ASTM C591-22 PDF

Full title and description

ASTM C591-22 — Standard Specification for Unfaced Preformed Rigid Cellular Polyisocyanurate Thermal Insulation. This material specification covers unfaced, preformed rigid cellular polyurethane-modified polyisocyanurate insulation supplied as buns, boards, or blocks for thermal insulation applications over a wide temperature range. It defines types, grades, physical properties, dimensional requirements, and required test methods for performance verification.

Abstract

ASTM C591-22 specifies physical, dimensional, and performance requirements for unfaced, preformed rigid cellular polyisocyanurate thermal insulation manufactured using blowing agents with zero ozone-depletion potential (ODP = 0). The standard classifies material by compressive resistance and service temperature grade, and references test methods for density, compressive strength, thermal conductivity, hot-surface performance, water absorption, dimensional stability, closed-cell content, tensile strength, and extractable ion content.

General information

• Status: Active
• Publication date: December 1, 2022 (approved 2022 edition, commonly referenced as C591-22)
• Publisher: ASTM International
• ICS / categories: 83.100 (Cellular materials); 91.100.60 (Thermal and sound insulating materials)
• Edition / version: C591-22
• Number of pages: 10

Scope

This specification covers unfaced, preformed rigid cellular polyurethane-modified polyisocyanurate thermal insulation intended for use on surfaces over a wide service temperature range (typical text covers roughly –297°F/–183°C up to about 300°F/149°C, with specific limits to be agreed between manufacturer and purchaser). It applies to material produced in bun, board, or block form and addresses classification by compressive resistance (multiple Types) and by service-temperature Grade. The standard is a material specification and is not a design document; fire performance and installation requirements may be governed by codes or separate project specifications.

Key topics and requirements

• Classification by Type (compressive resistance categories) and by Grade (service temperature ranges).
• Physical property requirements: apparent thermal conductivity (k or λ), density, compressive strength, tensile strength.
• Durability/performance tests: hot-surface performance, dimensional stability, water absorption, water-vapor permeability, closed-cell content, and surface bearing characteristics.
• Limits on extractable ions (leachable chloride, fluoride, silicate, sodium) where specified for certain applications.
• Application of referenced ASTM test methods (e.g., C165, C177, C303, C272/C272M, C303, C335 where applicable) for verification.
• Requirement that blowing agents used have ozone-depletion potential of zero (ODP = 0).
• Guidance that additional low-temperature performance criteria must be agreed for service below –70°F (–51°C).

Typical use and users

Used by insulation manufacturers, specification writers, mechanical and piping engineers, building-envelope designers, contractors, and purchasers specifying rigid polyisocyanurate insulation for industrial, commercial, and cryogenic or elevated-temperature service. Typical applications include pipe and equipment insulation, tank and vessel insulation, and thermal insulation in industrial process systems where unfaced rigid boards or blocks are appropriate.

Related standards

ASTM C591 commonly references and is used alongside ASTM test methods and standards such as C165 (compressive properties), C177 (guarded-hot-plate thermal measurements), C272/C272M (water absorption), C303 (dimensions and density of preformed block/board), C335 (pipe insulation heat transfer), and related material or installation practices and classifications in Committee C16 publications.

Keywords

polyisocyanurate, rigid cellular, unfaced insulation, thermal insulation, polyisocyanurate board, compressive strength, water absorption, thermal conductivity, closed-cell, ODP 0

FAQ

Q: What is this standard?

A: ASTM C591-22 is a material specification for unfaced, preformed rigid cellular polyurethane-modified polyisocyanurate thermal insulation (the 2022 edition identified as C591-22).

Q: What does it cover?

A: It covers types, grades, dimensional and physical property requirements, and required test methods for unfaced rigid polyisocyanurate insulation supplied as buns, boards, or blocks. It also specifies limits and test procedures for thermal performance, mechanical strength, moisture behavior, and certain extractable ions.

Q: Who typically uses it?

A: Insulation manufacturers, specifiers, engineers, contractors, and purchasers who select or supply unfaced rigid polyisocyanurate insulation for industrial, commercial, and specialized temperature-range applications.

Q: Is it current or superseded?

A: The 2022 edition (C591-22) is the current published edition (approved in 2022). Users should confirm they are referencing the latest edition or any amendments for contract or regulatory use.

Q: Is it part of a series?

A: It is maintained under ASTM Committee C16 (Thermal Insulation) and is related to other C16 standards and test methods; it forms part of the body of material and test standards used for thermal insulation products rather than a numbered subsection series.

Q: What are the key keywords?

A: Polyisocyanurate, rigid cellular, unfaced, thermal insulation, insulation board, compressive resistance, hot-surface performance, closed-cell content, water absorption, ODP 0.