JIS flanges for nominal pressure of not more than 2.5MPa pipe connections. JIS flange sealing surface can be made smooth style , lenticular and tenon slot three. Smooth type flat welding flange largest application . JIS flanges for nominal pressure of not more than 2.5MPa pipe connections. JIS flange sealing surface can be made smooth style , lenticular and tenon slot three. smooth type flat welding flange largest application . used for medium conditions more relaxed circumstances, such as low-voltage non- purified compressed air, low pressure circulating water .