Tool for sampling oil from electric distribution transformer tanks for PCB contamination

A tool for piercing an electric distribution transformer tank for obtaining a sample of oil therefrom to be tested for PCB contamination is disclosed. The tool includes a threaded body with a wrenchable fitting on one end and a tank punch pin on the other and is adapted for threadable insertion into a threaded hollow shaft of a ground lug nut attached to the tank. The pin is advanced in the lug nut shaft to pierce the tank by wrenchably rotating the fitting. Hollow shafts formed through the pin, punch body and fitting provide a path for the flow of oil from a space in the lug nut shaft between the hole in the tank and the end of the punch body to a syringe which contains a threaded tip inserted into a threaded shaft in the fitting when suction is drawn by the syringe on the shafts after the hole is punched and the pin is backed slightly out of the hole. A threaded nut seals the threaded shaft in the fitting after the filled syringe is removed from the tool to prevent oil leakage. A first nut having a compressible, resilient O-ring partially disposed in a tapered annulus thereof is threadably advanced on the threaded body against the lug nut to prevent oil leakage from the lug nut shaft around the threaded body of the tool. A washer and second nut on the punch body combine with the first nut to form a transformer ground wire attachment assembly to ground the transformer tank through the tool and lug nut.

BACKGROUND OF THE INVENTION 
This invention relates generally to a tool for punching a hole in the wall 
of an electric distribution transformer tank to remove a sample of oil 
therefrom without the necessity of deenergizing the transformer or 
removing the tank lid. More specifically, the invention relates to a 
transformer tank punch which is threadably insertable into an interiorly 
threaded hollow shaft in a conventional ground lug nut welded to the side 
of a transformer tank for removing a sample of oil from the tank through 
the tool itself by means of a suction device attached to the tool, the 
tool also providing a permanent seal for the hole punched in the tank and 
means for attaching a ground wire thereto to permanently ground the tank. 
Some years ago, over a span of many years, a large number of electric 
distribution transformers were manufactured in this country for use by 
electric utilities in which the transformer coil and core were disposed in 
a steel tank filled with oil, which oil contained the now dreaded 
polychlorinated biphenyls known as PCBs. Since the devastating adverse 
effects of PCBs on human health have been confirmed, a nationwide cleanup 
effort is underway under federal government mandate. 
Part of this effort involves the sampling and testing of oil contained in 
suspect electric distribution transformers currently in service or in 
place in this country which were manufactured and/or distributed during 
the time period when PCBs were in use in the electric utility industry. 
Those transformers found to contain PCB contamination in their cooling oil 
must be promptly removed from their location and the contaminated oil must 
be disposed of according to stringent EPA guidelines. The monumental task 
still lying ahead for the electric utility industry in this regard is 
staggering in its many aspects, one major aspect of which is the huge 
number of man hours of time that will be required for line crews to check 
the oil in each and every suspect transformer. 
In the past, it has been necessary in many cases to de-energize each pole 
mounted distribution transformer to be tested so that the tank lid, upon 
which a high voltage primary feedthrough bushing is mounted, can be safely 
unbolted and removed from the top of the tank to permit access to the oil 
within the tank by a lineman either secured by a belt from the pole or 
standing in a carefully positioned bucket of a line truck. In such cases, 
since the lineman is operating around the primary bushing and the line 
leading from the bushing to the high voltage primary distribution circuit, 
that portion of the circuit in which the lineman might conceivably come 
into contact, must be de-energized before the lid can safely be unbolted 
and removed. Then, following sampling of the oil from the transformer 
tank, the lid must be secured back in place on the transformer tank and, 
if the oil is determined to be free of PCB contamination, the transformer 
must be re-energized. Otherwise, if the sample is found to be 
contaminated, the lid is replaced and the transformer is removed from the 
pole and from further service. 
More recently, a gun containing a punch pin has been used to puncture a 
transformer tank in the air space above the oil level after which a 
pipette containing a manually compressible suction bulb is inserted into 
the puncture and down into the oil to remove an oil sample. Thereafter, 
the puncture is sealed using a resilient plug. Since the puncture must be 
made at a high level on the tank above the oil level, the worker is in 
dangerously close proximity to the primary circuit connected to the 
transformer. Moreover, the security of the resilient plug in maintaining 
integrity of the puncture seal over an extended period of years is 
questionable. Also, the violent effect of driving the puncture pin into 
the tank using an exploding shell exposes the worker to the possibility of 
contact of the pin with the energized transformer coil with the potential 
for disastrous results. Lastly, since some transformers under certain 
conditions may include a positive air pressure in the space above the oil 
relative to ambient, in such cases the worker could be exposed to rapid 
expansion of air mixed with oil expelled through the puncture which in the 
worst case could contain PCB and, in addition, hot or even boiling oil. 
Now since many of the distribution transformers in any given electric 
utility service area will be free of any PCB contamination, it would be 
highly advantageous from the standpoint of the time required to take oil 
samples from these units, if the samples could be safely taken without 
having to unbolt and remove the tank lids and without the necessity of 
first de-energizing that portion of the high voltage primary circuit in 
which the lineman might conceivably come into contact during the lid 
removal activity, and without having to replace and secure the tank lid 
after the sample is taken and, finally, without having to re-energize the 
contamination free transformers after the oil samples have been obtained. 
Even in the case of those transformers found to contain PCB contamination, 
it would be an enormous saving of time if the oil in the tank of such 
units could be safely sampled without the need to first de-energize the 
transformer, then unbolt and remove the lid to gain access to the oil, and 
then replace and secure the lid preparatory to bringing the transformer 
down off the pole. Moreover, it would also be advantageous to provide a 
relatively safe means for sampling oil from energized transformers by 
minimizing the risk of exposure to hot contaminated oil and explosion of 
the transformer assembly. 
Generally speaking, devices for punching holes in liquid filled containers 
to remove some or all of the liquid have long been known in the prior art. 
See, for example, the tap for drawing kerosene from cans as disclosed in 
U. S. Pat. No. 552,408 issued to G. Barnes on Dec. 31, 1895. One disclosed 
example of the reference device is a handgun shaped unit having a central 
projecting pin surrounded by rotatable cutter elements. The pin is punched 
into a tin can and the device is rotated to cut a circular opening into 
which a threaded punch body is screwed so as to jam a rubber washer 
surrounding the punch body against the can wall around the hole. A screw 
plug is then adjusted to permit kerosene to flow from the can through the 
punch body and handle as desired. Obviously, the can can not be reused 
without the punch body being in place in the hole with the rubber washer 
tightly abutting the can wall around the hole to prevent leakage. This 
assembly, while suitable for manually punching a hole in a thin walled tin 
can and thereafter scribing or cutting a hole therein, is clearly unsuited 
for safely penetrating the heavy gauge steel wall of an electric 
distribution transformer tank. 
Devices which permit the sampling of a fluid from within reaction vessels 
and other cylindrical containers with a needle syringe have also been 
known in the prior art. See U.S. Pat. No. 4,056,981 issued to J. Kalka et 
al. on Nov. 8, 1977 and U.S. Pat. No. 4,010,648 issued to R. J. Harris, 
Sr. et al. on Mar. 8, 1977. Both of these devices employ fittings which 
must be affixed to the container wall so as to communicate with the 
interior thereof, after which a needle syringe can be used to penetrate a 
seal in the fitting to access the fluid in the container. The use of such 
a resilient seal is not deemed satisfactory to seal a transformer tank 
over a term of years. 
See also U.S. Pat. No. 4,809,735 issued to F. R. Volstadt et al. on Mar. 7, 
1989 and U.S. Pat. No. 4,598,731 issued to D. G. Colson on July 8, 1986 
which disclose two different types of screw-in-valve tapping devices for 
gas mains and high pressure water lines, the latter being a screw-in-type 
punch and the former being a screw-in-type fitting. Neither of these 
devices have the capability of providing a grounding assembly for 
attachment of a ground wire to ground a transformer tank after an oil 
sample has been taken. Moreover, both devices require special fittings 
attached to the gas or water lines before those lines are placed in use. 
Lastly, see U. S. Pat. No. 3,915,192 issued to J. A. Skvarenina on Oct. 28, 
1975 which discloses another type of piercing valve for connection to a 
puncturable conduit. The device also contains a resilient pad seal for the 
area being punctured to prevent leakage and a wrenchable nut on the rear 
end of an internally threaded cap member for permitting wrenchable 
rotation of the device to punch a hole in the conduit. This device also 
fails to provide means for attaching a transformer ground wire thereto to 
provide a permanent ground for a transformer tank once a liquid sample is 
removed therefrom. Moreover, as previously mentioned, the long term 
integrity of a resilient seal for a hole punched in a transformer tank is 
highly questionable. 
By means of my invention, these and other difficulties encountered with 
such prior art devices are substantially overcome. 
SUMMARY OF THE INVENTION 
It is an object of my invention to provide a tool for piercing the metal 
wall of an active electric distribution transformer to obtain an oil 
sample from the tank without the need for de-energizing the transformer. 
It is yet another object of my invention to provide a tool for facilitating 
the sampling of oil from an electric distribution transformer with the aid 
of a syringe or other suitable suction generating device removably 
attached to the tool. 
It is yet another object of my invention to provide a tool for threadable 
insertion into an interiorly threaded shaft of a ground lug nut attached 
to the wall of an electric distribution transformer tank to punch a hole 
in the tank wall at the base of the lug nut shaft to obtain a sample of 
oil from the tank, which tool thereafter serves to permanently seal the 
hole to prevent oil leakage. 
It is also an object of my invention to provide a tool for facilitating the 
sampling of oil from an electric distribution transformer tank which also 
permits attachment of a ground wire thereto to permanently ground the 
transformer tank. 
Briefly, in accordance with my invention, there is provided a tool for 
sampling oil from an electric distribution transformer tank of the type 
which includes a ground lug nut containing an interiorly threaded hollow 
shaft rigidly attached to a wall of the tank. The tool includes a threaded 
body portion adapted for threadable insertion into the lug nut shaft and 
punch means attached to the body portion for punching a hole in the tank 
wall as the body portion is threadly advanced in the lug nut shaft. A 
wrenchable fitting for rotating the body portion to advance and retract 
the body portion in the lug nut shaft is also included. Shaft means 
defined by the punch means and body portion is also included which extends 
between a first opening on the punch means and a second opening on the 
body portion for providing an oil flow path between the openings upon 
application of suction to the second opening. 
These and other objects, features and advantages of my invention will 
become apparent to those skilled in the art from the following detailed 
description and attached drawings upon which, by way of example, only a 
preferred embodiment of my invention is illustrated.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now to the drawing figures, in particular FIGS. 1-3, there is 
shown a conventional single phase electric distribution transformer 
assembly 10 mounted in the usual manner on a wooden utility pole 12 as, 
for example, by means of brackets 14 and bolts 15. A tank 16 of the 
transformer assembly 10 is constructed of steel and defines an interior 
chamber containing the usual transformer core and windings, not shown, 
immersed in a pool of oil 18. The tank 16 has an open upper end covered by 
a removable lid or cover 20. A feed through insulator 22 is mounted on the 
cover 20 to which a high voltage electric distribution primary line 24 is 
attached. A series of feed through insulators 26 located on an upper 
portion of the tank 16 connect the transformer secondary windings, not 
shown, to a low voltage secondary customer distribution circuit 28 in the 
usual manner. A ground lug nut 30, exaggerated in size in FIG. 1 relative 
to the tank 16, is welded to the outer surface of the tank 16 and 
conventionally contains a hollow, interiorly threaded shaft 32 into which 
a bolt, not shown, can ordinarily be inserted to secure a ground wire so 
as to ground the tank 16 in the usual well known manner. 
Now, in accordance with my invention, there is shown in a preferred 
embodiment thereof, a tool 34 which includes a cylindrically-shaped body 
portion 36 containing screw threads 38 adapted for threadable insertion 
into the threaded shaft 32 of the transformer ground lug nut 30. A punch 
means in the form of a hardened steel pin 40 is provided which contains a 
cylindrically shaped body section 41 and a cone shaped pin head section 
42. The body section 41 is partially disposed and rigidly secured, as by 
press fitting, within a blind shaft 43 formed in a forward end segment of 
the body portion 36 such that a small portion of the section 41 projects 
forwardly out of the shaft 43 beyond a forward end 44 of the body portion 
36. A wrenchable fitting 45 which may be in the form of a hex nut is 
either rigidly attached to or integrally formed on a rear end segment of 
the body portion 36 for permitting the tool 34 to be rotated with a wrench 
to advance the body portion 36 and pin 40 into the lug nut shaft 32 to 
punch a hole in the tank 16 and to thereafter retract the tool 34. 
The body portion 36 defines an elongated hollow shaft 46 which extends 
along the longitudinal axis thereof from the base of the blind shaft 43 to 
the base of a threaded shaft 48 formed through the fitting 45 and opening 
onto a rear end of the latter. A forward end of the shaft 46 communicates 
with a hollow shaft 50 which extends along the longitudinal axis of the 
body section 41 of the pin 40 to a position just beyond the forward end 44 
of the body portion 36. A shaft 54 extends from an opening 55 (See FIG. 3) 
on the surface of the body section 41 just forward of the body portion end 
44 radially inwardly to intersect and communicate with a forward end of 
the shaft 50. The shafts 54, 50, 46 and 48 thus form an oil flow path from 
the opening 55 on the surface of the pin 40 to an opening of the shaft 48 
on the end of the fitting 45. 
The tool 34 also employs means for sealing the lug nut shaft 32 against oil 
leakage around and along the threads of the body portion 36 which includes 
a nut 56 containing a compressible, resilient O-ring 58 partially disposed 
in and around a tapered annulus 60. The nut 56 is threadably movable along 
the body portion 36 so that the O-ring 58 can be tightly compressed 
against an outer face 62 of the lug nut 30 around the periphery of the 
shaft 32 should such a seal be needed. 
An optional feature of the tool 34 includes means connected to the body 
portion 36 for securing a ground wire 62 thereto to provide a ground for 
the transformer tank 16 in the form of the nut 56, a second nut 64 and a 
washer 66. The washer 66 contains opposite edge portions 68 which are bent 
at right angles to the remainder of the washer body so as to confine the 
wire 62 next to the body portion 36 between the washer body and the nut 64 
when the nuts 56 and 64, washer 66 and ground wire 62 are tightly packed 
together. After a sample of oil is taken by means of the tool 34 as 
hereinafter explained, a cap screw 70 is threadably inserted in the 
threaded shaft 48 to seal the oil flow path. 
Referring now also to FIG. 4, the tool 34 may be used as follows. Initially 
the cap screw 70 is removed from the shaft 48 and the nuts 56 and 64 and 
the washer 66 are loosely disposed on a rear end portion of the body 
portion threads 38. A workman either climbs the pole 12 or positions 
himself in the bucket of a line truck at a proper position within reach of 
the lug nut 30 but safely away from the primary bushing 22. The threads 38 
of the body portion 36 are started into the threaded shaft 32 of the lug 
nut 30. A wrench is used on the fitting 45 to rotate the body portion 36 
until the tip of the pin 40 just touches the tank 16 at the base of the 
lug nut shaft 32. Now the wrench is rotated a measured number of turns in 
the same direction just sufficiently to cause the pin 40 to pierce the 
tank wall 16 such that the body section 41 seals the resulting hole. The 
number of turns of the wrench just necessary to punch the hole with the 
tip of the pin 40 and thereafter seal the hole with the cylindrical body 
section 41 will depend upon the pitch of the threads 38, the length of the 
pin head 42 and the thickness of the wall 16 but should be carefully 
counted. The nut 56 is then immediately advanced until the O-ring 58 is 
mashed tightly against the face 62 of the lug nut 30. 
A syringe 72 containing a tip 74 threaded in conformity with the threaded 
shaft 48 is threadably advanced into the fitting 45 while a plunger 75 of 
the syringe is fully depressed as shown in FIG. 1 until the connection 
between the tip 74 and fitting 45 is air tight. The plunger 75 is then 
retracted to determine if a vacuum can be drawn in a space 76 at the base 
of the lug nut shaft 32 between the tank wall 16 and the forward end 44 of 
the body portion 36. The purpose of this exercise is to determine if a 
weld 78 around and between the outside base of the lug nut 30 and the tank 
wall 16 is air tight. If not, as indicated by relative ease in drawing 
back on the plunger 75, the plunger 75 should be returned to its fully 
depressed condition, after which a suitable rapid drying glue should be 
applied over and around the weld 78 and allowed to harden to eliminate air 
leakage between the tank 16 and nut 30. The plunger 75 should then be 
drawn again, and the process repeated, as necessary, until a relatively 
strong vacuum can be obtained in the lug nut space 76. Once such a vacuum 
is obtained, a suitable spacer should be placed between a rear end of the 
syringe 72 and the cap on the end of the plunger 75 to hold the plunger 
cap in a retracted position so as to maintain the vacuum on the space 76 
while the worker's hands are free. I recommend using a piece of 
conventional ground wire insulation molding 80 for this purpose as shown 
in FIG. 4 or any other suitable spacer means. 
Now with the plunger 75 locked in a retracted position by the spacer 80 so 
as to hold a vacuum on the space 76, the worker uses one hand to torque 
the nut 56 and O-ring 58 tightly against the face 62 of the lug nut 30 
while, at the same time, using the other hand to rotate the wrench slowly 
in the opposite direction about one-half turn until oil begins slowly to 
fill the body of the syringe 72. Upon filling of the syringe 72, the 
wrench is then rotated the same one-half turn in the original direction to 
reseat the cylindrical body section 41 back in the hole to seal the same 
against oil leakage, the nut 56 is given a final hand torque to assure 
compression of the O-ring 58 against the lug nut face 62, the filled 
syringe 72 is threadably removed from the fitting 45 and the cap screw 70 
is tightly threaded into the threaded shaft 48 to permanently seal the 
same against oil leakage. 
It will be recognized that it is the cylindrical body section 41 of the pin 
40 which provides the permanent primary seal for the hole punched in the 
tank wall 16, the O-ring 58 and nut 56 providing, in combination, a 
secondary seal for additional security which may not be essential in all 
cases. In making the original measured number of rotations of the body 
portion 36 from the position where the pin head 42 just touches the wall 
16 to the position wherein the hole is formed and the cylindrical body 
section 41 just seals the same, it is desirable not to make any more 
rotations than necessary, such that the pin head 42 does not project any 
further into the tank 16 than absolutely necessary. I, therefore, 
recommend determining how many thread pitches of the threads 38 that it 
will take in order to be equal to or greater than the length of the pin 
head up to the edge of the cylindrical body section 41 and use this number 
as the number of initial wrench revolutions to make the hole in the tank 
and seal the same, then, after confirming that a vacuum can be drawn with 
the syringe, back off one-half turn in the opposite direction to see if 
oil can be drawn from the tank. If not, then turn the wrench one-half turn 
in the initial direction to place the pin 40 back at its original fully 
advanced position and rotate the wrench an additional one-half turn in the 
same direction. Then back off one-half turn and observe whether this 
allows the syringe 72 to fill with oil. Repeat this process to advance the 
body portion 36 and pin 40 by a one-half turn increment followed by 
backing off one-half turn until the tank wall 16 is finally punched and 
oil flows into the syringe 72. 
If the lug nut 30 is also to be used for permanently grounding the tank 16, 
the washer 66 should now be advanced along the body portion 36 until it is 
flush against the nut 56, an end portion of the ground wire 62 should be 
placed against the back of the washer 66, and the nut 64 should be 
threadably advanced until the wire 62 is tightly trapped between the 
washer 66 and the nut 64 with the nut 56 and O-ring 58 tight against the 
face 62 of the lug nut 30. The tool 34 can thus be left in this position 
to permanently seal the hole in the tank 16 from leakage through the lug 
nut shaft 32 around the body portion 36 and through the shaft 48 and to 
provide permanent grounding for the tank 16 when needed. Also, it will be 
appreciated that when used to provide grounding for the tank 16, the body 
portion 36, nuts 56 and 64 and washer 66 should be constructed of suitably 
electro-conductive metals. 
Although the present invention has been described with respect to specific 
details of a certain preferred embodiment thereof, it is not intended that 
such details limit the scope and coverage of this patent other than as 
specifically set forth in the following claims.