PTFE Piston Rings, Guide Rings, Backup Rings and Seals: Selection Guide

30 October, 2026 | Admin

PTFE Rings — Piston Rings, Guide Rings & Back

Short answer: PTFE rings are used in cylinders and
valves to guide moving parts, support seals and stop extrusion, or seal
directly. Each ring does a different job, so choose the type by
function, then choose the grade by load, speed, temperature and
fluid.

Hydraulic and pneumatic equipment have moving parts that must slide
with little friction and not leak. PTFE is popular here because it has
low friction, handles a wide temperature range and resists most
fluids.

Free engineering tools

Plastic weight calculator — Work out the weight of PTFE Piston Rings, Guide Rings, Backup Rings and Seals sheets, rods and tubes in kg
Engineering plastics comparison — Compare UHMWPE, HDPE, nylon, POM, PTFE and more side by side

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Table of Contents

Types and their job

Piston rings and seals: seal between the piston and
cylinder wall to hold pressure.
Guide rings (wear rings): keep the piston or rod
centred so metal does not touch metal. They carry side loads but do not
seal.
Backup rings: sit beside an O-ring or seal to stop
it being squeezed into the gap under pressure (extrusion).
Rod seals and wipers: seal or clean the rod as it
moves.

Choose the grade

Virgin PTFE is soft. Most dynamic parts use filled grades for better
wear and creep resistance:

glass filled for general use
carbon filled for dry or poorly lubricated
running
bronze filled for heavy loads

See filled PTFE guide for the differences.

Information the supplier
needs

Application: hydraulic, pneumatic, valve or
other.
Dimensions: bore, groove width and depth, rod
diameter, ring section.
Pressure, speed and stroke: high speed and pressure
need careful grade selection.
Fluid and temperature.
Mating surface: material and finish. A smooth, hard
surface protects the ring.

Design and fitting tips

Cut or split rings need a gap that allows for thermal movement.
Rough bore finishes increase wear, so check the surface.
Do not stretch PTFE rings past what is needed; use fitting tools
where supplied.
Keep rings clean and free of metal chips during assembly.
PTFE does not rebound like rubber, so energised designs (with an
elastomer or spring behind the PTFE) are used where continuous sealing
force is needed.

Machined to order

Rings can be machined from PTFE rod or tube to custom sizes. Send a
drawing for a quote. See PTFE rods and machined components.

Diode Trading EST supplies PTFE products across Saudi Arabia, and
every order ships with a Material Test Certificate. request a quote

Common mistakes to avoid

using a guide ring as a seal, or a seal as a guide ring
skipping a backup ring when pressure is high enough to extrude the
seal into the gap
using unfilled PTFE for a dynamic ring that needs wear
resistance
ignoring the surface finish of the rod or bore, which controls
wear
cutting ring gaps without allowing for thermal expansion

Quick checks before you
order

Measure the groove, not just the old ring, because old rings wear and
shrink. Record the bore diameter, rod diameter, groove width and depth.
Note the pressure range, the speed of the piston and the fluid. Send
photos of the old ring and the worn surface. If the ring failed early,
tell us how: scoring, extrusion or flat wear. The failure pattern
usually shows what grade or design is needed.

FAQ

What is the difference between a guide ring and a
seal? A guide ring carries side load; a seal holds
pressure.

What is a backup ring for? It stops an O-ring from
extruding into the clearance gap.

Which PTFE grade is best for piston rings? Often
carbon or bronze filled, depending on the conditions.

Can you make rings to my drawing? Send your drawing
and quantity.

Products related to this article

Diode Trading EST supplies these PTFE (Teflon) Products from stock in Dammam, with delivery across Saudi Arabia and the GCC.

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