The insulation thickness design for PE-RT II thermal pipes is supported by a complete standard system and must be determined through comprehensive calculation rather than fixed values. In terms of design methods, according to GB/T 8175 "Guidelines for Insulation Design of Equipment and Pipelines" and GB 50264 "Design Code for Insulation Engineering of Industrial Equipment and Pipelines," thickness is generally calculated using the economic thickness method-that is, the sum of insulation investment and annual pipeline heat loss is minimized. If heat loss exceeds the standard at economical thickness, the maximum allowable heat loss limit is used to calculate the thickness in reverse. Regarding heating special requirements, CJJ/T 81 "Technical Specification for Direct-Buried Hot Water Pipelines for Urban Heating" stipulates that the outer surface temperature of the insulation layer must be less than 50°C. During design, heat loss must be verified based on laying conditions, and thickness must be verified. For specific thickness references, product standards GB/T 29047 and CJ/T 480 specify that radial deformation of the insulation layer should not exceed 15% of the design thickness. Some local standards specify minimum thickness requirements, such as Xinjiang Landmarks: insulation layer thickness must not be less than 20mm for dn≤ 110 mm, and no less than 25mm for dn>110mm. Gansu, Heilongjiang, Jilin, and other regions have also issued dedicated technical specifications for PE-RT II, providing more detailed design references. In summary, design should be based on the economic thickness method, combined with external surface temperature constraints and local standards, and comprehensively determined by detailed thermal calculations.