(1) The wall thickness is represented by the pipe number "Sch".

The pipe number is the ratio of the design pressure of the pipe to the allowable stress of the material at the design temperature multiplied by 1000 and rounded.

That is: Sch＝P/[σ]t×1000

ANSI B36.10 wall thickness grades: Sch10, Sch20, Sch30, Sch40, Sch60, Sch80, Sch100, Sch120, Sch140, Sch160 ten grades.

ANSI B36.19 wall thickness grades: Sch5s, Sch10s, Sch40s, Sch80s four grades.

(2) Expressed in terms of steel pipe wall thickness dimensions, adopted by some steel pipe standards in China, ISO, and Japan.

(3) The pipe wall thickness is expressed by the weight of the pipe, which divides the pipe wall thickness into three types:

For pipes with DN Less than or equal to 250mn, Sch40 is equivalent to STD, and for pipes with DN<200mm, Sch80 is equivalent to XS.