Must the wall thickness of pipe fittings be indicated using the pipe size designation Sch series?
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When designing, one is always faced with the issue of choosing the wall thicknesses for pipes and fittings. One thing that has been clarified is that when selecting wall thicknesses in accordance with ASME B36.10, it is not necessary to follow the Sch values; instead, one can directly choose from the wall thickness series that do not include Sch values； 1. However, regarding the selection of wall thickness for American standard pipe fittings, I’m not sure what principles or regulations exist ； 2. Do the wall thicknesses of American standard pipe fittings always have to correspond to the Sch series? Some people say that the wall thickness of the fittings is roughly the same as that of the pipes ； Because when calculating the wall thickness of pipes, the final thickness chosen already takes into account a certain margin of safety; however, in some cases this margin is quite small, less than 1 mm or even less than 0.2 mm. In such cases, is the wall thickness of the pipe fittings still the same as that of the pipe itself? Thank you
It’s not necessary to rely on Sch. I think the wall thickness of the pipe should be chosen first; the wall thickness of the fittings should be greater than or equal to that of the pipe, but not more than 1-2 mm. When submitting materials, you can use outer diameter × wall thickness directly.
The wall thickness of the fittings should be the same as that of the pipes; otherwise, it will be difficult to create proper grooves during on-site welding. Generally, when using American standards, Sch is used to denote the wall thickness. In metric units, it is expressed as outer diameter × wall thickness.
The technical level of those who sell steel pipes is generally not very high; even if you write down SCH, they still won’t know what the thickness is. Therefore, it’s better to specify the pipe diameter and wall thickness when submitting a material plan.
It depends on the selection criteria; if the American standard, namely ASME36.19, is still chosen, then SCH will be used to denote the wall thickness. If national standards or Ministry of Chemicals standards are chosen, it is possible to determine the wall thickness based on the number of mm.
Thank you, sir. Sometimes if one insists on using Sch, the wall thickness of the pipe chosen ends up being too thick, resulting in waste； Also, if the wall thickness of the pipe is not based on Sch, and the fittings are positioned closer to Sch, the wall thickness of the fittings can sometimes be much greater than that of the pipe. This is not only uneconomical but also makes welding more difficult.
Pipelines are a system; choosing fittings based on the pipes is definitely the right approach! !
In American standards, wall thickness can be expressed in MM; it is best for the wall thickness of pipes and fittings to be consistent
It’s easy to make mistakes when specifying SCH. As far as I know, there are several standards that specify the wall thickness of SCH, but their requirements vary. I’m also quite troubled by this issue – I choose one standard, yet the procurement team refers to another
Use this for US standards; metric pipes use mm, which also helps with differentiation
One is the theoretical wall thickness, and the other is the actual wall thickness； The theoretical wall thickness is a value obtained through calculation; the actual wall thickness must also take into account any negative deviations in thickness, and should be greater than the calculated theoretical wall thickness
4# tzsh, bro, I also sell steel pipes at low prices. I can understand these SCH specifications; have you ever encountered anything that bad? Hehe, then get in touch with me instead
That’s how the American standards specify it. If other standards are chosen, it will not be necessary. Of course, you can convert it into one without SCH. In actual purchasing, if you don’t complete the conversion, it’s not necessarily certain that you’ll buy the wrong item.
The American standard \"Welded and Seamed Steel Tubes\" ANSI B36.10 specifies that the pipe designation is denoted by \"Sch.\", which is the rounded value obtained by multiplying the ratio of the pipe’s design pressure to the allowable stress of the material at the design temperature by 1000. Sch. = ×1000. P: Design pressure, MPa ； σ: Allowable stress of the material at the design temperature t, in MPa. Sch. (tube designation) is not the wall thickness, but rather a wall thickness series. Theoretical formula for wall thickness: t = Nominal pipe size × Outer diameter/D / (1.75×1000) + 2.5 (mm). For example: if the pipe DN is 200, the outer diameter is 219 mm, and it is of Sch40 grade, then: t = 40×219/（1.75×1000）+2.5 = 7.5 mm
Where did you get this subsequent formula?