"Double arm bellows DN300 = DE400? Size marking misunderstanding clarification"

In the field of plastic pipeline engineering, the problem of dimensional marking of double-arm bellows has always been the focus of the industry. In particular, the two marking methods of DN300 and DE400 often confuse engineering and technical personnel. This article will deeply analyze the differences and connections between these two marking methods to help you completely clarify this common sizing misunderstanding.

It needs to be made clear that DN300 and DE400 represent two different size standard systems. DN (nominal diameter) is a long-term pipe sizing method used in our country, and its value is similar to the inner diameter of the pipe. DE (outer diameter) is an international standard marking method gradually promoted in recent years, which directly represents the outer diameter of the pipe. Although these two labeling systems are different in numerical values, they actually refer to pipeline products of the same specification.

is specific to double-arm bellows, and DN300 corresponds to DE400 specifications. This is because bellows, as a special structure of pipes, have a larger wall thickness than ordinary pipes, so the outer diameter of bellows with the same nominal diameter is much larger than that of ordinary pipes. This size difference is determined by the unique structural characteristics of bellows. The alternating design of crests and troughs allows the pipeline to maintain a certain inner diameter while increasing the outer diameter.

In practical engineering applications, this size difference is crucial. Engineering designers need to accurately understand the correspondence between the two marking methods, otherwise it may lead to a series of problems such as wrong pipeline selection and mismatch of connectors. Especially when designing pipeline systems, if the marking standards of DN and DE are confused, it is likely to cause serious consequences that the entire pipeline system cannot be installed and operated normally.

It is worth noting that with the acceleration of the internationalization process, the DE marking system is gradually becoming the mainstream of the industry. More and more engineering standards and specifications have begun to adopt the outer diameter marking method, which requires engineering and technical personnel to timely update the knowledge system to adapt to this changing trend. At the same time, manufacturers should also indicate the two marking sizes on the product label so that users can accurately understand and choose.

The key to correctly understanding the dimension of double-arm bellows is to grasp a basic principle: DN marking focuses on the inner diameter characteristics of the pipeline, while DE marking directly reflects the outer diameter of the pipeline. For the same specification of bellows, although the values of DN and DE are different, they point to the same product. Engineers should choose the appropriate marking system for design and procurement according to the specific design requirements and use environment when selecting the type.

To sum up, the equation that DN300 is equal to DE400 is established in the field of double-arm bellows. This correspondence is determined by the special structure of bellows. With the continuous improvement of industry standards and the increasing frequency of international exchanges, it is believed that this misunderstanding of dimensional marking will be better clarified and solved. Engineering and technical personnel shall strengthen their study, accurately grasp the meaning and applicable occasions of various marking methods, and ensure the accuracy and reliability of engineering design and construction.