SCH and wall thickness
Thread Content
1. Can the wall thickness be determined based on SCH? 2. Can SCH be determined based on wall thickness? What are everyone's thoughts on these two issues?
By including the pipe diameter, the wall thickness can be determined using Sch. However, a definite SCH cannot necessarily be determined based on the wall thickness, as there are many wall thicknesses that do not correspond to any SCH.
It’s fine to determine the wall thickness based on SCH; however, it’s a bit difficult to determine SCH based on the wall thickness. Pipe specifications are divided into three series: IA, IB, and II. The wall thicknesses of the IB and II series do not necessarily correspond to SCH.
If the required wall thickness does not correspond to SCH, one should definitely choose a higher grade of SCH. Always take the higher one, never the lower one.
In general, increasing the SCH actually means raising the wall thickness until the corresponding SCH is achieved. So in fact, the wall thickness has increased. If the required wall thickness cannot be changed and there is no corresponding SCH, why force a match?
This is correct; it’s the principle behind the conversion between imperial and metric units
So, in other words, both can determine each other through lookups, right?
As far as I know, the correct order should be to determine the wall thickness first, and then find out the SCH. Inaccurate wall thickness determined using SCH may also result in waste
Should the operating temperature also be taken into consideration?
Surely, the wall thickness is calculated first; at least domestic standards require the calculation of the wall thickness. Suppose that, after adding the corrosion allowance to the calculated wall thickness, the required dimensions for a pipe are D323.8X5.1. In such a case, D323.8X6.35 sch20 is usually chosen, as standard sch grades are easier to obtain. But if the owner says they can only obtain D323.8X5.56 and asks you to design it according to that specification, then you cannot use sch20. Additionally, the sch value is generally selected in accordance with ASME B36.10M and ASME B36.19M; domestic standards such as HG/T 20553 are also based on ASME.