What Is The Difference Between De and DN for Plastic Pipes?

De and DN are two common marking terms for thermoplastic plastic pipes, and they often confuse many new buyers and project engineers.

De stands for the outer diameter of the pipe. It is widely adopted for UPVC, CPVC, PPH and PVDF piping products. The De value directly shows the actual outside dimension of the pipe, which is convenient for matching fittings, flanges and welding connections.

DN means nominal diameter. It is a general nominal size mark, mostly used for metal pipes. DN is not equal to the real inner or outer diameter of the pipe. It is only a reference specification for pipeline system matching.

Many customers mix them up when placing orders, which may lead to wrong size selection and project delay. For UPVC, CPVC, PPH and PVDF plastic piping systems, our products are marked with both DE and DN.

Understanding the difference between De and DN will help you pick out the correct pipe and fitting sizes efficiently for your water treatment, chemical and industrial fluid projects.

If you have any questions about size selection, feel free to send us your inquiry for professional support.