If you work in ammonia refrigeration daily, consider an IIAR Digital Library subscription. For a flat annual fee (often $500–$1,000), you get access to all IIAR standards, bulletins, and handbooks, including the piping handbook, in a searchable PDF interface.
The handbook is often used in conjunction with the following ANSI/IIAR standards: ANSI/IIAR 2-2021 iiar ammonia refrigeration piping handbook pdf link