PSI LineBacker® Sealing and Isolating Gasket

PSI LineBacker® Sealing and Isolating Gasket

Linebacker Gasket Seal and Isolator


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.

Benefits, Features, Sizes, and Ratings

Benefits and Features

  • 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 isolator.


  • 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.

Available Options

Aluminum Ceramic Buna-N(Nitrile)
Brass Epoxy Glass Buna-S
Carpenter 20 Glass Butyl
Carbon Steel Lucite EPDM
Cast Iron Melamine Hypolon
Clad Steel Materials Phenolic Kel-F
Copper Polyester Glass Natural Rubbers
Ductile Iron Polyethylene Neoprene
Hastelloy B Polyphenol Ether Nylon
Hastelloy C Pyrox Polimide
Hastelloy X Silicone Glass Polyurethane
Inconel X Vinl Silicone Rubber
Monel Teflon®
Nickel 200 Vinyl
Soft Iron Viton®
Stainless Steel

How The Seal Functions

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.
Linebacker Gasket Seal and Isolator
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.
Linebacker Gasket Seal and Isolator
Linebacker Gasket Type E Linebacker Gasket Type F
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.

LineSeal Gasket Seal and Isolator

Physical Properties of Retainer for
Common LineSeal™ Sealing Gasket
D149 Dielectric Strength
Volts/Mil (Short Term)
D695 Compressive Strength
D229 Water Absorption
D257 Insulating Resistance
Meg Ohms
D790 Flexural Strength
D256 IZOD Impact Strength
(Ft. Lbs./In.)
D638 Tensile Strength
D732 Shear Strength
Temperature Range
Cryogenic to +302°F Cryogenic to +150°C
Seal Element Temperature Range PTFE (Teflon)
Cryogenic to +450°F Cryogenic to +232°C
Seal Element Temperature Range Vitron
-20 to +350°F -29 to +177°C

LinkSeal™ Test Results
TEST LinkSeal™
Compression Test
EN 13555 @150®
140 Mpa Gasket Stress
Creep Relaxation
EN 13555 @150®
Leakage Test
EN 13555 @ 40 bar Helium
@5Mpa to 80 Mpa gasket stress
0.99 Relaxation Factor
Hot Blowout Test
HOBT@151®C @ 165 bar
No Blowout
Shell Leakage Test
T-2.232686 @ ambient @ 52Mpa
4.2 X 10-7 pa-m3/s/mm
Shell Cycle Test
T-2.232686 @ 150® @ 45.6Mpa
<0.10 bar pressure loss

Suggested Sealing Gasket Material Compatibility
Medium Retainer Seal Temp. Range °F Temp. Range °C
Carbon Dioxide G-10 Teflon -65 to +250 -54 to +121
Vitron -20 to +280 -29 to +138
Diesel Fuel G-10 Teflon -65 to +250 -54 to +121
Vitron -20 to +280 -29 to +138
Ethanol G-10 Teflon -65 to +250 -54 to +121
Vitron -20 to +280 -29 to +138
Fuel Oil G-10 Teflon -65 to +250 -54 to +121
Vitron -20 to +280 -29 to +138
H2S G-10 Teflon -65 to +250 -54 to +121
Gas, Natural G-10 Teflon -65 to +250 -54 to +121
Vitron -20 to +280 -29 to +138
Gas, Sweet G-10
Vitron -20 to +220 -29 to +138
Gas, Sour CO2 Mix G-10 Teflon -65 to +250 -54 to +121
Jet Fuel G-10 Teflon -65 to +250 -54 to +121
Vitron -20 to +280 -29 to +138
Nitrogen G-10 Teflon -65 to +250 -54 to +121
Vitron -20 to +280 -29 to +138
Oil, Crude G-10 Teflon -65 to +250 -54 to +121
Vitron -20 to +280 -29 to +138
Propane G-10 Teflon -65 to +250 -54 to +121
Vitron -20 to +280 -29 to +138
Propylene G-10
Vitron -20 to +80 -29 to +27
Sewage G-10 Teflon -65 to +250 -54 to +121
Vitron -20 to +280 -29 to +138
Water (Hot) G-10 Teflon -65 to +250 -54 to +121
Vitron -20 to +280 -29 to +138
Water (Sea) G-10 Teflon -65 to +250 -54 to +121
Vitron -20 to +280 -29 to +138
General Notes:
The foregoing performance data are intended as guidelines only.
Performance suitability for any specific applications should be determined by the user.
Variation in temperature, pressure, concentration or mixtures acting
synergistically may preclude suggested service use.
Material selection is at the sole risk of the user.
Consult with a specialist or PSI factory for specific applications.
PSI’s responsibilities will be limited to those listed
in the PSI standard warranties.

LineSeal Gasket Seal and Isolator

How to Order

To order LineSeal™ Sealing/Isolating Gaskets please indicate the following:

  1. Quantity
  2. Nominal Pipe Size
  3. Pressure Rating
  4. Gasket Type: E or F
  5. Gasket Style: LineSeal™
  6. Retainer Material
  7. Sealing Element
  8. Weld neck or slip-on application
  9. Note all special requirements.


Manufacturer’s warranty statement will be supplied upon request to Allied Corrosion Industries, Inc.

Typical Specifications

All Critical Service Applications
Materials for sealing gaskets on pipes containing water, aqueous fluids, oil, sour or natural gas (up to 302®F, 150®C) shall consist of the following components:

Isolating and Sealing Gasket
One isolating and sealing gasket, LineSeal Type “F”, 0.27 inch thick, 316 stainless steel core retainer laminated on both sides with a G-10 fiber glass reinforced laminate containing a precision tapered groove to accommodate the controlled compression of a PTFE(Teflon) spring energized seal. Sealing element placement shall accommodate either flat, raised or RTJ face flanges. The spring energized seal shall be pressure energized. The G-10 retainer shall have a 800 volts/mil dielectric strength and a minimum 69,000 psi compressive strength. The I.D. of the flange isolating gasket shall match the bore of the flange in which it is installed.

Gaskets shall be manufactured at a facility that has a registered ISO 9001:2008 Quality Management System.

Submittals shall include copy of valid registration. Performance suitability and material compatibility shall be determined by the user.

Gaskets shall be manufactured by PSI-Pipeline Seal and Insulator, Inc., Houston, Texas, U.S.A.
Telephone: 713-747-6948
Facsimile: 713-747-6029
Alternate products should be submitted to an engineer 10 days prior to bid due date.

Sealing and Isolating Gaskets

Two of PSI’s premier sealing gaskets are available with isolating retainers. Both LineBacker? and GasketSeal? gaskets may be ordered with isolating retainers to match your application. In addition, you may choose from a wide variety of sealing elements so your completed gasket will consist of a combination of the best materials to seal the flange and maintain that seal for the life of the piping system.

PSI LineBacker® Sealing and Isolating Gasket

PSI LineBacker® Sealing and Isolating Gasket

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