Flange insulation components: These include insulation gaskets, insulating sleeves, insulation bolts, and washers. They ensure electrical isolation of the flange and are commonly used to prevent corrosion or other electrical issues caused by the flow of current in the system.

Flange Insulation Kit

High Quality Flange Insulation Kit

SSM provides a Flange Insulation Kit, a set of components used in flange connections to provide electrical isolation and prevent current from flowing through the flange connection. This helps avoid issues such as electrochemical corrosion, grounding currents, or potential differences. Typically, industries such as petrochemicals, natural gas, and power generation use flange insulation kits in pipeline systems, especially when different metals come into contact.

Components of a Flange Insulation Kit

Insulation Gaskets: Serve as the electrical isolation layer between flanges, preventing current from flowing across the flange connection surfaces. These gaskets can be full-face or ring-type and are typically made from materials like PTFE, polyimide (PI), or rubber.

Insulation Sleeves: Inserted into the bolt holes of the flange, insulation sleeves prevent direct contact between the bolts and the flange, thus preventing current from passing through the bolts. Common materials include PTFE and rubber.

Insulation Washers: These are used with bolts further to ensure electrical isolation between the bolts and flanges.

Gaskets and Bolting Kit: A flange insulation kit typically also includes matching insulation gaskets, bolts, nuts, and washers, ensuring electrical isolation and sealing during installation.

Gasket Kit Types

We offer four main types of flange insulation kits, namely F, E, D, and O. Each type of flange kit is suitable for flanges with specific types of flange faces (RF, FF, RTJ).

F-Type Gasket

F-type gaskets are suitable for raised face flanges. The inner diameter of the bolt holes is slightly smaller than the gasket’s outer diameter to ensure automatic alignment. To prevent debris accumulation, special protective rings can be used on the joint assembly to enhance cathodic isolation further. They are made from 1/8-inch thick fabric-based phenolic boards, either uncoated or with nitrile rubber. F-type gaskets are also available in non-asbestos fiber materials with high isolation capability.

E-Type Gasket

In the full-face “E” type gasket, the outer diameter matches the outer diameter of the flange, ensuring that the gasket fully covers the entire flange surface. The gasket features precisely positioned bolt holes and is easily aligned at the center. This design prevents debris from accumulating between the flange faces, thereby enhancing the isolation performance of the kit. E-type flange insulation kits are available in phenolic, neoprene-coated phenolic, and high-temperature materials.

D-Type Gasket

The “D” type gasket is specifically designed to fit the ring grooves of RTJ flanges (R, RX, and BX types). It is made from medium-weave reinforced phenolic resin and other materials, with dimensions that conform to ANSI specifications. It is available in basic oval and octagonal shapes. This type of gasket is known as the “API ring joint.”

Flange Insulating Gasket Styles

MCG Sealing Gasket

MCG Insulation Gasket is made by bonding high-strength epoxy resin boards (G10 or G11) to both sides of stainless steel plates. This design maintains the high strength of the stainless steel and provides excellent electrical insulation properties. The gasket features a specially designed spring-loaded PTFE sealing strip for reliable sealing performance. Additionally, the sealing grooves on the gasket penetrate into the stainless steel, effectively preventing leakage of the medium through the gap between the two materials.

The MCG insulation gasket’s design is intended to provide both sealing and insulation for flanges under critical operating conditions. It can be used for all pressure class raised face (RF), flat face (FF), and ring-type joint (RTJ) flanges, including those with API 15000# ratings. The standard material for the stainless steel plate is SS316, though we can also offer special materials such as duplex steel, Hastelloy, Inconel, and other alloys upon customer request.

Performance and Advantages of MCG Gaskets:

Provides high reliability in sealing and insulation under critical operating conditions.
Capable of sealing and insulating at all pressure ratings, including ANSI 2500# and API 15000#.
The unique stainless steel core and high-strength laminated insulation can withstand critical conditions, including large bending moments, vibrations, and temperature and pressure cycling.
It is suitable for use in corrosive environments, including those with high concentrations of CO2, H2S, and produced water.
Excellent cathodic protection insulation performance.
Spring-loaded seals provide reliable sealing, preventing leakage incidents.
The gasket’s inner diameter matches the flange size, protecting the flange faces from medium corrosion and flow abrasion and preventing turbulence at the flange connection.
Reduces galvanic corrosion between different metal flanges.
It can be manufactured according to various flange standards (ANSI, API, BS, DIN, AS, etc.).
Capable of sealing misaligned RTJ flanges and raised face (RF) flanges.

Lseal Sealing Gasket

Lseal Sealing Gasket is suitable for sealing and insulation of all types of flanges. It features a square sealing element embedded in a uniquely designed groove on the gasket, providing near-zero “m” and “y” values and achieving sealing with minimal bolt pressure. This gasket can also use materials such as PTFE, fluoroelastomers, and others for the sealing element, offering flexibility in material selection for different operating conditions.

Due to their excellent sealing performance and the variety of sealing materials available, Lseal gaskets are widely used in medium and low-pressure environments. However, for better sealing performance in pressure environments of ANSI 600# and above, it is recommended to consider using MCG sealing gaskets.

Tseal Sealing Gasket

Tseal Sealing Gasket is made from G10 or G11 materials. The gasket features two sealing strips, which are placed in uniquely designed grooves on both sides of the gasket, overlapping and staggered. The sealing strips are securely held in place within the grooves without the need for external force. This design prevents the medium from leaking through the laminated layers. Additionally, the unique design of the sealing grooves allows for a wider selection of sealing materials.

This type of sealing gasket not only accommodates rubber sealing elements such as Viton, EPDM, and neoprene, but also features spring-loaded Teflon, which enhances the rebound performance of Teflon and further improves the gasket’s sealing capabilities.

Due to the superior corrosion resistance and temperature tolerance of Teflon compared to conventional rubber materials, it is considered the most reliable sealing element. We highly recommend using Teflon as the sealing material in all environments to achieve optimal sealing and insulation performance.

Rubber-Composite Phenolic Resin Sealing Gaskets

Rubber-Composite Phenolic Resin Sealing Gaskets are commonly used standard flat insulation gaskets in the oil and gas industry. Soft chloroprene or nitrile rubber is applied to both sides of the phenolic laminate to provide effective sealing, with a maximum operating temperature of +80°C. However, considering the superior sealing performance and material versatility of Lseal, Tseal, and MCG insulation gaskets, we recommend replacing rubber-composite phenolic resin gaskets with Lseal, Tseal, or MCG insulation gaskets when conditions permit.

Functions of Flange Insulation Kit:

Electrical Isolation: Prevents current from flowing through the flange connection, reducing the impact of electrochemical corrosion and grounding currents on pipeline equipment.
Prevents Corrosion: Electrical isolation reduces galvanic corrosion (electrochemical corrosion between dissimilar metals), particularly in cases where different metals come into contact.
Extends Equipment Life: Flange insulation kits help extend the lifespan of pipeline systems and equipment by reducing corrosion caused by electrical currents.

Application of Flange Insulation Kit

Oil and Gas Industry: Prevents electrochemical corrosion, especially in offshore platforms or underground pipelines.
Chemical Plants and Power Systems: Reduces current conduction to protect equipment from damage.
Water Treatment Facilities: Prevents corrosion between dissimilar metals and ensures the stable operation of equipment.

By using a Flange Insulation Kit, the safety, reliability, and durability of a piping system can be effectively enhanced.

One-Stop Flange Insulation Kit Provider for All Your Needs

SSM has significant product advantages in manufacturing Flange Insulation Kit, Whether it’s quality or price, we will meet your needs.

More Information About Flange Insulation Kit

Sealing Gasket Physical Properties

Material	Plain Phenolic	Rubber Faced Phenolic	G-7 Silicone Glass	G-10 Epoxy Glass	G-11 Epoxy Glass
Dielectric Strength (Volts/Mil, Short Time)	500	500	350	550	550
Compressive Strength (psi)	25,000	25,000	40,000	50,000	50,000
Water Absorption (%)	1.6	1.6	0.07	0.1	0.1
Tensile Strength (psi)	20,000	20,000	25,000	45,000	43,000
Operating Temp. (°F)	-65 to +220	-65 to +175	-292 to +450	-292 to +280	-292 to +349
Operating Temp. (°C)	-54 to +104	-54 to +79	-180 to +232	-180 to +138	-180 to +176

Note: G-7 material should not be used with hydrocarbons, not even trace amounts.

Seal Element Temperature Limits

Material	Nitrile	Viton	Teflon	Neoprene	EPDM
Operating Temp. °F	-40 to +250	-20 to +350	-292 to +300	-40 to +175	-65 to +248
Operating Temp. °C	-40 to +121	-29 to +177	-180 to +232	-40 to +79	-54 to +120

Note: Consider both retainer and seal element temperature limits together for sealing gaskets.

Sleeves and Washers

Insulating Sleeves

Our insulating sleeves are designed according to standard flange sizes to fit easily over bolts and into flange bolt holes. They are used in conjunction with separate insulating and metal washers.

Available sizes range from standard American bolt sizes 1/2” (12.7mm) to 3-1/2” (88.9mm) and metric bolt sizes from 12mm and larger.

We offer insulating sleeves in the following materials:

Mylar
Phenolic
Nomex®
G-7 Silicone Glass
G-10 Epoxy Glass
G-11 Epoxy Glass

Sleeve Material Physical Properties

Material	Mylar	Nomex	Phenolic	G-7 Silicone Glass	G-10 Epoxy Glass	G-11 Epoxy Glass
Dielectric Strength (Volts/Mil, Short Time)	4,000	400	400	350	400	400
Water Absorption (%)	0.8	N/A	1.6	0.1	0.1	0.1
Operating Temp. (°F)	-75 to +300	-65 to +450	-20 to +225	-292 to +450	-292 to +280	-292 to +349
Operating Temp. (°C)	-59 to +149	-54 to +232	-29 to +107	-180 to +232	-180 to +138	-180 to +176

Note: G-7 material should not be used with hydrocarbons or trace amounts.

Insulating Washers

Our insulating washers are designed to provide durable and effective insulation. They fit over insulating sleeves and are compatible with bolt sizes ranging from 1/2” (12.7mm) to 3-1/2” (88.9mm).

Available materials for insulating washers include:

High-Strength Glass Clad Phenolic
G-7 Silicon Glass
G-10 Epoxy Glass
G-11 Epoxy Glass

Washer Material Physical Properties

Material	Plain Phenolic	G-7 Silicone Glass	G-10 Epoxy Glass	G-11 Epoxy Glass
Dielectric Strength (Volts/Mil, Short Time)	500	350	550	550
Compressive Strength (psi)	25,000	40,000	50,000	50,000
Water Absorption (%)	1.6	0.07	0.1	0.1
Operating Temp. (°F)	-65 to +220	-292 to +450	-292 to +280	-292 to +349
Operating Temp. (°C)	-54 to +104	-180 to +232	-180 to +138	-180 to +176

Note: G-7 material should not be used with hydrocarbons or trace amounts.

Metal Washers

Our standard metal washers used in insulation kits are typically zinc-plated steel. However, we can also provide higher-performance materials such as SS304, SS316, duplex stainless steel, and others upon customer request.

Package & Installation

Each flange insulation gasket kit should include the following:

One flange gasket
One insulating sleeve per bolt-hole
Two insulating washers per bolt-hole
Two steel washers per bolt-hole

Each kit’s insulating sleeves, insulating washers, and steel washers are individually packaged in a vacuum-sealed plastic bag to prevent loss. Typically, the flange insulation kits are packaged in a corrugated box containing either a single or multiple kits of the same size. The box is labeled on the outside to indicate the size, pressure rating, material, and quantity for easy identification.

How to tighten the flange bolts

Clean the flange faces.
Insert the insulating gasket between the two flange faces.
Insert the insulating sleeve into each bolt hole.
Slide a steel washer and an insulating washer onto each bolt, then insert the bolt into the hole, ensuring that the steel washer is placed next to the nut.
On the other end of the bolt, slide on an insulating washer followed by a steel washer.
Tighten the bolts in a criss-cross pattern (as shown in the image).
Use a torque wrench to ensure even force distribution.
Do not over-tighten to prevent leakage.
Ensure that the bolt surfaces are well-lubricated.
Make sure the sealing surfaces are free of oil and grease.

More Resources:

https://en.wikipedia.org/wiki/Gasket