In order to isolate the high temperature of the pipeline, the high temperature resistant lining is poured inside the cylinder of the valve body (Fig. 1). The lining material is high alumina cement refractory castable. The fire resistance of the high alumina cement refractory castable can reach 1600 ℃ and the service temperature can reach 1300 ℃ It has good heat insulation effect, greatly reduces the heat load of the valve, and has a coefficient of thermal expansion similar to that of carbon steel, so it is not easy to loose when pouring on the inner wall of the cylinder. When the medium temperature is 300 ~ 650 ℃, the refractory lining thickness is 90 ~ 113 mm, so the lining thickness can be selected according to the diameter within this range, such as 100 mm for DN800 high temperature blind valve. Before pouring, V-shaped ribs are welded on the inner wall of the cylinder. The size of the ribs is determined according to the thickness of the lining. The adjacent two ribs are evenly distributed along the circumference at 90 degrees.

The sealing seat of the valve body is welded into a cavity, which not only increases the overall stiffness, but also adds a water cooling system on the sealing cavity. The water cooling system adopts the way of circulating in and out water to enter the sealing seat cavity and directly cool the sealing surface, which improves the cooling strength and sealing performance. The high temperature inside the valve makes it easy to form water vapor accumulation in the sealing chamber when water is flowing through the sealing chamber, so the water inlet of the water cooling device is set below the sealing chamber, and the water outlet is set above the sealing chamber, which is conducive to the emission of water vapor (Fig. 2).

A blowdown valve is set under the water chamber to regularly clean and discharge the dirt generated in the process of water supply, so as to prevent the water passage from blocking.