Reverse circulation drill pipe, also known as dual-wall drill pipe, is a type of drilling tool used for reverse circulation drilling. It consists of inner and outer layers of drill pipes (referred to as inner pipe and outer pipe). The annular gap between the inner and outer pipes forms a circulation channel, through which the drilling medium flows to the bottom of the hole during drilling. The central hole of the inner pipe discharges the circulating medium and carries the core sample back to the surface. Each dual-wall drill pipe is connected via the outer pipe's threaded coupling to ensure torque and pressure transmission. The inner pipes are typically connected by insertion, primarily serving as a conduit for the circulating medium, with sealing devices installed at the insertion points. Reverse circulation drilling effectively prevents borehole wall collapse and improves drilling efficiency.