NBR and FKM X Ring Seals for Oil Water and Gas Sealing Solutions

There’s a small moment in every hydraulic system where things either stay
orderly or begin to drift: first motion, first heat, first uneven contact. An x
ring, also called a quad ring, is purpose‑built for those moments. It shares
nominal sizes with AS568A O‑rings, drops into the same glands when needed, and
in dedicated low‑squeeze grooves it further trims friction. Its X‑shaped
profile creates four sealing lips and two micro‑lubrication pockets between
them, so films stabilize, start‑up is cleaner, and the seal is less prone to
roll in reciprocating motion.

How the profile works

· Pre‑compression plus pressure: Initial squeeze produces radial/axial
contact stress; system pressure adds to it, so sealing force scales with load
and remains bidirectional in both static and dynamic duties.

· Four lines of defense: The X profile spreads load across four contact lines,
lowering the chance of torsional twist and reducing spiral failure compared
with round‑section O‑rings.

· Friction under control: Lip cavities retain lubricant; starting friction
drops, running friction is more stable, and heat generation is easier to
manage.

Operating window and materials

Media and temperature: With compounds such as NBR for oils, FKM for higher
temperature and broader media, EPDM for water‑lean chemistries, VMQ for wide
temperature windows.

· Pressure and speed: With appropriate clearances and back‑ups, x rings can
be engineered for high‑pressure environments up to roughly 40 MPa. As sliding
speed rises, pay close attention to lubrication film stability and heat
dissipation; in rotary duties, account explicitly for temperature rise from
friction.

· Static and dynamic: The profile is at home in reciprocating, oscillating,
and low‑speed rotary sealing, while also delivering dependable static sealing
on flanges, covers, sleeves, and pipe joints.

Sizing and gland guidance

· Interchangeability with O‑rings: AS568A dimensional parity allows direct
substitution in many O‑ring glands, making trials and phased roll‑outs
simpler.

· Dynamic preference for thicker sections: In motion, thicker cross‑sections
better handle wear, improve compression‑set behavior, and tolerate larger
movement gaps; under higher pressure, add back‑up rings and tighten extrusion
gaps.

· Rotary allowances and static fits: For rotary shafts, choosing an ID about
2–5% larger than the shaft helps balance running‑in and thermal rise. For
static bore interfaces, keep the ring‑to‑gland dimensional deviation within a
small window (around 2%) to maintain uniform squeeze without over‑compression.

· Surface and finish: Use compatible lubricants and moderate surface roughness
to preserve films, limit wear, and prevent micro‑leak paths at edges.

Why engineers choose x rings over O‑rings in many cases

· Lower friction, cleaner starts: Lubrication pockets and multiple contact
lines reduce both running and breakaway friction.

· Less twist in sliding service: The non‑circular section resists rolling in
reciprocation, helping prevent premature leak paths.

· Higher efficiency per footprint: Four contact lines provide greater sealing
stability within the same gland envelope.

· Extrusion resistance: Distributed load and better hardware support reduce
extrusion risk at elevated pressures.

· Versatility: Works in standard O‑ring grooves and in special low‑squeeze
glands designed for reduced heat and wear.

Where the x ring series fits best

· Hydraulics and pneumatics: cylinders, actuators, manifolds

· Construction and agriculture: boom/steering cylinders, clamping and tooling

· Energy and wind power: pitch and yaw hydraulic modules

· Pumps and motors: end‑faces and low‑speed shaft positions

· Gearboxes and engines: auxiliary seals and test tooling

· Metallurgy and water treatment: high‑load reciprocating interfaces

· Industrial automation and robotics: joints, clamps, and fixture systems

· Chemical and petrochemical: valve actuators, metering, and test rigs

· Transportation sectors: marine and offshore equipment, rail vehicles,
automotive and heavy‑duty trucks (subject to material and compliance
validation)

A practical note to close: when you align geometry, compound, and lubrication—
and confirm it with staged pressure and thermal cycling—the x ring series
tends to fade into the background of your system. That’s a compliment.
Reliable seals don’t ask for attention; they give you uptime, predictable
maintenance, and room to focus on the work that matters.

Minimum Order: 500 pieces

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