Soft seal tap water and sewage treatment center plate 4-inch sewage treatment valve - Cast iron powder flanged butterfly valve for water and sewage transportation. Material: Cast iron powder, strong corrosion resistance. The center plate structure uses a soft seal design to provide a tight closure of the valve and prevent media leakage when the valve is closed. The special 4-inch size fits custom pipe diameters and is easier to attach to flanges for easy installation and stable operation of water and sewer systems.