On its commission in 1965, Beijing Design Institute attached to the Ministry of Petroleum designed a normal pressure distillation - thermal cracking installation, with the scale of 15 thousand tons of oil processing annually. The first installation of tubular normal pressure distillation - thermal cracking device of Yanchang Oilfield was established and put into production in 1966, after more than one year’s busy construction. Thereafter, it underwent two reforms and updates, with the chief equipments replaced and the operating and reconditioning environment updated. Thus the annual processing with normal pressure distillation was increased to 30 thousand tons and that with thermal cracking to 20 thousand tons. This set of device has run for 19 years.