STOP
A DEVICE WHICH PERMITS ROTATION BUT PREVENTS TRANSLATIONAL MOVEMENT IN AT LEAST ONE DIRECTION ALONG ANY DESIRED AXIS. IF TRANSLATION IS PREVENTED IN BOTH DIRECTIONS ALONG THE SAME AXIS, THE TERM “DOUBLING-ACTING STOP” IS PREFERABLY APPLIED. IN COMMON USAGE, A STOP NORMALLY ACTS ALONG THE DIRECTION OF THE PIPE AXIS.