A pipe-connecting device including a resin-made tube and an inner ring. The inner ring has a flared portion and a tip-contracted outer-circumferential flared surface. The tip-contracted outer-circumferential flared surface is press-inserted into an end portion of the tube to cause the end portion of the tube to be flared and deformed. A section shape of the outer-circumferential flared surface in a direction extending along an axis of the inner ring body is formed into a convex curved surface passing through a first place, which is a maximum-diameter portion of the flared portion, a second place, which is the tip end side of the flared portion of the inner ring body, and a third place, which is between the first place and the second place, and in which a diameter is equal to an outer diameter of the tube with respect to the axis.

A pipe joint made of synthetic resin comprises a first opposing surface formed in a joint body perpendicular to the axial direction, and a second opposing surface formed in a union nut that opposes the first opposing surface. An engagement projection is provided in the second opposing surface that projects toward the first opposing surface. An engagement recess is provided in the first opposing surface such that the engagement projection engages with the engagement recess when the union nut has been tightened up to an appropriate position.

A pipe-connecting device includes: an inner ring having: an outer circumferential portion having a tip-contracted outer-circumferential flared surface that is to be press-inserted into an end portion of a tube to flare the tube, and an inner circumferential portion constituting a fluid transfer path; a pipe joint body that has a tubular screwing portion having an external thread; and a union nut having an internal thread that is screwed with the external thread. The inner ring including the tube is inserted into the tubular screwing portion, and the tip-contracted outer-circumferential flared surface is pressed through the tube by a pressing portion of the union nut. The pressing portion of the union nut is formed into an inclined inner circumferential surface that is inclined in the same direction as the tip-contracted outer-circumferential flared surface with respect to the axis of the tubular screwing portion.

A fitting assembly may seal a wire within a tube to inhibit ingress of fluid outside the tube into the tube and into contact with the wire. The fitting assembly may optionally include a body and a nut, with a part of the nut received within the body. The nut may be threadedly connected to the body, such that threading and/or unthreading the nut translates the part of the nut within the body. Optionally, the nut may include a ring extension that is received within a ring cavity of the body, and an interfacing between the ring extension and the ring cavity may create a seal to inhibit leaking of the fluid past the seal. A method of sealing a wire within a tube may comprise positioning a tube with a wire therein within such a fitting assembly.

A fitting structure is provided for supply of gas and connectable between an air supply tube in the form of a hose or a plastic pipe and an air outlet of an air compressor and includes a fitting and a thermal insulation tube. The fitting includes a first coupling opening connectable with the air outlet of the air compressor and a second coupling opening connectable with the air supply tube. The thermal insulation tube has a first end part fixed inside the second coupling opening of the fitting and a second end part extending outside the second coupling opening such that a portion of the thermal insulation tube that extends outside the second coupling opening is received in the interior of the air supply tube. High-temperature air from the air compressor is conducted through the thermal insulation tube into the air supply tube without being directly applied to the fitting.

A joint is connected to a tube and includes a joint body, nut, and ring. The joint body has a tube coupling part and a main body thread part. The nut has a nut thread part and a constricted diameter part. The ring is arranged in a space radially inward of the nut thread part. The ring abuts an abutted part of the nut. The ring has a Young's modulus greater than the tube. The ring has a curved surface part at least at a radially inward portion of the ring axially on the joint body side, the curved surface part bulging radially inward of the ring and axially toward the joint body side. A maximum thickness of the ring in a radial direction is defined as 2r, an axial length of the curved surface part of the ring is defined as h, and =h/r being 0.5 to 1.2.

A resin-made pipe joint enhancing sealing property between a joint body and a sleeve. The joint body and the sleeve are produced by using a fluorine resin. A sealing portion which seals between the inner circumferential surface of an inserting portion of the sleeve and the outer circumferential surface of the inner cylinder portion is formed by press-inserting the inserting portion into a groove portion of the joint body. When, with respect to the inserting and groove portions, an insertion rate of the inserting portion to the groove portion is indicated by X, and a multiplying factor of the radial width of the inserting portion to the radial width of the groove portion is indicated by Y, the resin-made pipe joint has the insertion rate and multiplying factor which are within a range defined by following Expressions (1) and (2):

Y=0.218X+1.218(1)

and

Y=0.67X+1.67.(2)

A tubing junction assembly may include a body, and a collar coupled to the body. The body may include a head portion, a base portion, and an intermediate portion. At least a portion of an outer surface of the body at the intermediate portion may define a cross-sectional width that tapers from the head portion to the base portion. The collar may have an inner surface defining a passage. A tubing may be stretched over the outer surface of the body with a proximal end portion of the tubing stretched over at least a portion of the outer surface of the body at the intermediate portion. The inner surface of the collar may be sleeved over a portion of the outer surface of the tubing and coupled to the collar such that the proximal end portion of the tubing is sandwiched and compressed between the body and the collar.

A guide ring includes a guide ring body defining a guide outer surface, a guide inner surface opposite the guide outer surface, a first lateral end, a second lateral end opposite the first lateral end, a first circumferential end, and a second circumferential end opposite the first circumferential end, the guide inner surface defining a guide ring opening; a gap defined between the first circumferential end and the second circumferential end; and an arcuate guide slot extending laterally into the guide ring body and disposed radially between the guide outer surface and the guide inner surface and configured to receive a grip ring; wherein the guide ring body is configured to be compressed radially inward to reduce a width of the gap between the first circumferential end and the second circumferential end.

A pipe connecting device having a joint body including a fitting cylinder to which a flared synthetic resin-made tube is to be externally fitted, an external thread formed on a radially outward side of the fitting cylinder; and a union nut including an internal thread screwed with the external thread, and a tube pressing portion that presses a diameter changing portion formed between a flared portion in the tube, and a non-flared portion, in the direction of the axis. In a fastening completion state in which the tube pressing portion is caused to press the diameter changing portion by a screw advancement of the union nut, the screw advancement being produced by screwing the internal thread to the external thread, positions of a basal end of the external thread and a tip end of the union nut in the directions of axes coincident with each other.