Device for final cleaning of tubes

An apparatus for inserting cleaning plugs into the ends of tubes to be cleaned including a tool, a handle on the tool capable of being held by an operator, a chamber having an open end capable of being aligned with the open end of the tube to be cleaned, a first ram opposite the open end, a first piston-cylinder capable of moving the ram through the chamber and retracting it therefrom thereby forcing a cleaning plug into the tube, a magazine opening laterally from the first ram and open end into the chamber, a second ram positioned so as to move cleaning plugs from the magazine into the chamber, a second piston-cylinder capable of moving the second ram through and retracting it from the magazine, a housing for a chain of cleaning plugs, the housing opening into the magazine, a gas source maintaining a constant pressure on the chain of cleaning plugs so as to force a cleaning plug into the chamber when nothing else occupies it, and a trigger on the handle which in a first position pressurizes the second piston-cylinder, and in a second position pressurizes the first piston-cylinder.

BACKGROUND OF THE INVENTION 
In nuclear steam generators, great care is taken to maintain all of the 
equipment in a fairly clean state. This includes cleaning the inside of 
the heat exchange tubes before the unit is initially started up, and also 
periodically during regularly scheduled maintenance shutdowns. The tubes 
are generally cleaned by inserting and forcing felt plugs through each 
tube. Usually a plug wetted with a cleaning agent, such as isopropyl 
alcohol, is forced through, followed by a number of dry plugs. Since there 
are many tubes in each steam generator (upwards of 10,000), and the tubes 
are rather small in diameter (5/8 of an inch ID), the cleaning is a long 
and tedious job. The present invention is directed to apparatus by means 
of which workers can quickly and easily load felt plugs (either dry or 
wetted with a cleaning agent) into the tubes of a nuclear steam generator 
so that they can be forced therethrough by a pressurized inert gas. 
SUMMARY OF THE INVENTION 
In accordance with the invention, apparatus in the form of a tool or gun 
which can be hand-held by a worker is provided by a means of which 
cleaning plugs can be inserted into the open ends of steam generating 
tubes. A button or trigger on the handle of the tool permits isopropyl 
alcohol to be discharged into the tube being cleaned when desired. A 
second trigger on the handle is used to actuate sequential valves which 
moves a plug from the magazine to the firing chamber, and thence into the 
tube to be cleaned. High pressure gas is used as the actuating means. A 
pair of pins on the front of the tool are used to accurately align the 
tool or gun with the tube to be cleaned.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Looking now to the FIGURE, numeral 10 designates a tool or gun in its 
entirety which can be used to insert felt plugs into steam generating 
tubes 12 for cleaning them. The steam generating tubes 12 are usually 
U-shaped, and are attached to a tube sheet 14 at both of their ends. A 
typical nuclear steam generator has thousands of such U-shaped tubes, the 
interior of which must be cleaned. A plurality of felt plugs 16 are 
contained in a flexible tube 18, and are forced into magazine 20 by a 
constant low pressure gas source 22 acting on the end of the plugs. 
The plug 16 contained in magazine 20 is forced into chamber 26 by means of 
ramrod 28, which is secured to a piston rod 30 and piston 32. High 
pressure air is admitted to cylinder 34 behind the piston 32 when a plug 
is to be moved into chamber 26. Spring 36 moves the piston back to its 
original position in contact with stop member 38 when the pressure on 
piston 32 is released. Pressure is supplied to and released from cylinder 
34 by means of 3-way valve 40 contained in the handle 42 of the gun or 
tool 10. When valve stem 44 is depressed by trigger 46, high pressure gas 
from a source 48 and a line 50 is supplied to cylinder 34 through line 52. 
When the trigger 46 is released, 3-way valve 40 opens line 52 to the 
atmosphere. 
After a felt plug has been placed into chamber 20, trigger 46 is actuated 
so as to open the 3-way valve 54 by depressing valve stem 56, allowing 
high pressure gas from source 48 to enter the cylinder 58 through line 60. 
This actuates ram 62 through piston 64 and rod 66, forcing a plug into the 
tube 12. When the pressure is released from cylinder 58 through 3-way 
valve 54, spring 68 returns piston 64 to its original position against 
stop 70. 
When it is desired to add isopropyl alcohol to one of the cleaning plugs 
16, button or trigger 72 on the handle 42 is depressed, which opens valve 
74, permitting flow of the cleaning agent from a pressurized source 76 
through line 78, valve 74 and line 80 into nozzle 82, which discharges 
into the front part of chamber 26. When a plug is to be wetted, the button 
72 is actuated, forcing alcohol through the nozzle 82 into chamber 26 and 
tube 12, and then stuffing the plug in behind the alcohol. 
Spring 84 and plunger 86 on the handle 42 is only for the purpose of 
maintaining the trigger 46 in a neutral position, and to act as a stop 
when trigger 46 is pivoted clockwise about pivot 88. The spring biasing 
the valve 40 to its closed position is stronger than spring 84. Thus, both 
3-way valves 40 and 54 are normally in their closed position; i.e., with 
their respective cylinders 34 and 58 open to the atmosphere and not 
connected to the high pressure gas source 48. A pair of pins 90 and 92 are 
fit into adjacent tubes so that the chamber 26 is properly aligned with 
the tube a felt plug is being inserted into. These pins have tapered ends 
for ease of entry into tubes 12. 
The operation of the gun or tool 10 will now be described. A worker will 
hold the tool 10 by its handle 42 and bring the forward end into 
engagement with the tube sheet 14 with pins 90 and 92 extending into two 
of the tubes 12. Chamber 26 is thus firmly aligned with a third tube 12. 
If a saturated plug is desired, button 72 is depressed, forcing alcohol 
into the forward end of chamber 26 and the tube 12. Trigger 46 is 
thereafter pivoted in a counterclockwise direction about pivot point 88, 
opening 3-way valve 40, so that high pressure gas flows to cylinder 34, 
moving ram 28 upwardly, forcing a felt plug 16 into the chamber 26. The 
trigger 46 is then rotated clockwise about pivot point 88. This releases 
the pressure in cylinder 34 to the atmosphere, withdrawing plunger or ram 
28 to its original position and causing another felt plug to enter the 
magazine 20. It also opens valve 54, causing high pressure gas to enter 
cylinder 58, moving ram 62 to the right, forcing the felt plug into the 
open end of the tube 12. As many plugs can be placed in as many of the 
tubes as desired by the use of the tool 10, and then another tool can be 
used to blow the plugs through the tubes by means of pressurized inert 
gas.