Dresser Style 167 couplings actually “lock” the pipe and the coupling together to protect the line from pipe separation due to  unusual movement. These couplings are for exceptional conditions such as ash handling and coal transmission lines, or unanchored high-pressure surface lines where added holding strength is desired. Style 167 lick couplings utilize standard Style 38 parts with the addition of leak-proof locking pins. The locking arrangement consists of threaded steel locking plugs at each end which extend through the middle ring into corresponding holes drilled in the pipe ends. This construction permits a “universal joint” action of the pipe in the coupling, yet prevents the pipe from pulling out under excessive longitudinal stresses.