PTFE Gaskets and Seals

PTFE resists most acids, alkalis and solvents and has a very low friction coefficient. Its weaknesses are cold flow (creep) under sustained load, low elasticity, and poor recovery after compression. Good PTFE sealing practice works around those traits through filled grades, geometry such as envelopes, and correct bolt loading with re-torque where advised.

This page covers PTFE as a gasket and seal material. For the sheet and rod stock itself, see gasket sheets and materials. Values here are typical only; always confirm against the manufacturer's data for your application.

• Virgin PTFE sheet gaskets: cut from skived or moulded sheet for chemical service on flanges.
• Filled PTFE gaskets: glass, carbon, graphite, mineral or barium sulphate fillers that reduce creep and improve strength.
• Expanded PTFE (ePTFE): soft sheet or joint sealant tape that conforms to uneven or fragile flanges such as glass-lined or plastic.
• Envelope gaskets: a PTFE shell around a compressible core of fibre, rubber or metal; low cost for corrosive duty.
• PTFE seals: rotary lip seals, spring-energised seals, backup rings, V-packing sets and piston rings.
• Modified PTFE (TFM): improved creep and weldability for demanding gaskets.

PTFE is usually rated for continuous use up to roughly 260 °C, though pressure capability drops as temperature rises. It is attacked by molten alkali metals and some fluorine compounds. Always confirm against the manufacturer's data for your application. See the PTFE and graphite sealing guide.

1. Name the chemical, concentration and temperature.
2. Decide whether creep is an issue: high bolt loads or long service periods favour filled or modified grades.
3. For fragile or rough flanges (glass-lined, plastic, FRP), consider expanded PTFE.
4. For dynamic seals, state the shaft or rod size, speed and pressure; unfilled PTFE can wear quickly against a rough surface.
5. Think about contamination limits. Food, pharma and potable-water applications require technical review and the correct certification documents.

The more of the following you can supply, the faster the part can be identified and quoted.

• Chemical and concentration
• Temperature range and operating pressure
• Flange standard and dimensions, or seal drawing/part number
• Static or dynamic duty; speed and surface finish if dynamic
• Grade preference (virgin, filled, expanded, TFM)
• Whether food-contact, pharmaceutical or potable certification is needed
• Quantity and photos of the old part

Customers can enquire about genuine or compatible replacement parts for equipment from manufacturers such as Burgmann, John Crane, Chesterton, Grundfos, KSB, Flygt, Lowara, Goulds, Sulzer, Flowserve, Klinger, Flexitallic, Trelleborg and others. A genuine part is supplied by or made to the original equipment manufacturer's specification and part number. A compatible part is made to fit the same dimensions and duty, usually by another manufacturer, and may differ in material or finish. Compatible PTFE parts can look identical but differ in fill, density and creep behaviour. Specify the grade if you know it, or send the old part. State clearly in your enquiry which you want, and say whether a part number or sample is available.

Globseals supports three ways to buy, and the right one depends on how well the part is defined.

• Buy online where a product listing shows a confirmed price. Products are being added to the shop progressively, so not every item in this category is listed yet.
• Request a quote for custom, bulk or unpriced items. Gaskets cut to size, envelope sets and special PTFE seals are quoted. Use the quote request page.
• Technical review when identification is unresolved. Examples include unknown media, regulated applications and heavy-duty dynamic seals. Start with Find My Seal or upload a drawing.

You can also phone 011 079 6033 or WhatsApp 079 508 0989, or email info@globseals.com. See delivery and collection for how orders are handled; courier costs are quoted per order.

These pages help with identification and selection:

• Gasket sheets and materials
• Ring and full-face gaskets
• Rotary shaft and oil seals
• Backup rings
• PTFE and graphite sealing guide
• Gasket material selection guide