Flexible insert for tubing

The flexible insert for tubing includes an insert for water service tubing or the like that prevents the formation of stress cracks on the tubing when using a compression fitting. The insert is formed, at least in part, from an elongated, resilient, helical coil having opposed first and second ends. In one embodiment, the coil terminates in an enlarged turn or loop at one end of the coil that serves to retain the coil in the tubing. In another embodiment, the coil is butt welded to one end of a short, rigid sleeve having an annular flange at the opposite end. The insert also includes an O-ring and a compression nut.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to fittings for flexible tubing used in plumbing connections for water and gas, and particularly to a flexible insert for tubing having a stiffener made, at least in part, from a resilient, helical coil.

2. Description of the Related Art

Flexible tubing, such as polyethylene tubing, is used for a wide variety of applications, such as water delivery and in the delivery of natural gas. Hoses and tubes are often joined to a valve or other fixture of a water supply by a compression fitting. A great deal of stress is placed on the tubing near the point of connection, particularly from the weight of soil backfill for at least partially buried tubing. If the tubing bends at too sharp a radius, the tubing may develop cracks that deteriorate over time, causing expensive leaks. Rigid stiffeners are often used in combination with flexible tubing, particularly in combination with compression fittings, however, such rigid stiffeners exacerbate this problem. Thus, a flexible insert for tubing solving the aforementioned problems is desired.

SUMMARY OF THE INVENTION

The flexible insert for tubing includes an insert for water service tubing or the like that prevents the formation of stress cracks on the tubing when using a compression fitting. The insert is formed, at least in part, from an elongated, resilient, helical coil having opposed first and second ends. In one embodiment, the coil terminates in an enlarged turn or loop at one end of the coil that serves to retain the coil in the tubing. In another embodiment, the coil is butt welded to one end of a short, rigid sleeve having an annular flange at the opposite end. The compression fitting also includes an O-ring and a compression nut.

In use, the compression nut and O-ring are placed over the tubing, the insert is placed into the open end of the flexible tubing or conduit with the enlarged coil turn or sleeve annular flange abutting the open end, and the compression nut is threaded onto the valve or other threaded fitting, compressing the O-ring to form a seal. The insert provides sufficient stiffness for structural reinforcement of the tubing to prevent collapse of the tubing, but sufficient flexibility to permit the tubing to bend as needed, but not in a sharp radius.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The flexible insert10for flexible tubing has an insert for gas or water service tubing T that prevents the formation of stress cracks on the tubing T at the main line connection point. Rigid inserts typically used with compression fittings typically crack the tubing T near the main line connection point due to the stress caused by the weight of settling earth backfill on the tubing and the insert. The flexible insert10provides additional structural integrity and distribution of stress forces along the length of the tubing T.

In the drawings, the flexible insert10is shown being used with water service tubing T applied to a valve S or other threaded fitting and held by a compression nut N.FIGS. 1 and 3show an exemplary connection for tubing T using a flexible insert10. The compression fitting includes a compression nut N, an O-ring R, and an insert. As shown, the compression nut N is slid is onto the tubing T, followed by the O-ring R. The insert tube is then slid into the tubing T and the compression nut N is tightened. As the compression nut N is tightened, the O-ring R compresses, forming a seal around the tubing T.

The insert includes a relatively tightly wound, elongated, resilient helical coil12formed from stainless steel or any other suitable resilient, flexible material that is non-corrosive and resistant to water damage. The helical coil12preferably has an outer diameter corresponding to the inner diameter of the tubing T. In one embodiment, shown inFIGS. 1-3, the insert has a hollow, rigid, cylindrical sleeve14having an annular flange at one end22. The opposite end24is butt welded to the end of the coil12, as best shown inFIG. 2. Sleeve14is formed from stainless steel or any other suitable material that is non-corrosive and resistant to water damage.

In another embodiment, shown inFIG. 4, the insert100is an elongated, resilient, helical coil112having a single end turn116or loop at one end122of the coil that is of larger diameter than the remainder of the coil, and an opposite free end124.

In use, the insert is placed inside the tubing T with either the annular flange16or the wider diameter end turn116abutting the open end of the tubing T prior to threading the nut N on the valve fitting S. The resilience and stiffness of the coil12or112prevents the tubing T from collapsing, but has sufficient flexibility to permit bending the tubing without permitting such a sharp radius that the tubing T might crack.