Flange insulation gasket kits are engineered assemblies used to electrically isolate bolted flange joints while maintaining a pressure-tight seal. They prevent galvanic corrosion between dissimilar metals, block stray currents from cathodic protection systems, and eliminate spark risk in hazardous areas.
Kaxite Sealing manufactures complete insulation kits to ASME B16.5 and ASME B16.47 dimensions, plus fully custom configurations for oil & gas, chemical processing, water treatment, and power generation pipelines.
A complete kit isolates every metallic contact point in a bolted flange joint. Kaxite Sealing standard kits include the following components:
| Component | Function | Typical Material |
|---|---|---|
| Central insulating gasket | Primary seal and electrical barrier between flange faces | Epoxy glass (G10/FR4), phenolic, PTFE |
| Insulating sleeves (bushings) | Isolate bolts and studs from flange bolt holes | PTFE, polypropylene |
| Insulating washers | Isolate nut and bolt head from flange face | Epoxy glass, phenolic, PTFE |
| Steel washers | Distribute load and prevent crushing of insulating washers | Carbon steel, stainless steel |
| Nuts and studs (optional) | Complete assembly hardware, specified per project | ASTM A193 / A194, or client spec |
| Material | Dielectric Strength | Temperature Range | Best For |
|---|---|---|---|
| Epoxy Glass (G10/FR4) | High | -50°C to +150°C | General-purpose, high-strength isolation |
| PTFE (Teflon®) | Very high | -200°C to +260°C | Highly corrosive chemical service |
| Phenolic Laminate | High | -40°C to +120°C | Better fluid resistance than standard epoxy |
| Modified Elastomer | Moderate | Application dependent | Less demanding isolation with sealing needs |
| Material | Advantage | Limitation |
|---|---|---|
| PTFE | Low friction, excellent chemical inertness, easy installation | Lower mechanical strength |
| Polypropylene | Cost-effective, good dielectric properties | Lower temperature limit |
Kaxite Sealing flange insulation kits are manufactured and tested to the following typical ranges. Final values depend on the selected material and flange class.
| Parameter | Specification Range | Test Standard |
|---|---|---|
| Dielectric strength | 4 kV/mm – 15 kV/mm | ASTM D149 |
| Volume resistivity | > 10¹² ohm·cm | ASTM D257 |
| Compressive strength | 150 MPa – 300 MPa (epoxy glass) | ASTM D695 |
| Continuous service temperature | -50°C to +150°C (epoxy glass); -200°C to +260°C (PTFE) | Material dependent |
| Chemical resistance | Excellent against acids, alkalis, solvents (especially PTFE) | ASTM D543 |
| Flange pressure rating | Class 150, 300, 600, 900, 1500, 2500 | Matches insulated flange rating |
| Flange types | Weld neck, slip-on, blind, lap joint, orifice | ASME B16.5 & B16.47 |
Isolation of cathodically protected sections and prevention of galvanic corrosion at dissimilar metal joints.
Electrical isolation of flanged joints exposed to aggressive chemicals, acids, alkalis, and solvents.
Stray current and galvanic corrosion control in municipal and industrial water distribution systems.
Hazardous area spark prevention and electrical isolation in steam, cooling water, and fuel gas piping.
Seawater piping and dissimilar metal joints requiring long-term isolation in corrosive environments.
Isolation of process piping in corrosive chemical service with strict electrical continuity requirements.
A kit is required whenever electrochemical corrosion must be prevented. Common triggers include dissimilar metal connections (e.g., carbon steel to stainless steel), pipelines with cathodic protection, stray current environments, and hazardous areas where sparking must be eliminated.
No. Using only the gasket leaves the bolts in metallic contact with both flanges, which bridges the isolation circuit. A complete kit with sleeves and washers is essential to break all metallic contact points.
For general-purpose, high-strength isolation, choose Epoxy Glass (G10/FR4). For aggressive chemical service, choose PTFE. Consider fluid media, operating temperature, pressure class, and cleaning procedures. Kaxite engineers can assist with selection.
Use a low-resistance ohmmeter or megohmmeter to measure resistance between the two flanges and between each flange and its bolts. A reading above 1 MΩ indicates effective isolation. A low reading indicates a short—often from a missing sleeve, damaged washer, or conductive debris.
Generally no. The gasket and insulating washers compress during torquing and should be replaced on every flange re-opening. PTFE sleeves may be reused only if undamaged and inspected.
Yes. We manufacture complete insulation kits for RTJ flanges, including insulated sealing rings with the full set of sleeves and washers. The design ensures both a pressure-tight seal and full electrical isolation.
Provide: flange standard (ASME, DIN, etc.), nominal pipe size (NPS), pressure class (e.g., 150#), facing type (RF, RTJ), bolt size and quantity, and material specification. A flange drawing or equipment tag number is the most reliable reference.
Full control over material sourcing, tolerances, and lead times.
ASME B16.5 and B16.47 standard kits plus fully custom configurations.
Epoxy glass, phenolic, and PTFE sourced and tested to ASTM standards.
Material selection, installation guidance, and isolation testing recommendations.
Serving oil & gas, chemical, water, and power customers worldwide.
Technical quotes and material recommendations within 24 hours.
Send us your flange standard, size, pressure class, facing type, and material requirements. Our engineers will confirm the correct kit configuration and provide a technical quotation.
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