Each kind of steel pipe, with different wall thickness unit, would have corresponding OD. Today, our main topic would be focus on seamless steel pipe-carbon steel pipe. The list would show the relationship of wall thickness and OD for it.
From the list above, we can get the following information. With the increase of OD, the range of wall thickness unit would be different. If the OD is below Φ42, then the large WT would be 5mm. And of course, if the OD is larger than Φ68-Φ73, the WT would have no 3.5mm. Under this situation, we should choose the right OD according to the corresponding WT.
