Chemical industry tip: The difference between DN and De
Thread Content
A little chemical engineering tip regarding the difference between DN and De: DN refers to the nominal diameter of a pipe; note that this is neither the outer diameter nor the inner diameter； It should be related to the use of imperial units in the early stages of pipeline engineering development ； It is commonly used to describe galvanized steel pipes, and its correspondence with imperial units is as follows: 4-inch pipe: 4/8 inch: DN15 ； 6-pipe: 6/8 inch: DN20 ； 1-inch pipe: 1 inch: DN25 ； 1.5 inch pipe: 1 and 1/4 inches: DN32 ； 1.5-inch pipe: 1 and 1/2 inches: DN40 ； 2-inch pipe: 2 inches: DN50 ； 3-inch pipe: 3 inches: DN80 (often also denoted as DN75) ； Four-inch pipe: 4 inches: DN100 ； De mainly refers to the outer diameter of the pipe; it is generally denoted by De, and such values always need to be specified in the form of outer diameter X wall thickness ； It is mainly used to describe: seamless steel pipes, PVC and other plastic pipes, as well as other pipe types for which the wall thickness needs to be specified. Taking galvanized welded steel pipes as an example, the two marking methods, DN and De, are as follows: DN20 De25×2.5mm, DN25 De32×3mm, DN32 De40×4mm, DN40 De50×4mm. We are accustomed to using DN to mark welded steel pipes, and rarely use De for marking pipes when the wall thickness is not relevant ； But labeling plastic pipes is another matter altogether ； It’s still related to industry conventions; in the actual construction process, the terms 20, 25, 32, etc., which we use informally, refer to De rather than DN – there is thus a difference in specification. Failing to clarify this can easily lead to losses during the procurement and construction processes.
De clearly refers to the outer diameter; I hadn’t seen it before.
Dg is the diameter of the gong (the initial sound of the Chinese character for “public”); Dg refers to domestically produced products with Chinese characteristics, but such products are no longer in use nowadays.
Just a reminder to the original poster: the pipe sizes such as 20, 25, 32, etc., which we use informally during construction, refer to DN, not De; De is rarely used in chemical plants!
Thank you! These are my thoughts from back then!
During the construction process, DN is mainly referred to; De is rarely used, haha.
There’s also the DE thing, but I’ve never encountered it·····
De is generally used in design, seems like
These days, DN and Ø are generally used! ! !
De is generally used to describe the form of outer diameter and wall thickness for stainless steel, carbon steel, cast iron pipes, etc
DN is commonly seen in design and production. De is basically never seen. Hehe, I’ve learned something new!