JP3252286B2 - How to weld a pipe - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for connecting a welding portion of a pipe to form a long continuous pipe, and particularly to a system for performing welding by a machine.

2. Background of the Invention One of the main systems for transporting products such as oil, gas, and water is through the use of pipelines. These pipelines are usually buried vertically and horizontally underground in the United States and many other countries. Typically, trenches are excavated by an excavator along a predetermined pipeline route.

Pipe members of 30 to 60 feet (9 to 18 meters) or so length are transported to the area where the pipeline is being laid. The ends of adjacent joints of the pipe are connected by welding. These welds must be very accurate. Slight pinholes in the weld must also be avoided. The ends of the pipe are usually chamfered to improve the weld. These pipes are clamped together to obtain the best possible alignment between the two sections of the pipe. The welding material inside the pipe at the weld joint should form a smooth surface. In any case, the weld inside the pipe should be almost free of protrusions. Excessive protrusions cause any problems when traveling equipment travels inside the pipe, for example, equipment useful for detecting flow that may have occurred in the pipeline. The pipeline is also introduced with a pipeline pig that separates one product present in the pipeline from a second product. Sometimes gasoline lines are transported through pipelines. In this case, a plug is inserted to separate the two products, then the crude oil is transported through the same pipe, resulting in a consistent separation of the two substances.

A more common means today to prevent the projection of welded weld material into the inside of the pipe is to make a first or root pass of the weldment from inside the pipe. Special efforts, expensive machines are used commercially for this purpose.
The rental cost of such equipment for operating inside a three foot (3 ') diameter pipe is 1,20 per weld.
It's about $ 0,000, and almost $ 2 million in monthly rentals. This is a very time consuming and costly welding process. A better and cheaper method of welding pipe sections is desired.

In modern pipeline welding, welding bugs (bu
g) is sometimes used as a semi-automatic welding machine. There are trucks in combination with welding bugs. The truck is fixed around the pipe where the welding bug rotates around the pipe. The bug has a drive motor that drives the bug around the truck with the help of rollers. The rollers hold the welding bug along the track. Special clamp members are provided to provide storage of the bug on the truck.
There are also members to accommodate different size pipes. The welding bug has an oscillator that causes the welding tip to oscillate across the welding paddle.

The bag also has a wire feeder with a motor that drives the wire through a welding head to actually weld the two sections of pipe.

In operation, the drive motor drives the bug at a selected constant speed around the truck. However, the speed is constant when the bug travels from 12 o'clock at the top of the pipe to 9 o'clock in the middle. However, to balance the downward movement of the welding bug at 6 o'clock, the movement must be speeded up. This is due to gravity pulling the paddle at a faster speed. To accommodate this, current methods have stopped the bug drive motor. Next, the operator adjusts the speed of the drive motor to increase the speed. The operator starts the drive motor and continues the welding process. During this speed change, the movement of the bug is always stopped.

Stopping the drive motor causes a time loss to complete the weld. Other concomitant issues, such as preserving bead continuity, must also be considered. However, even with these problems, this method is widely used. This is mainly because this method is better than the conventional method.

Therefore, it is an object of the present invention to provide an apparatus and system that allows an initial or root welding pass to be made from outside the pipe, and that does not have internal protrusions of the welding paddle.

SUMMARY OF THE INVENTION The present invention relates to a method and apparatus for welding the end of a first pipe section to the end of a second pipe section by using an improved welding bug. The welding bug includes a wire feeder, a device for driving the wire feeder, and a drive member for driving the bug around an outer track around the pipe. A control member is provided to vary the speed of the bug while it continuously drives around the track. When welding a pipe, it is in a horizontal position, ie, the axis of the pipe is usually horizontal. An initial welding or root pass is applied from outside the first and second pipes and adjacent the ends of the first and second pipes. Internal line-up clamps with backup shoes need not be used for this method.

Usually two bugs are used, one around half of the track and the other around half. From 12 o'clock to 9 o'clock, one bug moves from almost horizontal to almost vertical. During this time, the speed of the bug is changed so that the electrode is kept just before the welding paddle with the welding wire. The other bug moves from 12 o'clock through 3 o'clock to 6 o'clock. The two bugs rotate or move at the same time. However, one bug starts slightly before the other, stops slightly before the other, and is removed from the middle area. This results in continuous welding where the welding paths from the two bugs merge. In the route pass, surface tension transfer (ST
T) Power supply is used. In this combination it is new. By using this system with the correct bug speed and welding wire speed, there is only a slight burn through each end of the bevel. The surface tension in the welding mode causes it to blend together, overlapping each side of the chamfer, leaving a small flat weld on the inside surface of the pipe. Thus, there is no longer a need to run the initial or root path from inside the pipe or to use the device inside the pipe. Prior to the present invention, when welding pipes in a system with welding bugs, there was always a root pass or initial pass from the inside, or additional equipment such as clamps, backup shoes, etc. was used. Such a device is not required in the present invention.

Means are provided for varying the speed of the wire feeder to feed a desired amount of wire to the welding paddle. In another aspect, the speed of the wire feeder is controlled by and changes in response to the change in the bug drive motor such that the desired feed speed of wire is achieved.

In operation, the welding operator observes the welding paddle in relation to the electrodes or the supplied welding wire ends. The operator wants to keep the end of the wire on top of the paddle. Therefore, the operator changes the speed of the bug to maintain the correct position of the welding head. This is done while the bug and welding operation proceed without stopping. During the actual movement of the welding bug, the wire feed carrier can be changed to provide the desired amount of welding wire to the electrode. In addition, if desired, a reference is made to vary the speed of the wire feeder depending on the speed of the welding bug.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram illustrating main elements of the present invention.

FIG. 2 shows a welding bug mounted on a truck, showing a pipe piece to be welded to another piece.

 FIG. 3 is a front elevation view of the welding bug of FIG.

 FIG. 4 is a rear elevation view of the welding bug of FIG.

 FIG. 5 shows the evaluation of the left part of the welding bug of FIG.

FIG. 6 is an explanatory view of a clapping member for detachably clamping a guide roller and a drive roller for running a bug on a guide track.

FIG. 7 is a view similar to FIG. 6, but showing the clamp in the released position.

Figures 8 and 9 show the wobble of the welding head when taken together.

 FIG. 10 shows a bottom view of the welding bug.

FIG. 11 illustrates the connection between the electrometer for driving the wire feeder and the electrometer for the traction motor, wherein the drive wire feeder is adjusted in response to changes in the traveling speed of the welding bug. FIG.

FIG. 12 is an explanatory diagram of an apparatus for controlling the speed of a traveling motor on a welding bug.

FIG. 13 is an explanatory diagram of a pulse in the control system of FIG.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring first to FIG. 1, this is a schematic diagram showing the main elements of a welding apparatus using a deformed welding bug. There is a first pipe joint 10 and a second to be welded together
A pipe joint 12 is shown. A guide track 14 is positioned and secured outside the weld pipe near the point where it connects the pipe ends. It is this guide track that runs the welding bug 16. Usually there are two bugs, but one
Only one is shown. An arrangement or guide bearing or roller 20 retains the welding bug on the truck 14 as the bug travels over it. There is a traveling motor during the welding bug,
This drives the jagged running rollers 21 around the track 14. The speed of the traveling motor is controlled by the electrometer control 22.

The welding head 30 is supported by the welding bug 16 and the welding wire 28
I support. The welding wire 28 is used as the electrode 29 and the welding head 30
Extend through. The truck 14 is placed on the pipe 12,
The ends of the welding wire 28 are properly positioned with respect to the ends of the pipes 10 and 12. A CO ₂ solenoid valve 32 is supported from the welding bug 16 and provides CO ₂ or other desired gas to exhaust around the end of the welding wire tip 29 at the lower end of the welding head 30.

In operation of the apparatus of FIG. 1, the CO ₂ solenoid is first operated such that all gas is scattered around the electrodes before power is applied to the electrodes 29. The power of the welding head 30 is
A tension-movement power supply 31 is provided through conductor 84. This is further described as a new kind of power supply for automatic welding equipment using welding bugs. This STT power supply is now turned on.

Next, the wire supply motor 24 and the welding bug traveling motor 18 are started simultaneously. This moves the welding bug along the track 14. The operator watches the operation, especially the welding paddle. The speed of the welding bug should be such that the wire tip 29 keeps the paddle advancing. Gravity alters the movement of the paddle as the welding bug moves around the pipe. The operator compensates for this by manipulating the electrometer control to change the drive speed 22 while the welding proceeds. If the wire feed motor does not feed the wire fast enough, the potentiometer control 26 of the wire may increase or decrease if demanded. This is also done while the welding bug is moving along the track 14. (Conventionally, the speed of the welding pad along the truck never changed during the actual welding.) The travel motor 18 was independent of the speed of the wire feed motor 24.
Instead of controlling the drive speed of the motor, the speed of the wire feed motor can be a function of the speed of the travel motor. The device that allows this is shown in FIG. In this device, the operator of the welding bug turns the knob 38 to adjust the traveling speed of the welding bug. This change is in the general way of changing the potentiometer settings to control the speed of the motor. In this case, the shaft or potentiometer 34 of the wire feeder 26 and the traveling motor 28
There is a drive chain or belt 40 connecting between the rotor 36 of the potentiometer. That is, as wheels 38 rotate, drive chain 40 drives rotor 34 to adjust the potentiometer of drive wire feeder 26. That is, as the speed of the welding bug changes, the speed of the drive wire feeder may change accordingly.

Pipeline tractor 33 has surface-tension-movement (ST
T) A generator is provided to supply power to the power supply 31. In principle, STT
The power supply is a power supply capable of carrying and changing the power supply on the order of microseconds. For example, 750 microseconds was effective. STT power is available commercially from The Lincoln Electric Company of Cleveland, 44117-1199, Ohio.

Next, FIG. 2 will be described. FIG. 2 shows a modified welding bug 16 mounted on a truck 14 surrounding a pipe 44. Truck 14 can be a conventional truck that guides welding bugs around pipes. The main element of welding bug 16 is electrode 31
Includes a welding tip or electrode in a welding head 30 having a gas cone 50 around which a welding gas, typically CO ₂ , is directed. A conduit 84 connects the STT power supply 31 to the welding head 30. The welding wire wound on the wire reel 58, which is an electrode, has a shield 6 with a wire feeder between the two shields.
Pass through 0,62. The wire feeder is conventional and has a tension adjustment 65. The wire feeder 64 is used to drive the wire through the welding head 30 at a selected speed. CO ₂ supply hose 82 connects the welding head 30 in a conventional manner. A vibration motor 66 is provided to drive a vibration mechanism 68, which connects to a connector 70 to oscillate the welding head 30, whereby the electrodes move back and forth across the opening between the ends of the pipe to be welded. . Welding head 30 using connector 70
Can be adjusted. Use knob 85 to adjust the height of the welding head.

Attention is best directed to FIG. 3, which shows welding bug 16 in an enlarged form. FIG. 3 shows a vibration adjusting mechanism 74 for adjusting the height of the vibration curve, that is, the width of the vibration. (This vibrator may be the same as that used for conventional welding bugs.) FIG. 8 shows the oscillator tip in one position, and FIG. 9 shows the welding tip in a second position. The welding tip 52 is supported by the welding head. This vibrating device is used for conventional welding bugs and is shown here only for ease of understanding of the entire device.

FIG. 3 also shows an adjustment knob for adjusting the height of the welding head relative to the welding bug and for adjusting the height of the welding pipe.
85 is shown.

It is important to provide the welding head with an insertion gas, preferably carbon dioxide. This is provided from a gas source hose 78 as shown in FIG. Gas source hose 78 is connected to a solenoid valve 80 having an outlet hose 82 that goes to the welding head.
Gas is provided from the solenoid when opened. STT
Power conductor 84 from power supply 31 provides operating current to welding head 30.

A variable swivel adjuster 86 provides a means to adjust the angle of the welding head as needed.

Attention is now directed to the travel motor 18 and travel and drive rollers. The running and drive rollers may be conventional and are shown here to complete the whole new combination. Attention is now directed to FIGS. Shown there are roller housings 88A, 88B, 88
C and 88D blocks. Block 88A, and 8
Shown at 8C is a side roller 90, which is a block 88.
B, 88D show jagged axles 92A, 9
2B is shown. These are indicated by the drive motor 18. Side rollers keep welding bugs on track. The jagged rollers move the welding bug along the track. 6 and 7 show a clamp lever for locking the rollers in place. FIG. 7 shows a clamping mechanism in which the rollers are detached so that they are properly arranged. The rollers should be in place with respect to the track band. That is, a spring and an adjustment nut 104 are provided there.

As shown in FIG. 5, the bearings 141, 143 at the top of the truck 14 and the bearings 145, 147 at the bottom of the truck 14.
Keeps welding bug 16 in contact with truck 14.

FIG. 10 shows a welding head 30 and a vibration drive motor.
FIG. 66 is a bottom view of 66 and a vibration adjuster 74.

The wire guide mechanism was modified from that of the aforementioned wire drive of a normal welding bug. A typical welding bug requires the bug to stop before the speed of the wire feed motor changes, or to stop before the bug drive motor is created. In the present invention, the deformation was performed such that the driving speed of the wire stopped changing the movement of the welding bug: it could be changed all the time. The drive mechanism that drives the drive bug around the track 14 has been modified from that of a normal weld bug in that the speed of the travel motor can be changed without stopping the welding process.

Control members for controlling the speed of the bug's travel motor and the speed of the wire drive motor will now be discussed with respect to FIGS.

Attention is next directed to FIG. 12, which shows one control means in graphical form for use in controlling the speed of the traction motor 18. (The illustrated device can also be used to control the speed of the wire feed motor 24.) FIG.
Includes a pulse width vibrator 120 with two. Pulse width vibrator 120
Has a reference voltage 124, which is typically 21/2 volts. The power circuit 132 is connected to the motor 18. Motor 18
Varies as a function of the voltage of the current in line 132. The output of the motor is provided through a variable register 128 returning to line 134 and to vibrator 120. There is a feedback line 130 from line 134 to vibrator 120. It has a register 126 and provides a little feedback to the vibrator 120. The register 128 controls the speed of the motor 18 (the potentiometer 22
(By moving the knob). As the resistance of resistor 128 changes, the output voltage on line 132 changes. The width of the pulses 140 and 142 shown in FIG.
The slight feedback of 130 changes until it equals the reference voltage. It then controls the speed of the motor 18.
Those skilled in the art can easily understand this speed control speed from the above drawings and description. Other means of providing this motor control speed may be used.

4 and 5 show a potentiometer welding bug running speed control knob 26.
A and the wire drive interlocking control knob 26A attached to the control box 27 are shown. These knobs can cooperate with the control of FIG. 2 to adjust either or both the speed of the bag running motor and the wire feed motor. Control conduits 147 and 149 connect control box 27 to travel motor 18 and wire feed motor 24, respectively.

Having described the main elements of the invention, a brief attention will now be given to its operation. In operation, the end portions 10, 12 of the pipes are placed next to each other as shown in FIG. A truck 14 is connected around the pipe section 12. STT power supply 31
Connected to the pipeline tractor generator 33 to power the welding operation. The track 14 is set so that the welding tip 29 is properly positioned with respect to the gap between the pipe sections 10,12. Normal adjustment for the height and vibration of the welding head 30 is performed.

Opening the CO ₂ source and energizing is then carbon dioxide solenoid 80, to be conveyed to CO ₂ to the welding head 30. Now the traction motor 18 and the wire feed motor 24 start substantially simultaneously after the wire tip 29 is in the correct position.

The initial pass or root pass of the welding operation is performed on the outside of the pipe at the position shown in FIG. The surface-tension-transfer (STT) power supply 31 is most important. STT power supplies are not operated in a constant current (CC) or constant voltage (CV) fashion. Rather, it is a high frequency (broadband-width), current controller and the power to the arc is based on instantaneous arc requirements and not on the "average DC voltage". It is a power supply capable of carrying and changing the electrode current on the order of microseconds.

When the traveling motor advances the welding belt around the track 14, the operator closely observes the welding paddle and checks the welding tip.
Keep 29 on the paddle. As the welding bug 16 moves downward, gravity causes the welding paddle to move faster. Therefore,
The welding operator simply turns knob 22A as shown in FIG. 4 to adjust the speed as needed. The operator sets the knob 26A in FIG.
The speed of the wire feed motor can also be adjusted by adjusting as shown in FIG. This is done without stopping either the travel motor 18 or the wire feed motor 24. There is another welding head (not shown) on the other side of the pipe, other than that seen in FIG. A second operator will operate this welding bug in the same manner. One of the bugs starts slightly before the other so that there is no gap at the top of the weld bead, and one of the bugs stops before the other and one of the bugs moves the weld bead continuously at the bottom. Be able to continue until it is. This is all from outside the pipe. Due to the novel device described here, there are no projections on the pipe, such as dripping. There is no need for a root path to be made inside. This eliminates very expensive operations. After performing the root pass, additional welding passes can be performed using conventional welding techniques, if desired.

Although the present invention has been described with a certain degree of specificity, it will be apparent that many changes may be made in structural details without departing from the spirit and scope of this description. It is understood that the invention is not to be limited to the embodiments shown herein for the purpose of implementation, but is to be limited only by the appended claims, including the full scope of equivalents considered to be equivalent. You.

Continuation of the front page (56) References JP-A-9-1340 (JP, A) JP-A 8-25049 (JP, A) JP-A 8-267242 (JP, A) JP-A 4-200866 (JP) U.S. Pat. No. 5,276,601 (US, A) U.S. Pat. No. 5,676,857 (US, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B23K 9/028

Claims (34)

(57) [Claims] 1. The end of a first pipe is welded to the end of a second pipe by use of a welding bug with a welding wire feeder and means for driving the bug along a track on the outer surface of the pipe. Moving the bug continuously along the track during the welding; b. Using a surface-tension-transfer (STT) power supply and a consumable welding wire during the first welding pass. From outside the first and second pipes to the adjacent ends of the first and second pipes to create a paddle between the ends of the pipes; c. Electrode current and / or Or controlling the voltage to melt a portion of the welding wire and minimize migration of molten metal from the paddle into the interior of the pipe; and d. During the first pass, Moving continuously around the track above Welding method while changing the speed of the welding bug, the tip of the welding wire and maintains to come ahead of the weld puddle without stopping the welding bug during that. 2. The method of claim 1 including the step of applying an additional welding pass after the first pass. 3. The method according to claim 1, wherein the power supply has a possible output for supplying and changing the electrode current in the order of microseconds through the welding wire. 4. The method according to claim 1, further comprising the step of observing the end of the welding wire in relation to the welding paddle. 5. The method of claim 1, further comprising the step of changing the speed of the welding bug in response to observation of the welding paddle as the welding wire is moving around the pipe so as to be ahead of the paddle. The method according to any one of claims 1 to 4. 6. The method according to claim 1, wherein the speed of the wire supplied by the welding wire feeder is varied. 7. The method of claim 6, wherein the speed of the wire supplied by the welding wire supply is a function of the speed of the welding wire bug turning around the track. 8. The method according to claim 5, wherein the speed of the welding bug is changed remotely. 9. The method according to claim 1, wherein the first welding pass is configured without the use of an internal line-up clamp with backup shoes. 10. The method according to claim 1, wherein the welding head oscillates between the ends of the first and second pipes. 11. The method according to claim 10, wherein the amplitude of the vibration is adjustable. 12. The method according to claim 1, wherein the height of the welding head can be adjusted from the ends of the first pipe and the second pipe.
The method described in the section. 13. The method according to claim 1, wherein an inert gas is applied to the welding head during the production of the welding paddle. 14. The method according to claim 1, wherein the angle of the welding head is adjusted with respect to the ends of the first and second pipes. 15. The method according to claim 1, further comprising the step of welding the ends of the first and second pipes together using a plurality of welding bugs. 16. The method according to claim 1, wherein the speed of the welding bug is varied independently of the position of the welding head on the pipe. 17. A welding tractor, b. A generator on and provided by the tractor, c. A welding bug including a wire feeder, a welding head, and the welding bug around the surface of the pipe. A. A guiding means, d. A surface-tension-transfer (STT) power supply connected to the generator, controlling the current and / or voltage by a consumable welding wire supplied through the welding head, e. A connection member for connecting to the STT power source; and f. A speed controller for continuously moving the welding bug around a track on the pipe during welding formation and controlling the speed of the welding bug during the welding. A device for welding one end of a first pipe to a first end of a second pipe. 18. The apparatus of claim 17 including means for changing the speed of the welding bug as it moves around the surface of the pipe. 19. The apparatus of claim 18, wherein the speed of the welding bug is remotely changed. 20. A welding wire feeder for varying the rate at which welding wire is fed by said wire feeder.
The described device. 21. The apparatus of claim 20, wherein the speed of the wire supplied by the welding wire feeder is a function of the speed of the welding bug turning around the track. 22. Apparatus according to claim 17, wherein the welding head is vibrated between the ends of the first and second pipes. 23. The device according to claim 22, wherein the amplitude of the vibration is adjustable. 24. Apparatus according to claim 17, including means for adjusting the height of the welding head from the ends of the first and second pipes. 25. Apparatus according to claim 17, wherein an inert gas is applied to the welding head during the formation of the weld. 26. Means for adjusting the angle of the welding head with respect to the ends of the first and second pipes.
An apparatus according to any one of the preceding claims. 27. Apparatus according to claim 17, comprising a plurality of welding bugs. 28. Apparatus according to claim 17, wherein an internal line-up clamp with backup shoes is not used. 29. The end of a first pipe is welded to the end of a second pipe by using a welding bug with a welding wire feeder and means for driving the bug along a track on the outer surface of the pipe. Moving the bug continuously along the track; b. Relocating the first welding pass with a welding wire without using an internal line-up clamp with backup shoes. From outside the first and second pipes to the adjacent ends of said first and second pipes, creating a paddle between the ends of the pipes; and c. During said first pass, Changing the speed of the welding bug while continuously moving around the track on the pipe without considering the angular position of the welding head and without stopping the welding bug; The tip of the wire Maintaining to come ahead of the contact paddles, welding method, characterized in that. 30. a welding tractor, b. A generator on and provided by the tractor, c. A surface-tension-transfer (STT) power supply connected to the generator, d. A wire feeder A welding bug, a welding head, and means for guiding the welding bug around the surface of the pipe; e. A connecting member connecting the welding head of the welding bug to the STT power supply; and f. One end of the first pipe, characterized in that it comprises a manual speed control means for remotely changing the speed of the welding bug as it moves around the truck, independent of any angle of the welding bug. For welding to the first end of the second pipe. 31. A welding bug comprising a welding wire supply for supplying a consumable welding wire, and the use of means for driving the bug along a track on the outer surface of the pipe.
Welding the end of the pipe to the end of the second pipe, comprising: a. Placing the ends of the first pipe and the second pipe very close to each other with an unobstructed gap therebetween; b. moving the bag continuously along the track; c. applying a first welding pass from outside the first and second pipes to adjacent ends of the first and second pipes; D. Changing the speed of the welding bug without stopping it while the welding bug is continuously moving around the track on the pipe so that the tip of the welding wire is And e. Using power from a surface-tension-transfer power source to control current and / or voltage through consumable welding wires when applying the first welding pass. Welding method. 32. The end of a first pipe is welded to the end of a second pipe by use of a welding bug with a welding wire feeder and means for driving the bug along a track on the outer surface of the pipe. Connecting the welding bug to an STT power source; b. Moving the bug continuously along the track; c. Making the first welding pass outside the first and second pipes. Apply to the adjacent ends of the first and second pipes, d. Observe the end of the welding wire in relation to the welding paddle, and e. Place the welding bug around the track on the pipe. A welding method characterized by changing the speed of the welding bug without stopping the welding bug while continuously moving the welding bug so that the tip of the welding wire is immediately in front of the welding paddle. 33. The end of a first pipe is welded to the end of a second pipe by use of a welding bug provided with a welding wire feeder and means for driving the bug along a track on the outer surface of the pipe. Moving the welding bug continuously along the track; and b. Moving the first welding pass from outside the first and second pipes using a welding wire to the first pipe. And applying to the adjacent end of the second pipe to create a paddle between the ends of the pipe, c. Removing the welding bug while the welding bug is continuously moving around the track on the pipe. Without stopping, changing the speed of the bug to keep the tip of the welding wire immediately in front of the welding paddle, and d. The welding as a function of the speed of the means by which the bug drives around the track. Change the wire speed from the wire feeder,
A welding method characterized in that: 34. a welding tractor, b. A generator on and provided by the tractor, c. A surface-tension-transfer (STT) power supply connected to the generator, d. A wire feeder A welding member comprising: a welding head, and means for guiding the welding bug around the surface of the pipe; e. A connecting member for connecting the welding head of the welding bug to the STT power source; f. Speed control means for remotely changing the speed of the welding bug as it moves around the track; andg. Means for changing the speed at which the wire is fed from the wire feeder as a function of the speed of the welding bug. An apparatus for welding one end of a first pipe to a first end of a second pipe.