THREADED UNION FOR TUBULARS USED IN HIGH-PRESSURE FLUID APPLICATIONS

1 . A threaded union for first and second tubulars having mating ends, comprising:

a unitary nut having a top wall, an outer sidewall, an inner sidewall and a depending skirt defining a box thread that engages a pin thread on a male end of the second tubular, the top wall extending past the inner sidewall to define a top flange that extends to and closely surrounds an outer sidewall of the first tubular;

at least two P-shaped nut retainer segments for supporting the top flange of the unitary nut, the P-shaped nut retainer segments having a head portion and a depending leg portion, the head portion being closely received in an annular segment retainer groove in an outer sidewall of the mating end of the first tubular and the depending leg portion substantially filling a gap between the inner sidewall of the unitary nut and the outer sidewall on the mating end of the first tubular; and

an O-ring received an O-ring groove in an outer sidewall of the P-shaped nut retainer segments to hold the P-shaped nut retainer segments in the annular segment retainer groove.

2 . The threaded union as claimed in claim 1 comprising at least two O-rings respectively received in spaced-apart O-ring grooves in the outer sidewall of the P-shaped nut retainer segments to hold the P-shaped nut retainer segments in the annular segment retainer groove.

3 . The threaded union as claimed in claim 1 further comprising an annular relief groove at a top of the inner sidewall of the unitary nut to inhibit the unitary nut from binding on the P-shaped nut retainer segments.

4 . The threaded union as claimed in claim 1 wherein the unitary nut comprises a wing nut.

5 . The threaded union as claimed in claim 1 wherein the unitary nut comprises a spanner nut.

6 . A threaded union for first and second tubulars having mating ends, comprising:

a unitary nut having a top wall, an outer sidewall, an inner sidewall and a depending skirt defining a box thread that engages a pin thread on a male end of the second tubular, the top wall extending past the inner sidewall to define a top flange that extends to and closely surrounds an outer sidewall of the first tubular;

at least two P-shaped nut retainer segments for supporting the top flange of the unitary nut, the P-shaped nut retainer segments having a head portion and a depending leg portion, the head portion being closely received in an annular segment retainer groove in an outer sidewall of the mating end of the first tubular and the depending leg portion substantially filling a gap between the inner sidewall of the unitary nut and the outer sidewall on the mating end of the first tubular; and

a pin slidably received in a smooth bore in a top wall of respective ones of the at least two P-shaped nut retainer segments and a set screw received in a threaded bore in an outer sidewall of respective ones of the at least two P-shaped nut retainer segments, the threaded bore communicating with the smooth bore so that the set screw can be tightened against a bottom end of the pin to force the pin into contact with a surface of the annular segment retainer groove to retain the respective P-shaped nut retainer segments in the annular segment retainer groove.

7 . The threaded union as claimed in claim 6 wherein the pin contacts a top surface of the annular segment retainer groove.

8 . The threaded union as claimed in claim 6 wherein the pin further comprises a smooth shaft and a head that is larger than the smooth shaft.

9 . The threaded union as claimed in claim 8 further comprising a box thread in a top end of the smooth bore for receiving a collar having a pin threaded outer wall, the collar surrounding the shaft of the pin and permitting the shaft to reciprocate freely there through, but preventing the head of the pin from passing so that the pin cannot fall out of the smooth bore.

10 . The threaded union as claimed in claim 6 further comprising an annular relief groove at a top of the inner sidewall of the unitary nut to inhibit the unitary nut from binding on the P-shaped nut retainer segments.

11 . The threaded union as claimed in claim 6 wherein the unitary nut comprises a wing nut.

12 . The threaded union as claimed in claim 6 wherein the unitary nut comprises a spanner nut.

13 . A threaded union for first and second tubulars having mating ends, comprising:

a unitary nut having a top wall, an outer sidewall, an inner sidewall and a depending skirt defining a box thread that engages a pin thread on a male end of the second tubular, the top wall extending past the inner sidewall to define a top flange that extends to and closely surrounds an outer sidewall of the first tubular;

at least two P-shaped nut retainer segments for supporting the top flange of the unitary nut, the P-shaped nut retainer segments having a head portion and a depending leg portion, the head portion being closely received in an annular segment retainer groove in an outer sidewall of the mating end of the first tubular and the depending leg portion substantially filling a gap between the inner sidewall of the unitary nut and the outer sidewall on the mating end of the first tubular; and

a U-shaped spring clip received in a spring clip groove in the head portion of respective ones of the at least two P-shaped nut retainer segments, the spring clips having spring clip ends that engage respective top and bottom surfaces of the annular segment retainer groove when the respective P-shaped nut retainer segments are inserted into the annular segment retainer groove.

14 . The threaded union as claimed in claim 13 wherein the spring clip further comprises inward bends near the spring clip ends, the inward bends engaging locking notches in the spring clip grooves to lock the respective spring clips in the respective spring clip grooves.

15 . The threaded union as claimed in claim 13 further comprising an annular relief groove at a top of the inner sidewall of the unitary nut to inhibit the unitary nut from binding on the P-shaped nut retainer segments.

16 . The threaded union as claimed in claim 13 wherein the unitary nut comprises a wing nut.

17 . The threaded union as claimed in claim 13 wherein the unitary nut comprises a spanner nut.