A resin tube fitting has a body with a sleeve allowing the longitudinal end of the tube to be put therein, an inner ring with a press-in portion configured to be pressed in the longitudinal end of the tube, and a union nut with a connector configured to be screwed to an outer periphery of the body to allow the longitudinal end of the tube to be put radially between the connector and the press-in portion. The inner ring and the union nut are made of resin, which has a property of contracting in response to change in ambient temperature. The radial contraction rate of the connector is higher by 0.05% or more than that of the press-in portion of the inner ring.

A double containment fitting for connection to a double containment tubing system with an outer, secondary containment tubing surrounding an inner, primary tubing. The fitting includes a fitting body defining a central passageway, the fitting body having a center portion disposed between opposed first and second body ports. The fitting body is configured to receive the tubing system into the first body port. The central passageway has a diameter in the first port selected to allow the secondary tubing into the first body port. A connection system mechanically secures the secondary tubing to the first body port.

An anti-rotation device for preventing a hydraulic connector assembly from leaking. Various embodiments of the anti-rotation device provide a mechanism whereby threadably engaged connectors, such as compression fittings, are permitted to rotate only a fraction of a turn after loosening. For many applications, the limited degree of loosening is sufficient to prevent the onset of leaking. Structurally, the anti-rotation device can include a band that is secured to a female nut of a hydraulic connector. Protrusions extend laterally from the band and engage with a stop tab on the male body of the hydraulic connector assembly, thereby limiting rotation of the female nut that would otherwise cause leaks.

A resin tube fitting has: a body with an outer sleeve; an inner ring including an insert portion insertable into the outer sleeve to contact the outer sleeve radially, and a press-in portion configured to be pressed into a longitudinal end of the tube; and a union nut configured to be engageable with the body. The body and the inner ring are made of resin, which has a property of contracting in response to change in ambient temperature. A radial contraction rate of the outer sleeve of the body is designed to be higher by 0.09% or more than that of the insert portion of the inner ring.

A method for manufacturing a resin pipe joint with a joint body includes the following steps. Preparing a mold and a supply device configured to supply molten resin. The mold includes a first mold for an outer shape of the joint body and a second mold for an inner shape of the joint body. Combining the second mold with the first mold to form a cavity, into which the molten resin is injectable, inside the mold. Supplying the molten resin to the cavity in the mold. Solidifying the molten resin in the cavity after stop of the supply of the molten resin from the supply device. The second mold has a gap that connects the cavity to a discharge space outside the cavity and allows gas to flow.

A dual containment fitting may include a primary tubing, a secondary tubing, and a dual containment body. The secondary tubing may surround and be concentric with a first portion of the primary tubing forming a first leak containment space between the primary tubing and the secondary tubing. The dual containment body may include a flare fitting portion and a primary containment nut portion. The flare fitting portion may surround and be concentric with the primary tubing forming a second leak containment space between the primary tubing and the flare fitting portion. The primary containment nut portion may surround and be concentric with the flared end of the primary tubing forming a third leak containment space between the primary tubing and the primary containment nut portion. The primary containment nut portion may include at least one leak passage hole connecting the third leak containment space with the second leak containment space.

A resin-made pipe joint with enhanced sealing property between a joint body and sleeve. A sealing portion which seals between an inner circumferential surface of an inserting portion of a sleeve and an outer circumferential surface of an inner cylinder portion is formed by press-inserting an inserting portion into a groove portion of the joint body. When the inserting portion is press-inserted into the groove portion, a space is formed between a body cylinder portion located opposite to an opening portion of the groove portion in the axial direction, and the projection end of the inserting portion. After completing press insertion of the inserting portion into the groove portion, in a section including axis of the inner cylinder portion, a region in the outer circumferential surface of the inner cylinder portion facing the space forms an angle of 5 to 15 to the axis of the inner cylinder portion.

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 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 pipe joint, made of synthetic resin, including: an inner ring; a joint body having an annular sealing groove and a male screw portion formed on an outer circumference; a union nut having a female screw portion formed on an inner circumference to be tightened onto the male screw portion of the joint body, such that a first opposing surface is formed in the joint body to be perpendicular to an axial direction, and a second opposing surface is formed in the union nut to oppose the first opposing surface. An engagement projection is provided in one of the first opposing surface and the second opposing surface. An engagement recess is provided in the other of the first opposing surface and the second opposing surface such that the engagement projection engages with the engagement recess when the union nut has been tightened up to an appropriate position.