Product Catalog

GPT Linebacker® Sealing/Isolating System

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GPT Linebacker Sealing with isolation 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.

LineBacker® sealing gaskets utilize a rectangular sealing element, referred to as a "quad" ring, in combination with a unique groove design to effectively seal and isolate flanges of all types. With the unique "quad" ring design, elastic memory is provided for elastomers not normally associated with this characteristic. Materials such as AFLAS, TFE (Teflon) and KALREZ may therefore be used as sealing elements which dramatically increases the options available for matching gasket materials to service and environmental conditions. This greater variety of materials also provides excellent temperature and chemical range compatibility. LineBacker® sealing gaskets are self energizing with theoretical near zero "m" and "y" factors resulting in effecting a positive seal without excessive bolt loads required with flat gaskets.

Before Tightening

The flange faces come into contact with the sealing elements, which extend slightly above the surface of the retainer. As the flange is tightened the sealing elements are compressed and move sideways into the inclined portion of the groove, developing a high unit pressure against the flange faces.

After Tightening

The flange faces have come into firm contact with the retainer, thus encapsulating the sealing elements within grooves. At the same time, the unique LineBacker seal configuration provides elastic memory for elastomers not normally associated with this characteristic - resulting in a simple flat gasket with extremely high loading and self energizing characteristics without adverse cold flow problems.

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.

Type F Gasket

The gasket retainer extends out to the I.D. of the bolt circle.

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 applications, 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 washers

  • 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 the relatively low compressive strength of this 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.


  • Eliminates Flange Leaks.

  • Guards against blowouts.

  • Protects against fire and hostile environments.

  • Usable with any type of flange.

  • Matches gasket materials to service conditions.

  • Lowest possible clamp and compressive load.

  • Increases gasket life.

  • Insulating version is both a positive seal and a superior insulator.


  • All standard ANSI and API flange sizes from 1/2" and above.

  • Custom odd sizes and shapes.

Pressure Ratings

  • All ANSI and API rated flanges.

  • Pressures from hard vacuum to 50,000 psi and higher