ASME STS-1-2021 standard, titled "Steel Stacks," provides the mandatory requirements and comprehensive guidance for the design, fabrication, and maintenance of steel stacks used to vent process exhaust gases. American National Standards Institute - ANSI Key Sections of the Standard
You can purchase the official PDF or print version directly from the ASME website. This ensures you have the most accurate, legal, and up-to-date version.
If you are a student or work for an engineering firm, your institution likely has a subscription to the ASME Digital Collection or a database like IHS Markit or Knovel that allows you to view and download the standard.