Calculation of Tempreture Decrcase for Oil Product during Shutdown of Heated 0il Pipeline

Based on the varied thermal condition of oil product and soil around the pipeline after shutdown of heated oil pipeline, the article raises an equalion for heat transfer and some mathematical solutions have been found for it。Tbus, it obtains the analytic solutions for various tempreture profile of oil product along pipeline with variation of time。Such method provides the basis of calculation for determining the safe shutdown period of pipeline in different seasons in a more reason able way.