1. Field of the Invention
The present invention relates to methods and devices used to repair damaged pipelines, walls of physical structures and holding tanks. More particularly, the present invention relates to the field repair and patching of undesirable ruptures, holes or punctures in a previously constructed and/or installed wall of a pipeline, tank or other physical structure.
2. Description of Related Art
The repair, and especially the field repair, of punctures in pipelines, storage or chemical processing tanks, and other physical structures is a matter of considerable import in numerous industrial and domestic settings, e.g. septic tanks and petroleum pipelines. The approach by a repair technician to the puncture is often limited to an interior side of the puncture, and a timely repair is best executed from an exterior side only. Welding tools and techniques are sometimes effective, but only where the pipeline, structure or tank is made of a relatively few appropriate materials, e.g. steel or aluminum. Welding can be dangerous to apply, requires rigorous technical training and expensive tooling, can cause obvious and non-obvious structural damage to the pipeline, structure or tank, is difficult to monitor for quality and may be difficult to perform in remote areas away from required facilities.
A variety of expanding element assemblies, generally referred to as molly bolts, are used to establish an opposing surface against an interior side of a wall. The molly bolt includes an expanding element and a threaded bolt, where the expanding element is initially passed through a puncture and the threaded bolt is then rotatably driven into the expanding element. It is intended by the design of the molly bolt that the shape of the expanding element changes to form a surface as the threaded bolt is advanced into the expanding element and through the puncture, and where a perimeter of the formed surface grows larger than the puncture. The perimeter of the formed surface is then forced against the interior side of the pipeline or wall as a result of the advance of the bolt into the expanding element. Molly bolts are often used to establish load bearing anchor points in drywall and other materials.
Molly bolts do not establish sealing surfaces of continuous perimeter around a puncture, hole or rupture. Molly bolts are, therefore, not useful as hole plugs to repair and seal holes in physical structures, such as tanks and pipelines, that process, contain or store chemicals or materials, to include vapors or liquids.
There is, therefore, a long felt need in various domestic and industrial arts to provide a widely applicable and easily attached hole plug of simple and inexpensive construction and that requires access to only one side of the hole for installation.