Stainless steel pipe: ANSI standards & chart

Stainless steel pipe is one of the more standardized materials in the building and engineering industries. The thickness of the pipe walls, diameter of the pipe and even the chemical composition are all written as part of the American National Standards Institute standards, which is just one of multiple standards available.

Wall Thickness
Stainless steel pipe categorized by the American National Standards Institute uses the term schedule in reference to the pipe's wall thickness. Despite this standardization, the wall thickness is not the same for every diameter of pipe. Instead, the schedule refers to the general strength of the pipe. Therefore, a schedule 40S stainless pipe has a wall thickness of approximately 1.73mm for a pipe with outside diameter of 10.3mm but increases to 9.53mm for a pipe of the same schedule but 323.9mm in diameter. There are four general schedules for stainless pipe; 5S, 10S, 40S and 80S.

Diameter
Within each schedule of pipe there are multiple diameters of stainless steel pipe standardized by ANSI. These diameters range from 10.3mm (or .405 inches) to 323.9mm (or 12.75 inches). It is important to note that some diameters are not available in every schedule. For instance, the smallest diameters are not available in schedule 5S and many diameters are very difficult to find in some schedules, or very expensive if they are available.

Materials
Though ANSI standardizes stainless steel pipe, there are multiple formulas of stainless steel available. The two primary steels used in the manufacture of stainless steel pipe are ANSI 304 stainless steel and ANSI 316. Both steels have similar chemistry and differ only slightly in the amount of chromium in the steel.

Stainless Steel Pipe Chart

American National Standards Institute - ANSI