Kaxite Type D flange insulation kits are engineered for RTJ (ring joint) flanges — the gasket is profiled to sit inside the ring groove rather than on a raised face. Each kit is supplied as a complete isolation set: insulating gasket, insulating sleeves and insulating washers, pre-packed to match the flange bolt pattern and labelled with flange size and rating. The kit breaks electrical continuity between two mating flanges to prevent galvanic corrosion between dissimilar metals and to isolate the joint from cathodic protection currents on buried or submerged pipelines. Materials include reinforced phenolic, Minlon and Mylar. Kits are available for all common flange standards (ASME B16.5, ASME B16.47, API 6A, DIN/EN) across Class 150 to Class 2500.
Type D flange insulation kits are designed specifically for RTJ (ring joint) flanges. Unlike the flat gasket types used on raised-face flanges, the Type D gasket is profiled to sit inside the ring groove of the RTJ flange, providing the same dielectric isolation and seal performance under the same bolt load as a standard ring joint gasket.
The kit breaks the electrical continuity between two mating flanges, preventing galvanic corrosion between dissimilar metals and isolating the flanged joint from cathodic protection currents on buried or submerged pipelines. Each kit ships complete with gasket, insulating sleeves and insulating washers, labelled with the flange size and pressure rating.
Flange insulation is used wherever two dissimilar metal flanges must be joined without creating an electrical path between them. The Type D kit is the RTJ variant of that system — it is the version specified when the flange faces are ring joint type, not raised face or flat face.
The kit serves three functions at once:
Each kit is labelled with the flange size and rating so the installer can match it to the joint without second-guessing. All components are dielectric-rated and supplied pre-matched to the flange specification.
Available for all flange sizes, types and pressure ratings — ASME B16.5, ASME B16.47, API 6A and DIN/EN, in Class 150 through Class 2500 and equivalent pressure classes.
The dielectric components of the Type D kit are made from reinforced composite materials chosen for high dielectric strength, mechanical stiffness under bolt load, and dimensional stability across the service temperature range. Three standard material families are supplied.
The standard material for general service. High compressive strength, excellent dielectric properties, and good temperature resistance. Used for the gasket, sleeves and washers in most Type D kits.
Specified where higher toughness and impact resistance are needed. Retains dielectric properties under vibration and thermal cycling, common on offshore and heavy industrial piping systems.
Used for thin isolating washers and specific kit configurations where the profile is tight. High dielectric strength in a very thin section, allowing the isolation layer to be integrated without losing bolt load.
The primary dielectric barrier. Profiled to the RTJ ring groove, sized to the flange bore and bolt circle, and drilled with the correct bolt pattern for the specified flange standard.
Inserted into each bolt hole to isolate the bolt shank from the flange body. Sized to the bolt diameter and flange thickness, so the bolt cannot contact either flange face.
Placed under each nut (and often under each bolt head) to isolate the fastener from the flange face. Combined with the sleeves, they break the last remaining current paths through the bolting.
Kits are supplied pre-packed in the correct quantity for the specified flange — no counting, no missing parts on site. Each kit is labelled with the flange size and rating on the outside of the pack.
Isolating a cathodically protected pipeline from unprotected structures at every flanged joint.
Carbon steel to stainless, stainless to copper alloy, and any other mixed-metal joint where galvanic corrosion is a risk.
API 6A RTJ flanges on wellheads, christmas trees and flowlines where electrical isolation is part of the design.
High-pressure RTJ piping where corrosion monitoring systems require the flange joint to be electrically isolated.
Isolating ductile iron, steel and concrete-lined pipe sections from each other and from pumps or valves.
Deck piping, seawater systems and subsea spools where salt water accelerates any galvanic couple.
Steam and cooling water piping where the piping material changes across a flanged joint.
Transmission lines that use cathodic protection, where every insulated joint must remain isolated for the life of the line.
Tank farm piping where isolation is needed to prevent stray current corrosion at tank nozzles.
| Kit Type | Flange Face | Gasket Position | Typical Service |
|---|---|---|---|
| Type D | RTJ (ring joint) | Inside the ring groove | High-pressure oil & gas, API 6A wellheads, refineries |
| Type E | Raised face / full-face | Same OD as the flange, precision bolt holes | General piping isolation, full protection of the flange face |
| Type F | Raised face | Inside the bolt circle | Standard raised-face flanged joints |
| Type B / Type C | Raised face | Inside the bolt circle (B) or ring-groove style (C) | Application-specific variants |
If you are unsure which type matches your flange, send the flange drawing or standard (ASME B16.5, B16.47, API 6A, etc.) and we will confirm the correct kit type and material.
To receive a quotation for Type D flange insulation kits, provide the following five details. Kaxite will confirm the correct kit type, material and lead time.
Send your specification and we will return a quotation with lead time — typically within one working day for standard sizes.
The Type D kit is designed for RTJ (ring joint) flanges, so the gasket is profiled to sit inside the ring groove. The Type E kit is designed for raised-face or full-face flanges, with a gasket that has the same outside diameter as the flange and precision bolt holes. The two kits are not interchangeable — the choice depends on the flange face type.
Yes. Type D kits are produced for all common flange standards including ASME B16.5, ASME B16.47, API 6A and DIN/EN, covering Class 150 through Class 2500 and equivalent pressure classes. Send the standard and size on your drawing and we will confirm availability.
For high-pressure API 6A service, reinforced phenolic is the standard starting point. Minlon is specified where higher toughness and vibration resistance are needed — common on offshore and heavy industrial systems. Send the working pressure, temperature and media and we will confirm the correct material.
Each kit is supplied pre-packed as a complete set — one gasket, the correct number of sleeves and washers for the flange bolt pattern, and any additional isolation components required. The pack is labelled with the flange size and rating so it can be matched to the joint on site without error.
Standard sizes ship from stock or on short lead time — typically within 7–15 days depending on quantity. Custom or non-standard sizes are produced to order, generally 15–30 days. Send the specification for a confirmed delivery schedule.
Yes. In addition to complete kits, Kaxite supplies insulation washers and insulation sleeves as separate components for maintenance and replacement needs. See the insulation washer and insulation sleeve ranges.
Send the flange standard, size, pressure class and quantity. Kaxite will confirm the correct kit type, material and lead time — and if the flange is not RTJ, we will recommend the appropriate Type E or Type F alternative.
