Standard available 1.Design and fabrication per GB12238-1989 general purpose industrial valve-Flanged and wafer butterfly valves. 2. Flange size per GB9113.1-2000 steel pipe glanged of flat or male face 3.Length per GB12221-1989 Metal valves for use in flanged pipe systems -face to face and center to face dimensions. 4.Inspection and test per GB/T 13927-1992 Pressure testing for general purpose valves Performance