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arc welder and thawing frozen lines

on a recent job my pipe thawing machine kept pooping out. One of the other fellows brought a portable arc welder to thaw the pipes. This welder was on the system for six hours, no luck. I have heard pro and con on using a arc welder. Does anybody have any input on using a welder for thawing pipes ? thanks
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Comments

  • hot rodhot rod Posts: 1,387Member
    Got plenty of insurance?

    Unless you can be absoultely positive that you have disconnected any grounds to the water lines, there is a very real possibility of the current arcing in the wall. Generally it will arc from a pipe to the ground conductor in the romex or wiring. Used to be common practice in Utah to ground the electrical panels to the copper water line at the point of entry. This and any other grounds MUST be disconnected. Even phone grounds to water lines will get fried.

    Welders generate way to much current to do this safely, sorry. It's hard to know where the current is going. It could be following a main line to the neighbors, and arcing in their walls!

    Years ago Lincoln used to sell a pipe thaw attachment for their SAE-400 portable welders. I had one. Basically it was two big fuses that prevented the welders from cranking the current too high. It also kept you from burning up the welder!

    Also some of the old red Lincoln buzz boxes used to have a thaw setting, usually the 75 amp setting had a circle around it to indicate the maximun setting for thawing.

    Keep in mind a direct short is being presented to the welder. A welder with a low duty cycle won't tolerate this for long periods, another reason Lincoln tried to limit the output for thawing.

    I'd exhaust all other possibilities before "hooking up" the welder. And never leave the job unattended, while thawing, regardless of the machine!!

    hot rod

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  • tombigtombig Posts: 291Member
    Pipe Thawing

    Back in ,77 I worked with a welding co. He had a Hobart gen. w/a flathead six power plant. It had 3 phase taps off it. You could weld,power a second electric welder, and run power tools all at the same time!! We thawed many residential services that winter (50% in one subdivision, obviously the services were not dug deep enough)and did none the next winter. hr, you're absolutely right about the grounds. I had to stand in the truck,sub-zero, cycling the gen. (90sec on/30sec off running AC 150amps) while my boss hung inside drinking shots with the owner waiting for that first drip. Longest one took about 4hrs. because we couldn't find the buffalo box and had to ground to a hydrant 200' away. Average time, 1-2 hrs. Moral of the story...bring the right equipment to the job. You could easily burn up a light duty welder or burn up the switch cycling it.

    Tombig
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  • Randy TibbitsRandy Tibbits Posts: 91Member


    Thanks for the imput. Safty is my main concern. The fellow that brought the welder kept it at 60 amps but it still made me nervous. The time has come to purchace a more powefull pipe thawer. This past week has been frozen pipe jamboree.
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  • hot rodhot rod Posts: 1,387Member
    It's the combination

    of voltage and amperage, I think. Pipe thaw machines run very low output voltage.

    The biggest mistake would be to keep cranking the amperage on a welder.

    Frozen under ground lines take a lot of heat. The best thing you can do is start thawing them as soon as possible. The longer they stay below freezing the further the ice plug grows! The old garden hose scenario.

    When you pull the meter lid off, sprinkle snow on the meter and piping, if the snow melts, that ain't where it's frozen!

    Even on high setting I never could get my General Pipe Thawer to weld or strike an arc :) Basically a HEAVY duty 6 volt battery charger.

    hot rod
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  • elefteleft Posts: 509Member


    In the early 60's we used 300 amp Lincoln & Hobart DC 100% duty cycle machines at low amperage with fuse boxes. We hooked to a near hydrant or the house side of the in ground meter and the other where the line came thru the foundation.

    I remember one job when the phone line glowed and burnt off at the pole. There was no continuity because the line, from the meter where we connected the ground, had been previously repaired. The freeze up pushed the repair apart. That was the only wire problem we ever encountered.

    al
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