The “precision” aspect is critical. GOST 2685-75 classifies pipes into precision classes:
The alloys are generally categorized by their heat treatment capabilities and operational environments: gost 2685-75 pdf
The fluorescent lights of the State Archive for Technical Documentation buzzed like trapped flies. In the farthest corner of Room 14B, a young engineer named Lena Markova ran her finger down a shelf labeled ГОСТ 2685-75—Консервы. Методы определения физико-химических показателей . The “precision” aspect is critical
: Often allows for the highest levels of impurities (up to 2.10% total) to accommodate the rapid cooling and manufacturing process. Key Alloy Examples and Properties gost 2685-75 pdf