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Thermal Grade Glass Polyester

Peerless Hi-Temp fabricates products from a variety of thermal grade glass polyester materials for OEM equipment builders, general contractors, architects, and end users. Let us know your specifications, including thickness and surface area, and we’ll help you choose the best material to use for your application.


GlasGuard Grade 1130 is a fiberglass-reinforced thermoset polyester composite system which is available as sheet stock or in a variety of pultruded shapes. Grade 1130 was developed to meet the challenging requirements of the New York City Transit Authority. It has been pultruded into channel-shaped covers for the electrified third rail; and molded in flat panels for both a sign material and for switchgear components. Grade 1130 is approved against NYCTA Specifications 62, 64 and 65.


Glastherm heat insulation systems are specially designed for when plant components need to be thermally insulated for operational or economic reasons. The glass-fibre reinforced composite material is extremely strong, resistant to high temperatures and boasts a long service life. Given these exceptional properties, Glastherm is advantageous in terms of economic efficiency and process engineering.

Key Products

GlasGuard Grade 1130

GlasGuard 1130 is a low toxicity polyester sheet.

Application – Developed for the NYC transit authority for third-rail covers, sign material and switchgear components. 

Characteristics – Flame and corrosion resistant, dielectric properties, meets NEMA criteria for grade GPO-3.

Sheet Size – 3′ x 6′; 4′ x 8′ 

Water Absorption – .1% by weight

Operating Temperature –  130°C

Flexural Strength – @130°F = 11.3 psi

Arc Resistance – 192 seconds

Manufacturer – Rochling

Glastherm Grade HT200

Glastherm HT200 is a thermal insulating sheet with superior strength and heat resistance with continuous use temperatures to 550°F.

Application – Mold bases or platen press insulation

Characteristics – Resists the effects of molding pressure. Resistant to oil and water absorption. Asbestos free.

Sheet Size – 36” x 48” and 48” x 96” sheets 1/4” to 1” thick.

Thickness tolerance – ± .002 in.

Density – 1.23

Operating temperature – 550°F

Compressive Strength – 49,000psi @ 75°F; 18,000psi @ 392°F; 17,500 @ 425°F

Thermal conductivity – 1.90

Manufacturer – Rochling

Glastherm HT220

Glastherm HT220 is a thermal insulating sheet with use to 550°F.

Application – Molds

Characteristics – Heat resistant, compressive strength, low thermal conductivity

Sheet Size – 4′ x 8′

Thickness tolerance – +/-.004

Operating temperature – 600°F

Compressive Strength – 72,500 psi @ 68°F

Thermal conductivity – 1.75

Manufacturer – Rochling

Glastherm HT250

Glastherm HT250 is a thermal insulating composite sheet with use up to 550°F.

Application – Molds

Characteristics – Compressive strength, low conductivity, thermal insulation

Sheet Size – 4′ x 8′

Thickness tolerance – +/- .004

Operating temperature – Continuous > 482°F Maximum 752°F

Compressive Strength – 87,000 psi @ 68°F

Thermal conductivity – 1.45

Manufacturer – Rochling

Glastherm S

Glastherm S is a general purpose thermal insulating sheet with use to 550°F.

Application – Platens and molds

Characteristics – Compressive strength and low conductivity 

Sheet Size – 3′ x 6′; 4′ x 8′

Thickness tolerance – +/- .002

Density – 145

Operating temperature – 425°F

Compressive Strength – 45,000 psi @ 75°F

Thermal conductivity – 1.8

Manufacturer – Rochling

Durostone Glastic FHT

Durostone Glastic FHT (Flexible High Temperature) Laminate provides numerous high performance features and benefits, such as high flexibility and excellent dielectric strength at elevated temperatures.

  • Highly Flexible
  • Excellent Dielectric Strength
  • High Heat Resistance
  • Ideal For Dry-Type Transformers
  • Easily Fabricated
  • Asbestos-Free

It also exhibits the highest UL temperature index in the industry for a flexible glass-reinforced polyester in 1⁄32 inch and 1⁄16 inch thicknesses:

• 1⁄32″ – 190° C Electrical • 1⁄16″ – 200° C Electrical
• 1⁄32″ – 190° C Mechanical • 1⁄16″ – 200° C Mechanical

With its high resistance to heat, FHT Laminate offers a cost-effective alternative to aramid paper in
220°C insulation for dry-type transformers.

Manufacturer – Rochling

Durostone Glastic SG-200

Durostone Glastic SG-200 High-Strength & High-Temperature Laminate offers the same high-performance features and benefits as FHT Laminate. In addition, SG-200 offers much higher mechanical strengths than FHT with temperature ratings of up to 210° C.

Because of its capabilities, SG-200 is ideal for a wide variety of product applications requiring hightemperature NEMA GPO-1 products. Grade SG-200 is also a superior replacement material for epoxy-bonded mica in layer insulation applications. SG-200 has a UL Temperature Index of 210° C Electrical and 210° C Mechanical.
Grade SG-200 is available in thicknesses of 1⁄32″ to 2 1⁄2″. Special sheet sizes of 64″ x 64″ are
available for large lifting magnets.

  • Extremely Strong
  • Excellent Retention of Properties at Elevated Temperatures
  • Ideal For High Temperature Application
  • Easily Fabricated
  • Asbestos-Free

Application – Layer and core insulation for transformers

Characteristics – High flexibility, dielectric strength at elevated temperatures

Sheet Size – 3′ x 6′; 4′ x 8′; 1/32

Operating temperature – 410°F

Compressive Strength – 36,000 psi 

Thermal conductivity – 1.7

Arc Resistance – 139 seconds

Manufacturer – Rochling


HST-II is a high temperature polyester laminate that exhibits excellent retention of electrical and mechanical
properties at elevated temperatures.

Applications – High voltage transformers, DC motors and
elsewhere when materials with high thermal indices are required.

Characteristics – High temperature resistance with excellent retention of electrical and mechanical properties

Sheet Size – 3′ x 6′; 4′ x 6′; .032-2″ thickness

Operating temperature – 220°F

Compressive Strength – 33,000 psi 

Arc Resistance – 150 seconds

Manufacturer – Haysite Reinforced Plastics

Cogetherm M

Cogetherm M is a natural mica replacement for asbestors and other insulating boards.

Application – Forge press insulation, glass molding guides, high voltage appliance insulation, gas distribution seals, induction and arc furnace insulation. brazing insulation for aluminum and copper

Characteristics – Resistance to pressure at high temperatures, high voltage composed of Cogemica Muscovite and +/-10% bonding material.

Sheet Size – 39” x 47”

Thickness tolerance – ~+/-5% 

Operating temperature – 700°F

Compressive Strength – 400MPa

Thermal conductivity – .3 W/mK

Arc Resistance – 420 seconds

Manufacturer – COGEBI

A Comparison of Two Common Structural Insulation Options

Are you trying to select the right insulation product to use that requires strength, thermal stability, electrical insulation or machinability?

There are two popular materials being used — Transite 1000 and NAD-11. Let’s compare them and help you decide which to use.

Why Choose Peerless Hi-Temp?

As a leader in safety, Hi-Temp understands the importance of fabricating specialized insulation products and laboratory work-surfaces that meet your specifications.

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