Novel modified dorn structures

Abstract

Novel thermoplastic pipes which can withstand extremely high internally generated and/or applied pressures for utilization within, primarily, high pressure underground liquid and gas transport systems are provided. Such pipes are improvements over standard metal (i.e., steel, lead, and the like) pipes due to construction costs, shipping costs, implementation costs (particularly underground), modulus strength allowances to compensate for underground movements (i.e., earthquakes and tremors), non-rusting characteristics, and ease in manufacture. Such pipes are preferably reinforced with specific fabric articles which permit a lower thickness of plastic to be utilized than is generally required to withstand high pressure situations. A simplified, potentially on-site production method for producing more uniform, better-performing pipes as well as a specific molding dorn for such a purpose are also contemplated within this invention.

What is claimed is:  
     
         1 . A molding dorn comprising a first end and a second end with areas in between said first and said second end, wherein said dorn exhibits the same diameter over its entire length and wherein said dorn exhibits a reduction in surface area numerically from said first end consecutively through all areas in between said first end to second end and ultimately to said second end.  
     
     
         2 . The molding dorn of  claim 1  wherein said dorn is substantially round at said second end.