Method and apparatus for securing tubes in a steam generator against vibration

Abstract

A method of and apparatus for securing tubes within a steam generator against vibration with a metallic anti-vibration bar in a tube bundle. The tube bundle has a plurality of tubes, arranged in rows and columns, with lanes between the tube columns. The method comprises the steps of: inserting the anti-vibration bar in the tube bundle; plastically expanding the wall of the anti-vibration bar from an unexpanded position to an expanded position. In the unexpanded position there are a plurality of gaps between the anti-vibration bar and the tubes of the tube bundle. The gaps decrease in size as the wall of the anti-vibration bar moves from the unexpanded position to the expanded position.

What is claimed is: 
     
         1 . A method of securing tubes within a steam generator against vibration with a metallic anti-vibration bar in a tube bundle, wherein the tube bundle has a plurality of tubes, arranged in rows and columns, with lanes between the tube columns, the method comprising the steps of:
 inserting the anti-vibration bar in the tube bundle;   plastically expanding the wall of the anti-vibration bar from an unexpanded position to an expanded position;   wherein in the unexpanded position there are a plurality of gaps between the anti-vibration bar and the tubes of the tube bundle, the gaps decreasing in size as the wall of the anti-vibration bar moves from the unexpanded position to the expanded position; and   wherein in the unexpanded position the anti-vibration bar is substantially flattened.   
     
     
         2 . The method of  claim 1  wherein a residual preload is created between the anti-vibration bar and the tubes of the tube bundle when the wall of the anti-vibration bar is in the expanded position; and
 wherein more than a tangential contact is created between the anti-vibration bar and the tubes in the tube bundle when the wall of the anti-vibration bar is in the expanded position. 
 
     
     
         3 . The method of  claim 1  wherein the anti-vibration bar is another tube, the another tube having a first end that is sealed and a second end that is coupled to a pressure source, the another tube being disposed in a longitudinal axis situated between the first end and the second end;
 wherein the pressure source plastically expands the wall of the another tube from the unexpanded position to the expanded position. 
 
     
     
         4 . The method of  claim 3  wherein the first end is welded shut. 
     
     
         5 . The method of  claim 3  wherein the pressure source is a hydraulic or pneumatic pressure source and the second end includes a coupling assembly, the hydraulic or pneumatic pressure source being removably coupled to the coupling assembly. 
     
     
         6 . The method of  claim 5  wherein the pressure source is a hydraulic pressure source and the hydraulic pressure source is removed before the steam generator is placed into service. 
     
     
         7 . The method of  claim 5  wherein the pressure source is a pneumatic pressure source, the pneumatic pressure source being removed before the steam generator is placed into service, and wherein the pressure required to plastically expand the wall of the another tube is less than 500 psi. 
     
     
         8 . The method of  claim 1  wherein the anti-vibration bar has a first end, a second end, and a first chamber disposed within the anti-vibration bar between the first end and the second end, the first end being coupled to a pressure source, the pressure source plastically expanding the wall of the first chamber from the unexpanded position to the expanded position. 
     
     
         9 . The method of  claim 8  wherein the anti-vibration bar has a second chamber disposed within the anti-vibration bar between the first end and the second end, the pressure source plastically expanding the wall of the second chamber from the unexpanded position to the expanded position. 
     
     
         10 . The method of  claim 9  wherein the first chamber and the second chamber are each either round shaped or oval shaped. 
     
     
         11 . The method of  claim 9  wherein the pressure source is a hydraulic pressure source and the first end includes a coupling assembly, the hydraulic pressure source being removably coupled to the coupling assembly. 
     
     
         12 . A steam generator having a primary side for circulating a heated fluid and a secondary side having an axial dimension, for circulating a fluid to be heated by the heated fluid circulating in the primary side, comprising:
 a channel head for receiving the heated fluid;   a tube sheet that separates the channel head from the secondary side;   a tube bundle having a plurality of tubes, arranged in rows and columns, with lanes between the tube columns, the tube bundle extending from the channel head, through the tube sheet and through at least a portion of the secondary side;   at least one metallic anti-vibration bar disposed within the tube bundle;   wherein the wall of the at least one anti-vibration bar is structured to plastically expand from an unexpanded position to an expanded position;   wherein in the unexpanded position there are a plurality of gaps between the at least one anti-vibration bar and the tubes of the tube bundle, the gaps decreasing in size as the wall of the at least one anti-vibration bar moves from the unexpanded position to the expanded position; and   wherein in the unexpanded position the at least one anti-vibration bar is substantially flattened.   
     
     
         13 . The steam generator of  claim 12  wherein more than a tangential contact is created between the at least one anti-vibration bar and the tubes of the tube bundle when the at least one anti-vibration bar is in the expanded position; and
 wherein a residual preload is created between the at least one anti-vibration bar and the tubes of the tube bundle when the wall of the at least one anti-vibration bar is in the expanded position. 
 
     
     
         14 . The steam generator of  claim 12  wherein the at least one anti-vibration bar is another tube, the another tube having a first end that is sealed and a second end that is adapted to be coupled to a pressure source, the another tube being disposed in a longitudinal axis situated between the first end and the second end;
 wherein the pressure source plastically expands the wall of the another tube from the unexpanded position to the expanded position. 
 
     
     
         15 . The steam generator of  claim 14  wherein the first end is welded shut. 
     
     
         16 . The steam generator of  claim 14  wherein the pressure source is a pneumatic pressure source, the pneumatic pressure source being removed before the steam generator is placed into service, and wherein the pressure required to plastically expand the wall of the another tube is less than 500 psi. 
     
     
         17 . The steam generator of  claim 12  wherein the at least one anti-vibration bar has a first end, a second end, and a first chamber disposed within the at least one anti-vibration bar between the first end and the second end, the first end being adapted to be coupled to a pressure source, the pressure source being structured to plastically expand the wall of the first chamber from the unexpanded position to the expanded position. 
     
     
         18 . The steam generator of  claim 17  wherein the at least one anti-vibration bar has a second chamber disposed within the at least one anti-vibration bar between the first end and the second end, the pressure source being structured to plastically expand the wall of the second chamber from the unexpanded position to the expanded position. 
     
     
         19 . The steam generator of  claim 18  wherein the first chamber and the second chamber are each either round shaped or oval shaped. 
     
     
         20 . The steam generator of  claim 18  wherein the pressure source is a hydraulic or pneumatic pressure source and the first end includes a coupling assembly.