WELDING MONITORING SYSTEM

SYSTEME DE MONITORAGE D'OPERATION DE SOUDAGE

English Abstract

An apparatus and method of welding-two pipe sections together by use of an
electrode and
moving the electrode toward a gap between the pipe sections as the electrode
is moved about the
outer peripheral surface of the pipe sections during the welding operation.
During the welding
process, welding parameters are recorded and correlated with a determined
position. The position
of the formed weld bead is determined by GPS satellites.

Claims

16
What is claimed is:
1. A welding system for welding two plates together which comprises:
a. a welder including a welding circuit and a welding head to supply heat to
said
plates to form a weld bead therebetween, said welding circuit directing a
controlled amount of
current through an electrode to form said weld bead on said two plates;
b. a welding monitor to monitor at least one welding parameter during the
formation of said weld bead;
c. a positioning circuit to sense a plurality of electromagnetic signals
originating
from a relatively fixed, remote location and to determine the location of said
formed weld
bead;
d. a record circuit to electronically record mechanical and electronic errors
during
a welding process and said determined location to the remote location; and,
e. a transmit circuit to transfer said recorded information to a location
remote of
said welder.
2. The welding system as defined in claim 1, wherein said positioning circuit
senses a
plurality of signals from global satellites and determines a global
longitudinal and latitudinal
position of said formed weld bead.
3. The welding system as defined in claim 1 or 2, wherein the record and
transmit circuit
transmits at least a portion of said one monitored welding parameter in real-
time-
4. The welding system as defined in any one of claims 1 to 3, wherein said
record circuit
records additional information selected from the group consisting of the
amount voltage
across the electrode, the amount of current across the electrode, the amount
of voltage
produced by the power supply, the voltage profile, the amount of current
produced by the
power supply, the current profile, the amount of power directed to the
electrode, the rate of
power directed to the electrode, the electrode type, the electrode feed rate,
the flux type, the
flux feed rate, the shielding gas type, the shielding gas feed rate, the
welding gas type, the
welding gas feed rate, the welding cycle, the direction of movement of welding
head, the rate
of speed of welding head, the time of day, the ambient conditions, the date,
the type of

17
welding procedure, the type of power supply, the type of welder, the type of
welding
components, the position of the welding head on the workpiece, the polarity of
the electrode
during welding, the interruptions during the welding process, the type of the
workpiece, the
shape of the workpiece, and combinations thereof.
5. The welding system as defined in any one of claims 1 to 4, wherein the
welding circuit
has a first circuit to create a transfer current arid a second circuit to
create a melting current,
said second circuit supplying a sufficient amount of current to said electrode
to form said weld
bead on said two plates.
6. The wielding system as defined in any one of claims 1 to 5, wherein the
welding
circuit creates a series of small width current pulses and controls the
polarity of the current
pulses between a first polarity with said electrode which is positive and a
second polarity with
said electrode which is negative, said series of current pulses constituting a
welding cycle with
a short circuit transfer portion and a plasma arc melting portion, said
current pulses in said
cycle each having a given electrical polarity of said electrode with respect
to said two plates.
7. The welding system as defined in any one of claims 1 to 6, further
including a welding
carriage adapted to move said welding head about the outer peripheral surface
of said plates
sections and along a gap between said plates.
8. The welding system as defined in any one of claims 1 to 7, further
including a
consumable electrode for forming said weld bead.
9. The welding system as defined in claim 8, wherein said consumable electrode
is a
cored electrode.
10. The welding system as defined in claim 8 or 9, wherein said electrode is a
self-
shielding electrode.
11. The welding system as defined in any one of claims 8 to 10, wherein said
electrode
includes

18
alloying components to form said weld bead having a substantially similar
composition as the
composition of said plates.
12. The welding system as defined in any one of claims 5 to 11, wherein said
second
circuit directs a preselected amount of energy to said electrode to melt a
relatively constant
volume of an electrode during each welding cycle.
13. The welding system as defined in any one of claims 5 to 12, wherein said
welding
circuit limits an amount of energy directed to said electrode to prevent
molten metal from
passing through a gap between said two plates.
14. The welding system as defined in any one of claims 5 to 13, wherein said
welding
circuit reduces the amount of current to said electrode before said molten
metal on said
electrode forms a short circuit condition with a gap between said two plates.
15. The welding system as defined in any one of claims 5 to 14, wherein said
welding
circuit creates an alternating current.
16. The welding system as defined in any one of claims 5 to 15, wherein said
welding
circuit forms part of an STT power supply.
17. The welding system as defined in any one of claims 5 to 16, wherein said
electrode
moves about the outer peripheral surface of said metal plates and
substantially along a gap
between the plates.
18. The welding system as defined in claim 7, wherein said welding carriage
continuously
moves along said plates sections and wherein the speed of said welding
carriage can be varied.
19. The welding system as defined in any one of claims 5 to 18, wherein said
two metal
plates are two pipe sections.

19
20. A method of welding two plates together, said method comprising the steps
of
a. providing a welding circuit, a welding head and a consumable electrode;
b. moving said welding head toward said plates;
c. directing a controlled amount of current through said electrode to form a
weld
bead between said plates;
d. monitoring mechanical and electrical errors during the formation of said
weld
bead;
e. determining the position of said formed weld bead relative to a remote
location
by sensing a plurality of electromagnetic signals originating from the remote
location;
f. electronically recording and saving said monitored mechanical and
electrical
errors and associating said errors with said determined position; and,
g. transmitting said recorded information to a location remote of said welder.
21. The method as defined in claim 20, wherein the transmitting step transmits
at least
a portion of said one monitored errors in real-time.
22. The method as defined in claim 20 or 21, further including the step of
monitoring and
recording welding parameters selected from the group consisting of the amount
voltage across
the electrode, the amount of current across the electrode, the amount of
voltage produced by
the power supply, the voltage profile, the amount of current produced by the
power supply, the
current profile, the amount of power directed to the electrode, the rate of
power directed to
the electrode, the electrode type, the electrode feed rate, the flux type, the
flux feed rate, the
shielding gas type, the shielding gas feed rate, the welding gas type, the
welding gas feed rate,
the welding cycle, the direction of movement of welding head, the rate of
speed of welding
head, the time of day, the ambient conditions, the date, the type of welding
procedure, the type
of power supply, the type of welder, the type of welding components, the
position of the
welding head on the workpiece, the polarity of the electrode during welding,
the interruptions
during the welding process, the type of the workpiece, the shape of the
workpiece, and
combinations thereof.

20
23. The method as defined in any one of claims 20 to 22, wherein said step of
determining
the
position of said formed weld includes the step of sensing a plurality of
signals from global
satellites.
24. The method as defined in any one of claims 20 to 23, wherein said step of
determining
the position of said formed weld includes the step of determining a global
longitudinal and a
lateral position of said formed weld bead.
25. The method as defined in any one of claims 20 to 24, wherein said two
plates are ends
of two pipe sections.
26. The method as defined in any one of claims 20 to 25, wherein said weld
bead is
formed from a consumable electrode.
27. The method as defined in claim 26, wherein said consumable electrode is a
self --
shielding electrode.
28. The method as defined in any one of claim 26 or 27, wherein said electrode
is a cored
electrode.
29. The method as defined in any one of claims 26 to 28, wherein said
electrode includes
alloying components to form said weld bead having a substantially similar
composition as the
composition of said two plates.
30. The method as defined in any one of claims 26 to 28, further including the
step of
providing a welding carriage which moves said welding head about the outer
peripheral
surface of said plates.
31. The method as defined in claim 30, wherein the speed of said welding
carriage is
varied as said carriage moves about said plates.

21
32. ~The method as defined in any one of claims 26 to 31, further including
the step of
melting said electrode by an electric wave, said step of directing a
preselected energy to said
electrode to melt a relatively constant volume of said electrode during each
welding cycle.
33. ~The method as defined in claim 32, wherein said electric wave includes a
background
current, said background current having a high inductance component and a low
level just
above the level necessary to sustain an arc after the termination of a short
circuit condition
which is maintained throughout each welding cycle.
34. ~The method as defined in any one of claims 26 to 33, further including
the step of
limiting the amount of energy directed to said electrode to prevent molten
metal from passing
through a gap between said two plates.
35. ~The method as defined in any one of claims 26 to 34, further including
the step of
reducing the amount of current to said electrode prior to said molten metal on
said electrode
forms a short circuit condition with a gap between said two plates.
36. ~The method as defined in any one of claims 32 to 36, wherein said
electric wave is an
alternating current.
37. ~The method as defined in any one of claims 32 to 36, wherein said
electric wave is
formed by an STT power supply.
38. ~The method as defined in any one of claims 26 to 37, including the step
of moving said
electrode about the outer peripheral surface of said metal plates and
substantially along a gap
between the plates.
39. ~The method as defined in any one of claims 20 to 38, wherein said metal
plates are two
pipe sections.

Description

l0l5202530CA 02265215 2001-11-01WELDING MONITORING SYSTEMThe invention relates to the art of welding with an electric arc andmore particularly to a method an apparatus for monitoring and controlling a weldingsystem during the welding process.The present invention relates to the welding of pipe sections and monitoringthereof. United States Letters Patent No. 5,676,857 may be referred to as backgroundinformation for its discussion of welding sections of pipe together.BACKGROUND OF THE INVENTIONThis invention relates to the field of arc welding and particularly to anapparatus and method of welding two steel plates together by use of a consumableelectrode and monitoring the welding parameters during the welding process, andmore particularly to an apparatus and method of short circuiting arc welding pipesections together with a cored electrode and the monitoring of the welding parametersand the determining of the location of the formed weld bead.Pipe systems are used to transport a variety of materials such as oil, gas and waterto a desired location. Such pipe systems can extend hundreds and even thousands ofmiles. In many instances, these pipe systems traverse remote and many timesundeveloped locations. In the art of welding the ends of large diameter pipe, it isconventional to machine the ends of each pipe to provide an external bevel and a narrowflat land; bring the machined ends into axle alignment with the lands in close but usuallyspaced relationship to form a gap between the two ends of the pipe; and then to positionone or more welding heads around the pipe so as to form a 360° weld. The weld beadis usually made in several steps. First, a root pass is made where at least the inner edgesor lands of the pipes are fused and the gap between the lands filled with weld metal.Thereafter, several filler passes are made wherein the space formed by the bevel is filledso that the weld metal is at least flush with the outer surface of the pipe. The root passis a very important part of the welding operation. Once the root pass is completed, thealignment of the pipes is assured. Thus, during the root pass, a 100% sound weld beadmust be laid. Soundness of the weld bead means the complete fusion of both the landsclear through to the inner surface of the pipes and the complete filling of the10152025‘CA 02265215 1999-03-llL-2041gap between the lands with the weld metal. Depositing of the weld metal in the gap is difficultbecause the weld bead must be made by moving the weld heads around the pipe such that thewelding position varies from downhand welding, vertical up or down welding, to overhead weld asthe root pass is formed around the pipe. Furthermore, weld metal formed during the root pass shouldfill the gap between the pipe sections, but should not be allowed to pass through the gap andaccumulate on the interior surface of the pipe. The weld bead should also form a relatively smoothsurface with respect to the interior of the pipe which has very little, if any, protrusion into the interiorof the pipe. Excessive protrusion of the weld bead in the pipe can: 1) create problems withapparatuses running inside the pipes to detect the soundness of the pipe system, and 2) causeunwanted fluid mixing and turbulence as the fluids are transported through the pipe system.A welding apparatus which creates an acceptable root bead is disclosed in United StatesLetters Patent No. 5,676,857. This patent discloses two welding bugs which continuously move ona track around the periphery of the pipe and include a special short circuiting power source to applya root bead between the two ends of a pipe. This patent discloses that by selecting the proper bugspeed and welding wire speed, only a slight burn through each edge of the bevel occurs and a smallflat weld is formed on the interior of the pipe. The Lincoln Electric Company has found that thewelding apparatus disclosed in United States Letters Patent No. 5,676,857 can be modified for usewith a flux cored electrode to obtain the desired composition-of the weld bead so that compositionof the weld metal closely matches the composition of the metal pipe to form a strong and durableweld bead. The welding apparatus can be further modified to ensure that a shielding gas protectsthe weld head from the adverse effects of the environment by using a self shielding flux systemwhich forms a shielding gas during welding.Pipe systems are typically designed to be hundreds of miles in length. Due to the length ofsuch pipe systems, the assembly of the pipe system may be formed in parts along the route of thepipe system. In view of the extensive length of the pipe systems and the importance of properlywelding the pipe sections together, a team of welding technicians must be present to inspect theprogress and quality of the pipe system and the quality of the weld bead formed between each pipe-2-10152025CA 02265215 1999-03-llL-2041section. In remote locations, the costs associated with using a team of technicians can be very costly.Such costs may prevent the pipe line fi'om ever being built. In addition, the team of technicians maybe exposed to undesirable conditions when laying the pipe system in remote and/or undevelopedlocations. Such undesirable conditions may adversely affect the health of the technicians and/orimpair their ability to_ constantly monitor the quality of the welding process, thus causing delays,increased costs and defective weld beads along the pipe system. In addition to the problemsassociated with the maintaining of a team of technicians at the welding site, there are inherentproblems associated with the determination of the progress of welding along the pipe line andidentifying the location of a welding problem or other problem which has occurred ‘along the pipeline. In remote and/or undeveloped locations, it can be very difficult, if not impossible, to ascertainthe geographic location of the welder along the pipe system and the location of the weld beadsformed by the welder along the pipe line so as to report the progress and/or problems of the weldingprocess.In view of the problems associated with the welding of pipe sections of large pipe systems,there is a need for a welding monitoring system which monitors the quality of a formed weld beadand the location of such weld bead.SUMMARY OF THE INVENTIONThe present invention relates to a method and apparatus of welding together two steel platesand monitoring the parameters of the welding process and more particularly to a method andapparatus of welding pipe sections together and to monitor one or more welding parameters duringthe formation of the weld bead between the pipe sections and associating such welding parameterswith a location. However, the invention has broader applications and can be used to weld togetherother long metal workpieces such as track rails, airplane and ship components, bridges, etc..In accordance with the preferred embodiment of the present invention, there is provided aworkpiece having one or more components, a welder designed to produce a weld bead to weld oneor more components of the workpiece, a welding monitor to record one or more parameters of thewelding process, and a location identifier to determine the location of a formed weld bead. TheI -3-10152025CA 02265215 1999-03-llL-2041monitored welding parameters can include, but are not limited to, voltage and/or current across theelectrode, voltage and/or current produced byethe power supply, electrode type and/or electrode feedrates, flux type and/or flux feed rates, shielding gas type and/or shielding gas feedrates, welding gastype and/or welding gas feedrates, welding cycle, direction and/or speed of welding head, time ofday, ambient temperature and/or conditions, date, type of welding procedure, position of the weldinghead on the workpiece, interruptions during the welding process, errors (electronic and/ormechanical) during the welding process, the type and/or shape of the workpiece. One or more ofthese parameters or others can be electronically stored, electronically transferred to another location,printed out and/or displayed on a monitor. The location identifier is designed to determine thelocation of a particular formed weld bead. This location information or location parameter can thenbe associated to one or more welding parameters of the formed weld bead. For long workpieces suchas pipe lines, railroad tracks, and other large workpieces wherein the welder is moved along theworkpiece to perform a welding operation at a plurality of locations, the location identifierdetermines the position of the welder with respect to a certain reference point and the monitoredwelding parameters are correlated with or associated with the determined location. The recordedwelding parameters and location parameter can be electronically stored, electronically transferredto another location, printed out and/or displayed on a monitor. The recorded data can beimmediately analyzed and/or analyzed at a later time to review the welding parameters at a particularlocation on the workpiece for purposes of quality control.In accordance with another embodiment, the location identifier is designed to detect two ormore signals from a relatively fixed location and to calculate a location parameter based upon thedetected signals. The signals are preferably land based and/or global satellite based signals. In onepreferred embodiment, the location identifier calculates a location parameter using satellites of theGlobal Positioning System (GPS). The GPS is a multiple-satellite based radio positioning systemin which the GPS satellite transmits data that allows a device to precisely measure the distance fromselected ones of the GPS satellites and to thereafier compute position and time parameters to a highdegree of accuracy, using known triangulation techniques. The signals provided by the GPS can be-4-....-.......W....._.....................l............,...a,... .. ..10152025CA 02265215 1999-03-llL-2041received both globally and continuously. The GPS comprises space and control segments. Thespace segment, when fully operational, consists of twenty-one operational satellites. These satellitesare positioned in a constellation such that typically seven, but a minimum of four, satellites areobservable by a device anywhere on or near the earth’s surface. Each satellite transmits signals ontwo fiequencies known as L1 (1575.42 MHZ) and L2 (l227.6 MH2), using spread spectrumtechniques that employ spreading functions. C/A and P pseudo random noise (PRN) codes aretransmitted on frequency L1 and/or L2. Both P and C/A codes contain data that enable a receiverto determine the range between a satellite and the device. Superimposed on both the P and C/Acodes is the navigation (Nav) message. The Nav message contains GPS system time; a handoverword used in connection with the transition from C/A code to P code tracking; ephemeris data forthe particular satellites being tracked; and almanac data for all of the satellites in the constellation,including information regarding satellite health, coefficients for the ionospheric delay model for C/Acode users, and coefficients used to calculate universal coordinated time (UTC). The controlsegment comprises a master control station (MCS) and a number of monitor stations. Updatedephemeris and clock data are uploaded to each satellite for re-transmission in each satellite’snavigation message. The purpose of the control segment is to ensure that the information transmittedfrom the satellite is as accurate as possible. A GPS receiver includes an antenna assembly, an RFassembly, and a GPS processor assembly. The antenna assembly receives the L-band GPS signaland transmits the received signal to the RF assembly. The RF assembly mixes the L-band GPSsignal down to a convenient IF frequency. Using various known techniques, the PRN codemodulating the L—band signal is tracked through code-correlation to measure the time oftransmission of the signals from the satellite. The Doppler shift of the received L-band signal is alsomeasured through a carrier tracking loop. The code correlation and carrier tracking function can beperformed using either analog or digital processing. The control of the code and carrier trackingloops is provided by the GPS processor assembly. By differencing this measurement with the timeof reception as determined by the device’s clock, the pseudo range between the device and thesatellite being tracked may be determined. This pseudo range includes both the range to the satellite-5-10152025CA 02265215 1999-03-llL-2 041and the offset of the device’s clock from the GPS master time reference. The pseudo rangemeasurements and navigation data from thesatellites are used to compute a position and calibratethe device’s clock offset, and to provide an indication of GPS time. The processing andmemory fimctions include monitoring channel status and control, signal acquisition andreacquisition, code and carrier tracking loops, computing pseudo range (PR) and delta range (DR)measurements, determining data edge timing, acquisition and storage of almanac and ephemeris databroadcast by the satellites, processor control and timing, address and command decoding, timedinterrupt generation, interrupt acknowledgment control, and GPS timing, for example. The _navigation processing and memory fimctions performed by a the GPS receiver include‘-satellite orbitcalculations and satellite selection, atmospheric delay correction calculations, navigation solutioncomputation, clock bias and rate estimates, computation of output information, and preprocessingand coordinate conversion of aiding information, for example. When using GPS to determine thelocation of the formed weld bead on the workpiece, the GPS provides global longitudinal andlatitudinal accuracy of about l—l00m.In accordance with yet another aspect of the present invention, the location parameter andM one or more welding parameters are electronically stored and/or printed out for real-time reviewand/or for later review on-site and/or electronically stored for transmission to a remote location. Theability to record one or more welding parameters and associate such welding parameters with alocation parameter enables a technician to periodically monitor the quality of a formed weld beadwithout having to be present at each welding location. Upon review of the recorded and/or printeddata, the technician can determine what weld parameters existed during the formation of a particularweld bead along the workpiece. The technician may review the data hourly, daily, weekly or evenmonthly, and upon review of such data, determine the quality of a formed weld head at each locationon the workpiece. In addition to or alternatively, the recorded data may be sent electronically viathe telephone, Internet, satellite, ratio signal, etc. to a remote location for real time and/or delayedmonitoring of the welding process at specific locations. When the welding process is performed ata remote location, a satellite may be the only way to form a communication link between the welding-6-10,152025CA 02265215 1999-03-llL-2041site and remote location. The data storage mechanism, such as a computer, can be designed to storeinformation and, at preselected times during the day, a data link may be formed manually orautomatically with a remote location via the satellite. In addition, the data storage unit may bedesigned to receive signals from a remote location and download, upon command, the informationwhich is electronically stored.In accordance with still yet another aspect of the present invention, the welding controllerfor the welder is designed to receive information from a remote location via a telephone, Internet,satellite, radio signal, etc. and/or an on-site technician and thereby use such received information toalter one or more of the welding parameters during the welding process. In one particularembodiment, the weld controller alters one or more welding parameters upon analyzing the locationparameter and determining that the welder is at a particular location. In another particularembodiment, a technician and/or control device at a remote location receives data from the weldervia the telephone, Internet, satellite, radio signal, etc. and upon determining that the welder is at aparticular location, sends updated information to the welding controller via the telephone, Internet,satellite, radio signal, etc. to alter one or more welding parameters.In accordance with another embodiment of the present invention, the workpiece includes twopipe sections which are positioned together and form a gap between the ends of the two pipesections and are welded together by a welding system which includes a welding carriage positionedaround the gap formed by the two pipe sections, a welding power supply, a welding current circuitwhich controls one or more welding parameters during the welding process, a location device thatdetermines the location of the welder relative to a fixed location, and a data storage device. The pipesections are preferably aligned together by the use of clamps at least until a root bead has beenapplied to the gap between the pipe sections. The welding carriage preferably extends at least 180°around the circumference of the gap and preferably 360° around the circumference of the gap. Thewelding carriage is designed to slide along a track as it moves around the circumference of the gap,which track is secured about the periphery of the pipe. The welding carriage includes a drive motorto move the welding carriage along the track and around the circumference of the gap at a desired-7-10152025CA 02265215 1999-03-llL-2041speed. If an electrode is used during welding, the welding carriage includes a mechanism whichcontrollably moves the consumable electrode toward the gap during the welding process. Themechanism for controlling the movement of the electrode may be integrated with or separate fromthe mechanism for controllably moving the carriage about the gap during welding. The locationdevice is designed to receive two or more radio signals to calculate a location of the formed weldbead relative to a particular location. The data storage device is designed to store one or morewelding parameters during the welding process and a location parameter from the location device.In accordance with yet another aspect of the present invention, the welding current circuitincludes a first circuit for controlling the current flow during the short circuit condition wherein themolten metal at the end of the consumable cored electrode is primarily transferred into the moltenmetal pool between the gap by surface tension action. The transfer current includes a high currentpinch pulse across the shorted melted metal which helps facilitate the transfer of the molten metalfrom the electrode to the weld pool. The welding current circuit also includes a second circuit tocreate a melting current. The melting current is a high current pulse which is passed through the arewhich preferably has a preselected amount of energy or wattage used to melt a relatively constantvolume of metal at the end of the consumable cored electrode when the electrode is spaced from thewelding pool. The second circuit of the welding current circuit is preferably designed to providea high energy boost during the initial portion of the arcing condition. The high current boostpreferably has a preselected I(t) area or energy for melting a relatively constant volume of metal onthe end of the consumable wire when the wire is spaced from the welding pool. Preferably after theinitial high current plasma boost current, the high current is maintained for a preselected period oftime and then subsequently decayed over a period of time until the desired amount of energy orwattage is applied to the electrode to melt the desired volume of the electrode. The welding currentcircuit is also preferably designed to limit the amount of energy directed to the electrode so as toprevent the unnecessary melting of the workpiece during the application of the weld bead and/or tomaintain too hot of a weld bead during welding to thereby prevent molten metal from reducing thequality of the welded area. The welding current circuit also preferably includes a circuit to produce-3-10152025CA 02265215 1999-03-llL-2041a background current. The background current is a low level current which is maintained just abovethe level necessary to sustain an are after the termination of a short circuit condition. Thebackground current is preferably maintained throughout the welding cycle to insure that the arc isnot inadvertently extinguished during welding.The primary object of the present invention is the provision of a welding system whichmonitors one or more welding parameters during the formation of a weld bead on a workpiece andthe determined location of the weld bead formed under by welding parameters.Another object of the present invention is the provision of a welding system which stores oneor more welding parameters during the formation of a weld bead on a workpiece and the determinedlocation of the weld bead formed by such welding parameters.Still another object of the present invention is the provision of a welding system whichdetermines the location of a formed weld bead on a workpiece by receiving two or more signals froma relatively fixed location and calculating a position based upon the received signals.Yet another object of the present invention is the provision of a welding system whichutilizes GPS to determine the location of a formed weld bead.Another object of the present invention is the provision of a welding system transmitswelding information and corresponding weld bead location information to remote locations.Still another object of the present invention is the provision of a welding system whichprovides access to welding information and corresponding weld bead location information fromremote locations.Still yet another object of the present invention is the provision of a welding system whichallows for real time or delayed quality control review of a welded workpiece.Another object of the present invention is the provision of a welding system which providesfor cost effective quality control of welding operations in remote and/or undeveloped areas.Still another object of the present invention is the provision of a short circuiting arc weldingsystem and method which forms a high quality weld bead between two metal plates.Another objective of the present invention is the provision of a short circuiting arc welding-9-10152025,CA 02265215 2002-11-26L-2041system and method whic_h accurately tracks a desired current profile during the welding of two metalplates together. _I Other objectives and advantages will become apparent from the following description taken 0together with the accompanied drawings.I 1 BRIEF DESCRIPTION OF THE DRAWINGSFigure 1 is a schematic diagram illustrating the welding system of the present invention usinga satellite system to determine the location of the formed weld beadialong the pipeline; and. Figure 2 is a block diagram of the operation of the welding system.0 PREFERRED EMBODIMENTS or THE INVENTION ’Refening now to the drawings wherein the showings are for the purpose of illustrating thepreferred embodiments of the invention only and not for the purpose of limiting same, Figure 1illustrates a welding system 10 for welding pipe sections 20 of a pipe system togetherand fordetennining the location of the formed weld bead 30 along. the pipe system. The pipe sections 20 ‘are illustrated as being welded by a short circuiting arc welding system 40. The preferreditype ofshort circuitingwelding is SURFACE TENSION TRANSFER or STT type of welding. The weldingcircuit and control arrangement for such type of welding is disclosed in United States ‘Letters PatentNos.’ 5,148,001; 5,001,326; 4,972,064; 4_,897,5_23:; 4,866,247; and 4,7 17,807._The weldingsystem 10 for welding pipe sections 20 includes power supply 42 is preferably 1a D.C._ power supply. The power supply preferably includes a motor, such as a gas motor, whichpowers a generator to produce an AC current. The AC current is _then rectified by a rectifier to forma -DC current. A phase controller controls the rectifier to produce a substantially uniform DCcurrent. The current is then directed into a pulse widthrnodulator. The shapes of the pulse ° Hwidths are controlled by a shaping circuit to thereby create a desired pulse with the DC. current. Ascan be appreciated, the power supply 42 need not be a rectified output but can be any otherappropriate DC source. The DC current from the pulse width modulator is directedacross a welding' area which includes a consumable cored electrode 50 _ andpipe section 20.-10-10152025CA 02265215 1999-03-llL-2041Referring to the welding of the pipe section 20, the current to electrode 50 alternates betweena short circuit condition when the electrode 50 engages pipe sections 20 and an arcing conditionwhere the electrode 50 is spaced fi'om the pipe sections 20. During the arcing condition, an electricarc is created between the pipe and the electrode for purposes of melting and maintaining molten theend of the electrode as it is fed toward pipe sections for a subsequent short circuit condition.Referring to Figure 1, each pipe section 20 includes an edge 22. Edge 22 is a beveled surfacewhich forms a groove when two pipe sections are positioned closely adjacent to one another. Whentwo pipe sections are positioned next to one another, the pipe edges are spaced apart such that a gap24 exists between the pipe edges. In accordance with known practice, the pipe edges are positionedand secured together, preferably by clamps, until at least a root bead is applied to the groove betweenthe pipe edges, thereby filling the gap. A pipe ground engages the pipe to complete the arc circuitbetween electrode 50 and the pipe sections 20. Electrode 50 is unwound fiom electrode and spool52 directed toward gap 24 between the two pipe ends by electrode nozzle 44. During the weldingcycle, the electrode is fed through electrode nozzle 44 so as to transfer the molten metal at the endof the electrode into the gap between the pipe ends to form a weld bead 30.Electrode 50 is a consumable cored electrode which includes an outer metal sheath and anelectrode core. Preferably the metal electrode sheath is made up of carbon steel, stainless steel orsome other type of metal or metal alloy. Preferably the composition of the metal sheath is selectedto be similar to the base metal component of the pipe sections 20. The electrode core preferablyincludes fluxing agents and/or alloy and metals. F luxing agents may include compounds to createa slag over the weld bead to protect the weld bead until it solidifies, to retain the weld bead inposition until it solidifies and/or to shield the weld metal during the fonnation of the weld bead. Theflux may also include components which produce a shielding gas to protect the weld bead from theadverse effects of the environment. Preferably the flux components include fluoride and/orcarbonate to generate a shielding gas during welding so as to eliminate the need for externalshielding gases during welding. When a self shielding electrode is used, the need for an externalshielding gas is eliminated. The slag which forms on the weld bead further shields the weld bead-11-10152025CA 02265215 1999-03-llL-2041from the environment, thus resulting in the formation of quality weld beads. The alloying agentsare preferably included in the electrode core. The alloying agents are selected such that the alloyingagents in combination with the composition of the metal electrode sheath form a weld bead havinga composition substantially similar to the metal composition of the pipes 20.A desired current profile to produce low spatter during welding and to prevent the weld beadfrom passing through the gap and into the interior of the pipe system includes a pinch portion, aplasma boost portion, a plasma portion and a background portion wherein the arc is to be maintained.‘The plasma boost portion includes a decaying portion referred to as the plasma portion. Followingthe decaying portion, the welding circuit shifis to the background current level which‘ maintains theplasma or arc. The welding circuit maintains a preselected background current level, therebypreventing the current level through the are from ever falling below the preselected current lowcurrent level and allowing the arc to extinguish. The welding circuit is designed to produce all themelting of the electrode during the plasma boost and plasma portion of the welding cycle. Furthermelting of electrode 50 does not take place when the background current level occurs since the IRnecessary for melting the electrode is not obtainable through an are maintained only by thebackground current. Thus, the background current only serves to maintain the arc and the ball ofmolten metal in the molten state. The amount of molten metal at the end of electrode 50 which isformed by the plasma boost and plasma portion is selected to melt a preselected volume of moltenmetal at the end of the electrode, and the plasma portion of the current is reduced to the backgroundcurrent once the preselected volume is obtained. The duration of the plasma boost and plasmaportion is also selected to prevent unnecessary melting of the metal around pipe ends 22. Such over-melting of the metal can result in the weld metal seeping into the interior‘ of the pipe sections.During the formation of the molten metal ball, the jet forces of the high current repel the meltedmetal from the welding pool until the preselected amount of molten metal has been melted at the endof the electrode. Once the current is reduced, the molten metal is allowed to form into a ball and themolten metal pool in the gap is allowed to stabilize, thereby allowing for a smooth contact betweenthe substantially spherical ball and the quelled weld metal pool. The desired amount of molten metal-12-10152025CA 02265215 1999-03-llL—2041at the end of the electrode is controlled by directing a preselected amount of energy or wattage intothe electrode during the plasma portion of the welding cycle. All during the time the molten metalball is being formed at the end of the electrode, the core components are releasing shielding gasesto shield the molten ball and the weld metal in the gap from the atmosphere. The shield gasescontinue until the molten ball is transferred into the molten metal in the gap. Once the molten metalball is formed during the plasma boost and the plasma portion of the welding cycle, the molten ballis forced into the molten pool by feeding the electrode into the pool, thereby forming a short circuitcondition. When the melted metal ball engages the molten metal pool, it is transferred into the poolby surface tension. This action causes an ultimate necking down of the molten metal extendingbetween the pool and the wire in the electrode, and then a rupture and separation of the ball fiom thewire occurs. Since there is only a low background current during the separation, little if any spatteroccurs. Preferably, the necking of the molten metal ball is monitored such that when the neckrapidly reduces in diameter by electric pits, the current flow during the pinch curve increases moregradually until a detection of an impending fuse is obtained. Once the detection of an impendingfuse occurs, the current is reduced to the background current until the molten metal at the end of theelectrode transfers into the weld pool.The welding cycle which is repeated several times per second must be accurately controlledby a welding circuit to reduce spatter during the welding cycle. In the preferred embodiment, theoperating frequency of the pulse width modulator controller is 20 KHz with a width of the successivecurrent pulse being determined by a current shape controller. The demanded current for the weldingcycle changes 220,000 times each second. Since the highest rate of the welding cycle is generallyin the neighborhood of 100 to 400 cycles per second, many update pulses are provided during each, welding cycle.Referring to Figure 1, a welding monitor 60 is provided which monitors one or more weldingparameters during the formation of weld bead 30. Preferably welding monitor 60 monitors thecurrent to electrode 50, the feed rate of electrode 50, the total amount of energy to electrode 50during each weld cycle, and the speed at which the welding head travels around pipe sections 20.-13-10152025CA 02265215 2002-11-26L-2 04 1Additional welding parameters may be monitored. Furthermore, data from other sensors and/orinspection instruments may be monitored by welding monitor 60. Welding monitor 60 includes adisplay to allow a technician to view real-time and/or historical data which is or has been monitoredby welding monitor 60. Welding monitor 60 also includes a data entry arrangement 64 to a) allowa technician to alter one or more welding parameters to welder 40, b) display different data ondisplay 62, 3) access historic data, d) activate or deactivate a welding control program or some otheroperation. Preferably welding monitor 60 includes one or more components of the welding circuitthat controls the current to electrode 50.Welding monitor 60 includes a data storage device to store a portion or all of the monitoredinformation. Preferably, one or more welding parameters are stored on a disk drive or tape. Asufficient number of welding parameters are preferably stored so that the quality of the weld bead30 formed between the two pipe ends 22 can be reviewed‘ by a technician.Welding monitor 60 also includes a location circuit to locate the geographic position offormed weld bead 30. The location circuit includes an antenna 66, a GPS reference receiver and a 'microprocessor for calculating the position of the formed weld bead. Antenna 66 may comprise anyof a number of commercially available low-gain antennas. The GPS reference receiver is designedto determine the global latitude and longitude of the formed weld bead welding system by sensingthe signals 70 fiom satellites 80. A memory unit is provided in welding monitor 60 for storinglocation information supplied by a GPS unit, record the history of travel of the GPS unit, and includeinformation corresponding to the global latitude and longitude information. A clock is provided inwelding monitor 60 for supplying time and date information to the tracking circuit. The weldingmonitor 60 preferably includes a telecommunicating circuit to link to a remote location so as toupload and/or download information to and from the welding monitor. Preferably aptelephonesystem and a satellite transmission unit are included in the welding monitor to provide a data linkto a remote location. The operation of the GPS tracking circuit is known in the art and will not befurther described.The welding system 10 shown in Figure 1 may include a welding carriage adapted tomove the welding head, e.g. electrode 50, about the outer peripheral surface of the plates andalong a gap between the plates. The welding carriage may continuously move along the plates.The speed of the welding carriage may be varied.Referring to Figure 2, the operation of the welding system will now be briefly described.-14-101520CA 02265215 1999-03-llL-2041The welding circuit includes preset and/or loaded welding parameters. The welding circuit controlsthe formation of the weld bead 30 on pipe sections 20. Weld monitor 60 monitors and stores variouswelding parameters during the formation of the weld bead. The welding monitor also monitors andstores information provided by other sensors and inspection instruments used to form the pipesystem. The monitored information is stored, preferably on a disk drive. As the weld bead is beingformed, the positioning circuit senses signals 70 from GPS satellites 80. Preferably three or moresignals are sensed and processed to determine the global longitudinal and latitudinal position of theformed weld bead. The positional information is correlated with the monitored parameters andstored on the disk drive. The stored location and corresponding monitored parameters can beimmediately reviewed or later reviewed on-site or at a remote site via telephone, Internet, radio waveor satellite connection. A technician, upon reviewing the recorded data on-site and/or at a remotelocation can review the stored information to determine the quality of a formed weld bead at aparticular location along the pipe system. The technician after reviewing the data can input newwelding parameters for future weld bead formation and/or correct a problem with a previouslyformed weld bead.The ability of the welding system to provide information on how a particular weld bead isformed and the location of such weld bead along a pipe system, allows a technician to monitorwelding operations world-wide and to ensure that quality weld beads are formed. The recordedinformation can be used to ascertain future failure problems of a weld bead and/or to correct aproblem with a previously formed weld bead.The invention has been described with reference to a preferred embodiment and alternatesthereof. It is believed that many modifications and alterations to the embodiments disclosed willreadily suggest themselves to one skilled in the art upon reading and understanding the detaileddescription of the invention. It is intended to include all such modifications and alterations insofaras they come within the scope of the present invention.-15-

Representative Drawing