SCH. WALL THICKNESS COMPARISION

SCH. WALL THICKNESS COMPARISION

This is specified in the 1938 American National Standards Institute ANSIB36.10 (Welded and Seamless Steel Pipe) standard.
The pipe table number (Sch.) is the ratio of the design pressure to the allowable stress of the material at the design temperature multiplied by 1000, and the rounded value. which is
Sch.=P/[ó]t×1000 (1-2-1)
where P—design pressure, MPa;
[ó]t—the allowable stress of the material at the design temperature, MPa.
The pipe table number of seamless steel pipe and welded steel pipe can be determined by checking the information.
The pipe table numbers in ANSI B36.10 and JIS standards are; Schl0, 20, 30, 40, 60, 80, 100, 120, 140, 160.
The table numbers of stainless steel pipes and tubes in ANSI B36.19 are: 5S, 10S, 40S, 80S.
The tube table number (Sch.) is not the wall thickness, but the wall thickness series. The actual wall thickness, the same pipe diameter, has different thicknesses in different pipe gauges. The wall thickness of different pipe numbers is calculated in the United States and Japan by applying the Barlow formula for calculating the thickness of thin-walled pipes under internal pressure, and after considering the corrosion allowance, thread depth and negative wall thickness deviation -12.5%, it is determined. as formula
(1-2-2) and (1-2-3). tB=D0P/2[ó]t (1-2-2)
t=[D0/2(1-0.125)×P/[ó]t]+2.54 (1-2-3)
where tB t——represents the theoretical and calculated wall thicknesses, respectively, mm
D0——The outer diameter of the pipe, mm
P——Design pressure, MPa
[ó]t——The allowable pressure of the material at the design temperature, MPa
The actual wall thickness is calculated after the wall thickness and diameter are rounded off.
If the pipe table number of the steel pipe is known, the design pressure that the steel pipe can adapt to can be calculated according to the formula (1-2-1), namely
P=Sch.× [ó]t/1000 (1-2-4)
For example, the stock Sch40, carbon steel 20 seamless steel pipe, when the design temperature is 350oC, the design pressure that the steel pipe can adapt to is:
P=40×92/1000①=3.68MPa