1.Common product outer diameter size resolution can be viewed in the way of product outer diameter + wall thickness. For example, for a product with an outer diameter of 65mm and a wall thickness of 3mm, we can directly express it as: φ57×3
2.The inner diameter of stainless steel pipes is generally used, such as a pipe with an outer diameter of 57mm, which we express as DN50
3.It is also expressed in inches, that is, the number of inches and points often mentioned on plumbing pipes. For example, a pipe with an outer diameter of 57mm is expressed as 2 inches (1 inch = 25.4mm).