Thermal insulation performance of cast-in-place foamed cement for pipeline insulation at medium and high temperatures

Traditional pipeline insulation materials, such as polyurethane and aerogel, often experience performance degradation at temperatures above 150°C, along with high costs and inadequate mechanical strength. To overcome these limitations, this study explores cast-in-place foamed cement for medium- to high-temperature pipeline insulation (75°C to 240 °C). The thermal performance was evaluated, focusing on thermal conductivity and cross-sectional heat transfer characteristics. Based on 90 test datasets, we quantified the thermal conductivity, which increased nonlinearly from 0.064 W·(m·K)−1 at 75°C to 0.209 W·(m·K)−1 at 240°C, resulting in an exponential prediction model. A strong linear relationship (R2 = 0.99331) was found between the insulation layer temperature difference ΔT and the inner wall temperature T2. Based on this relationship, a cross-sectional heat transfer linear equation was proposed to streamline engineering inspection procedures. The results confirm the exceptional thermal stability of cast-in-place foamed cement (up to 240 °C), effectively mitigating the risk of material failure in high-temperature zones such as pipeline welds. This research challenges the conventional perspective that foamed cement is limited to building insulation, offering a novel solution for industrial pipelines (e.g. petroleum, district heating). The developed models (114 mm pipeline diameter, 64 mm insulation thickness, during winter conditions) require further validation to ensure broader applicability.