|
Joint Sealant Application Notes
- PTFE is the most universal gasketing material available. “Expanded” PTFE (ePTFE) has the inherent properties of PTFE, plus it is much more compressible to allow sealing even problem flanges having irregular or rough surfaces, at lower flange bolting torque than other gasketing materials
- To install:
- Clean flange surface.
- Remove release liner from back of joint sealant.
- Apply to flange crossing ends at bolt hole.
- Typical Performance Limits of expanded PTFE:
- Temperature Limits: -450 to 600oF
- pH: 0-14 (except molten alkali metals and elemental fluorine).
- Sealing pressure from full vacum up to 3000+ psi internal pressure can be achieved and depends on a number of factors including:
- Flange Type and Pressure Rating – ANSI 1501b, 3001b, etc. (higher pressure flanges have more or larger bolts and heavier flanges allowing higher gasket loads)
- Condition of Flange Surface – expanded PTFE joint sealant is more conformable than other more rigid gasketing materials for better sealing of scratched or pifted surfaces.
- Temperature – higher temperatures provide lower sealing pressure capability.
- Type of Liquid or Gas being Sealed – liquids generally require less pressure to seal than gases. The surface tension of the PTFE for a particular fluid is also a factor.
- Temperature Cycling – can cause problems if the cycling results in significantly reduced pressure on the gasket. Installation of spring washers on the flange bolts is a proven means of minimizing temperature cycling effects. In critical applications, testing should be performed to verify the suitability of the material. In some low pressure applications gasket conformability is important and a larger nominal size may offer the best seal. In the case where a high pressure seal is required smaller nominal size joint sealant should be used if the sealant does not compress adequately.
- Failure to select the proper sealing products could result in property damage and/or serious personal injury.
|
