Selection of pipe diameter for seamless steel pipes used in instrument heating steam lines
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For the instrument heating branch pipes, the design drawings specify: \"seamless steel pipe, 20#, GB/T8163-2008, Φ22x3\". However, I have been wondering how it is determined that Φ22x3 corresponds to DN15 Which regulation and which clause of it? And when the pipe material is changed to stainless steel, what should be the corresponding outer diameter and wall thickness for a pipe with the same DN15 size? I also couldn’t find specific clauses in GB/T14976-2012
Why is φ22*3 equal to DN15? Just look it up in a table... Actually, for Ia, Ib, and II, the outer diameter of the pipe is specified; in your case, it’s an Ib DN15 pipe with an outer diameter of 22 and a wall thickness of 3……
This has nothing to do with the pipe material at all; it’s just a dimension rule.
Φ22x3 means an outer diameter of 22 mm and a wall thickness of 3 mm; 22 – 3 – 3 = 16 mm. After accounting for the manufacturing tolerances, this corresponds roughly to DN15. Stainless steel should not be used for the heating tubes, as their pressure resistance decreases significantly at high temperatures.