GasketSeal Sealing/Isolating System:

Flange Isolation Kits consist of an isolating gasket and isolating sleeves and washers which are all correctly sized for the application and conveniently packaged to minimize the possibility of lost component parts during installation isolating gaskets may be specified as either "E" or "F" type while single, double or one-piece sleeve and washer sets are offered as options for varying degrees of electrical isolation between the flanges. In addition, a wide variety of material options exist for both isolating gaskets and sleeve and washer materials.

The Gasket:

GasketSeal sealing gaskets are considered to be one of the most effective methods for sealing mating surfaces of all types. The gasket consists of two molded half "O" rings (with precise crown to void ratio) mounted in grooves on opposite sides of a retainer.

While maintaining all the advantages of a full "O" ring seal, the half "O" rings eliminate the need to sealing grooves in the mating surfaces which also eliminates positioning and alignment concerns. GasketSeal gaskets are available in a wide variety of retainer and sealing element combinations for matching gaskets to service and environmental conditions.

Before Tightening:

The flange faces come into contact with the crown of the sealing elements. As the flange is tightened the crowns are compressed into the molded-in voids in the sealing elements, resulting in a seal that will maintain positive, dynamic contact against the flange faces under all conditions.

After Tightening:

The flange faces have come into firm contact with the retainer, thus encapsulating the sealing elements within grooves and guarding them from exposure to external environments or internal media. At the same time, the elastic memory characteristics of the confined sealing elements results in zero "m" and "y" factors, making it possible to effect and maintain a positive seal at the lowest possible compressive load.

Type E Gasket:

The gasket retainer extends out to the O.D. of the flange. Holes are cut in a type "E" gasket at the bolt circle to accommodate threaded studs or bolts.

Single Washer Set

Single washer set flange isolation kits include the following items for each bolt:

One 1/8" thick steel washer
One Isolating Washer
One Isolating Sleeve

Application Considerations:

In buried application, single washer configurations may be used to allow the Cathodic Protection (CP) current to reach the nuts and bolts. If desired, nuts on the opposite side of the cathodically protected flange may be included as part of the CP system.

Double Washer Set

Double washer set flange isolation kits include the following components for each bolt:

Two 1/8" thick steel washers
Two Isolating waters
One Full length isolating sleeve

Application Considerations:

Double washer configurations may be used for added protection against the possibility of shorting out the nuts and bolts. In addition, double washer sets electrically isolate the nuts and bolts from both flanges.

One-Piece Sleeve and Washer Sets

One-piece sleeve and washer set flange isolation kits include the following items for each bolt:

Two 1/8" thick steel washers
One One-piece isolating sleeve

Application Considerations:

Easier to install, one-piece sleeves also allow the inspector a visual indication of sleeve usage. Due to relative low compression strength of the material, its use is not recommended for high pressure or large diameter flanges that require high torque loads.

Note: G-10 One-Piece sleeve/washer assembly available for additional strength and convenience.

Materials for flange isolation kits on pipes containing water, aqueous fluids or natural gas (up to 220°F, 104°C) shall consist of the following components:

Isolating and Sealing Gasket:  One full faced isolating and sealing gasket, LineBacker® Sealing Gasket-Type "E", 1/8" thick, phenolic retainer containing a precision tapered groove to accommodate the controlled compression of an EPDM quad-ring sealing element. Sealing element placement shall accommodate either flat, raised or RTJ face flanges. The quad-ring seal shall be pressure energized. The phenolic retainer shall have a 500 volts/mil dielectric strength and a minimum 25,000 psi compressive strength. The full faced flange isolating gasket shall be 1/8" less in I.D. than the I.D. of the flange in which it is installed.

Full Length Bolt Isolating Sleeves:  One full length Mylar sleeve (extending half way into both steel washers) for each flange bolt. The Mylar shall be a 1/32 inch thick tube with a 4000 volts/mil dielectric strength and water absorption of 0.8% or less.

Washers:  Two, 1/8 inch thick, glass clad phenolic isolating washers for each bolt. Their compressive strength shall be 33,000 psi, dielectric strength 500 volts/mil and water absorption 1.6% or less.

Two, 1/8 inch thick steel washers for each bolt. The I.D. of all washers shall fit over the isolating sleeve and the steel and isolating washers shall have the same I.D. and O.D.

Materials for flange isolation kits on pipes containing natural gas, oil and aqueous fluids (up to 280°F, 138°C) shall consist of the following components:

Isolating and Sealing Gasket:   One full faced isolating and sealing gasket, LineBacker® Sealing Gasket-Type "E", 1/8" thick, G-10 retainer containing a precision tapered groove to accommodate the controlled compression of a Teflon (or Viton) quad-ring sealing element. Sealing element placement shall accommodate either flat, raised face or RTJ flanges. The quad ring seal shall be pressure energized. The G-10 retainer shall have a 550 volts/mil dielectric strength and a minimum 50,000 psi compressive strength. The full faced flange isolating gasket shall be 1/8" less in I.D. than the I.D. of the flange in which it is installed.

Full Length Bolt Isolating Sleeves:   One full length G-10 sleeve (extending half way into both steel washers) for each flange bolt. The G-10 shall be a 1/32 inch thick tube with a 400 volts/mil dielectric strength and water absorption of 0.10% or less.

Washers:   Two, 1/8 inch thick, G-10 isolating washers for each bolt. Their compressive strength shall be 50,000 psi, dielectric strength 550 volts/mil and water absorption 0.10% or less. Two, 1/8 inch thick zinc plated, hot rolled steel washers for each bolt. The I.D. of all washers shall fit over the isolating sleeve and both the steel and isolating washers shall have a same I.D. and O.D.

Type "D" Gaskets are available for RTJ flanges but the LineBacker°. Sealing Gasket is an excellent alternative to "D" gaskets because the sealing element may be positioned anywhere between the I.D. of the gasket and I.D. of the ring groove

Type "E" Gaskets extend to the outside diameter of the flange. They feature precision located bolt holes, to automatically center the gasket, and offer maximum protection against foreign material "shorting-out" the flange.

Type "F" Gaskets are made to fit within the bolt hole circle of the flange. The O.D. of the gasket extends out to the I.D. of the bolt hole circle for good protection against foreign material "shorting-out" the flange. When configured as a LineBacker® Sealing Gasket, the sealing element may be positioned anywhere between the I.D. and O.D. of the gasket

Type "E" and “F” gaskets may be ordered in any one of the following configurations:

LineBacker® Sealing Gaskets
GasketSeal® Sealing Gaskets
Rubber Faced Phenolic Gaskets
Plain Phenolic Gaskets
Red Devil Gaskets
Yellow Jacket Gaskets
Garlock Gaskets
Teflon® Gaskets

When configured as a LineBacker® Sealing Gasket, the sealing element may be positioned anywhere between the I.D. of the gasket and I.D. of the bolt circle.