Patent ID: 7980598

Claim:
A pipe joint locking device preventing accidental loosening of a pipe joint after tightening, the pipe joint connected by tightening a joint member having an internal thread over a joint member having an external thread in a state in which the joint member having the external thread and a pipe member face each other via a seal portion, wherein the device comprises: a first component member including a mounting portion mounted to the joint member having the external thread while being prevented from relative rotation, a cover portion provided to be contiguous with the mounting portion and brought into contact with an outer peripheral face of the joint member having the internal thread from one side, and a coupling portion provided to be contiguous with the cover portion and brought into contact from the one side with a round portion of the pipe member protruding from the member having the internal thread; and a second component member including a cover portion brought into contact with the outer peripheral face of the joint member having the internal thread from the other side and a coupling portion provided to be contiguous with the cover portion and brought into contact from the other side with the portion of the pipe member protruding from the joint member having the internal thread, and the coupling portion of the first component member and the coupling portion of the second component member are coupled and fixed to the round portion of the pipe member protruding from the joint member having the internal thread, and relative rotation of the pipe member with respect to the joint member having the external thread is prevented even if a rotational force acts on the pipe member.