Structural Comparison and Installation Guidelines for PTFE V-Ring Packing and Composite Seals

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PTFE V-Ring versus PTFE Composite Seal In Reciprocating Seal Applications
Comparison of two common sealing structures in reciprocating sealing system:

PTFE V-ring packing (Chevron/V-packing set) and PTFE composite seals (PTFE slipper seal with elastomer O-ring energiser). Both are employed in dynamic sealing although they have rather different architectures, functioning principles and installation requirements.

1. Structure Comparison 2.
A. V-Ring Packing made of PTFE (V-Packing Kit / Chevron)
A PTFE V-ring packing set usually comprises a series of stacked V-shaped rings axially squeezed in a stuffing box. A common setup is as follows:

Male Adapter Ring (Header Ring / Pressure Side)

Multiple Chevron V-rings (intermediate seal rings)

Female adapter ring (gland ring / compression ring)

Optional pressure ring, support ring or anti-extrusion back-up ring

Depending on operational conditions, Freudenberg V-packings may also consist of pressure rings, V-sealing rings and support rings.

Principle of operation:

The gland is compressed axially to provide initial sealing force.

The sealing lips are further energised by system pressure and contact stress is increased (self-energizing effect).

Principales características:

Re-adjustable: sealing performance can be re-established by re-tightening the gland.

Robust design for heavy-duty and misalignment-prone applications.

Typically utilised in older equipment and harsh working environments .

Rule of thumb for fitting:
"V-groove toward pressure side."

B. PTFE Composite Seal (PTFE Sliding Ring + O-Ring Energizer) 
A PTFE composite seal is typically made up of:

PTFE sealing ring (slipper seal / sliding ring)

An elastomer O-ring as energizing/preload element

Backup rings (optional anti-extrusion)

Like with the Parker Slipper Seal® systems the sealing function is achieved by coupling a PTFE slide ring with an elastomer O-ring.

Operation principle:

The O-ring provides initial radial preload for sealing at zero or low pressure.

The PTFE ring was pressed and squeezed against the mating surface improving its sealing capability.

Main features:

Less friction than V-ring packing.

Better performance at higher speeds and more dynamic motion systems.

More sensitive to groove geometry, extrusion gaps and alignment.

Usually not adjustable. Worn seals are usually replaced rather than re-tightened.

C. Fast Comparison Table
Item PTFE V-Ring Packing (Chevron)PTFE Composite Seal (PTFE + O Ring)
Structure Multiple V-rings + adapters + optional support rings PTFE slide ring + elastomer O-ring (energiser)
Preload method Axial gland squeeze O-ring radial energisation
Adjustability Retighten to compensate for wearFixed groove design, non-adjustable
Direction of pressure Mainly in one direction (or two sets back to back)Mostly one way
Friction Higher owing to several sealing lipsFriction lower, better for dynamic motion
Tolerance to misalignment High tolerance, strongsensitive to clearance and misalignment
Typical application Heavy duty, low speed legacy equipmentHydraulics, high speed, low friction
2. PTFE V-Ring Packing Installation Instructions 2.1 Inspection and Preparation before Installation
Prior to installation:

Thoroughly clean stuffing box, eliminating any residues, rust and burrs.

Check rod or cylinder surface for scoring, scratches or wear.

Ensure groove integrity is maintained and correctly chamfered

Lead-in chamfers are required to avoid damage or inversion of lips when they are installed.

Apply a light lubricant compatible with the process media to reduce friction and prevent damage to the seal during assembly.

2.2 Installation Order and Orientation
Proper alignment is essential:

The V-groove should face the pressure side.

Typical installation sequence (pressure side to gland side):

Adapter ring, male

Chevron V-rings (stacked seal rings) 2.

Female adapter ring

Both Freudenberg and Garlock stress the right orientation to the pressure medium.

2.3 Staggering of Butt Joints (Split Rings)
For split ring designs:

Joints in adjoining rows should be staggered to prevent leakage routes.

Freudenberg recommends an offset between joints of approx. 120°

Garlock normally advises a 90° offset as a minimum.

Proper staggering prevents the leakage pathways from being in-line.

2.4 Compression and Correction Control
One of the main causes of failure is over-compression.

Main tips:

Lightly compress at first until the packing is seated.

Do low pressure test runs before final adjustment.

If there is leakage tighten gently in small increments.

Tighten gland bolts evenly so that load is not distributed unevenly.

Excessive compression can cause:

Increased heat production and friction

Stick-slip phenomenon

Increased wear of the rod surfaces

Freudenberg and Garlock both stress the need for controlled, progressive adjustment, not over-tightening.

3. Guidelines for installation of PTFE composite seals (PTFE + O-Ring)
3.1 Preparation before installation
Groove clean, dry and free from pollutants.

Groove entrance chamfer check.

Use protective tape or sleeves to shield sharp edges, ports, keyways and threaded areas.

Parker also recommended blocking all possible cutting edges to avoid damaging the seal during installation.

Use proper installation equipment such as expansion sleeves, instead of metal tools, to prevent PTFE damage.

3.2 Sequence of Installation (Critical)
Parker Slipper Seal® installation principles:

Install the elastomer O-ring in the groove first.

The PTFE sealing ring is to be fitted using a consistent expansion tool.

If the distortion is present, a sizing (burnishing) sleeve can be used to restore the roundness.

Warning Important:

Do not let the PTFE circle expand unevenly.

Non-uniform straining can cause irreversible deformation and premature failure.

Inadequate expansion without re-rounding is often the source of early leakage.

3.3 Orientation in Direction
Each manufacturer has a different geometry but:

The pressure side is the side of the PTFE ring that has the open side or sealing lip.

This provides pressure assisted lip activation against the mating surface .

Always verify proper orientation with manufacturer marks or chamfers.

4. Frequent installation failures
A. PTFE V-Ring Sealing Failures
Incorrect orientation (V-groove not facing pressure side) → leakage, instant or gradual

Improper joint alignment -> direct leakage channel development

Overcompression → heat, stick slide, shaft damage

Lip twisting or inversion → early leak failure

B. PTFE Composite Gasket Failures
PTFE ring installation before O-ring (particularly in tight grooves) => O-ring twist or seal damage

Sharp edges not protected -> PTFE ring cut during installation

Irregular or excessive PTFE expansion → irreversible deformation and premature leaking

Loss of sealing integrity following expansion → Failure to re-size

This content may also be adapted into, if necessary:

Datasheet style comparison

A training document for maintenance crews

Or a more basic version of field installation checklist