Patent ID: 6929023

Claim:
A natural gas pipeline having a back flow prevention device installed therein, the natural gas pipeline being formed of polyethylene having a given external diameter and an interior, the back flow prevention device being formed primarily of plastic material compatible with the polyethylene pipeline, the combination comprising: a check valve mechanism press-fit within the interior of a surrounding body making up a portion of pipeline and seated against a pre-existing register provided within the interior of the pipeline, the check valve mechanism allowing flow of fluids in a first direction and preventing the flow of fluids in a second, opposite direction; wherein the surrounding body has opposing ends formed of a plastic material which is compatible with the polyethylene of the pipeline, and wherein the surrounding body has an external diameter which is substantially equal to that of the remainder of the pipeline, whereby the surrounding body can be installed in the pipeline in co-axial fashion by directly joining and fusing the opposing ends thereof to opposing mating pipe ends at a selected location within the pipeline.