Flange Insulating Gaskets

Flange insulating sets are packaged for one flanged joint, including gasket, sleeves and washers. Each flange set is securely packaged in a cardboard box, clearly labeled as to size, ASA Rating, style and material.

Type F gaskets are designed to fit the raised face portion of flanges. The outside diameter of the gasket is slightly smaller than the inside diameter of the bolt hole circle. The outside diameter is designed for alignment by the insulating sleeves. The central gaskets are available in the same materials as Type E. Upon installation, it is recommended that tape be wrapped around the outside of the flange to prevent foreign material from lodging between the exposed portions and causing “shorting out” of the flanges.

Type E gaskets are designed for full protection of flanges, and have the same outside diameter as the flange. Each gasket has precision-located bolt holes. Upon installation, it is recommended that tape be wrapped around the outside of the flange to prevent foreign material from lodging between the exposed portions and causing “shorting out” of the flanges. All Type E gaskets are easily centered with the flange inside diameter. Gaskets with slightly larger outside diameters are available on request.

Type D gaskets are insulating ring joint gaskets made to fit the ring groove of Ring Type Joint flanges. The Type D central gasket is made of medium weave fabric-reinforced phenolic, manufactured to ASA (ANSI) gasket dimensions. Properties are similar to those of phenolic flat central gaskets and are available in the basic octagonal shapes. Oval shapes can be ordered by special request. When installing Type D gaskets, it is also recommended that tape be wrapped around the outside of the flange to prevent foreign material from lodging between the exposed portions and causing “shorting out” of the flanges. Alignment pins should be used whenever possible to assure proper alignment of flanges when installing all flange insulation sets. Pins should be a minimum of 3/32″ (2.38mm) larger than the bolt size.

Insulating Gasket Material Plain Faced Phenolic Nitrile Faced Phenolic Non-Asbestos
Water Absorption In Percent 1.10% 0.45% ---
Hardness Rockwell M 105 --- ---
Tensile With Grain psi 13,000 13,000 ---
Compression Flatwise psi 39,000 39,000 ---
Flexural Flat W/Grain psi 22,000 22,000 3,000
Dielectric Strength VPM 200 200 400
Dielectric Constant 4.5 4.5 ---
Max. Cont. Operating Temp. 225øF/107øC 175øF/79.5øC 700øF/371øC
Nema Grade CE --- None
Insulating Sleeve Material Dielectric Strength volts/mil Water Absorption % Max Continuous Operating Temp.
Integral 450 0.90 180§F / 82§C
Mylarr 4,000 .80 300§F / 149§C
Nomexr* 720 --- 600§F / 315§C
Phenolic** 140 2.00 225§F / 107§C
Polyethylene*** 400-500 0.01 150øF / 66øC

All insulating sleeves are 1/32″ (.794mm + .000 – .010″) thick.
* Available on special request for high temperature applications.
**Made of NEMA (National Electrical Manufacturers Association) grade laminated phenolic.
***Low moisture permeability and absorption rate make sleeves excellent for wet application. Flexible and tough. Dupont trademark

Insulating Washer Materials Dielectric Strength volts/mil Compressive Strength (Flatwise) psi Flexural Strength (Flatwise with grain) psi Max. Continuous Operating Temp.
Non-Asbestos 400 --- 3,000 700§F / 371§C
Phenolic 200 39,000 22,000 225§F / 107§C

Flat insulating washers, placed on the studs between the flange and flat steel washers, manufactured from the customer’s choice of either: 1/8″ (3.175mm) thick fabric-reinforced, laminated phenolic or non asbestos. These washers may be used with polyethylene or phenolic sleeves. Note: If not specified, washers will be plain faced phenolic.

Steel Back-Up Washers
Steel washers fit between the nut and the insulating washer to prevent damage to the insulating washer. The outside diameter is sized to fit within the bolt facing on ASA standard flanges. Steel washers are 1/8″ (3.175mm) thick for extra strength. Insulating washers are not necessary on both sides of the flange, but it is a good practice.

ANSI B16.5 Flange Gaskets
Lone Star Sealing is your single source for ANSI B16.5 flange gaskets. With the ability to die cut, waterjet and flash cut materials our service truly is “Non-Stop”.

Materials include:
Compressed Non-Asbestos
NBR- Carbon
NBR – Aramid
SBR – Aramid
CR – Aramid
Flexible Graphite
Foil Reinforced Laminate
Tang Foil Reinforced Laminate
Corragated Insert
Mechanical Grade
Virgin Grade
Glass Filled
Silica Filled
Barium Sulfate Filled
Corragated Insert

Flexitallic Spiral Wound Gaskets
Gaskets can be made from a large selection of alloys and filler materials in a variety of shapes and sizes. Some of the most common shapes are as follows.

Style S (Sealing Element)
Designed for tongue and grove applications, the style S gasket is a stand alone sealing element where the ID is reinforced with several layers of metal winding, filler material is then introduce to offer greater sealing ability and the gasket is finished with several more layers of metal to help insure stability.

Style SI (Sealing Element with Inner Ring)
The SI configuration is the same as the S except that a solid inner ring is utilized to prevent over compression. This design is also helpful in turbulent applications which are prone to cause erosion of the flange faces.

Style CS (Centering Ring with Sealing Element)
The CS gasket utilizes an external ring where the ID is grooved to insert a sealing element. The external ring or centering ring is designed to properly guide the gasket on a bolted flange accurately centering gasket. The Centering also provides additional radial strength to prevent gasket blowout and acts as a compression limiter.

Style CSI (Centering Ring with Sealing Element and Inner Ring)
The CSI gaskets is best suited where high pressure and temperature is a factor or in applications where corrosive or toxic media maybe present. Like the CS profile, the CSI gasket includes an inner ring which has proven to be very helpful to eliminate inward buckling of the sealing element.

ASME B16.20 requires the use of CSI gaskets when PTFE is used as the filler in all ANSI B16.5 applications as well as:
Pressure Class 900, nominal pipe sizes 24″ and larger
Pressure Class 1500, nominal pipe sizes 12″ and larger
Pressure Class 2500, nominal pipe sizes 4″ and larger

Ring Type Joint Gaskets
RTJ gaskets are designed to seal by “initial line contact” or wedging action between the mating flange and the gasket. By applying pressure on the seal interface through bolt force, the softer metal of the gasket flows into the micro-fine structure of the harder flange material, creating a very tight and efficient seal. These basic shapes are used in a variety of applications with pressures up to 20,000 PSI. The dimensions are standardized and require specially grooved flanges by where a corresponding “R” or “BX” number is assigned for pipe size and pressure class for gasket identification.
R-Oval – Ring Gasket
R-Octagonal – Ring Gasket
RX – Ring Gasket
BX – Ring Gasket