Technical Data Sheet
PTFE Envelope Gasket
Specialized Items
Polytetra Processors
Rakhial, Ahmedabad, Gujarat, India
www.automatasia.com
Envelope gaskets for trouble-free sealing from mild to severely corrosive service, ideal for alloy, standard steel and glass-lined flanges as well as plastic, ceramic and conical end glass pipe.
Specification
| Sizes | Standard and custom flange sizes |
|---|---|
| Tolerances | Envelope profile and thickness to approved drawing |
| Grades | Virgin PTFE, 15% Glass-filled PTFE, 25% Glass-filled PTFE, 25% Carbon-filled PTFE, Bronze-filled PTFE |
| Standards | ASTM D4894, ASTM D4745 |
| Typical uses | Glass-lined flange sealing, Corrosive media sealing, Glass pipe joints |
| Industries | Chemical, Pharmaceutical, Dyes & intermediates |
Typical properties — virgin PTFE
| Property | Typical value | Test method |
|---|---|---|
| Specific gravity | 2.14 – 2.20 | ASTM D792 |
| Tensile strength | 20 – 35 MPa | ASTM D638 / D4894 |
| Elongation at break | 200 – 400 % | ASTM D638 / D4894 |
| Hardness | Shore D 50 – 65 | ASTM D2240 |
| Coefficient of friction (dynamic) | 0.04 – 0.10 | ASTM D1894 |
| Continuous service temperature | −200 °C to +260 °C | — |
| Melting point | ≈ 327 °C | ASTM D4894 |
| Dielectric strength | ≈ 32 kV/mm (short time, thin section) | ASTM D149 |
| Water absorption | < 0.01 % | ASTM D570 |
Typical values for guidance only, not guaranteed minimums. Filled grades, linings and finished parts differ; confirm limits for your application. Issued 2026.