Gallagher Fluid Seals stocks soft gasketing material from various manufacturers in many different thicknesses. Read on to better understand how to choose the correct gasketing material for your specific application.
To discuss soft gasketing, we must also understand the forces at work within a bolted joint flange assembly, also known as a BJFA. This understanding is important as these forces affect how a soft gasket performs and how long it lasts.
There are three main forces at work in a BJFA:
- Flange/bolt load – This force must compress the gasket enough to account for any imperfections and avoid leaks.
- Hydrostatic end load – This force is the result of internal fluid pressure in the system, and tries to push the flanges apart.
- Internal blowout pressure – This force acts upon the gasket and tries to force it out through the space between flanges.
A key concern is figuring out the gasket stress or load that will be applied to the gasket. The load is determined by subtracting hydrostatic end load from the flange/bolt load. The difference must be greater than the internal blowout pressure to keep the seal’s integrity.
Gasketing materials
Soft gaskets are also known as non-metallic gaskets. As that name suggests, they are constructed without metal, but rather made from elastomers, natural fibers, polytetrafluoroethylene (PTFE) or mineral-based materials.
These gaskets are used in an array of applications, both general service and corrosive, suitable for low, medium and high temperatures, depending on their material. In some higher-pressure piping systems, pressure and temperatures may be too high for soft gasketing material.
Gasket selection
When choosing a gasket, consider these factors: pressure, temperature, and media. Gasket makers often provide pressure vs. temperature charts when dealing with soft gasketing materials, allowing users to conclude whether the material is suitable.
Other factors to consider include joint type, the loading effects on the gasket material, operating conditions and the conditions of the sealing faces.
Keep these tips in mind when installing new gaskets:
- Make sure the flanges are clean. Look for dings, marks or dents in the sealing faces. Use a soft wire brush to remove debris or any foreign material. Be gentle. Avoid using chisels, scrapers or grinders to remove foreign material.
- Make sure flanges are aligned properly to maximize sealing contact and ensure a uniform gasket load. All fastening components should be lubricated to provide enough friction.
- Make sure the material and bolts are in good condition, and that the nuts move freely onto the thread and do not lock before installation.
- Bolts should be numbered and tightened according to an established tightening sequence. Use a calibrated torque tool to be sure the correct torque values are applied.
- Keep assembly records for each BJFA. This allows installers to verify the right procedures were followed, and for investigation if errors occur.
If you have questions about soft gasketing material, contact Gallagher Fluid Seals. We’ll be happy to assist you in finding the right material for your next project.