As for a ladle with capacity of 30t, its ultimate vacuum during refining process is 66.66Pa. The highest temp of VHD can reach 1700 degrees. VOD furnace temperature can reach up to 1800 degrees after argon blowing 60min. The argon blowing pressure is up to 1Mpa, and the normal argon blowing rate is 0.2Mpa. The ventilation refractory brick is not only affected by the static pressure of molten steel, but also by the erosion of molten steel by cyclic movement, and subjected to high temperature melting at from 1750 to 1800 degrees and air shock. Therefore, breathable fire bricks in addition to good permeability, it must have enough high temperature strength. Therefore, the phosphate corundum permeable brick ensures safe use under the condition of high temperature and vacuum refining of VHD/VOD furnace. The maximum service life of the VHD furnace is 6 times, and the average service life is from 3 to 4 times. The service life of the VOD furnace is from 2 to 3 times, and the average corrosion rate is from 8 to 13mm/h and from 10 to 17.5mm/h.