Confused: flange A/B series, pipes Ia, Ib, II series, metric, imperial, European and American standards
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I’ve just started working with piping systems and I don’t understand this concept. I’ve read many posts on HaiChuan, but I’m still confused. If any expert could explain this systematically and tell me how to use it, as well as what corresponds to what, I would be extremely grateful! !
Page 5 of HG/T 20592-2009 and HG/T 20553-2011 – these two standards can basically clarify the meaning of these codes.
Thank you, so how do I match it when using it?
I remember that in the flange workshop, steel stamps were used to mark “A***” corresponding to “B***”; we decided on the values for the * symbols ourselves, and I’m not sure about anything else
I’ll explain it myself; please point out any mistakes I make. Pipes are divided into Series A (large diameter) and Series B (small diameter). When connecting flanges to pipes, PN series flanges (European standard) can be used with both A series pipes and B series pipes. When connecting to B series pipes, the letter B should be indicated after the DN value; when connecting to A series pipes, no such indication is needed ； Class series flanges (American standard) can only be connected to pipes with large diameters (Series A). Among them, the A series (large-diameter) pipes are divided into Ia and Ib; the only difference between the two is the decimal place in the outer diameter – can this be considered as one category? Please help to correct it, thank you
Not all pipes in Series A have large diameters; the diameters of Series A pipes range from DN300 to DN1200, which are smaller than those of Series B pipes
In fact, it’s a difference in outer diameter; some specifications are essentially the same while others differ completely. For example: 2\" = DN50. Outer diameter A is 60.3, while B is 57 – A represents the American standard diameter, and B is the commonly used diameter in China. La = Lb = A = American Standard; II = B = Chinese Standard. There are sizes that conform to both the Chinese standard and the European standard
Flanges A/B refer to those with a diameter of DN600 or larger; flanges are divided into A/B types based on the differences in their bolt holes； Pipes of series Ia, Ib, and II differ in outer diameter; the outer diameter of Ia is the same as that specified by American standards, and it is also quite commonly used nowadays. Ib is an integer value of the Ia series. Series II is not commonly used. For this, you can take a look at HG 20553; the European standard and the American standard represent two different systems that have evolved independently. Either one will do. It depends on the project.
Personal opinion: As for which series are closely related to the industry in which a project operates – such as the emerging petrochemical industry versus traditional industries – as well as the software used by design firms and their usual practices, it isn’t important which series they use. What’s crucial is to ensure accurate procurement; otherwise, installation can be troublesome: pipes, flanges, and other components must match properly； Pay special attention to the instrument flanges and pipeline flanges.