THE PTFE EXTERNAL ENVELOPE
Commonly named “envelope”, it has the purpose of protecting the internal part of the gasket from the substances which they are in contact with; these envelop are mostly made of:
- Virgin PTFE FLON-CHEM 1000
- Modified PTFE FLON-CHEM 1075
- Antistatic/Conductive PTFE FLON-CHEM 1022
- Modified/Antistatic/Conductive PTFE FLON-CHEM 1023
All the enlisted materials are complying with the US law: FDA, Food and Drug Administration, department of Health and Human Services, Code of Federal Regulations 21 CFR Ch.1; USA regulations sections 177.1550 (a) (1) and (b) Perfluorocarbon Resins;
There is different type of envelop due to the applications and the customers desires, in case of big diameters and small quantities the cost could be too high so we could weld the sealing in one point.
The welding process are done to the “head” without overlapping the two PTFE parts; the perfect execution of the welding is ensured by using the correct parameters of temperature, pressure and time in activity of the part to be welded. Destructive and non-destructive trials are done frequently to homologate the welding process.