many friends who have just come into contact with PE pipe will have questions: Does the model of PE pipe refer to the inner diameter? In fact, the answer to this question is not a simple "yes" or "no", the key is to figure out the marking rules of PE pipe model.

First of all, the most commonly used model label for PE pipe (especially water supply pipes and gas pipes) is the beginning of "De", such as De20, De25, De32... The "De" here represents the nominal outer diameter, that is, the number after De refers to the outer diameter of PE pipe (unit: mm). For example, the PE pipe of De20 has an outer diameter of 20mm, and the inner diameter is the outer diameter minus twice the wall thickness - assuming the wall thickness is 2.0mm, the inner diameter is 20-22 = 16mm; if the wall thickness is 2.3mm, the inner diameter is 20-22.3 = 15.4mm.

So why do some people mistakenly think that the model is the inner diameter? It may be confusing the concepts of "De" and "DN". "DN" is the nominal diameter (such as DN15, DN20), which is a "nominal size" and is not directly equal to the inner diameter or outer diameter. It is mainly used to facilitate the interchangeable reference of different pipes. For example, the pipe of DN20 corresponds to the De25 (outer diameter 25mm) of the PE pipe and the inner diameter of the galvanized pipe is about 20mm - this cross-reference is easy to misunderstand for beginners.

Take another practical example: the PE water supply pipe commonly used in home decoration, the De25 model is very common. Its outer diameter is 25mm, assuming the wall thickness is 2.3mm, the inner diameter is 25-22.3 = 20.4mm, which is almost close to the nominal diameter of DN20. But if you directly say "De25 has an inner diameter of 25mm", it is wrong - its inner diameter is actually only about 20mm.

Why should PE pipes be marked with an outer diameter? This is related to its connection method. PE pipes are often connected by hot melt or electric fusion. This connection method requires that the outer diameter of the pipe and the pipe fittings match exactly, so it is more direct and accurate to mark the model with the outer diameter, which can avoid errors in connection.

What if we need a PE pipe with a specific inner diameter? In fact, it is very simple: first calculate the required inner diameter according to the demand, and then extrapolate the outer diameter and wall thickness. For example, if you need a PE pipe with an inner diameter of 16mm, if you choose a wall thickness of 2.0mm, the outer diameter is 16 + 22 = 20mm, and the corresponding model is De20. Or just tell the supplier the inner diameter you need and ask them to recommend the appropriate combination of outer diameter and wall thickness.

To summarize: the model of PE pipe (usually starting with De) is not the inner diameter, but the nominal outer diameter. To know the inner diameter, you need to subtract twice the wall thickness from the outer diameter. Next time you choose a PE pipe, don't take the model as the inner diameter!