ASTM C591-22 PDF

Overview

ASTM C591-22, published by ASTM International, specifies the requirements for unfaced preformed rigid cellular polyisocyanurate thermal insulation. This standard covers the types, physical properties, and dimensional tolerances for this insulation material, which is commonly used for thermal insulation on various surfaces operating in temperature ranges from –297°F (–183°C) up to 300°F (149°C). The specification primarily addresses properties relevant to material performance, quality assurance, and product classification. The material is manufactured using polymeric polyisocyanurate, ensuring it has a zero ozone depletion potential (ODP).

Key Topics

• Material Types & Classification: Polyisocyanurate insulation under this standard is classified into six types according to compressive resistance (Types I, IV, II, III, V, VI). Each type is defined by minimum density and strength requirements, ensuring suitability for specific loads and applications.

• Physical Properties & Performance: The specification establishes requirements for:

  • Density and Compressive Strength
  • Apparent Thermal Conductivity
  • Water Absorption
  • Water Vapor Permeability
  • Dimensional Stability
  • Closed-Cell Content
  • Hot-Surface Performance

• Service Temperature: The covered grade (Grade 2) is suitable for service temperatures between –297°F (–183°C) and 300°F (149°C). Applications requiring performance outside this temperature range should be negotiated with the manufacturer.

• Fabrication and Tolerances: Polyisocyanurate insulation is supplied in large "bun" forms. Fabricators cut the buns to produce boards, pipe shells, or custom shapes. Dimensional tolerances for length, width, thickness, edge trueness, and squareness are defined to ensure fit and thermal performance.

• Testing and Quality Assurance: The standard references numerous ASTM test methods to verify required properties, including ASTM C165 (compressive properties), ASTM C177 (thermal conductivity), and ASTM D1622 (density measurement).

• Fire and Safety Considerations: The material is combustible and not to be installed near flames. Compliance with building codes and fire safety regulations is essential. Fire performance is addressed by additional project or regulatory specifications as required.

• Environmental Responsibility: Only blowing agents with ODP 0 may be used in manufacturing, supporting compliance with environmental and sustainability directives.

Applications

ASTM C591-22 polyisocyanurate thermal insulation is widely used in industrial, commercial, and building construction sectors. Typical applications include:

• Insulation for piping, ducts, tanks, and vessels in power plants and chemical processing facilities
• Building envelope insulation for walls, roofs, and floors
• Refrigeration equipment and cold storage units
• Insulation for process equipment exposed to cryogenic or high-temperature conditions

This standard supports the selection of high-performance, durable insulation products for energy efficiency, condensation control, and process stability.

Related Standards

To ensure comprehensive quality and compatibility, ASTM C591-22 cites and should be used in conjunction with several other ASTM standards, including:

• ASTM C168 - Terminology Relating to Thermal Insulation
• ASTM D1622 - Test Method for Density of Rigid Cellular Plastics
• ASTM C177 & C518 - Test Methods for Thermal Transmission Properties
• ASTM C585 - Dimensional Practices for Pipe and Tubing Insulation
• ASTM C411 - Test Method for Hot-Surface Performance
• ASTM E96 - Water Vapor Transmission Rate Testing
• ASTM C390 - Sampling and Acceptance

Users should refer to these and related standards for guidance on testing procedures, installation, and long-term product performance.

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