machine tool like a Mirage Flange Facing Machine if it has scored.
- Flexitallic, a company that makes gaskets, says that the surface finish should be between 3.2 and 6.3. A useful tool for checking the finish is a surface comparator.
- The flange faces should be parallel and centered without having to use a lot of force to pull them into place.
- Never use a spiral-wound gasket again. Use a new one every time.
- Before you install the gasket, make sure it is not broken and that it meets the right specifications.
- Compounds or lubricants should not be used to join things together.
- Check that the faces of the flanges are parallel after the installation. This can be done with a tool for measuring the gap between the flanges.
Benefits of Spiral Wound Gaskets
- Spiral wound gaskets have many uses, such as padding, sealing, preventing leaks, mounting, protecting against things in the environment, and reducing vibration.
- They work well in environments with high pressure, high temperature, and corrosion, and they need less clamping force than solid gaskets.
- Because they are in the shape of a chevron, these gaskets provide padding like a spring and can be used in a wide range of work environments.
- Because they are reliable and strong, these gaskets also keep gears from breaking and the costs that come with that.
- By using different winding materials and metals, spiral wound gaskets can be made to work in a wide range of conditions. They are also easy to install.
- The outer ring of spiral-wound gaskets makes it easier to put the gasket together and keeps it from blowing out.
- The inner ring stops soft fillers from moving in a radial direction and reduces turbulence, so flow resistance is kept to a minimum.
- When the spiral wound gaskets are exposed to high temperatures, the inner ring also acts as a heat shield.
- Along with the inner ring, the center ring of a spiral-wound gasket protects the spiral-wound part and helps keep the gasket from blowing out.
- The center ring also prevents the spiral wound element from being overloaded or compressed too much.