Technical data · STB-1 Cryogenic Insulator

G10 Cryogenic Insulator Specifications

STB-1 Cryogenic Insulator is a load-bearing thermal and electrical isolator rated from −270 °C (−454 °F) to 135 °C (275 °F) continuous service. It is the same thermoset, glass-reinforced epoxy composite as Benchmark’s STB-1 Structural Thermal Break, qualified here for cryogenic supports and isolation, and is used as an alternative to G10 Micarta insulation blocks.

Material: thermoset, reinforced epoxy composite, manufactured by Benchmark
Load capacity: compressive strength of 48,000 psi (330.9 MPa) with little to no deflection and limited creep under load
Isolation: conducts heat more than 1,300 times less than aluminum, more than 350 times less than steel and more than 100 times less than stainless steel; dielectric strength of 500 VPM
Thicknesses: 1/4″, 1/2″, 3/4″, 1″ and 2″ (6.4, 12.7, 19.1, 25.4 and 50.8 mm), supplied as sheet or cut to size
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Thermal Performance

STB-1 Cryogenic Insulator holds its structural and electrical properties from near absolute zero up to 135 °C continuous.

Thermal metric	Specification value	Notes
Minimum operating temperature	−270 °C (−454 °F)	Near absolute zero; retains its physical properties at cryogenic levels
Max continuous operating temperature	135 °C (275 °F)	Safe limit for long-term structural and electrical insulation service
Glass transition temperature (Tg)	~130 °C to 140 °C (266 °F to 284 °F)	Typical threshold where the epoxy matrix begins to soften
Short-term excursion max	Up to 180 °C (356 °F)	Intermittent, brief exposures without immediate severe degradation
Thermal conductivity, ASTM C518	1.055 BTU·in/hr·ft²·°F	Nominal, at room temperature
Coefficient of thermal expansion, ASTM D696	2.2 × 10⁻⁵ in/in/°C	Nominal, at room temperature

Mechanical Properties

All values are nominal, tested at room temperature.

Property	Test method	Value
Compressive strength	ASTM D695	48,000 psi (330.9 MPa)
Compressive modulus, 1″ (25.4 mm) thick	ASTM D695	400,671 psi
Shear strength	ASTM D732	16,326 psi
Flexural strength	ASTM D790	25,000 psi (172.4 MPa)
Modulus of elasticity in flexure	ASTM D790	1.6 × 10⁶ psi
Tensile strength	ASTM D638	11,000 psi (75.8 MPa)
Impact strength, Izod edgewise	ASTM D256	8.5 ft·lb/in notch
Bond strength, 1/2″ thick	ASTM D229	1,200 psi
Barcol hardness	Barcol scale	48
Water absorption	ASTM D229	0.35 %
Density	—	115 lb/ft³ (1,842 kg/m³)

Fire Properties

Property	Test method	Value
Flame spread	ASTM E84	25
Smoke developed	ASTM E84	120
Heat release rate	ASTM E1354	1.5 kW/ft²
Oxygen index	ASTM D2863	21.8 % O₂
UL flammability	UL 94	Class HB
Ignition time	ASTM D229	103 s
Burning time	ASTM D229	211 s

Electrical Properties

Property	Test method	Value
Dielectric strength, short time in oil, 1/16″	ASTM D149	500 VPM
Dielectric strength, parallel, step-by-step in oil	ASTM D149	60.0 kV
Arc resistance	ASTM D495	150 s
Dielectric constant @ 60 Hz	ASTM D150	4.8
Dissipation factor @ 60 Hz	ASTM D150	0.02

Notes and Limitations

Mechanical, fire and electrical values are room-temperature results; they do not state strength or conductivity at cryogenic temperature.
Do not exceed 135 °C (275 °F) in continuous service; above the glass transition range of ~130–140 °C the epoxy matrix begins to soften.
Account for differential thermal contraction between the insulator (2.2 × 10⁻⁵ in/in/°C) and adjoining steel in bolted joints.
Values are nominal and subject to change; confirm current data with Benchmark before final design.

Writing a specification? Use our cryogenic insulator guide specification. Designing cold shoes? See cryogenic pipe support insulation.

Request a Quote

Send your drawings, operating temperature and design loads to sales@bmssi.ca or call 800-580-4195. We cut and drill every cryogenic isolation pad in house and quote quickly.