The meaning of pipe diameter De, DN, d, ф

The meaning of pipe diameter De, DN, d, ф

The respective ranges of De, DN, d, ф

　　De-- PPR, PE pipe, polypropylene pipe outer diameter

　　DN--the nominal diameter of polyethylene (PVC) pipe, cast iron pipe, steel-plastic composite pipe, galvanized steel pipe

　　D - Nominal diameter of concrete pipe

　　Ф-- Nominal diameter of seamless steel pipe, its specification is, such as ф100:108 X 4

　　 pipe diameter difference between DE and DN

　　1, DN refers to the nominal diameter of the pipeline-this is neither the outer diameter nor the inner diameter (it should be related to the imperial unit in the early stage of pipeline engineering development, usually used to describe the galvanized steel pipe) its corresponding relationship with the imperial unit is as follows:

　　4 in charge: 4/8 inch: DN15;

　　6 in charge: 6/8 inch: DN20;

　　 1 inch pipe: 1 inch: DN25;

　　Inch two pipe: 1 and 1/4 inch: DN32;

　　Inch half pipe: 1 1/2 inches: DN40;

　　 Two-inch tube: 2 inches: DN50;

　　 Three-inch tube: 3 inches: DN80 (also marked as DN75 in many places);

　　Four-inch tube: 4 inches: DN100;

　　2, De mainly refers to the outer diameter of the pipe (usually marked with De, which needs to be marked in the form of outer diameter X wall thickness)

　　 is mainly used to describe: seamless steel pipes, PVC and other plastic pipes, and other pipes that require a clear wall thickness.

　　 Take the galvanized welded steel pipe as an example, the two labeling methods of DN and De are as follows:

　　DN20 De25X2.5mm

　　DN25 De32X3mm

　　DN32 De40X4mm

　　DN40 De50X4mm

　　We are accustomed to using DN to label welded steel pipes, and rarely use De to label pipes when the wall thickness is not involved;

　　 But labeling plastic pipes is another matter; it is still related to industry habits. In the actual construction process, the pipes 20, 25, and 32 that we abbreviate refer to De instead of DN.

　　Do not rely on the practical experience of the field:

　　A. The connection of the two pipe materials is nothing more than: threaded connection and flange connection.

　　B. Both galvanized steel pipes and PPR pipes can be connected by the above two types, but it is more convenient to use threaded fasteners for pipes smaller than 50, and flanges for pipes larger than 50 are more reliable.

c. If two metal pipes of different materials are connected, consider whether there will be a galvanic reaction, otherwise it will accelerate the corrosion rate of the active metal material pipe, z* It is better to use flange connection, and use rubber gaskets to connect Separate the two metals, including bolts, with spacers to avoid contact.

　　3, the difference between DN, De, Dg

　　DN Nominal diameter

　　De external diameter

　　 Dg diameter gong (the initials of "gong" in Chinese Pinyin) Now you will understand that Dg is a domestic product, a domestic product with Chinese characteristics, and it is no longer needed

　　A. Different marking methods for various tubes:

　　1. Pipes such as water gas conveying steel pipes (galvanized or non-galvanized), cast iron pipes, etc. The pipe diameter should be expressed by the nominal diameter DN (such as DN15, DN50);

　　2, seamless steel pipe, welded steel pipe (straight seam or spiral seam), copper pipe, stainless steel pipe and other pipes, the pipe diameter should be expressed by outer diameter D×wall thickness (such as D108×4, D159×4.5, etc.);

　　3, reinforced concrete (or concrete) pipes, clay pipes, acid-resistant ceramic pipes, cylinder tile pipes and other pipes, the pipe diameter should be expressed by the inner diameter d (such as d230, d380, etc.);

　　4. For plastic pipes, the pipe diameter should be expressed according to the product standard method;

　　 5. When the design uses the nominal diameter DN to indicate the pipe diameter, there should be a comparison table between the nominal diameter DN and the corresponding product specifications.

　　B, DN, De, Dg relationship:

　　De is the diameter of the outer wall of the pipe

　　DN is the number obtained by reducing the thickness of the pipe wall by half

　　Dg is generally not used

　　1 The pipe diameter should be in mm.

　　2 The expression of pipe diameter should meet the following requirements:

　　1 Water gas transportation steel pipe (galvanized or non-galvanized), cast iron pipe and other pipes, the pipe diameter should be expressed by the nominal diameter DN;

　　2 Seamless steel pipes, welded steel pipes (straight seam or spiral seam), copper pipes, stainless steel pipes and other pipes, the pipe diameter should be expressed by outer diameter x wall thickness;

　　3 For pipes such as reinforced concrete (or concrete) pipes, clay pipes, acid-resistant ceramic pipes, cylinder tile pipes, etc., the pipe diameter should be represented by the inner diameter d;

　　4 For plastic pipes, the pipe diameter should be expressed according to the product standard method;

　　5 When the design uses the nominal diameter DN to indicate the pipe diameter, there should be a comparison table between the nominal diameter DN and the corresponding product specifications.

　　 The specifications of rigid PVC pipes for construction drainage are expressed by de (nominal outer diameter) × e (nominal wall thickness) (GB 5836.1-92).

　　 Polypropylene (PP) pipe specifications for water supply are expressed in de×e (nominal outer diameter×wall thickness)

　　The marking of the plastic pipe on the engineering drawing　

　　 metric dimension size

　　 expressed in DN

　　 is generally called "nominal size", it is not the outer diameter of the pipe, nor the inner diameter of the pipe. It is the average of the outer diameter and inner diameter, we call the average inner diameter.

　　For example: Metric marking (mm dimension size) of 63mm outer diameter plastic pipe 　DN50

　　ISO metric dimension size

　　Da represents the outer diameter of PVC pipe and ABS pipe

　　De indicates the outer diameter of PP pipe and PE pipe

　　For example: Metric marking of plastic pipe with outer diameter of 63mm (mm dimension size)

　　Da63 For PVC pipes and ABS pipes.