Is KLINGERSIL C-4430 a sealing gasket or an insulating gasket

author: Qishine Industry

2026-05-26

KLINGERSIL C-4430 is both a fluid sealing gasket and the core gasket in flange insulation gasket kits. Its primary design function is to stop fluid leakage at the joint; its dielectric properties let it isolate current between metal flanges when built into a full insulation kit.

One-Minute Overview

KLINGERSIL C-4430 is both: a fluid sealing gasket and the core gasket in flange insulation gasket kits.
Primary function: pressure sealing for steam, hot water, oils, fuels and hydrocarbons.
Secondary function: dielectric isolation — dielectric strength around 16–21 kV/mm.
Used alone as a cut gasket, it seals. Built into a kit with insulating sleeves and washers, it isolates.
Specify the full kit whenever galvanic corrosion or cathodic-protection isolation is the goal.

What KLINGERSIL C-4430 Is

KLINGERSIL C-4430 is a general-purpose non-asbestos compressed fibre sealing sheet. Synthetic aramid fibres and glass fibre are bonded with nitrile butadiene rubber (NBR) and cured under high temperature and pressure. The glass fibre brings heat resistance and dimensional stability; the aramid and NBR bring flexibility and conformability, so the sheet seats on imperfect flange faces.

Composition — aramid + glass fibre, NBR-bonded, vulcanised under heat and pressure.
Sealing action — fills face roughness and recovers after compression, so the joint stays tight.
Stress relaxation — low creep at temperature; about 35 MPa residual stress remains at 300 °C.
Service range — sealing duty from about -50 °C to +300 °C.

Primary Function — Fluid Sealing Gasket

Under bolt load the sheet compresses and fills the microscopic gaps between two flange faces, then recovers enough to hold the joint as pressure and temperature change. That is what stops gas and liquid from escaping — the everyday job of a flange gasket. Its stability in hot water and high-temperature steam is why it is specified across general industry, chemicals, oil and gas, energy, marine and food plants.

Secondary Function — Electrical Insulation and Dielectric Isolation

C-4430 is non-conductive and carries useful dielectric properties:

Dielectric strength: about 16–21 kV/mm
Volume resistivity: high (published surface resistance in the 10^13 Ω range)
Effect: under conventional operating voltages the sheet blocks current across the flange face

That is why producers and suppliers routinely use C-4430 as the core gasket in flange insulation gasket kits — combined with insulating bolt sleeves and insulating washers — to prevent galvanic corrosion and isolate current between metal pipeline flanges.

How C-4430 Works in a Flange Insulation Gasket Kit

└KLINGERSIL C-4430 insulating gasket kit with G10 sleeves and washers.

A flange insulation gasket kit interrupts every electrical path at the joint. The standard build is 1 gasket : N insulating sleeves : 2N insulating washers : 2N steel washers (N = bolt count):

Component	Typical material	Role
Core gasket	KLINGERSIL C-4430	Sealing + dielectric barrier across the flange face
Insulating sleeves	G-10 / G-11	Isolate the bolt shank from the flange bore
Insulating washers	G-10 / G-11	Isolate under nut and bolt head
Steel washers	Hardened carbon steel	Distribute load, protect the insulating parts

The logic is simple: used alone as a standard cut gasket, C-4430 is a sealing gasket. Installed in an insulation kit with insulating sleeves and washers, it serves as an insulating / dielectric sealing gasket — sealing the joint and breaking the electrical path at the same time.

Typical kit applications: galvanic isolation between dissimilar metals, cathodic-protection current retention, and valve / actuator electrical isolation.

C-4430, Epoxy Sheet and Mica: What to Specify

└Design positioning of three gasket types.

Two other materials show where the boundaries are: 3240 epoxy resin sheet for structural insulation with high mechanical strength, and mica gasket for extreme heat. The table sets both against C-4430.

Criterion	KLINGERSIL C-4430 (sealing + kit core)	3240 epoxy resin sheet (structural insulation)	Mica gasket (extreme heat)
Positioning	Sealing with dielectric function; core gasket in insulation kits	Structural insulation, high mechanical strength	Extreme-temperature insulation
Base material	Aramid + glass fibre + NBR	Alkali-free glass cloth + epoxy resin	Natural or synthetic mica flakes
Dielectric strength	About 16–21 kV/mm	High (12 kV creepage class systems)	Around 20 kV/mm
Temperature	Sealing duty about -50 °C to +300 °C	Continuous about +155 °C	800–1000 °C (up to 1200 °C synthetic)
Core advantage	Low creep sealing + reliable isolation in kit form	Mechanical + dielectric strength, machinability	Extreme heat, chemical stability

Choose by the problem you are solving:

Steam, hot water, oil, gas, chemicals — C-4430 as sealing gasket.
Galvanic / cathodic isolation at a flange joint — C-4430 core gasket inside a full insulation kit with sleeves and washers.
Structural insulation or extreme heat — epoxy sheet or mica, not C-4430.

Conclusion: if the problem is sealing — especially high-temperature steam or oil media — C-4430 is a sound choice on its own. If the problem is electrical isolation and system safety at the joint, build it into a flange insulation gasket kit: C-4430 as the core dielectric sealing gasket, with insulating sleeves and washers completing the circuit break.

FAQ

Is KLINGERSIL C-4430 a sealing gasket or an insulating gasket?

Both. Its primary design function is fluid sealing — the NBR-bonded fibre construction is optimised for compression, recovery and stress relaxation. Its dielectric properties (16–21 kV/mm) let it serve as the core gasket in flange insulation kits, where it seals and isolates at the same time.

Can C-4430 block an electric current?

Yes. With dielectric strength around 16–21 kV/mm and very high volume resistivity, it blocks current across the flange face under conventional operating voltages — which is exactly why it is used as the core gasket in insulation gasket kits.

When do I need a full insulation gasket kit rather than a plain cut gasket?

Whenever the joint must break an electrical path — galvanic corrosion between dissimilar metals, cathodic-protection current, or valve / actuator isolation. The kit adds insulating sleeves and washers so the bolt path is interrupted as well as the flange face.