How do Φ and DN correspond to each other for pipes and pipe fittings?
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How do Φ and DN correspond to each other for pipes and pipe fittings? I’m a bit confused. Especially at pipe joints, such as when different flanges are used for connection.
This mechanical industry standard clearly states that DN denotes the nominal diameter, while Φ denotes the diameter
OP, go and check the standards for piping engineering; for American standards, refer to ASME B36.10M/B36.19M. There are corresponding tables inside, so you can find it easily by checking them. For example, 2\"=DN50=60.3mm outer diameter.
There are two types: small diameter and large diameter. For example, for a pipe with DN100, if a large diameter is chosen, the outer diameter will be 114; if a small diameter is chosen, the outer diameter will be 108. In the petrochemical industry, large diameters are generally preferred, and the corresponding flanges are of type A, which are American standard flanges. Small diameters correspond to type B flanges, which are Chinese standard flanges
DN denotes the nominal diameter, while Φ represents the diameter
The most direct method is to check the flange standards. . .
DN refers to the nominal diameter of a pipe, but it is neither the outer diameter nor the inner diameter; Φ denotes the outer diameter of a steel pipe. For example, steel pipes with the same nominal diameter have different outer diameters due to their varying wall thicknesses. As can be seen from the table below: Table of engineering pipe diameters (commonly used); Standards for pressure pipes. Specifications: DN – Nominal diameter; Ф – Outer diameter. Large outer diameter series: DN15-ф22mm, DN20-ф27mm; DN25-ф34mm, DN32-ф42mm; DN40-ф48mm, DN50-ф60mm; DN65-ф76(73)mm, DN80-ф89mm; DN100-ф114mm, DN125-ф140mm; DN150-ф168mm, DN200-ф219mm; DN250-ф273mm, DN300-ф324mm; DN350-ф360mm, DN400-ф406mm; DN450-ф457mm, DN500-ф508mm; DN600-ф610mm. Small outer diameter series: DN15-ф18mm, DN20-ф25mm; DN25-ф32mm, DN32-ф38mm; DN40-ф45mm, DN50-ф57mm; DN65-ф73mm, DN80-ф89mm; DN100-ф108mm, DN125-ф133mm; DN150-ф159mm, DN200-ф219mm; DN250-ф273mm, DN300-ф325mm; DN350-ф377mm
“Especially at pipe joints, such as when different flanges are used for connection. ” What do you mean by this sentence?
It is best to express it as Φ outer diameter * wall thickness. Using DN to denote pipes and fittings is an amateurish approach; DN is merely a code for the pipe diameter
DN denotes the nominal diameter, while Φ represents the diameter
DN is the nominal diameter; it should not be considered as the actual value of w, and can be approximated as the inner diameter. Φ refers to the accurate outer diameter of the pipe