【目的】现行 GB 14907—2018仅以耐火时间认证膨胀型防火涂料等级，导致检测报告缺失结构设计关键参数——等效热阻，进而造成结构工程师难以直接确定涂层的厚度。【方法】提出一种创新性工程方法，直接对接国标耐火试验强制检测项（钢梁跨中最大挠度、基材最高温度、耐火时间），基于热传导理论和钢材高温力学性能，建立“国标检测参数-等效热阻-涂层厚度”的计算模型，并给出超越方程求解实用设计曲线。【结果】通过实际品牌涂料检测数据验证，该方法计算的等效热阻值与实验实测值相比，相对误差不超过 12%，且结果普遍偏保守，符合工程安全设计原则。该方法可节省测定等效热阻的实验需求。显著简化工程防火设计。【结论】本方法首次有效弥合了防火涂料产品国标认证（GB 14907—2018）与结构设计规范（GB 51249—2017）之间的关键数据鸿沟，为膨胀型防火涂料的工程应用提供了科学、直接且可操作的厚度确定方案，可有效推动膨胀型防火涂料在结构防火设计中的标准化进程。

［Objective］ The current national standard GB 14907—2018 certifies the grade for intumescent fire-retardant coatings（IFCs） based solely on fire resistance time. Consequently，test reports for IFCs lack the critical parameter required for structural design—equivalent thermal resistance— making it difficult for structural engineers to directly determine the required coating thickness inpractice.［Methods］ In this paper，a novel engineering method utilizing the mandatory test itemsspecified in the national standard fire resistance test（namely，the maximum mid-span deflection of steel beams，the substrate peak temperature，and the fire resistance time）is proposed. Based on heat transfer theory and the high-temperature mechanical properties of steel，a computational model linking “national standard test parameters -equivalent thermal resistance -coating thickness”is established， Practical design curves are also provided by solving the transcendental equations.［Results］Validation based on actual test data from commercial IFC products demonstrated that the equivalent thermal resistance values acquired by this method deviated by no more than 12% from experimentally measuredvalues. Furthermore，the results were generally conservative，aligning with the principle of engineeringsafety design. This approach can eliminate the need for dedicated experiments to determine equivalentthermal resistance，significantly simplifying the process of fire-resistant design.［Conclusion］ The proposed method effectively bridges the critical data gap between the national product certification forfire-retardant coatings（GB 14907—2018） and the structural design code（GB 51249—2017）. It provides a scientific，direct，and operable solution for determining coating thickness in the engineering application of IFCs. This advancement is expected to promote the standardization use of IFCs instructural fire-resistant design.