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API Specification 6A, 21st Edition, is the current industry standard for wellhead and Christmas tree equipment, focusing on enhanced safety, structural reorganization, and stricter material requirements . Officially replacing the 20th edition in late 2019, this standard mandates heat treatment surveys, introduces Boarding Shutdown Valves (BSDV), and utilizes API 20E/20F for bolting . For more details, visit American Petroleum Institute . API Spec 6A 21st Edition Overview | PDF - Scribd api specification 6a 21st edition pdf link
API Specification 6A, 21st Edition Overview | PDF | Computing - Scribd : You can purchase print or PDF copies