How to Select Materials for Cold-insulated Pipes? Comparison of PIR, Rubber-Plastic and Aerogel

The performance of low-temperature cold-insulated pipes largely depends on the selection of cold insulation materials. In projects such as LNG facilities, cryogenic chemical plants and central air conditioning refrigerant systems, PIR (polyisocyanurate), rubber-plastic foam and aerogel blanket are the three most widely used cold insulation materials on the market. They differ greatly in thermal conductivity, temperature resistance range, moisture resistance, construction method and cost. Choosing materials only by experience often leads to condensation, cold leakage, aging failure and frequent maintenance. This article compares the three mainstream materials from core performance, application scenarios, advantages and disadvantages to help designers and purchasers make decisions.

PIR is a rigid closed-cell foam and the preferred material for cryogenic projects. Its closed-cell ratio exceeds 90% with low static thermal conductivity and stable performance under sustained low temperature. Its working temperature ranges roughly from -196℃ to 120℃, suitable for pipelines transporting ultra-low-temperature media such as LNG, liquid oxygen and liquid nitrogen. PIR features low water absorption and good frost resistance. Its fire rating generally reaches Class B1 flame retardant. However, it is hard and brittle with poor flexibility. Cutting and installation on special fittings and small-radius elbows are inconvenient and it cannot be bent freely on site. Usually supplied as boards and curved segments, PIR is ideal for large-diameter straight pipes, storage tanks and long-distance cryogenic pipelines, widely adopted in large chemical and energy insulation projects. With properly constructed vapor barriers, PIR maintains stable cold insulation performance for a long time.

Rubber-plastic foam is a flexible closed-cell elastic material and the most common choice for central air conditioning refrigerant pipes. Soft and elastic, it can wrap pipes, valves and special fittings flexibly. It is easy to cut and install with dedicated adhesive without complicated prefabrication. Its applicable temperature is normally -40℃ to 105℃, so it cannot be used for ultra-low-temperature working conditions like LNG. Thanks to its closed-cell structure, rubber-plastic foam has inherent moisture resistance, and vapor barrier arrangements are often simplified in small and medium HVAC projects. Its obvious drawbacks: thermal conductivity rises rapidly as temperature drops; outdoor exposure causes yellowing, cracking and aging. Its fire performance is limited, making it unsuitable for high-risk chemical zones. Its advantages are moderate price and low labor cost, perfect for conventional cold insulation of central air conditioning refrigerant pipes in civil buildings, shopping malls and workshops.

Aerogel blanket is a new nano-porous thermal insulation material. Its biggest advantage is ultra-low thermal conductivity. To achieve the same insulation effect, the required thickness is much smaller than PIR and rubber-plastic foam. It has a wide temperature range and excellent fire resistance up to Class A1 non-combustible. It is hydrophobic, aging-resistant and has a long service life. Lightweight and thin, aerogel fits utility tunnels and equipment interlayers with limited installation space. The main disadvantages are high material cost, far above PIR and rubber-plastic foam. It generates fine dust during handling and requires construction protection. Low mechanical strength makes it fragile, so reliable outer cladding is mandatory. It is mostly used for confined spaces, alternating hot and cold conditions and special projects with strict fire standards as a premium insulation solution.

Selection guidance: PIR is preferred for ultra-low-temperature LNG and long cryogenic chemical pipelines. Rubber-plastic foam is suitable for conventional HVAC refrigerant pipes when easy installation and budget control are priorities. Aerogel is recommended for narrow spaces, high fire ratings and complex special working conditions. Never select insulation material merely by thermal conductivity. Medium temperature, ambient humidity, fire codes, installation space and budget should all be considered. Cooperated with qualified vapor barriers and outer cladding, the whole cold insulation system can operate reliably.