Differences in application scenarios for wall thickness of STD and Sch40 steel pipes
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I saw on GB/T 12459 that the wall thickness of steel pipes is classified as STD and Sch40. It was found that steel pipes of 10 inches and below have the same wall thickness as STD and Sch40. Could someone please explain in detail the differences in the origins and application scenarios of these two wall thicknesses? 1. Why do STD and Sch40 coexist? Is Sch40 the only one that won’t work? 2. For Sch40, the larger the diameter, the greater the wall thickness; why doesn’t the STD wall thickness increase as well? 3. Why are the wall thicknesses of some pipe diameters hollow? For example, the wall thickness of a 22-inch steel pipe with Sch40 grade is negligible.
SCH is the pipe size grade, STD XS XXS indicate the wall thickness grade based on the quality of the pipe; the third category refers to the wall thickness dimensions of the steel pipe, and the fourth one is the pressure grade. For details, refer to Page P189 in the fifth edition of the Chemical Process Design Manual
Thank you, I’ll go look for this book