ISOMAX HPS Flange Insulation Set

The HPS is a high strength and high reliability flange gasket designed for electrical insulation and sealing in very critical service applications. The gasket is manufactured using a composite seal retainer material bonded to a high integrity metal core, 316 Stainless Steel is standard. The spring energized PTFE seal offers excellent sealability even at low loads.

  • The HPS gasket is a high reliability gasket used for both insulating and general sealing application.
  • The HPS is suitable in all services up to and includingANSI 2500# and API 15,000# classes.
  • Each HPS insulation set comprises one central insulating gasket, one insulation sleeve per bolt and two insulating and two plated steel washers per bolt.


  • Metallic Core: 316 Stainless Steel
  • (Duplex & Inconel available)
  • Gasket Insulating Material: G-10 Glass Reinforced Epoxy (GRE) as standard (G-11 available)
  • Seal Material: Spring-energized PTFE as standard
  • (Viton available)
  • Insulating Sleeve Material: GRE as standard
  • (Mylar available)
  • Insulating Washers Material GRE (standard)
  • Steel Washer Material Zinc Plated Steel as standard
  • (stainless steel available).

General Characteristics

  • Flange insulation as well as cathodic protection
  • Reduces galvanic corrosion in dissimilar metal materials used in flange joints
  • Allows mismatched ring-joint to raised-face flanges to be effectively sealed. HPS will seal in ring joint, raised-face and flat face/slip-on flange applications.
  • Will withstand corrosive environments including high CO2, H2S and processed water.
  • The bore construction protects flange faces
    from media-induced corrosion and flow-induced erosion.
  • The pressure energised seal allows for reduced flange assembly stress.
  • Easy to install and remove.
  • Reusable seal retainer and seals
  • Suitable for all ANSI and API rated flanges
  • High strength laminate material reduces failure due to over compression

HPS Design

The design of the HPS gaskets incorporates a high-strength reinforced epoxy laminate bonded to a 316 stainlesssteel core as standard (other core materials available). This design results in the gasket having the strength of a traditional metallic gasket while at the same time allowing complete electrical insulation between the flange faces.
PTFE Spring-energised seals are installed into machined grooves to provide a pressure-activated sealing system that allows the HPS to be used as a high pressure insulating gasket.
(Viton o-rings also available if specified)

Electrical Insulation

The HPS distinguishes itself by providing electrical flange insulation in a high-strength gasket.
The HPS significantly reduces the potential for electrical conductivity between two flange faces by providing a non-conducting, non-metallic interface.
This eliminates potential corrosion resulting from dissimilar metals making contact or from ground induced current corrosion of metal components in pipeline systems.
The HPS is an effective sealing system used in breaking electrical conductivity in piping systems with cathodic protection.
The HPS’s steel core and construction enables the gasket to withstand higher system pressure, pressure cycling, over torquing than conventional insulating gaskets.

Sealing raised face to Ring Joint flanges

The positioning of the sealing elements of the HPS gasket are designed to fit Raised Face, Flat Face and Ring Type Joint flanges. Because of this design we are able to replace the old design of Phenolic RTJ gaskets commonly designated Type “D-Ring Joint Gasket” which
were limited in their ability to take high stresses or excessive bolt loads which often resulted in gasket fracture, damage or failure in service with the ISOMAX HPS.


Because the HPS uses pressure-activated sealing elements which are designed to sit inside the ring groove on RTJ flanges it has the additional advantage of allowing the HPS to seal mismatched RTJ to raised face or flat faced flanges. This can be of great benefit to the customer when replacing flanges or valves using current stock inventory that may have a different flange face than the mating flanges in situ.

HPS Flange Insulation Kit Components
The gasket set comprises the following as listed below:

Insulation Kit Contents:

Insulating facing:

G-10 glass reinforced epoxy resin standard. G11 also available on request.


Spring energised PTFE (Viton also available)


Stainless steel 316

Standard Thickness:

7.0 mm.

Insulating Washers:

G-10 glass reinforced epoxy resin (other materials are available)
3.2mm thickness


2 washers per bolt

Steel Washers:

Zinc-plated steel,
3.2mm thickness (stainless steel washers also available)


2 washers per bolt

Insulating Sleeves:

G-10 glass reinforced epoxy resin.


(Mylar and Nomex also available)


1 insulating sleeve per bolt

Insulation Kit Properties

Material type:

G-10 Glass-reinforced epoxy resin

G-11 High temperature resin

Compressive strength:

50,000psi – minimum

50,000psi – minimum

Dielectric strength:

24.1-31.5 kV/mm

24.0 kV/mm

Maximum temp:



Water absorption:

0.1% – maximum

0.1% – maximum

Flexural strength:



Tensile strength:



Temperature range:

– 130°C to 150°C
(limited by gasket material)

– 46°C to 200°C
(limited by gasket material)


Spring-energised PTFE (Viton rubber also available)