The Defender™ sealing/isolating gasket system is designed for critical/extreme applications. Manufactured with a 316 stainless steel core retainer and laminated on both sides with high strength laminates,gaskets150100 the Defender™ gasket is resistant to deforming under load and is used when electrical isolation and corrosion control are required on pipes containing gas, natural gas, oil and other hydrocarbon based medias up to 392ºF (200ºC). Available for flat face, raised face and ring type joint flanges from 1/2" to 36", ANSI 150-2500# and API 2-10K, the Defender™ gasket is an engineered solution for trouble-free operation that eliminates costly leaks and provides a solution for fugitive emissions. It is manufactured with an innovative industry first Press-n-Lock™ "Glue-Less Seal & Groove Technology" that combines a press-in, pressure activated and spring energized seal with a unique groove that retains the seal element without the use of glue on key contact surfaces! The Press-n-Lock feature provides a higher confidence in sealing.

gasketLogo150100 dateStamp150100 partNumberStamp150100 Defender Gaskets are laser engraved with company name/logo, date of manufacture, and product description/part number.

The flange face makes initial contact with the sealing element which protrudes above the gasket retainer surface (isolation material) laminated on both sides of the stainless steel core.


The spring energized, pressure activated sealing system is initiated. The base of the Teflon® seal is contained within the stainless steel core to provide superior sealing strength for critical/extreme sealing applications. The spring prevents over-compression of the Teflon® seal thereby allowing the pressure of the media within the pipe to activate the seal. G10 or G11, laminated on both sides, provides the dielectric strength needed to isolate the flange application and has the compressive strength to easily withstand high bolt loads.

Retainer Materials (G10S, G11S)

  • 1/4" (0.250") total thickness
  • Metal Core 0.120" thick = 316SS
  • Laminate 0.065" per side

Gasket/Retainer Material Specifications






Dielectric Strength Volts/Mil Short Time




Compressive Strength (psi)




Water Absorption (%)




Flexural Strength (psi)




IZOD Impact Strength (Ft-lbs/Inch




Tensile Strength (psi)




Bond Strength (lb)




Temperature - Operating

Cryogenic -238°F (-150°C) to +302°F (+150°C)

-100°F (-73°C) to +392°F (+200°C)

NOTE: Operating Temperature for Gaskets and Flange Isolation Kits is based off the Gasket Retainer Temperature. Seal element temperature does not dictate the min. and max. gasket operating temperature.

Seal Element Materials

  • PTFE (Teflon®) Spring Energized. Spring is Stainless Steel
  • Nitrile
  • Viton®

Seal Element Material Specifications

Sealing Element

Temperature - Operating


Cryogenic to +525°F (+274°C)


-40°F (-40°C) to +250°F (+121°C)


-20°F (-29°C) to 392°F (+200°C)

Configurations for Gasket Type and Sleeve and Washer Sets

Type "E" Gasket
Fits over the bolt holes and extends to the O.D. of the flange to assist contractors as the bolt holes automatically center the gasket. Provides excellent protection against shorting out of the corrosion mitigation hardware.

Type "F" Gasket
Fits within the bolt hole circle of the flange and extends to the I.D. of the bolt circle providing good protection against shorting out of the corrosion mitigation hardware.


"E" or "F" Type Gaskets
In general, 99% of Steel Core Gasket Applications are type "F", no bolt holes. The Defender gasket is also available in a Type "E" configuration.

Single Washer Set
One isolation sleeve, one steel washer and one insulating washer for each stud/bolt.

Double Washer Set
One isolation sleeve, two steel washers and two insulating washers for each stud/bolt.

Suggested Sleeve/Washer Set

SD = Standard (G10 Sleeves, Steel Zp Washers and G10 Washers) - Double Washer Set

Other information

Lamons CoreGuart Gasket


  • Seals/isolates pressure ratings through ANSI 2500 and API 10,000 psi service.
  • Spring energized seal element.
  • Press-n-Lock™ "Glue-Less Seal Groove Technology".


Defender gaskets were engineered for extreme, high reliability sealing and electrical isolation critical service applications.

  • High Pressure Flanges: 2500# or API 10K.
  • Critical/Extreme service.
  • High Ph service.
  • pS/CO2 service.
  • Locations where end users prefer an integral seal element.


  • Ethanol
  • Ethylene
  • Fuel Oil
  • Natural Gas
  • Sour Gas
  • Gasoline
  • Crude Oil
  • Propane
  • Nitrogen
  • Butane
  • Diesel
  • Methane
  • Hydrocarbons
  • Hydrogen Sulfide
  • Carbon Dioxide


  • Oil
  • Gas

Production Fields, Petroleum Marketing Facilities, LNG/SNG Systems, Pipeline and Distribution Piping, Refineries


"Proven design based on the industry leader."
"Enhanced with innovative engineered features."
"Tested to Shell Certification Standards."

"Industry First! The Press-n-Lock™ "glue-less seal & groove technology", an engineered Lamons design, has significant sealing advantages vs. other brands."

General Installation Tips

  1. Always use proper safety equipment.
  2. Installation should be done with a torque wrench or stud tension measuring device.
  3. Lamons packaged product to inspect and determine that components are as specified.
  4. Flanges shall be free of pits, gouges, rust, debris, oil and grease. Surface finish shall be no greater than 250 RMS.
  5. Check bolts and nuts to ensure they are clean.