Abstract: Through an engineering example, the method for calculating the insulation thickness of cryogenic liquid nitrogen pipeline is discussed. The problems in calculating the insulation of cryogenic pipeline by limiting the outer surface temperature, Ts, are analyzed. For different outdoor cryogenic pipelines, appropriate limitations and calculation methods are selected according to different insulation purposes. The method of limiting cold loss and the method of limiting the temperature rise, Δt, of the internal medium should be used respectively for calculating the insulation thickness of cryogenic liquid nitrogen pipelines

Key words: cryogenic liquid nitrogen pipeline, insulation thickness, calculation method