Franklin Valve Franklin Valve was originally formed as a repair center for double block and bleed plug valves, as well as four-way diverter valves for bi-directional meter proving. Now Franklin has designed and is manufacturing its own valve line, the DuraSeal Double Block and Bleed Plug valve in 2″-20″ Class 150, 2″-12″ Class 300 and 2″-12″ Class 600 as well as component parts. The DuraSeal DBB plug valve meets the requirements under the Buy American Act and is API 6D monogrammed and API 591 (destructive) & API 622 (emissions) certified. Franklin’s new facility is currently pending formal ISO 9001 approval.