Generally speaking, the diameter of the tube can be divided into outer diameter (De), inner diameter (D), nominal diameter (DN). Let's distinguish between them
DN refers to the nominal diameter of the pipe
Note: This is neither the outer diameter nor the inner diameter, it is the average of the outer diameter and the inner diameter, which is called the average inner diameter.
When the design uses the nominal diameter DN to represent the pipe diameter, there should be a comparison table between the nominal diameter DN and the corresponding product specifications.
Water. Gas transmission steel pipes (galvanized steel pipes or non-galvanized steel pipes), cast iron pipes, steel-plastic composite pipes and polyvinyl chloride (PVC) pipes should be marked with the nominal diameter "DN" (such as DN15.DN20)
DE mainly refers to the outer diameter of the pipe:
Generally, if De is used, it needs to be marked in the form of outer diameter X wall thickness;
It is mainly used to describe: seamless steel pipes, plastic pipes such as PVC, and other pipes that require a clear wall thickness.
Take galvanized welded steel pipe as an example, and use DN and De to mark as follows:
DN20 25×2.5mm
DN25 32×3mm
DN32 40×4mm
DN40 50×4mm
We are accustomed to using DN to label welded steel pipes, and rarely use De to label pipes without involving wall thickness; But labeling plastic pipes is another matter; It is still related to industry habits, and in the actual construction process, the pipelines we abbreviate call 20, 25, and 32 all refer to De, not DN, and there is a difference of one specification here. If you don't figure it out, it's easy to cause losses in the process of procurement and construction.
The connection methods of the two pipe materials are nothing more than the following: thread connection and flange connection. Other connection methods are rarely used.
Galvanized steel pipes and PPR pipes can be connected with the above two kinds, but it is more convenient to use threads for pipes less than 50, and flanges for pipes greater than 50 are more reliable.
Note: If two metal pipes of different materials are connected, it is necessary to consider whether there will be galvanic cell reaction, otherwise it will accelerate the corrosion rate of the active metal material pipes, it is best to use flange connection, and use rubber gasket type insulation material to separate the two metals, including bolts should be separated by gaskets to avoid contact.
D generally refers to the inner diameter of the pipe
d represents the inner diameter of the concrete pipe
Φ denotes the diameter of an ordinary circle
Of course, Φ can also represent the outer diameter of the pipe, but in this case it should be multiplied by the wall thickness.
For example, Φ25×3 means a pipe with an outer diameter of 25mm and a wall thickness of 3mm.
For seamless steel pipes or non-ferrous metal pipes, the "outer diameter × wall thickness" should be marked.
For example: Φ107×4, where Φ can be omitted.
Some steel pipe callouts in China, ISO and Japan use wall thickness dimensions to indicate the wall thickness series of steel pipes. For this type of steel pipe, the expression method is the outer diameter × wall thickness of the pipe.
Such as: Φ60.5×3.8
De, DN, d, ф!
De-- PPR、PE管、聚丙烯管 外径
DN -- Nominal diameter of polyethylene (PVC) pipe, cast iron pipe, steel-plastic composite pipe, galvanized steel pipe
d -- 混凝土管公称直径
ф-- Seamless steel pipes or non-ferrous metal pipes should be marked with "outer diameter × wall thickness"