Double Expansion Boiler Tube Plug

Abstract

The following substitute specification does not contain and new matter as that submitted in the Provisional Patent Application No. 61/018,908 filed on Jan. 4, 2008. The boiler plug system of the invention is intended for plugging leaks in the steel tube flue gas-to-water heat exchangers of steam boilers. The boiler plug of the invention is adaptable to the varied sizes of heat exchanger tubes. In this specification, the elements of the invention will be described as applied to two (2) inch ID (inside diameter) steel tubing heat exchangers with the understanding that the boiler plug of the invention can be made smaller or larger as the particular application may require. The boiler plug of the invention is readily adaptable to heat exchanger tubing of one and one-half (1.5) to three (3) inch ID. The boiler heat exchanger panel consists of a closely packed bundle of lengthy steel tubes having a diameter of about two (2) inches. Hot flue gasses passing from the firebox exchange heat through the tube wall with circulating water. Due to the hot flue gasses corrosive nature, tubing leaks frequently occur. These leaks must be corrected relatively promptly before a leak compromises the integrity of adjoining tubes and worsens the problem. The boiler plug of the instant invention seals the tube at the point of the leak by combining two techniques: 1. Inserting a copper sleeve of a slightly smaller diameter than the faulty tube into the faulty tube, and two (2) tapered, cast-iron plugs of a slightly smaller diameter than the sleeve until the sleeve is directly over the corroded area of the tube; 2. Threading a bolt through the center of both plugs and then tightening the plugs together. By this technique, the rod brings the cast-iron plugs together within the copper sleeve and compresses the copper sleeve against the inner surface of the tube thus sealing the leak. This eliminates the need to drain and cool the boiler before the tube can be patched from both ends or replaced. The major parts of the boiler plug of the instant invention are as follows: A tool smaller than the diameter of the tube the length of which can be adjusted depending on the length of the tube. A sleeve made of an outer layer of rubber and an inner layer of copper having a maximum circumference marginally smaller than the circumference of the tube. Two (2) tapered plugs made of cast-iron with a slightly smaller diameter than the sleeve which are threaded onto a threaded steel bolt which has a cap on one end the same diameter of the sleeve. The rod is longer than the length of the plug-sleeve assembly allowing the tool to be threaded onto it. An important element of the boiler plug of the instant invention is the design and composition of the sleeve. When the plugs are pulled together inside the sleeve, by turning the tool onto the threaded bolt, the plugs are forced together compressing the sleeve against the interior of the tube, thereby sealing the tube end and assuring the end of the leakage. Another important element of the invention is the design of the tool. The tool, which is reusable, can be made longer or shorter by the use of extension pieces and may be used with any length or diameter tubing. It is to be understood that the present invention is not limited to the embodiments described above, but encompasses any and all embodiments within the scope of the following claims.

1 . In a boiler plug repair system, the combination of an adjustable length tool; a tubular sleeve; two tapered plugs; a threaded bolt longer in length than the plug-sleeve assembly, which has a cap on its end the same diameter as the sleeve. 
   
   
       2 . The combination in  claim 1 , wherein the tool can be adjusted depending of the length of the boiler tube and is of a smaller diameter than the diameter of the boiler tube and has a mechanism by which. 
   
   
       3 . The combination of  claim 1 , wherein sleeve used to seal the leak is comprised of an outer layer of rubber and an inner layer of copper. 
   
   
       4 . The combination of  claim 1 , wherein said threaded bolt full threaded rod. 
   
   
       5 . The combination of  claim 1 , wherein said tapered plug is made of cast-iron. 
   
   
       6 . A method for sealing leaking boiler heat exchanger tubes comprising the combination in  claim 1 ; inserting the combination of the sleeve, plugs, threaded bolt into the tube, turning the tool which is connected to the threaded bolt which forces the plugs into the sleeve, expanding the sleeve and sealing the leak.