Thermal Performance Data

Measured thermal conductivity (K-values) and thermal resistance (R-values) for all GlassRock product densities across the full service temperature range.

Understanding Thermal Data

Thermal Conductivity (K-Value)

Thermal conductivity (λ) is measured in W/m·K. A lower value indicates better insulating performance. GlassRock products are tested in accordance with ASTM C177 (guarded hot plate) and ASTM C518 (heat flow meter) methods. K-values vary with temperature and density — higher density products generally perform better at elevated temperatures, while lower density products are optimal for ambient and low-temperature applications.

Thermal Resistance (R-Value)

R-value (m²·K/W) measures resistance to heat flow and is calculated as thickness divided by thermal conductivity (t/λ). A higher R-value indicates better insulation performance for a given thickness.
All thermal data is determined at accredited testing conditions. Values shown are nominal — contact our technical team for design-specific calculations.

Stone Wool Boards — K-Values (W/m·K)

Mean Temperature D-40 kg/m³ D-60 kg/m³ D-80 kg/m³ D-100 kg/m³ D-140 kg/m³ D-200 kg/m³
10°C 0.033 0.032 0.031 0.030 0.030 0.031
50°C 0.041 0.039 0.038 0.037 0.037 0.038
100°C 0.052 0.049 0.047 0.046 0.045 0.046
200°C 0.078 0.073 0.069 0.066 0.063 0.064
300°C 0.116 0.108 0.100 0.095 0.090 0.089
400°C 0.168 0.155 0.144 0.136 0.128 0.125
500°C — — 0.202 0.190 0.178 0.172

Tested per ASTM C335 / C177 / C518. Values are nominal means — for detailed design data, request full product TDS.

Glass Wool Blankets — K-Values (W/m·K)

Mean Temperature D-10 kg/m³ D-16 kg/m³ D-24 kg/m³ D-32 kg/m³ D-48 kg/m³
10°C 0.038 0.034 0.032 0.031 0.031
25°C 0.042 0.037 0.035 0.034 0.034
50°C 0.051 0.044 0.041 0.039 0.038
100°C 0.074 0.062 0.056 0.053 0.051
150°C 0.105 0.088 0.079 0.074 0.070
200°C 0.145 0.121 0.108 0.101 0.095

Max service temperature: 300°C. Tested per ASTM C177 / C518.

Stone Wool Pipe Sections — K-Values (W/m·K)

Mean Temperature D-80 kg/m³ D-100 kg/m³ D-120 kg/m³ D-160 kg/m³
50°C 0.039 0.038 0.037 0.037
100°C 0.048 0.046 0.045 0.044
200°C 0.070 0.067 0.064 0.062
300°C 0.101 0.096 0.091 0.088
400°C 0.145 0.137 0.129 0.124
500°C 0.203 0.190 0.178 0.170
600°C 0.275 0.257 0.240 0.228

Max service temperature: 650°C (ASTM C547). Pipe section dimensions DN15–DN600.

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