1. DN is the nominal diameter of the pipe
Often used to describe: galvanized steel pipe.
Nominal diameters can be expressed in metric mm or in imperial in. Pipe accessories are also expressed in nominal diameter, with the same meaning as seamed pipes. The correspondence between it and imperial units is as follows:
| Inch | DN | Nominal Outside Diameter |
|---|---|---|
| 1/2 | 15 | Φ20 |
| 3/4 | 20 | Φ25 |
| 1 | 25 | Φ32 |
| 11/4 | 32 | Φ40 |
| 11/2 | 40 | Φ50 |
| 2 | 50 | Φ63 |
| 21/2 | 65 | Φ75 |
| 3 | 80 | Φ90 |
| 4 | 100 | Φ110 |
| 5 | 125 | Φ140 |
| 6 | 150 | Φ160 |
Nominal diameter (nominal diameter), also known as the average outside diameter (mean-outside diameter). This is due to the metal tube of tube being very thin, tube outside diameter and tube inside diameter difference, so take the tube outside diameter and tube inside diameter of the average as the tube diameter name.
DN is the nominal diameter, nominal diameter (or called the nominal diameter), is a variety of tubes and piping accessories of the common caliber.
Nominal diameter is a convenient round number for reference, and processing size is not strictly related. The same nominal diameter of the pipe and piping accessories can be connected to each other, with interchangeability. It is not the actual sense of the outer diameter or inner diameter of the pipe, although its value is closer to or equal to the inner diameter of the pipe.
For example, welded steel pipe can be divided into thin-walled steel pipe, ordinary steel pipe and thickened steel pipe according to its thickness. Its nominal diameter is not the outer diameter, not the inner diameter, but a nominal size approximating the inner diameter of ordinary steel pipe. Each nominal diameter, corresponding to an external diameter, the value of its internal diameter with different thicknesses.
2. De is mainly the outer diameter of the pipe
Mainly used to describe: seamless steel pipe, PVC and other plastic pipes, and other pipes that need to specify the wall thickness.
General use of De labeling needs to be labeled into the form of outer diameter X wall thickness. Take galvanized welded steel pipe as an example, with DN, De two labeling methods are as follows:
DN20 De25X2.5mmDN25 De32X3mmDN32 De40X4mmDN40 De50X4mm
We are accustomed to using DN to label welded steel pipe, in the case of wall thickness is not involved in the rare use of De to label the pipe; but the labeling of plastic pipe is another matter; or with the industry habits, the actual construction process, we briefly called 20, 25, 32 and other pipelines are referred to as De, rather than referring to DN.
In addition, according to practical experience in the field:
a, the two piping materials are connected to the way: screw connection and flange connection.
b, galvanized steel pipe, PPR pipe can be used in the above two kinds of connections, just less than 50 of the pipeline with a wire fastening is more convenient, and more than 50 of the flange is more reliable.
PS: If two different materials are connected to the metal pipe, to consider whether the primary battery reaction will be generated, otherwise it will accelerate the corrosion rate of the active metal material pipe, it is best to use the flange to connect and use the rubber gasket type of insulating material to separate the two metals, including bolts should be separated by gaskets to avoid contact.
Φ also indicates the outer diameter of the pipe, but at this point, it should be followed by the wall thickness.
3. Φ denotes the diameter of an ordinary circle
Of course, Φ can also indicate the outer diameter of the pipe, but then you should multiply it by the wall thickness. For example: Φ25×3, indicates that the outer diameter is 25mm and the wall thickness is 3mm.
Seamless steel pipe or non-ferrous metal pipe should be marked “outer diameter × wall thickness”. For example, Φ107×4, where Φ can be omitted.
China, ISO, and Japan’s part of the steel pipe labeling using wall thickness dimensions to indicate the wall thickness of steel pipe series. For this type of steel pipe, the method of expression for the pipe outside diameter × wall thickness. For example Φ60.5×3.8
Relationship between DN, De, Φ
De measures the diameter of the outer wall of the pipe DN is the number obtained by subtracting the thickness of the pipe wall by half from De.
Φ denotes the diameter of an ordinary circle Pipe diameter should be expressed in mm, and the expression of pipe diameter should be in accordance with the following provisions:
- For pipes such as steel pipes (galvanized or non-galvanized) for water and gas transportation, cast iron pipes, etc., the pipe diameter shall be expressed in terms of nominal straight diameter DN;
- Seamless steel pipe, welded steel pipe (straight seam or spiral seam), copper pipe, stainless steel pipe and other pipe materials, pipe diameter should be expressed in outside diameter × wall thickness Φ;
- Reinforced concrete (or concrete) pipe, clay pipe, acid-resistant ceramic pipe, tile pipe and other pipes, pipe diameter should be expressed in terms of the inner diameter of the d. Plastic pipe, pipe diameter should be expressed in terms of the inner diameter of the d;
- Plastic pipe, pipe diameter should be expressed according to the method of product standards;
- When the design is used to indicate the nominal diameter DN pipe diameter, there should be a nominal diameter DN and the corresponding product specification comparison table.
Construction drainage with rigid PVC pipe specifications with de (nominal outer diameter) × e (nominal wall thickness) that (GB 5836.1-92), water polypropylene (PP) pipe specifications with de × e that (nominal outer diameter × wall thickness) Plastic pipe in the engineering drawings on the labeling.
Metric dimension size (metric dimension size) to DN is generally referred to as the “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 the inner diameter, which we call the average inner diameter.
For example, the metric dimension size of 63mm OD plastic pipe is DN50ISO metric dimension size is expressed in Da for the OD of PVC pipe, ABS pipe, and De for the OD of PP pipe, and PE pipe. dimension size)
Da63 for PVC pipe, ABS pipe.
Summarize
The respective ranges of representation of De, DN, d, ф!
De– PPR, PE pipe, polypropylene pipe Outer diameter
DN — polyethylene (PVC) pipe, cast iron pipe, steel-plastic composite pipe, galvanized steel pipe nominal diameter
d — concrete pipe nominal diameter
ф — seamless steel pipe or non-ferrous metal pipe should be marked “outside diameter × wall thickness”.