9.0 OVERVIEW DESIGN FEATURES OVERVIEW API6D THROUGH CONDUIT GATE VALVES Through conduit Full bore The through conduit opening design provides full flow passage and allows for the smooth passing or pipeline pigs. Pressure drop through the valve is no greater than that through an equal length of equal diameter pipe. External pressure relief system for cavity over pressure protection Due to the double tight sealing isolation design for expanding gate valve, cavity pressure can increase significantly through thermal expansion of fluid in the cavity. A body cavity thermal relief system can be provided to relive this excess body cavity pressure. In Line repairable The top entry design allows for access to all internal parts if maintenance is required with the valve still in the pipeline. Ease of on-line stem packing maintenance Top and bottom Chevron PTFE packing + lantern ring is the standard stem seal equipped with a stem injector with integrated check valve. Injectable packing material can be injected directly into the packing box through the injector to enhance stem sealing while the valve is under pressure. Australian Pipeline Valve - Installation, Operation and Maintenance Manual 24 API6D THROUGH CONDUIT EXPANDING GATE VALVE - AP400-405 SERIES Slab Gate Expanding Gate