Kaxite G-10 glass epoxy washers are cut from a continuous woven glass fabric laminated with an epoxy resin system. They are used as the insulating washer component in flange isolation kits — fitted under each nut (and typically under each bolt head) to break the current path between the fastener and the flange face. G-10 offers the highest combination of mechanical strength and electrical insulation in a thin section, with very low water absorption that keeps dielectric strength stable across wide temperature and humidity ranges. Washers are supplied in standard bolt sizes or cut to your specific inside diameter, outside diameter and thickness. Standard sizes ship in 5–10 days; custom sizes in 10–20 days. OEM / wholesale pricing applies for volume orders.
G-10 Glass Epoxy Washers for Galvanic Corrosion Isolation on Flanged Joints — OEM and Wholesale Supply
G-10 glass epoxy washers are cut from a continuous woven glass fabric laminated with epoxy resin — a dielectric material specified wherever two dissimilar metals must be bolted together without creating an electrical path between them. The washer sits under the nut (and typically under the bolt head) and, together with an insulating sleeve in the bolt hole and an insulating gasket at the flange face, completes the electrical isolation of the joint.
Compared with phenolic and other composite insulating materials, G-10 offers the highest combination of mechanical strength and electrical insulation in a thin section. It also has very low water absorption, which keeps dielectric strength stable across wide ranges of temperature and humidity — a key requirement on outdoor and marine joints where moisture-driven degradation would otherwise break the isolation.
Key PropertiesHigh mechanical strength, low water absorption
Primary FunctionElectrical isolation between dissimilar metals
01
What G-10 Glass Epoxy Is and Why It Is Used
G-10 is a composite material made from continuous woven glass fabric impregnated with an epoxy resin system, then cured under heat and pressure into a rigid laminate. The result is a dense, dimensionally stable sheet that behaves like a structural material while retaining the electrical insulation and moisture resistance of a dielectric laminate.
That combination is what makes G-10 the material of choice for the bolting insulation components in a flange isolation kit. In a fully insulated flanged joint there are three insulating elements — the gasket at the flange face, the sleeve through the bolt hole, and the washer under the nut — and each one must hold its mechanical and dielectric properties under bolt load, temperature cycling and moisture exposure over the life of the line.
What G-10 brings to a flange insulation kit
High mechanical strength. Withstands bolt torque loads without crushing or extruding, keeping the isolation layer intact when the flange is torqued to specification.
Low water absorption. Retains dielectric strength in wet, humid and marine service — a failure mode that degrades phenolic washers on extended outdoor exposure.
Superior electrical characteristics. Dielectric strength and dissipation factor are stable across wide temperature and humidity ranges, giving predictable isolation performance.
Wide temperature range. Performs within the standard industrial pipeline service envelope, from low ambient through typical process temperatures.
Long service life. Does not creep or fatigue under continuous bolt load, so isolation is maintained without re-torquing or replacement.
02
Where G-10 Washers Are Used in the Insulation System
The G-10 washer is one of three dielectric components in a flange insulation kit. Isolating a flanged joint requires breaking every current path through the connection — the gasket breaks the face-to-face path, the sleeve breaks the hole-to-bolt path, and the washers break the nut-to-flange and bolt-head-to-flange paths. Remove any one of the three and the whole isolation system fails.
Component 01
Insulating Gasket
The primary dielectric barrier at the flange face. Type D, E or F geometry depending on the flange standard.
Component 02
Insulating Sleeve
Fits through each bolt hole. Prevents the bolt shank from contacting either flange plate.
Component 03
Insulating Washer — G-10
Fitted under each nut and under each bolt head. Sized to the fastener diameter and to the required dielectric thickness for the joint.
Component 04
Additional Isolators
Where required by the specification: flat washers, secondary washers or combination sets supplied as a matched kit.
03
Technical Data — G-10 Glass Epoxy Laminate
Typical properties — G-10 glass epoxy laminate
Property
Typical Value
Notes
Composition
Continuous woven glass fabric + epoxy resin
Cured laminate, not a moulded composite
Colour
Light green / yellowish green
Standard G-10 laminate colour
Water Absorption
Low — typically below 0.15%
Stable dielectric performance in wet or humid service
Dielectric Strength
High — consistent across temperature and humidity
Key property for isolation washers
Dissipation Factor
Low
Minimises signal loss in sensitive circuits
Mechanical Strength
Extremely high for a dielectric laminate
Withstands bolt torque without crushing
Service Temperature
Within standard industrial pipeline range
Confirm specific limit against your application
Available Formats
Standard bolt sizes / cut to drawing
OD and ID to customer specification
Exact values vary by thickness and batch. If your specification calls for a fixed limit on water absorption, dielectric strength or temperature, request a batch certificate at the quotation stage.
04
Typical B2B Applications
01
Flange insulation kitsThe standard washer component of Type D, E and F isolation kits for flanged joints.
02
Terminal boardsElectrical terminal boards and mounting panels where insulation and mechanical stiffness are both required.
03
Structural electrical componentsInsulating bushings, standoffs and mounting plates in electrical equipment.
04
Petrochemical and refineryInsulated flange bolting on process piping and cathodically protected lines.
05
Oil and gas surface facilitiesWellhead and surface flowline flanges where the bolting must be electrically isolated.
06
Water and marine systemsJoints exposed to moisture, salt spray or immersion where low water absorption is critical.
07
Power generationSteam, cooling water and auxiliary piping with mixed-metal flanged joints.
08
Gas transmissionAbove-ground stations on cathodically protected mains where isolation is part of the design.
09
Heavy electrical equipmentInsulation washers and shims in transformer, switchgear and control equipment assemblies.
05
Ordering G-10 Glass Epoxy Washers
Washers are supplied either as standard bolt-size stock items or cut to your specific inside diameter, outside diameter and thickness. Send the following details and Kaxite will return a quotation — typically within one working day for standard sizes.
Step 01Bolt diameter and washer ID
Step 02Washer outside diameter
Step 03Washer thickness (single or stacked)
Step 04Quantity required
Step 05Shipping term and destination port
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G-10 Glass Epoxy Washers — FAQ
What is G-10 glass epoxy made from?
G-10 is a composite laminate made from continuous woven glass fabric impregnated with an epoxy resin system, cured under heat and pressure. The result is a dense, rigid sheet with high mechanical strength, low water absorption and stable dielectric properties across wide temperature and humidity ranges.
What is the difference between G-10 and G-11 glass epoxy?
Both are glass fabric / epoxy laminates. G-10 is the standard grade for general industrial electrical insulation. G-11 uses a higher-temperature resin system and is specified where the joint operates at elevated temperatures beyond the standard G-10 service limit. Kaxite supplies both — see the G-11 glass epoxy washer page.
How do G-10 washers fit into a flange insulation kit?
In a fully insulated flanged joint there are three dielectric components: the gasket at the flange face, the sleeve through the bolt hole, and the washer under the nut (and typically under the bolt head). The G-10 washer is the third of these — it breaks the current path between the nut and the flange face. Removing or omitting any one of the three components will cause the isolation to fail.
Can G-10 washers be cut to custom sizes?
Yes. G-10 washers are supplied in standard bolt-size stock sizes and cut to your specific inside diameter, outside diameter and thickness. Send the dimensioned drawing or the bolt specification and we will confirm availability and lead time.
Why choose G-10 over phenolic for the insulation washers?
G-10 offers higher mechanical strength and much lower water absorption than standard phenolic laminate. On outdoor, marine or buried joints where moisture exposure is continuous, phenolic washers can degrade over time and lose dielectric strength. G-10 maintains its electrical properties in wet and humid service, which is why it is preferred for washers on outdoor and marine insulation kits.
What quantity is required to receive OEM pricing?
OEM / wholesale pricing applies from the first order for standard bolt sizes and from 500 pieces per size for custom-cut washers. Send the annual or project quantity for volume pricing — larger orders are scheduled directly with the production line for shorter lead time.
What is the lead time for G-10 washer orders?
Standard bolt-size washers ship from stock or on short lead time — typically 5–10 days depending on quantity. Custom-cut sizes are produced to order, generally 10–20 days. Send the specification for a confirmed delivery schedule.
Can G-10 washers be supplied together with sleeves and gaskets?
Yes. G-10 washers are supplied as individual components or as part of a complete flange insulation kit with matched sleeves and gaskets. See the flange insulation kits range, or contact us with the flange standard and size to receive a complete kit quotation.
Request a G-10 Glass Epoxy Washer Quotation
Send the bolt diameter, washer OD, thickness and quantity — or the flange standard and size for a complete kit quotation. Kaxite supplies G-10 washers for OEM flange insulation kits, maintenance replacement and standalone electrical insulation applications.
