Type F Nitrile Faced Phenolic Flange Insulation Gasket Kit — Style NFIK 605 — is a raised-face flange insulation gasket kit comprised of a high-strength reinforced phenolic core compressed between two conformable Nitrile (NBR) facing layers. The Type F design centers the gasket between the bolts, making it suitable for raised-face RF flanges up to ANSI Class 600. The Type F kit is excellent for isolating flanges made of dissimilar metals and for preventing flange-face corrosion. The complete kit includes phenolic and steel washers with Mylar sleeves. Related Type E and Type D flange insulation gasket kits are also available from Kaxite.
A Type F nitrile faced phenolic flange insulation gasket kit is a raised-face flange insulation gasket composed of three bonded layers. The core is a high-strength reinforced phenolic sheet — the load-bearing and electrically insulating layer. On each face of the phenolic core, a layer of conformable Nitrile (NBR) rubber is bonded. The two NBR facing layers form the sealing element of the gasket and conform to the surface of the flange under bolt load.
The Type F design centers the gasket between the bolts — meaning the gasket OD is sized so that it sits inside the bolt circle without interfering with the bolts or studs. This makes the Type F kit suitable for raised-face RF flanges in all pressure classes up to ANSI Class 600.
The purpose of the Type F kit is to interrupt the electrical continuity between two adjacent flanges. When two flanges made from dissimilar metals are bolted together and an electrolyte is present, an electrical current can flow between them and corrode one of the metals — a process known as galvanic corrosion. The Type F kit breaks that circuit without interfering with the correct tightening of the flanges.
The parameters below define the fit and function of the NFIK 605 kit. Confirm the exact flange size and pressure class on the enquiry.
The Type F kit works because three layers do three different jobs. Understanding how the layers combine makes it easy to see why the Type F kit is used in the applications where it performs best.
Phenolic core — carries the load and blocks the current
The reinforced phenolic core is the mechanical and electrical heart of the gasket. It carries the bolt load without crushing and, because phenolic is a dielectric material, it blocks the flow of electrical current across the flange joint.
Nitrile (NBR) facings — seal the joint
The two NBR facing layers are the sealing element. NBR is conformable, so it flows into the microscopic imperfections on the flange face and creates a leak-tight seal at moderate bolt load. Because the NBR is bonded to the phenolic core, it stays in place during handling and installation.
Kit components — complete the electrical circuit break
The gasket alone only insulates the flange faces. To isolate the joint fully, the bolt holes and bolts must also be insulated. The complete Type F kit includes phenolic washers, steel washers and Mylar sleeves — so every electrical path through the joint is broken.
Centered gasket — keeps the bolts clear
The Type F gasket is centered between the bolts. This means the gasket OD is sized so that it does not interfere with the bolts or the studs. The flange can be tightened to the specified torque without the gasket being pinched or distorted by the bolts.
The Type F kit is specified wherever a raised-face flange joint must be sealed and electrically isolated at the same time — most commonly to stop galvanic corrosion between dissimilar metals or to protect a flange face from corrosion attack.
Dissimilar Metal Flange Isolation
Where a carbon steel flange is bolted to a stainless steel, brass or cast iron flange, the Type F kit breaks the electrical circuit that drives galvanic corrosion.
Flange Face Corrosion Prevention
Where the flange face is at risk of localized corrosion, the NBR-faced gasket keeps the aggressive medium away from the sealing surface.
Cathodic Protection Isolation
On buried or submerged pipelines, the Type F kit isolates one section of the pipeline from the next so that the cathodic protection system is not short-circuited.
Oil & Gas Transmission Pipelines
Flow lines, gathering lines and transmission lines where isolation joints are required at regular intervals for corrosion control.
Refineries & Petrochemical Plants
Process piping, heat exchanger nozzles and vessel connections where dissimilar metals meet at a raised-face flange joint.
Water & Wastewater Mains
Large-diameter water and wastewater pipelines where the flange joint must be isolated to protect the pipeline coating and the cathodic protection system.
The three standard flange insulation gasket kit designs — Type D, Type E and Type F — are used on different flange types. Use the comparison below to see which one matches your flange.
What is a Type F nitrile faced phenolic flange insulation gasket kit?
A Type F nitrile faced phenolic flange insulation gasket kit — Style NFIK 605 — is a raised-face flange insulation gasket comprised of a high-strength reinforced phenolic core compressed between two conformable nitrile (NBR) facing layers. It is designed to interrupt the electrical continuity between two adjacent flanges without interfering with the correct tightening of the flanges.
What is the difference between the Type F, Type E and Type D flange insulation gasket kits?
Type D is designed for RTJ ring groove flanges and has an octagonal cross-section. Type E is for ring-type gasket joints. Type F is for raised-face RF flanges and has a full-face style gasket with nitrile (NBR) facings on both sides of a reinforced phenolic core. Each is designed to fit a specific flange geometry — send us the flange type and we will confirm which design is right for your application.
What pressure class can the Type F kit handle?
The Type F nitrile faced phenolic flange insulation gasket kit is suitable for raised-face RF flanges up to ANSI Class 600. The Type F design centers the gasket between the bolts, so the gasket OD does not interfere with the bolts or studs and the flange can be tightened to the specified torque without pinching or distorting the gasket.
What is included in the Type F flange insulation gasket kit?
The complete Type F kit includes the nitrile faced phenolic gasket, phenolic washers, steel washers and Mylar sleeves. Together, these components break every electrical path through the flange joint — across the flange faces, through the bolt holes and around the bolts.
Why does the Type F kit use nitrile (NBR) facings instead of a bare phenolic surface?
Bare phenolic gaskets need a higher bolt load to seal because phenolic is rigid and does not conform to the flange face. The nitrile (NBR) facing layers are conformable — they flow into the microscopic imperfections on the flange face at moderate bolt load and create a leak-tight seal. The NBR facings also protect the flange face from localized corrosion attack from the process medium.
What is the Type F kit used for?
The Type F kit is used for isolating raised-face flange joints made from dissimilar metals (to prevent galvanic corrosion), for protecting the flange face from localized corrosion attack, for isolating cathodic protection systems on buried or submerged pipelines, and for sealing flange joints in oil and gas, refinery, petrochemical and water transmission service.
Tell us the flange size, the pressure class (up to ANSI Class 600), the flange face type (raised-face RF), the quantity and the required kit scope (gasket only, or the complete kit with phenolic washers, steel washers and Mylar sleeves). If you are not sure whether you need a Type D, Type E or Type F kit, send us the flange drawing and we will match the correct design.
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