API 6D and API 6A are both used as standards for valves in the oil and gas sector. API 6D is the standard for valves in pipelines, such as in rigs, platforms, skids and production plants. API 6A is the specification for valves used in wellhead equipment and Christmas tree accessories . In terms of usage, there are many more pipeline valves used as compared to wellhead valves. When it comes to ease of manufacture, pipeline valves are more easily manufactured as comparedto wellhead valves. As for pressure rating, the most common rating for API 6D valves are from 150LB to 2500LB. And API 6A valves are pressure rated for 2000LB up to 20000LB,i.e.2000LB, 3000LB, 5000LB, 10000LB, 15000LB, and 20000LB. Generally, the pressure rating for API 6A valves is higher than API 6D valves, after all, they are usually used in harsher working conditions. XIAMEN TAVAL VALVES INDUSTR...