Double-layer pipe joint structure

PURPOSE: A double-pipe joint structure is provided to prevent the leakage of fluid by employing a sealing part which is formed on the exposed end of an inner pipe. CONSTITUTION: A double-pipe joint structure comprises a pair of double pipes(110a,110b), a sealing part(130), and a joint pipe(120). Each double pipe comprises inner and outer pipes(115,111), where the length of the inner pipe is greater than that of the outer pipe so that an end of the inner pipe is exposed to form a joint portion. Threads(112) are formed on the exterior of an end of the outer pipe. The sealing part is formed on the periphery of the joint portion. Screw grooves(121) are formed on the interior of both sides of the joint pipe to be coupled with the threads of the outer pipe.