: This edition marks a formal separation from ISO 10423. Compliance with one no longer automatically implies compliance with the other.
API Specification 6A, 21st Edition - American Petroleum Institute api specification 6a 21st edition pdf link
: The 21st Edition introduced Boarding Shutdown Valves (BSDV) and more clearly defined the differences between slip and mandrel hangers. : This edition marks a formal separation from ISO 10423
: The specification now mandates stricter bolting requirements, specifically citing API 20E for alloy/carbon steel and API 20F for corrosion-resistant bolting. api specification 6a 21st edition pdf link
As of early 2026, the 21st Edition remains the active standard, though it has seen several updates to correct errors and clarify technical points.