For specifiers and engineers

Micarta Guide Specification

A three-part guide specification for glass-epoxy Micarta pads, insulation blocks, washers and sleeves used as load-bearing thermal and electrical insulators, written around STB-1. Copy it into your project manual and edit the lists to suit the project.

Part 1 — General

Section includes: load-bearing glass-epoxy laminate insulators at pipe supports and shoes; equipment, tank and vessel supports; structural steel connections through the building envelope; and bolted joints requiring insulating washers and sleeves.
Related sections: pipe supports, structural steel, mechanical equipment, electrical equipment supports and insulation, as applicable.
Reference standards: ASTM C518, D149, D150, D229, D256, D495, D638, D695, D696, D732, D790, D2863, E84 and E1354; UL 94.
Submittals: product data with the properties in Part 2; shop drawings showing pad and block sizes, thicknesses, hole locations and washer and sleeve dimensions; samples on request.
Design: the supplier provides material properties for use in the connection and support calculations. Calculations confirm that the insulator does not crush, deflect or creep at the design load over the full service temperature range.
Delivery and storage: deliver in original packaging, labelled with product and thickness; store flat, dry and off the ground.

Part 2 — Products

Manufacturer: Benchmark Site Services, bmssi.ca.
Product: STB-1, thermoset glass-reinforced epoxy laminate.
Service temperature: −270 °C (−454 °F) to 135 °C (275 °F) continuous; brief excursions to 180 °C (356 °F).
Compressive strength, ASTM D695: 48,000 psi. Compressive modulus, ASTM D695 (1″ thick): 400,671 psi.
Shear strength, ASTM D732: 16,326 psi.
Thermal conductivity, ASTM C518: 1.055 BTU·in/hr·ft²·°F.
Dielectric strength, ASTM D149: 500 VPM. Arc resistance, ASTM D495: 150 s.
Water absorption, ASTM D229: 0.35 %.
Surface burning, ASTM E84: flame spread 25, smoke developed 120.
Thickness: 1/4″, 1/2″, 3/4″, 1″ or 2″ as scheduled. Washers and sleeves sized to suit bolt diameter and grip.

Part 3 — Execution

Install pads and blocks on clean, flat, dry bearing surfaces with full contact across the bearing area.
Cut or drill in the field only with carbide tooling; seal cut edges where specified.
Install insulating sleeves and washers so that no bolt contacts both sides of the joint.
Tighten bolts to the torque shown on the approved shop drawings.
Where electrical isolation is specified, test the joint for isolation after tightening.

Property tables are on the Micarta specifications page.

Need Help With Your Spec?

Email sales@bmssi.ca or call 800-580-4195 and we will help you set thicknesses, washer sizes and submittal requirements.