Stainless Steel Pipe Sizes – Common Specifications of Stainless Steel Water Pipes

With the growing emphasis on the health and safety of residential drinking water, stainless steel water pipes have become an ideal choice for water supply systems. Stainless steel pipes can effectively prevent secondary water pollution, offer excellent corrosion resistance, high strength, and long service life. In addition, they are suitable for conveying water, steam, and certain oils, which makes them widely used in residential, commercial, and industrial applications.
So, what are the common sizes of stainless steel water pipes?

Types and Materials of Stainless Steel Water PipesCommon stainless steel water pipes mainly include stainless steel welded pipes and plastic-coated stainless steel pipes. Although these two types differ in structure and surface treatment, their dimensional specifications are basically the same. Common materials include 304, 304L, 316, and 316L stainless steel. Among them, 304 stainless steel is the most widely used due to its good corrosion resistance and cost-effectiveness.
Stainless Steel Water Pipe Sizes According to European Standards
At present, most stainless steel water pipes on the market adopt European standards (DN). The nominal diameter corresponds to the pipe’s outer diameter and wall thickness, making it convenient for engineering selection and installation.
Common sizes of stainless steel water pipes are as follows:
DN15 : Outer diameter 18 mm × Wall thickness 1.0 mm
DN20 : Outer diameter 22 mm × Wall thickness 1.2 mm
DN25 : Outer diameter 28 mm × Wall thickness 1.2 mm
DN32 : Outer diameter 35 mm × Wall thickness 1.5 mm
DN40 : Outer diameter 42 mm × Wall thickness 1.5 mm
DN50 : Outer diameter 54 mm × Wall thickness 1.5 mm
DN65 : Outer diameter 76.1 mm × Wall thickness 2.0 mm
DN80 : Outer diameter 88.9 mm × Wall thickness 2.0 mm
DN100 : Outer diameter 108 mm × Wall thickness 2.0 mm
DN125 : Outer diameter 133 mm × Wall thickness 2.5 mm
DN150 : Outer diameter 159 mm × Wall thickness 2.5 mm
DN200 : Outer diameter 219 mm × Wall thickness 3.0 mm
DN250 : Outer diameter 273 mm × Wall thickness 4.0 mm
DN300 : Outer diameter 325 mm × Wall thickness 4.0 mm

Plastic-Coated Stainless Steel Water Pipe Sizes
Plastic-coated stainless steel water pipes are manufactured by adding a protective plastic layer to the outer surface of stainless steel pipes, further improving corrosion resistance and operational safety. Their commonly used sizes are basically the same as those of standard stainless steel water pipes, mainly including:
Plastic-coated Stainless Steel Water Pipe
Nominal Diameter (mm) Pipe Outer Diameter (mm) Material
DN15 :18*1.0 304
DN20 :22*1.2
DN25 :28*1.2 
DN32 :35*1.5
DN40 :42*1.5
DN50 :54*1.5
DN65 :76.1*2.0
DN80 :88.9*2.0
DN100 :108*2.0
Conclusion
Stainless steel water pipes are available in a wide range of specifications to meet the needs of different water supply systems. When selecting stainless steel water pipes, factors such as pipe diameter, wall thickness, material grade, and application environment should be carefully considered to ensure the safety, durability, and hygiene of the piping system. Properly selected stainless steel water pipes provide a reliable guarantee for healthy drinking water.