The crude gas from underground coal gasification( UCG) containing sulfide is corrosive to the steel borehole casing and gas transmitting pipeline in front of purification system,which in the long run will influence the safe and stable operation of UCG station. Aiming at this problem,an idea applying cement pipe to replace steel tube was proposed,and the application of concrete pipe in the UCG project was discussed. Stress state of the venting borehole casing was analyzed, structure of the cement pipe was de...