What are the common specifications and sizes of galvanized pipe?

What are the common specifications and sizes of galvanized pipe?
Galvanized pipe specifications and sizes are typically identified by nominal diameter (DN), which corresponds to specific parameters such as outer diameter and wall thickness. Standards may vary between countries and regions. Currently, the national standard (GB/T 3091-2015) is commonly used in China.
II. Key Parameters
Outer Diameter:
This is the actual outer diameter of the steel pipe. The tolerance range is generally ±0.5mm (according to the national standard). For example, the outer diameter of a DN100 pipe is 114.3mm, which is the industry standard.
Wall Thickness:
The same nominal diameter may have multiple wall thicknesses (such as "normal" and "heavy"). The choice should be based on actual load-bearing and pressure requirements. For example, the normal wall thickness of a DN25 pipe is 3.25mm, while the thickened wall thickness is 4.0mm.
Length:
The common fixed length of galvanized pipe is 6 meters. Custom lengths (such as 9 meters and 12 meters) are also available upon request, but this requires prior consultation with the manufacturer. III. Other Notes
The specifications of cold-dip galvanized pipe (banned) are essentially the same as those of hot-dip galvanized pipe. However, due to its poor corrosion resistance, it has been banned for use in water, gas, and other pipelines.
The outer diameters of some specifications in international standards (such as the Imperial system) may differ slightly from those in national standards (for example, DN100 corresponds to the Imperial 4-inch system, with an outer diameter of 114.3mm being the common value).
When purchasing, be sure to clearly identify the "nominal diameter" and "actual outer diameter" to avoid misidentification due to misidentification.