Some PTFE material can be used for gaskets and seals in the food and medical equipment industries, and some cannot. Here’s why you might want to use PTFE, and the difference between material that is and is not FDA approved.

PTFE as a Sealing Material

Polytetrafluoroethylene, a.k.a. PTFE, also sold under the tradename Teflon®, has properties that make it an excellent choice for many sealing applications.

• Extremely inert chemically – fluorine and nitric acid are its only vulnerabilities
• Soft, so it conforms to uneven sealing surfaces
• Remains plastic down to -400°F and is still usable at 500°F (-240 to 260°C)
• Slippery surface assists fastener tightening

PTFE is sold in both sheet form and as expanded PTFE. Expanded, it’s softer and more compliant than the sheet version.

In high bolt load applications PTFE suffers from creep. This is reduced by adding fillers. Glass, carbon and graphite are the most commonly used. They increase strength without significantly impairing the other properties.

Safe and UnSafe PTFE

Pure or virgin PTFE is completely inert so can safely be used in applications where it will come into contact with food, pharmaceuticals or healthcare products. In fact it’s so safe the FDA classes it as “Generally Recognized As Safe” (GRAS). (The relevant regulation is 21CFR177.1550.) This means it’s suitable for gaskets, seals and washers on mixers, storage vessels, kettles and similar equipment.

Filled PTFE does not meet the GRAS criteria and is therefore not FDA approved for food and medical applications. Despite their higher strength, these grades of PTFE must not be used in places where they could be ingested or otherwise taken into the human body.

Expert Advice on Gasket Materials

When choosing a gasket material for food processing or medical equipment applications, a PTFE gasket can be a good choice. However, only the virgin grades are considered safe, and these are prone to creep under high bolt loads. Filled PTFE offers more strength but doesn’t come in FDA-approved grades.

Gasket material selection can be complicated. For expert advice on materials, chemical compatibility and FDA-approved materials, contact us and speak to a product specialist.