Material Performance and Technical Innovations of Gylon 3500 Insulating Gaskets

Gylon 3500 is a silica-filled polytetrafluoroethylene (PTFE) insulating gasket used in flange insulation kits on process piping and equipment. Among industrial flange gaskets it stands out for chemical resistance, low creep and stable bolt-load retention, so engineers specify it wherever a joint must break the electrical path and still hold pressure.

Composition and Service Limits

The substrate is PTFE, a fully fluorinated high-molecular polymer with outstanding chemical inertness and low surface energy. Virgin PTFE is mechanically weak and prone to cold flow, so Gylon 3500 adds finely divided silica (SiO₂) as a reinforcing filler. Filler share and dispersion are controlled so that mechanical properties improve markedly while chemical stability stays largely unchanged.

• Temperature range from -268 °C to +260 °C, covering cryogenic duties through steam service.
• Pressure capability up to 83 bar for standard sheet grades at ambient temperature.
• Strong acids other than hydrofluoric acid, solvents, hydrocarbons and steam are accepted media; hydrofluoric acid attacks the silica filler and is outside the service range.
• Low creep relaxation and good bolt-load retention limit stress loss after torque-up and stretch maintenance intervals.

The material also resists cold flow and keeps resilience at low seating stress, so it seals imperfect surfaces without fracturing under overload.

Gylon Grade Comparison

Table: filler system, optimum service media and key features by Gylon grade.

Grade 3500 is the balanced, general-purpose option; 3504 trades media range for compressibility on irregular faces, 3510 targets strong alkalis and chlorine, and 3545 adds a rigid PTFE core that resists extrusion at higher pressure.

Surface Profile, Manufacturing and Applications

The patented hexagonal surface profile reduces the contact area against the flange face, concentrates initial seating stress and improves tightness. The same pattern raises compression-recovery, so the sheet conforms to damaged or uneven faces on pipe flanges instead of losing the seal.

Gylon 3500 insulating gasket

Seamless large-diameter gaskets are produced by a proprietary welding process that removes the traditional dove-tail joint and its potential leak path. A 3/32 in (2.4 mm) sheet combines the sealing and bolt-load retention of 1/16 in (1.6 mm) with the compressibility and conformability of 1/8 in (3.2 mm), so engineers do not have to trade tightness against adaptability.

• Chemical and petrochemical plants: strong-acid, solvent and hydrocarbon service, where a leak also drives corrosion.
• Power generation and steam systems: hot media plus long bolt-load retention over the operating cycle.
• New-energy equipment: 800 V vehicle platforms raise the number of insulating gaskets per unit and push service temperature above 180 °C.
• Battery energy storage and UHV grid components: micron-level thickness tolerance and ageing resistance support stable electrical isolation.

In every one of these cases selection starts from the medium, the temperature and the seating stress available at the joint, then moves to geometry and thickness.

FAQ

What is the base polymer of Gylon 3500?

PTFE (polytetrafluoroethylene), a fully fluorinated high-molecular polymer, reinforced with finely divided silica (SiO₂) particles to offset the mechanical weakness of virgin PTFE.

Which media can Gylon 3500 handle?

Strong acids other than hydrofluoric acid, solvents, hydrocarbons and steam. Hydrofluoric acid dissolves the silica filler, so it is outside the service range.

Why is the surface profile hexagonal?

The hexagonal protrusions cut the contact area against the flange face, concentrate seating stress and improve compression-recovery, which helps the gasket seal damaged or uneven faces.

What temperature and pressure can it take?

Standard sheet grades run from -268 °C to +260 °C and to 83 bar at ambient temperature. Confirm the rating of the exact grade and thickness selected.

Why choose a 3/32 in (2.4 mm) sheet?

It gives the sealing and bolt-load retention of a 1/16 in (1.6 mm) sheet with the compressibility and conformability of a 1/8 in (3.2 mm) sheet.