A sleeve, a cylindrical member for connecting a tube to a tubular body of a fitting, includes a first peripheral wall end portion facing a peripheral wall end portion of the tubular body, and a second peripheral wall end portion pressed into an open end of the tube. The first peripheral wall end portion includes either an annular protrusion or groove. The annular protrusion is pressed into an annular groove in the peripheral wall end portion of the tubular body. The annular groove allows an annular protrusion axially projecting from the peripheral wall end portion of the tubular body to be pressed thereinto. The second peripheral wall end portion includes a bulge portion to expand the diameter of the open end of the tube. An outer periphery of the first peripheral wall end portion includes a flange to axially face the peripheral wall end portion of the tubular body.

A pipe fitting includes a fitting body defining an inner surface, an outer surface, a first fitting end, and a second fitting end, the inner surface defining a channel extending from the first fitting end to the second fitting end, a portion of the inner surface defining a tapered region tapering towards the first fitting end; and an engagement assembly comprising a metal grip ring received in the channel, the metal grip ring defining a substantially frustoconical ring body, the ring body defining a diameter that tapers from a first lateral end of the ring body to a second lateral end of the ring body, the engagement assembly configured to slide along the tapered region.

A method and apparatus for assembling a high purity liquid distribution system is described. A distal end portion of the tube is heated then pushed over a sleeve so that the distal end portion can have a shrink seal fit over the sleeve to mitigate accidental or inadvertent pull out of the tube from a fitting. Other benefits are also achieved such as minimal flow restriction of the liquid flowing through the joint and the tube.

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 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 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 grip ring includes a substantially frustoconical metal ring body defining a diameter that tapers from a first lateral end of the ring body to a second lateral end of the ring body opposite the first lateral end, the ring body further defining a first circumferential end, a second circumferential end opposite the first circumferential end, an inner surface defining a guide ring opening, and an outer surface opposite the inner surface; and a gap defined between the first circumferential end and the second circumferential end; wherein the 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 fitting nut made of a resin material includes: a hollow, large-diameter tube portion having a female thread formed on its inner peripheral wall; and a small-diameter tube portion that is continuous to the large-diameter tube portion and having a hollow cylindrical shape with a smaller diameter than the large-diameter tube portion. The small-diameter tube portion includes, in the outer peripheral wall thereof, a plurality of engagement grooves that are depressed inwardly in the diameter direction of the small-diameter tube portion and extend along the longitudinal direction that is orthogonal to the diameter direction.

A method and apparatus for assembling a high purity liquid distribution system is described. A distal end portion of the tube is heated then pushed over a sleeve so that the distal end portion can have a shrink seal fit over the sleeve to mitigate accidental or inadvertent pull out of the tube from a fitting. Other benefits are also achieved such as minimal flow restriction of the liquid flowing through the joint and the tube.

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.