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How To Weld On Used Oil Field Drill Pipe

In many areas of the U.S. and Canada used oil field drill pipe is cheap and easy to find. But welding it can sometimes be tricky.
  The problem is that during normal use, drill pipe acquires the properties of a permanent magnet. The strong magnetic fields at the ends cause the electric welding arc to sputter, fluctuate, and leap wildly from side to side of the joint, making it difficult to get a good weld. Retired drill pipe is rarely used outside the oil fields in full lengths. When lengths are cut into two or more pieces, both ends of each segment will exhibit the same permanent magnet properties.
  The challenge is to remove or completely neutralize the strong magnetic fields. To do that, we simply take advantage of the basic electro-magnetic principle used in creating an electro-magnet - that of wrapping an insulated wire around an iron core and then applying a direct current.
  In this case the iron core is the drill pipe, the insulated wire is a few feet of your stinger whip lead, and the direct current is supplied by the welding machine as soon as you strike an arc. It will continue as long as you are welding.
  Both north and south polarities can be neutralized by this same method, the difference being the direction that you wrap the stinger lead around the pipe. Wrapping clockwise will produce one polarity and counter clockwise will produce the other. Polarity can be established by a simple compass test but it isn't necessary to use this principle. If you're wrong you'll intensify the magnetic field and your arc disturbance will be intensified also. Simply stop and rewrap the other direction.
  There is no simple field test to establish the intensity of the existing permanent magnetic field. The intensity of your induced electro-magnetic field will be affected by the amperage setting of the machine and the number of wraps of cord you put around the pipe. The amperage is usually set by the rod size and the technicians preferred arc heat so the easiest way to adjust the electro-magnetic field strength is with the number of wraps.
  Experience shows, if your machine is set for 1/8-in. rod, you would start with six wraps and adjust more or less until you achieve the desired results. It's important that the lead be tightly wrapped both against the pipe and against each other, while keeping the wraps 4 to 5 in. back from the end being welded so as not to burn the insulation covering the lead. Start your wraps far enough back from you stinger that you don't restrict your freedom of movement of the stinger. Tests show that once the root pass has been completed the wraps can be removed and normal welding will resume.
  Contact: FARM SHOW Followup, Ron Galloway, 70 TeeMont Circle, Afton, Wyo. 83110 (ph 307 886-3673).

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2005 - Volume #29, Issue #4