ISO 2477:2005

Overview

ISO 2477:2005 specifies a standardized test method for determining the permanent change in dimensions on heating of shaped insulating refractory products. The procedure measures the residual dimensional change (shrinkage or expansion) when a shaped insulating refractory is heated in an oxidizing furnace to a prescribed temperature, held for a specified period, then cooled to ambient temperature. This method supports product quality control and material characterization for high-temperature insulating refractories.

Key Topics and Requirements

• Scope: Applies to shaped insulating refractory products (absolute porosity ≥ 45 % as per ISO 5016).
• Test principle: Cut rectangular prism specimens from bricks, dry to constant mass, measure pre‑ and post‑heat dimensions, and calculate permanent linear change as a percentage of initial length.
• Specimen preparation: Typical prism sizes: 100 × 114 × 76 mm or 100 × 114 × 64 mm; when full size is not possible, cut 100 mm length and record other dimensions.
• Measurement accuracy: Measuring instruments should be capable of 0.1 mm resolution (examples: calipers, dial gauges); measurements for the procedure are recorded to 0.2 mm.
• Furnace and atmosphere: Use an oxidizing atmosphere; electric furnaces recommended (gas allowed if oxygen content is monitored).
• Temperature control and monitoring: At least three thermocouples distributed above the specimen zone; temperature uniformity within ±10 °C; continuous recording of temperature/time.
• Heating programme: Prescribed ramp rates depending on target temperature (examples provided for ≤1250 °C, >1250 °C and gas furnaces up to ≥1500 °C). Special limitation for siliceous insulating products: rate to 500 °C should not exceed 1 °C/min to avoid cracking.
• Soak time: Maintain test temperature (average of thermocouples) within ±10 °C for 12 hours.
• Reporting: Includes specimen ID, furnace type, oxygen content (if relevant), heating cycle, nominal and actual temperatures, measured dimensional changes (four points per specimen), appearance, test deviations and anomalies.

Applications and Users

Who uses ISO 2477:2005:

• Refractory manufacturers for quality control and batch acceptance
• Material testing laboratories performing dimensional stability tests
• R&D and product development teams assessing thermal performance
• End-users and specifiers (steel, glass, ceramics, petrochemical, heat‑treating industries) for material selection and supplier verification
• Procurement and compliance teams to confirm conformity with contractual requirements

Practical benefits include reliable comparison of thermal stability, detection of unacceptable shrinkage/expansion, and improved specification of insulating refractory products for high‑temperature service.

Related Standards

• ISO 5016 - Determination of apparent density and true porosity (referenced)
• ISO 5022 - Sampling and acceptance control for shaped refractories
• ISO 5019-1 - Dimensions of rectangular refractory bricks
• ISO 836 - Terminology for refractory materials
• EN 1094-6 - Related European method (ISO 2477:2005 aligned to EN 1094-6)