In liquefied natural gas (LNG) storage and transportation and related supporting projects, the design of the insulation system directly affects energy consumption control and operational safety. Among these, the thickness of LNG elastic felt, a commonly used cryogenic insulation material, is a crucial factor determining system performance. Insufficient thickness leads to increased cold loss, while excessive thickness may cause cost and construction problems. This article explains the basic principles for selecting the thickness of LNG elastic felt from an engineering application perspective.

First, thickness selection should be based on the design temperature conditions. LNG medium temperatures are typically extremely low, and the elastic felt needs to withstand cryogenic environments for extended periods under actual operating conditions. Thickness design should be based on thermal calculations considering the minimum design temperature, operating temperature difference, and surrounding environmental conditions to ensure that system cold loss is controlled within the design limits at the target temperature, rather than solely relying on material parameters under ambient temperature conditions.

Second, the temperature-dependent thermal conductivity characteristics should be considered. The thermal conductivity of LNG elastic felt changes with temperature, making its thermal performance under low-temperature conditions particularly significant for engineering applications. Therefore, when selecting the thickness, thermal conductivity data for the low-temperature range should be prioritized for calculation to avoid deviations in actual operating performance due to improper parameter selection.

Third, the thickness selection needs to consider both anti-frost and anti-condensation requirements. In cryogenic systems, if the insulation layer thickness is insufficient, the outer surface temperature is prone to falling below the ambient dew point, leading to condensation or frost formation. This not only increases cold loss but may also affect the safety of surrounding equipment and structures. A reasonable thickness design helps increase the outer surface temperature and reduce the risk of frost formation, making it a crucial factor in thickness selection.

Fourth, the structural adaptability and construction factors of the elastic felt should be considered. LNG pipelines and equipment often have complex structures, requiring the insulation layer to have good fit. Excessive thickness may affect the construction quality of elbows, valves, and other parts, increasing the number of joints and sealing difficulties. In engineering selection, a thickness scheme with higher construction controllability should be chosen while meeting thermal requirements.

Fifth, from the perspective of system safety and durability, the thickness design should have a certain degree of redundancy. LNG systems typically operate under long-term continuous conditions, and material properties may undergo slight changes over many years of use. An appropriate thickness margin helps improve the system's tolerance to construction deviations and long-term operational uncertainties, enhancing overall reliability.

Finally, thickness selection should also be comprehensively evaluated in conjunction with economic considerations. LNG elastic felt is a high-performance insulation material with relatively high material costs. In engineering practice, thermal calculations and operating cost analysis should be conducted to avoid blindly increasing thickness while meeting technical requirements, striving for a reasonable balance between initial investment and long-term operating costs.

Overall, selecting the thickness of LNG elastic felt is a comprehensive decision based on thermal calculations, system safety, and construction conditions. Only through scientific analysis of design conditions, reasonable selection of material parameters, and consideration of engineering realities can a suitable elastic felt thickness scheme be determined, ensuring that the LNG insulation system achieves its expected goals in terms of efficiency, safety, and durability. This is also one of the important technical aspects of insulation design in LNG engineering.