What are the outer diameter specifications of galvanized round tubes?

Galvanized pipe models and specifications are generally executed according to the GB/T3091-2001 standard, mainly including: DN15 with an outer diameter of 21.3mm, commonly referred to as 4-inch pipe. DN20 with an outer diameter of 26.8mm, commonly referred to as 6-inch pipe. DN25 with an outer diameter of 33.5mm, commonly referred to as 1-inch pipe. DN32 with an outer diameter of 42.25mm, commonly referred to as 1-1/4-inch pipe. DN40 with an outer diameter of 48mm, commonly referred to as 1-1/2-inch pipe. DN50 with an outer diameter of 60mm, commonly referred to as 2-inch pipe. DN65/70 with an outer diameter of 75.5mm, commonly referred to as 2-1/2-inch pipe. DN80 with an outer diameter of 88.5mm, commonly referred to as 3-inch pipe. DN100 with an outer diameter of 114mm, commonly referred to as 4-inch pipe. DN125 with an outer diameter of 140mm, commonly referred to as 5-inch pipe. DN150 with an outer diameter of 165mm, commonly referred to as 6-inch pipe. DN200 with an outer diameter of 219mm, commonly referred to as 8-inch pipe.