First, the technical background: the existing valve in the valve body, valve cover and the components are intact, only a slight deformation or corrosion of the sealing surface, the valve can not be used. Repair these valves non-professional factory does not work, resulting in great waste. Therefore, the valve unit is expected to use is: valve seat, valve plate sealing surface is not easy to deformation, corrosion-resistant, vulnerable sealing material can be changed. Valve plate in the opening and closing with the sealing surface do not have friction or minimize friction, so you can avoid the soft seal gate valve deficiencies. Second, the purpose of the invention: to solve the valve seat and the valve plate sealing surface corrosion or deformation, the valve plate can automatically compensate and compress the sealing surface and the pressure between the valve and the valve automatically balance the problem, to solve the soft sealing material by friction and damage the seal Surface problems, due to the sealing of the valve can be changed, greatly increasing the use of the valve. Third, the practical range: diameter φ50-φ400mm, pressure 2.5-4.0MPa, less than 200 ℃ of various liquid at room temperature Fourth, the technical program: the valve for the double parallel gate valve, inlet seal, the inlet valve plate from the gland and Force relief valve plate composed of the main seal gate. The sealing sleeve moves synchronously with the unloading valve plate but it is not connected. The pipe pressure is transmitted to the valve seat on the outlet side through the unloading valve plate and the leveling arm, which greatly improves the bonding force of the soft sealing surface. The valve plate is covered with a corrosion-resistant rubber gland. Soft sealing material in the process of opening and closing, with the valve seat to maintain a certain distance, so that the soft sealing material in non-friction non-pressure environment work. The gland isolates the fluid being delivered in the pipe from the parts inside the spool to protect it from fluid corrosion and impurities. This valve sealing material replacement is very convenient, so the service life is more than 5 times the general valve.