Nut turning tool and fitting nut turning method

A fitting nut turning method for turning a fitting nut using a nut turning tool to thereby engage the fitting nut with a joint body or to release the engagement with the joint body,

• wherein the nut turning tool used includes
• a single arc-shaped attachment portion formed of a semicircular curved plate having a constant thickness along its length and being shaped like an arc with an opening, the single arc-shaped attachment portion being attached to the fitting nut, and
• a shaft portion continuous to the single arc-shaped attachment portion and extending linearly to join with an arc shaped radially outer circumferential surface of the single arc-shaped attachment portion,
• the single arc-shaped attachment portion includes, on a radially inner circumferential surface thereof, one or more claws protruding toward the nut,
• the constant thickness of the curved plate is thinner than the thickness of the shaft portion, and
• the arc-shaped outer circumferential surface of the single arc-shaped attachment portion exhibits a concave arc shape such that the single arc-shaped attachment portion exhibits elasticity in a direction in which the opening is closed after being expanded,
• the fitting nut turning method comprising:
• causing the fitting nut to enter the opening while expanding the opening with the fitting nut;
• engaging the claw with an engagement groove formed in an outer peripheral wall of the fitting nut, while, when the entry of the fitting nut into the opening ends, closing the opening by the elasticity of the single arc-shaped attachment portion to attach the arc-shaped attachment portion to the fitting nut;
• and
• applying thereafter torque to the fitting nut through the shaft portion to turn the fitting nut.