Abstract:
Samples of contaminants are obtained from the interior surface of a pipe main by inserting, through an opening in the pipe main, an inflatable pillow bag or balloon-like element in deflated and collapsed condition, and having a swab affixed to its outer surface. The balloon-like element is inflated inside the pipe main to extend the swab to a generally planar configuration and to press it against the inner surface of the pipe main so that it absorbs contaminants from the surface. The balloon-like element, with the swab attached, is then deflated and recollapsed; and together with the swab, is withdrawn from the pipe main.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to the obtaining of contaminant samples which have been deposited along the interior surface of a pipe; and more particularly it concerns a novel method and apparatus for applying a large area swab to the inner surface of a pipe so that a representative sample of the contaminant can be recovered from the pipe without interfering with the flow of fluid through the pipe. 
     2. Description of the Related Art 
     Large diameter pipes, such as gas mains, are often required to convey gasses which may contain harmful contaminants such as polychlorinated biphenyls (PCBs) or Benzine. These contaminants may precipitate out of the gas stream and become deposited along the interior service of the pipe. Thereafter, when clean gas passes through the pipe, it comes into contact with the contaminant deposits so that it may also become contaminated. 
     It is therefore important, at any given time, to know whether sufficient contaminants have become deposited long the inner surface of a pipe such that they would be likely to cause further contamination of clean gas passing through the pipe. It is also important not to interrupt gas flow through the pipe or otherwise disrupt its operation while inspecting its inner surface for contaminants. This becomes a difficult problem in that in order to obtain an accurate indication of the condition of a pipe&#39;s inner surface, a minimum area of the surface, usually at least four square inches (25 square centimeters), must be examined; and to expose this much of a pipe&#39;s interior while maintaining normal gas flow through the pipe is especially difficult. 
     U.S. Pat. No. 5,269,968 discloses a technique for removing PCBs from the contaminated inner surface of a pipe by means of a swab sampling technique in which the pipe is first cut into pieces to expose its inner surfaces. 
     U.S. Pat. No. 5,686,674 discloses the use of a sensor which is dragged through the interior of a pipe to sense radioactive contamination along the inner surface of the pipe. 
     U.S. Pat. No. 4,919,892 discloses the use of a perforated housing which is positioned in the path of fluid flow in a pipe to absorb contaminants from the fluid passing through the pipe. 
     U.S. Pat. Nos. 5,463,908 and No. 5,531,130 relate to the use of probes which are inserted into pipes to measure conditions in the fluids which flow through the pipes. 
     U.S. Pat. Nos. 3,842,864, 3,910,298 and 5,400,826 show the use of inflatable balloons inside of pipes to stop the flow of fluid in the pipe. 
     U.S. Pat. No. 1,636,243 shows the use of an inflatable balloon to press a pad against the interior of a pipe joint to prevent sealant, which is being applied to the exterior of the pipe joint, from leaking into the pipe. 
     A satisfactory method or means for effectively ascertaining the contamination of an inner pipe surface while fluids are flowing normally through it appears not to be disclosed in the prior art. 
     SUMMARY OF THE INVENTION 
     The present invention, in one aspect, provides an novel method of obtaining surface samples from the inner surface of a pipe main through which a fluid is flowing. According to this novel method, an opening is provided in the pipe main. There is also provided an inflatable balloon-like element with a swab affixed to its outer surface. The balloon-like element is inserted, in deflated and collapsed condition and with the swab affixed thereto, through the opening in the pipe main and into the interior of the pipe main. Then the balloon-like element is caused to inflate and expand inside the pipe main to extend the swab into a generally planar configuration and to press the swab against an inner surface of the pipe main. Thereafter, the balloon-like element is deflated and collapsed; and the collapsed balloon-like element with the swab attached, is removed from the interior of the pipe main. 
     In another aspect the invention involves a novel apparatus for use in obtaining samples of contaminants from the inner surface of a pipe main. This novel apparatus comprises a first pipe which is constructed and arranged to be connected to a pipe main so that one end of the first pipe opens into the interior of the pipe main while its other end extends outside of the pipe main. There is also provided a second pipe having attached at one end thereof, a balloon-like element made of a flexible material and which can be inflated by application of fluid pressure through the second pipe. A swab is attached to the balloon-like element so that when the balloon-like element is inflated, the swab extends generally in a plane. When the balloon-like element is deflated, it collapses, together with the swab; and in this condition the balloon-like element and the swab may be pushed by means of the second pipe, through the first pipe and into the interior of a pipe main. Means are provided for applying fluid pressure through the second pipe to inflate the balloon-like element inside the pipe main so that it presses said swab against the interior surface of the pipe main, whereby material from the interior surface adheres to said the swab. Means are provided for thereafter releasing the fluid pressure to deflate and collapse the balloon-like element and the swab so that they can be withdrawn together from the interior of the pipe main through the first pipe. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a cross-sectional view of a pipe main from the interior surface of which a contaminant sample may be obtained according to the present invention; 
     FIG. 2 is a view similar to FIG. 1 but showing a precleaning tool applied to the interior of the pipe main; 
     FIG. 3 is a view similar to FIG. 2 but showing the insertion of a sampling swab into the interior of the pipe main; 
     FIG. 4 is a view similar to FIG. 3 but showing the extension of the sampling swab by means of a balloon-like element inside the pipe main; and 
     FIG. 5 is a view similar to FIG. 4 but showing the removal of the sampling swab from the interior of the pipe main. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     As shown in FIG. 1 a gas pipe main  10  (shown in cross-section) is provided with an opening  12  at its upper portion. This opening  12  is surrounded by a threaded nipple  14  which is welded to the exterior of the pipe main. A cap  16  is threaded onto the nipple  14  to prevent escape of gas from the interior of the pipe main while allowing convenient access to the opening  12 . The pipe main may be constructed in this fashion when it is installed. Alternatively, the opening  12  may be drilled and the nipple  14  installed at any later time, as when there is a suspicion of contaminants on the inner surface of the pipe main. 
     FIG. 2 shows an arrangement for precleaning the inner surface of the pipe main  10  to remove non-chemical contaminants, such as iron cuttings, which may have been formed and dropped inside the pipe main upon drilling the opening  12 . As shown in FIG. 2, the cap  16  is replaced by a precleaning adapter  18  which is threaded onto the nipple  14 . The adapter  18  has handles  19  for tightening it onto the nipple  14 . The precleaning adapter  18  has a central opening  20 ; and a bushing assembly  22  is threaded into the central opening. 
     An elongated cleaning rod  24  extends through the bushing assembly  22  and is moveable up and down and rotationally in the assembly without significant loss of gas from inside the pipe main  10 . The upper end of the rod  24  is bent to form a handle  26  for manipulating it during a precleaning operation. 
     The lower end of the cleaning rod  24 , which is inside the pipe main  10 , is flexible and has several magnets  28  mounted thereon. 
     As shown in FIG. 2 the interior of the pipe main  10  is cleaned from magnetic objects, such as cuttings, by manipulating the rod  24  so that its lower end flexes and the magnets  28  are caused to slide over the inner surface of the main  10 . The magnets  28  cause the magnetic objects to adhere thereto so that they can be removed from the pipe main  10  by removing the precleaning adapter  18  and pulling the rod  24  and the magnets  28  out from the opening  12  in the pipe main  10 . 
     FIG. 3 shows arrangements according to the present invention for obtaining a sampling of contaminants, such as PCBs or benzine, which may have become deposited on the inner surface of the pipe main  10 . As shown, there is provided a sampling adapter  30  which is threaded onto the nipple  14 . The adapter  30  also has handles  31 , which may be used to tighten the adapter onto the nipple. The sampling adapter  30  is tapered inwardly above the nipple  14  and has a gas lock collar  32  at the upper end thereof. The gas lock collar  32  allows a pipe to be inserted into the sampling adapter  30  without leakage of gas from the pipe main  10 . 
     An elongated first pipe  34  is inserted into the gas lock collar  32  in the sampling adapter  30  so that the lower end of the first pipe opens into the interior of the pipe main  10 . The first pipe is held to the collar  32  by means of setscrew bolts  33 . The first pipe  34  extends up from the pipe main  10  by any desired distance. For example, if the pipe main  10  is buried in the ground at a particular depth, the first pipe  34  should be long enough to extend up out of the ground. 
     An elongated second pipe  36 , of smaller diameter than the first pipe  34 , is inserted into the upper end of the first pipe and is moved down through the first pipe as indicated by the arrow A in FIG.  3 . As shown, the second pipe  36  extends through the first pipe  34  and into interior of the pipe main  10 . 
     At the lower end of the second pipe  36 , there is provided a pinch clamp  38  to which is attached an inflatable pillow air bag or balloon-like element  40 . In FIG. 3, the pillow air bag or balloon  40  is shown deflated and collapsed, in which condition it can be pushed down through the first pipe  34  until it exits into the interior of the pipe main  10  below the first pipe  34 . The pillow or air bag balloon-like element  40  has a swab  42  attached to its bottom surface. The swab  42  is also in collapsed condition and is pushed down through the first pipe  34  with the pillow air bag  40 . 
     As shown in FIG. 4, a bell reducer  44  is threaded onto the upper end of the first pipe  34 . The bell reducer  44  has a smaller diameter central opening  38  into which a fitting  46  extends. The fitting is connected to the upper end of the second pipe  36  and to an air line  48  to supply pressurized air down through the second pipe  36 . A T-connector  50  is connected to the air line  48 . The T-connector has two branches which are connected, respectively, to quick-connect fittings  52  and  54 . The first quick-connect fitting  48  is connected to an air pump  56 , which may, for example, be an ordinary bicycle tire pump; and the second quick-disconnect fitting  54  is connected to a pressure release valve  58 . 
     The second pipe  36  is lowered through the first pipe  34  so that the pillow air bag or balloon  40  exits through the lower end of the first pipe. The pressure release valve  58  is closed and the air pump  56  is then operated to force pressurized air through the T-connector  50 , the air line  48  and the fitting  46  into the second pipe  36  and down into the pillow air bag  49 . This inflates the pillow air bag  40  and expands it to the condition shown in FIG.  4 . This expansion causes the swab  42  to extend to a generally planar configuration so that its entire surface area faces the internal surface of the pipe main  10 . By positioning the second pipe near the surface of the pipe main  10 , the expansion of the pillow air bag  40  by the pressure applied through the second pipe  36  causes the full surface area of the swab  42  to be pressed against the inner surface of the pipe main so that it will absorb a proper amount of contaminants from the pipe main inner surface. 
     The opening  12  in the pipe main  10  in the illustrated example is two inches (5.08 cm) in diameter but the swab  42 , when fully extended by inflation of the pillow air bag  40  may be four inches (10.16 cm) square so as to obtain a sufficient sample from the pipe main surface. The swab  42  may be attached to the pillow air bag  40  by any convenient means which will hold it securely to the pillow air bag and yet allow ready detachment. Some of the means for holding the swab to the air bag could include snap fasteners, barb and hook material such as Velcro®, zippers or even stitching. 
     The pillow air bag  40  does not necessarily have to have the identical contour of the pipe main inner surface. The pressure inside the pillow air bag needs only to be high enough to expand it and extend the swab  42 . The pillow air bag, however, when inflated may be pressed against the inner wall of the pipe main  10 ; and, because of its flexibility, it and the swab will conform to contour of the pipe main inner surface. 
     In order to be certain that the swab  42  has obtained a full sample, the second pipe  36  may be rotated at its upper end as indicated by the Arrow B so as to cause the swab to rub against the inner surface of the pipe main  10 , as shown in FIG.  4 . This ensures a good recovery of any contaminants that may be present on the pipe main inner surface. 
     When the contaminant sample has been absorbed onto the swab  42 , the pressure release valve  58  is opened and the pillow air bag or balloon-like element  40  is deflated and collapsed along with the swab  42 , as shown in FIG.  5 . Then the second pipe  36  may be pulled up to draw the collapsed pillow air bag  40  and swab  42  up through the first pipe  34  as indicated by the arrow C in FIG.  5 . In order to recover the swab, the bell reducer  44  is unscrewed from the upper end of the first pipe  34  so that the pillow air bag and swab may be removed through the upper end of the first pipe  40 . The swab may then be detached from the pillow air bag and submitted to testing to determine the nature and quantity of the contaminant. A new swab may then be attached to the pillow air bag  40  to obtain a subsequent contaminant sample. Also, if a different size pillow air bag is desired for removal of a contaminant sample from a different size pipe main, the pinch clamp  38  may be released and the pillow air bag  40  may be removed and replaced by a new pillow air bag at the bottom end of the second pipe  36 . 
     When all required samples have been obtained, the sampling adapter  30  may be removed from the nipple  14  on the pipe main  10  and replaced by the cap  16 . 
     It will be appreciated that with this invention, it is possible to obtain a representative sample of a contaminant from the inner surface of a pipe by means of a swab which has an extensive surface area, even though there is only a small opening in the pipe through which the web may be inserted.