Fitting for tubing containment system

A fitting for use with metal tubing includes an adaptor, the adaptor having a longitudinal passage having a longitudinal axis for fluid flow; a body for receiving the tubing, the body positioned opposite the adaptor and aligned with the longitudinal axis; a metal sealing member positioned between the adaptor and the body; a nut positioned opposite the body; a jacket lock ring positioned radially inwardly of a portion of the nut, the jacket lock ring for making a mechanical connection with an outer jacket of the tubing; and at least one fastener coupling the nut, body and adapter.

BACKGROUND OF THE INVENTION

Embodiments relate generally to tubing systems and in particular to a fitting for use with a double containment tubing system. Currently, flexible tubing, such as corrugated stainless steel tubing, is used in a number of applications requiring primary and secondary containment. Various plumbing, as well as local and federal, mechanical codes and specifications require that certain types of installations of flexible tubing be protected by a secondary containment system. Tubing containment systems exist in the art to contain fluids if the tubing leaks. One existing double containment tubing system is disclosed in U.S. Pat. No. 7,857,358, the entire contents of which are incorporated herein by reference.

SUMMARY

Embodiments include a fitting for use with metal tubing includes an adaptor, the adaptor having a longitudinal passage having a longitudinal axis for fluid flow; a body for receiving the tubing, the body positioned opposite the adaptor and aligned with the longitudinal axis; a metal sealing member positioned between the adaptor and the body; a nut positioned opposite the body; a jacket lock ring positioned radially inwardly of a portion of the nut, the jacket lock ring for making a mechanical connection with an outer jacket of the tubing; and at least one fastener coupling the nut, body and adapter.

Embodiments also include a fitting-tubing assembly including metal tubing having peaks and valleys and an outer jacket; and a fitting secured to the tubing, the fitting including: an adaptor, the adaptor having a longitudinal passage having a longitudinal axis for fluid flow; a body for receiving the tubing, the body positioned opposite the adaptor and aligned with the longitudinal axis; a metal sealing member positioned between the adaptor and the body, the sealing member positioned in a valley of the tubing; a nut positioned opposite the body; a jacket lock ring positioned radially inwardly of a portion of the nut, the jacket lock ring making a mechanical connection with the outer jacket of the tubing; and at least one fastener coupling the nut, body and adapter.

Other exemplary embodiments are described herein, and encompassed by the appended claims.

DETAILED DESCRIPTION

FIG. 1is a cross-sectional view of a fitting and tubing in a closed state in an exemplary embodiment. The fitting includes an adaptor1, a body2and a nut3. Adaptor1, body2and a nut3all in include a passage therethough formed along a central axis, C. The fitting forms a fluid tight seal on tubing10by compressing a portion of the tubing10between a sealing surface of sealing member7and an adaptor sealing surface of adaptor1, as described in further detail herein.

Adaptor1has longitudinal passage along longitudinal axis, C, for fluid flow. Adaptor1is generally cylindrical and includes an annular, adaptor sealing surface20on an interior portion thereof, radially outward of central axis, C. Adaptor sealing surface20has a rounded or radiused surface that contacts tubing10. An annular pocket22is formed in adaptor1radially outwardly of adaptor sealing surface20. Pocket22receives a rib28of body2. An annular recess24is formed in adaptor1radially outwardly of pocket22. Recess22receives an outer shoulder32of body2.

Sealing member7is an annular element having a sealing surface21that faces adaptor sealing surface20. Sealing surface21may be planar, and generally frusto-conical. Sealing member7may be a formed by split ring washers, a collet or other member.

Body2is generally cylindrical and includes an annular, inner shoulder26having a surface perpendicular to central axis, C. Inner shoulder26engages one side of sealing member7. An annular rib28is formed radially outwardly of inner shoulder26, parallel to central axis, C. Rib28is positioned radially outwardly of sealing member7. Rib28includes a groove30on a radially outward face of rib28. Annular groove30receives a seal, such as an o-ring, to form a fluid tight seal between body2and adaptor1. An annular outer shoulder32is formed radially outwards of rib28and serves to align body2with adaptor1. Outer shoulder32is received in recess24.

Body2includes a vent opening34that extends through a wall of body2to provide fluid communication with the interior of body2. Vent opening34provides for egress of fluid leaking from piping10and/or a port for monitoring of leaking fluid by sensors. Body also includes an annular groove36formed on a radially inward face of body2, juxtaposed a finger38of nut3. Groove36receives a seal, such as an o-ring, to form a fluid tight seal between body2and nut3.

Nut3is generally cylindrical and includes an annular finger38positioned radially outwardly of a jacket lock ring4. Jacket lock ring4is positioned on a rear end of the body2and engages the outer jacket11of tubing10, The jacket lock ring4is received in an annular recess on the rear end of body2where outer jacket11enters the fitting. When fully assembled, finger38of nut3axially slides over jacket lock ring4thereby radially compressing jacket lock4. A distal end of finger38may have an enlarged thickness to aid in driving jacket lock ring4into outer jacket11. Jacket lock ring4includes interior barbs that engage the outer jacket11.

An annular slide ring6is positioned between nut3and outer jacket11. Slide ring6is radially inward of finger38and abuts jacket lock ring4. Slide ring6serves to drive jacket lock ring4axially towards body2. A washer8and elastomeric seal9may be positioned in an annular groove40on an interior surface of nut3. Washer8and elastomeric seal9provide an enhanced seal between the nut3and the outer jacket11. Slide ring6also pushes axially against washer8and elastomeric seal9, thereby radially compressing elastomeric seal9creating a secondary seal on outer jacket11.

As shown inFIG. 2, fasteners (e.g., cap screws)5slide through opening50in nut3, opening52in body2and engage the threads54in adaptor1. It is understood that threads may be formed on nut3, rather than adaptor1. As fasteners5are tightened, nut3, body2and adaptor1are compressed together. Shoulder26of body2interacts with a sealing member7and adaptor1to compress corrugated tubing between the adaptor1, body2and sealing member7to form a liquid tight seal. Adaptor sealing surface20is rounded a coacts with sealing surface21of sealing member7. The use of a rounded adaptor sealing surface20and planar sealing surface21reduces the load required to create a liquid tight seal.

FIG. 3is an end view of the tubing, comprising tubing10, inner jacket12, and outer jacket11. The tubing10may be corrugated stainless steel. An inner jacket12, manufactured from EFEP, for example, is positioned on the flexible tubing10. An exemplary material for inner jacket12is a fluoropolymer, available as RP-5000, from Daikin America. This material has the inherent properties of minimal permeation thus providing the secondary containment, this allows fluids (e.g., gas, liquid, etc.) to flow to ends of the outer jacket11for venting as described in U.S. Pat. No. 7,857,358. An outer jacket11surrounds the inner jacket12. An exemplary material for outer jacket11is Nylon12available as Vestamid X7297, product of Degussa. Contained in the inner diameter of outer jacket11are a number of ribs60separated by spaces. The ribs60are longitudinal and run the length of outer jacket11. Ribs60inFIG. 3are triangular in cross-section, but it is understood that other geometries may be used. In one embodiment, the fluid transported by tubing10is gasoline or diesel. In the event that tubing10leaks, fluids travel along spaces between ribs for venting through vent opening in body2. As described in U.S. Pat. No. 7,004,510, a sensor may be coupled to the vent opening34in body2to detect fluid leaks and signal such an event.

FIG. 4illustrates the fitting in an open or unassembled stated. Tubing10includes a number of peaks and valleys. Tubing10is cut in a valley and the inner jacket12and outer jacket11are removed, exposing about4peaks of tubing10. Nut3and body2are placed over the outer jacket11so that tubing10extends beyond body2. Sealing member7is placed in a first valley at the distal end of tubing10and then adaptor1is placed over the end of tubing10. As fasteners5are tightened, body3, nut2and adaptor1are compressed axially along axis, C. The peak of tubing10is compressed between adaptor sealing surface20and sealing surface21of sealing member7. This compresses a double layer of tubing10between adaptor sealing surface20and sealing surface21of sealing member7for a fluid tight seal. Also, as nut3is driven into body2, finger38drives jacket lock ring4into outer jacket11. This provides a mechanical attachment between the fitting and the tubing to control axial extension of the fitting under pressure. Also, slide ring6applies axial pressure against elastomeric seal9, thereby radially compressing elastomeric seal9creating a secondary seal on outer jacket11.

The above-described fitting and tubing provides a double containment self-venting feature and a jacket lock. By virtue of the jacket lock4and nut3, the fitting makes the outer jacket11a structural member of the joint, that is, axial extension under pressure is eliminated with this fitting.

One benefit of the fitting disclosed herein is that the fitting may be reused. Referring toFIG. 4, fasteners5may be removed from nut3, body2and adaptor1to allow the fitting to be removed from tubing10. The fitting may then be re-used with no loss of sealing or containment ability.

The tubing containment system may be used in a number of applications including direct underground burial, above ground outdoor use, indoor use at elevated pressure for safety and/or other secondary containment and sensing systems for petrochemical lines.