Plastic-lined metallic pipe for conveying drinking-water and the connectors for the same

Abstract

A plastic-lined metallic pipe for conveying liquid or gas includes a continuous inner plastic sleeve and an outer seamless metallic pipe. The outer diameter of the plastic sleeve is circumferentially melt-bonded to the inner diameter of the outer pipe. The plastic sleeve constitutes an uninterrupted lining for the metallic pipe. Also disclosed is a connector used for connecting the plastic metallic pipe. The connector includes a body, a cap, and three washers. The body has a section of thread in its outer wall for coupling with the cap which has a section thread in its inner wall. In operation, first insert the pipe into the cap, then insert the rubber washer, the metallic washer, and spring washer into the body, and then screw the cap into the body, such that the pipe is locked with the body.

1 . A plastic-lined metallic pipe for conveying liquid or gas, comprising:
 a continuous inner plastic sleeve; and   an outer seamless metallic pipe,   the outer diameter of said plastic sleeve being circumferentially melt-bonded to the inner diameter of said outer pipe, said plastic sleeve constituting an uninterrupted lining for said metallic pipe.   
   
   
       2 . The plastic-lined metallic pipe of  claim 1 , wherein said plastic sleeve is formed of a non-poisonous plastic suitable for conveying drinking-water. 
   
   
       3 . The plastic-lined metallic pipe of  claim 2 , wherein said plastic sleeve is formed of polypropylene. 
   
   
       4 . The plastic-lined metallic pipe of  claim 2 , wherein said metallic pipe is formed of aluminum alloy. 
   
   
       5 . A method for a plastic-lined metallic pipe for conveying liquid or gas, comprising steps of:
 heating a metallic pipe evenly to a first temperature;   cooling a plastic pipe evenly to a second temperature;   inserting the plastic pipe into the metallic pipe to constitute an inner sleeve;   drawing the metallic pipe from its two ends; and   cooling the sleeved pipe to a storage temperature.   
   
   
       6 . The method of  claim 5 , wherein said plastic pipe is formed of a non-poisonous plastic suitable for conveying drinking-water. 
   
   
       7 . The method of  claim 6 , wherein said plastic pipe is formed of polypropylene. 
   
   
       8 . The method of  claim 7 , wherein said metallic pipe is formed of aluminum alloy. 
   
   
       9 . A connector used for connecting pipes, comprising:
 at least one body having a first stepped cylindrical inner space and a section of thread in its outer wall, the first stepped cylindrical inner space including a first cylindrical space as a conveying channel, a second cylindrical space for holding a pipe to be connected to the body, a tapered cylindrical space, and a third cylindrical space, the first cylindrical space's diameter being identical with the pipe's inner diameter and the second cylindrical space's diameter being slightly larger than the pipe's outer diameter;   a cap having a second stepped cylindrical inner space and having a section of thread in its inner wall for coupling with the body, the second stepped cylindrical inner space including a fourth cylindrical space for coupling with the body and a fifth cylindrical space in the cap's end wall for holding the pipe;   a tapered rubber washer for filling the gap between the pipe and the wall of the second cylindrical space;   a metallic washer for pressing the rubber washer; and   a “c” type spring washer for locking the pipe when the cap is being coupled with the body;   wherein when connecting the pipe to the body, the following assembling order is complied: inserting one end of the pipe into the cap from the cap's end wall, then into the spring washer, the metallic washer and the rubber washer, then inserting the one end of the pipe into the second cylindrical space of the body, then sliding the rubber washer and the metallic washer into the third cylindrical space of the body, then slightly squeezing the spring washer and inserting it into the third cylindrical space of the body, and then screwing the cap in.   
   
   
       10 . The connector of  claim 9 , wherein the metallic washer has a cylindrical extruding member facing the spring washer, such that when the cap is screwed in, the extruding member applies a force to the spring washer to make the spring washer squeeze and lock around the pipe. 
   
   
       11 . The connector of  claim 10 , wherein the spring washer has a tapered cylindrical surface facing the metallic washer, such that when the cap is screwed in, the tapered cylindrical surface transforms the force from the extruding member into a concentrating force required to squeeze and lock the spring washer. 
   
   
       12 . The connector of  claim 9 , wherein the cap's end wall has a cylindrical extruding member facing the spring washer, such that when the cap is screwed in, the extruding member applies a force to the spring washer to make the spring washer squeeze and lock around the pipe. 
   
   
       13 . The connector of  claim 12 , wherein the spring washer has a tapered cylindrical surface facing the extruding member, such that when the cap is screwed in, the tapered cylindrical surface transforms the force from the extruding member into a concentrating force required to squeeze and lock the spring washer. 
   
   
       14 . The connector of  claim 9 , wherein the spring washer has a rough inner surface for locking around the pipe. 
   
   
       15 . The connector of  claim 9 , wherein the spring washer has a section of thread in its inner surface for locking around the pipe.