Can you melt frozen pipes with a welder? What if they aren't entirely metal?

December 30, 2005 6:16 AM

So here's my dilemma. The pipe that brings water to our house freezes. It’s not four feet deep. We've lived here three years. It happened the first year, not the second year, and then again a few days ago. When it happens I have to go to the neighbors and fill two five gallon buckets and bring them into the house to meet our needs. Flush our toilets, clean our dishes, water our pets and plants, fill the humidifiers in our two babies' rooms, etc. Fifty gallons a day, at least. And that doesn’t include cleaning clothes. This continues until the ground thaws. Now the question. It seems the folks who lived here before us knew of this problem. No, it wasn’t in the disclosure. What they did was weld wires to the pipe, from the well and then at the house, and then hook those up to an arc welder. The current would melt the pipes and the water would flow again. So, yes, in the spring we’ll dig a very expensive new supply pipe, but in the mean time, I’d like advice about circuits.? A condition of the sale of the house required a new septic. The contractor who put in the septic broke the pipe from the well and then he repaired it with PVC. Will the arc welder method still work or would that end in catastrophe? Did he build a fuse? There's water in the pipe and ice is conductive, but how will the PVC respond?
posted by Toekneesan to home & garden (30 comments total)

PVC is not conductive, that method will no longer work. It seems like an incredibly dangerous thing to do anyway. Instead of using the pipe itself as a conduit, taking advantage of the resistance to generate heat, I'd suggest you wrap the pipe in insulated wire that's designed to heat up. I don't know what this stuff is technically called, but it's used in electric blankets, car seat heaters, engine block heaters, etc.
posted by odinsdream at 6:27 AM on December 30, 2005

Hm - well, I see that the section you want to melt is underground, so... that won't work.
posted by odinsdream at 6:29 AM on December 30, 2005

Wow I don't know about using an Arc Welder, but I grew up on the New York / Canadian border, and we used heat tape to avoid these problems.

The only time we'd get frozen pipes would be when we'd forget to turn on the heat tape in the autumn. Worked really, really well; during winter we'd typically spend at least two weeks sometimes more with daytime highs well below freezing, and we'd usually have several bone chilling nights went it went subzero.
posted by Mutant at 6:31 AM on December 30, 2005

What you're looking for is called, ironically, a pipe heater. It's just a length of insulated wire that is wrapped around the pipe. When plugged in, the wire generates heat, preventing that section of the pipe from freezing. It's safe, and commonly used on pipes that freeze (like under mobile homes).

The arc welder method you described sounds just plain stupid to me. I wouldn't even entertain the idea.
posted by porntips guzzardo at 6:31 AM on December 30, 2005

I have a doubt: won't any external heating method affect the PVC section structural integrity very quickly? I remember seeing workers heating PVC pipes to hack a turn when the proper connection was not available and the thing is, it melts pretty well.
posted by nkyad at 6:39 AM on December 30, 2005

These suggestions assume I have access to the pipe, but it's in the frozen ground. The repaired PVC section is about 5 feet in lenghth in the middle of a 30 foot pipe. Pipe heaters won't work because the frozen section is too far from the accessible ends.
posted by Toekneesan at 6:41 AM on December 30, 2005

As a fall back, if you can get it thawed just let the water run inside the house. This was common practice if someone's heat tape would fail. Usually just a trickle suffices.

I'm not sure how you can thaw the buried section, but I'd be surprised if someone hadn't run across this problem before.

Why not try this - pump out what water you can. Pour boiling water down the pipe and repeat until you thaw the blockage.
posted by Mutant at 6:51 AM on December 30, 2005

If you have access to both ends, you could possibly run some of this insulated heating wire inside the pipe, where the water is.

Note that you should be sure to say "It's just so crazy it might work." out loud after reading the above.
posted by odinsdream at 6:57 AM on December 30, 2005

odinsdream : "If you have access to both ends, you could possibly run some of this insulated heating wire inside the pipe, where the water is."

Won't access to one end (namely the house end) of the pipe be enough?
posted by nkyad at 7:10 AM on December 30, 2005

The frozen ground thing...that's right. Without access to the ground surrounding the pipe, your options are pretty limited.
An inline pipe heater would fit the bill. However, I'd imagine installing would be as much (or more) of an inconvenience than digging & wrapping heat tape, as you'd need to disconnect your supply pipe somewhere inside your house, and deal with the plume of incoming water in order to feed the heat wire into the pipe. Also, if the line is completely frozen, there'd be less water to deal with upon disconnecting inside, but this would also prevent you from feeding the heat wire past the problem area. Digging seems inevitable for a permanent solution.

It seems to have been shot down well enough already, but the arc welder thing is still resonating very uncomfortably with me. Water supply lines are usually connected to the same ground in your house as the natural gas (or propane, since it sounds like you're rural) supply lines, and obviously your fuse/breaker panel. While the possibility is remote, can you imagine the result of a spark from connecting/disconnecting/meddling with an effing ARC WELDER in the vicinity of a gas fitting that is perhaps equally as in need of repair as your septic tank was?

Arc welders pull a crapload of current (aka: amps - the stuff that eletrocutes you) for a reason, and are dangerous enough when used for their intended purpose. Please, please, please pretend that you never even heard the idea of using one to solve this problem, and instead seek out any other method.
posted by porntips guzzardo at 7:16 AM on December 30, 2005

I doubt the arc welder method will still work, because you're losing conductivity in the PVC.

I rented in an old house about 30 years ago where the pipes would routinely freeze inside the house when it got very cold. Occasionally it would be so bad that the heat tape wouldn't help and I would run to the rental store to get what I only know as a "pipe thawer" - and looking back it very well might have been a small arc welder with a couple of huge clamps on it.

Once the pipes were thawed, what saved me was to leave a faucet inside the house cracked slightly on when it got really cold. It wastes a bit of water, but is better than nothing.

I can't tell from your profile where you live, but the root problem might be worth fixing now, rather than waiting until spring.
posted by SteveInMaine at 7:18 AM on December 30, 2005

nykad; well, yes, but the end in the house is probably not as convenient a point of entry as the one at the well. So, yeah, poor choice of wording.

Another reason not to put a voltage on the line with something like an arc welder: Some houses have their electrical ground connected directly to the plumbing. You could risk frying stuff plugged in to outlets wired this way.
posted by odinsdream at 7:42 AM on December 30, 2005

The arc welder method was once very common, some arc welders have a specific setting just for it. Not only won't the welder work with pvc, you may have a much worst problem. PVC will often split when frozen, so you may have a huge leak when it does thaw.
Having dealt with frozen pipes many times here are some hints. If you can, place a row of straw bales on the ground over the pipe. They insulate better than dirt, so a single layer is often equal to the 4' of dirt (and you can use them for mulch in the spring). Unfortunatly, you need to do this before the ground freezes. Leaving the water dripping does work, better is probably running the water full on for a few seconds ever hour or so. We used to set the timer on the dishwasher so it would run in the middle of the night.
posted by 445supermag at 8:01 AM on December 30, 2005

Forget the arc welder... remarkably dangerous and if it worked it would melt the PVC.

It's a pain, but you might have to bit the bullet and have the work done now. A good plumbing contractor can work through frozen ground, it just cost more.

"It seems the folks who lived here before us knew of this problem. No, it wasn’t in the disclosure."

Talk to the lawyer you had for the closing. The previous owners may be on the hook for the fix, they should not have gotten a certificate of occupancy if the water supply line isn't below the frostline.

If you have to wait until spring, when the pipe thaws leave one faucet cracked open. Moving water freezes at a lower temperature.
posted by Marky at 8:06 AM on December 30, 2005

Can you dig up the section with PVC and replace it with brass or whatever?

Once you do that, the arcwelder technique should still work. Assuming it worked in the first place.
posted by delmoi at 8:21 AM on December 30, 2005

The issue of melting the PVC depends on what grade of PVC was used (admittedly something you cannot know). I only know this because I used to live someplace that had a "chill water HVAC system." This particular system also did heating in the winter, sort of like a big radiator with a fan at the end. One fine summer a leak in the water pipes was fixed, using the wrong type of PVC. When they turned on the heat in the fall, the pipe melted. The good news is that the repair people could tell exactly where the leak was by the steam rising from the ground.

Try leaving a faucet running at a trickle. It might get you through until spring. And find out what your legal options are regarding the disclosure. Laws and the rules regarding certificate of occupancy vary from state to state (and sometimes city to city) so you will have to call someone local about that.
posted by ilsa at 8:24 AM on December 30, 2005

If you need to thaw the pipe, consider contacting the street department and seeing if you can pay them to bring one of their trucks with the big pavement heater on it. These trucks are used to soften asphalt when they're doing repairs. It's essentially a dump truck with a big propane heater that gets pointed at the ground. I imagine they'd be able to thaw your pipe pretty quickly with that.
posted by cosmicbandito at 8:37 AM on December 30, 2005

Seems like you're making this much harder than it need to be.

You know the location of the shallow pipe, yes? Insulate it from the cold air. Lay down a line (a good bit wider than the pipe, maybe two feet wide) of good polystyrene insulation and then cover that with dirt. You're going to work on raising the frost line in that specific area.

This is the method used for "Frost Protected Shallow Foundations" and there's little reason why it wouldn't help you here.
posted by Kickstart70 at 8:52 AM on December 30, 2005

AFAIK, you can sue the previous owners for failing to disclose the problem. I'd contact a lawyer.
posted by malp at 9:21 AM on December 30, 2005

can you use a jumper cable around the pvc?
posted by hortense at 10:02 AM on December 30, 2005

The arc welder method isn't necessarily dangerous. You wouldn't melt the PVC by trying it but it won't melt the ice as the PVC isn't a conductor.

Definately contact a lawyer or someone about failing to disclose the problem.

To get the pipe unfrozen this winter I think you'll have to dig. The methods for insulating the ground might have worked before it froze but I doubt insulating at this point will unfreeze the pipe as the pipe and ground around it are frozen.
posted by 6550 at 10:14 AM on December 30, 2005

Thawing frozen buried water lines with an arc welder has been done safely for years. It has to be done correctly. It is not a safety issue because of electrocution -- the voltage is only around 15V -- but because of the possibility of fire damage. As long as the pipe is a good conductor of electricity, the current will follow the pipe and not go into your home. The treatment takes only a few minutes.

However, in your case the pipe has been replaced by plastic so that is not an option and could force current into your home.

Some plumbers have equipment that will thaw pipes by forcing steam into one end. This can sometimes take several hours to thaw the length of the pipe with a resulting bill of a few hundred dollars. Call around to see if someone can do this for you.

The only real solution is to bury your pipes deeper. Your local building code office should be able to tell you the recommended depth. It depends on your local climate. In the northern tier of the US that can be as deep as 6 to 8 feet. You don't have to wait until spring. You can do this any time. Excavating equipment can slice right through frozen ground.

Another possibility is that the pipe is not frozen in mid-length but only at one end or the other where it comes nearer the surface. In that case you may be able to get results by attaching electrical heat tape to any exposed sections.

An interesting phenomena is that cold penetrates the ground very slowly. This means that your frozen pipes could be caused by a below zero cold snap that occurred several weeks ago. An old saying was that warm weather drives the frost deeper because it was often April when the pipes would freeze. But the real cause was a cold snap in February and the cold was only later reaching the 8-foot depth.

This might give you a clue as to where you waterline is frozen. If it only occurred due to a recent cold spell, then it is more likely near the surface at the ends. If it was due to a previous cold spell, it would indicate a deeper depth. I would guess that the frost level has not yet penetrated four feet deep this early in the winter. You could determine this by just digging a shallow hole with a pickaxe.

Good luck.
posted by JackFlash at 10:39 AM on December 30, 2005

I can't imagine why it should be more advantageous to wait for spring than to fix it now. To a backhoe, frozen earth and warm earth are about the same. The trench-digging, pipe-laying, and pipe-welding are all going to cost about the same regardless the time of year, I should think.

If you are fixed on waiting, though, you might want to combine a couple of the ideas here: asphalt truck heater unit to thaw out the ground, then lay down a heater cable and straw bales, for warmth and insulation. Should keep you limping until spring.
posted by five fresh fish at 1:43 PM on December 30, 2005

Not a VVS expert, but I'd start by measuring the resistance of the pipe and wire assembly. Borrow a multimeter. If the PVC section is not long, the ice and surrounding matter could be enough to provide a current path. I would not worry about melting the PVC - the ice water within is a good cooler unless you apply insane amounts of power.

The reason for using an arc welder is that it provides a high current even through a small resistance, such as an unbroken pipe. If you don't have one or feel uncomfortable using one, you can try using car batteries. It might work, depending on the size of the plug and the resistance of the assembly.

Anyways, measure the resistance first. Can you get back to us with some more detailed information?
posted by springload at 3:51 PM on December 30, 2005

This may sound silly, but if I was in your shoes I would build a nice bon-fire over the section of pipe in question. If you can dig at all go about 6 inches deep for the fire pit, and make it about 3 feet wide. Have fun with the fire and keep it going for about 4 hours.

Once the ground and your pvc pipe are thawed out, keep the water running and yea, a trickle will suffice. As is often the case with winter emergencies, this provides a good excuse to have a cool bon-fire party. Good luck!
posted by snsranch at 4:26 PM on December 30, 2005

Adding insulation and dirt sound like good ideas. I was going to suggest black plastic to absorb sun and warm the ground. Might make it warm up a bit faster.
posted by theora55 at 4:47 PM on December 30, 2005

Building a bonfire or using an asphalt heater will not help. You have to realize how slowly heat travels in the earth. It might take a month for the heat to travel 4 feet deep. Since it is early in the winter season, I also doubt that the frost has penetrated that deep. This suggests that the frozen section in either at the well or at your house. I would consider digging up those sections first to locate the problem.
posted by JackFlash at 6:15 PM on December 30, 2005

I had a simular problem and got the flow going again by pumping hot salt water directly against the ice head in the pipe. This was done pushing 1/4" soft hose down into the supply pipe until the plug was located. I had an old 2 1/2" air cylinder that was used like a big syringe. Fill the syringe with salt water heated on a hot plate. connect to the hose and slowly pump the hot water against the ice plug. Be prepared to be very wet when the ice plug lets loose. The arc welder (or big battery charger) tecnique was commonly used years ago by plumbers.
posted by Penguin at 8:29 PM on December 30, 2005

So here's what happened. After four days of toting water over, the straw seemed to have worked. On frozen ground, and across asphalt. A local plumber suggested it and I was very skeptical, but it seems it worked. You have to know were the pipe is though. Chalk one up for folk contracting. Another neighbor said if that didn’t work, we might try manure under straw.

The PVC repair/septic installer guy, suggested the place it was freezing was where the pipe entered the house. After the first year we built a small herb garden above that spot adding at least another 18 inches, 3 feet wide. Since it didn’t freeze last year, we assumed that fixed it. We then extended our driveway over it. So now I have no idea where it’s freezing. I do know that heater tape on the house end makes no difference. It didn’t two years ago. I don’t think it diffuses far enough. Straw seemed to worked then but it also warmed up, so I didn’t attribute it to the straw. And the welder thing is common out here (mountains of central PA). But the guy who used to do it was warned by his insurance company not to. I thought about buying one myself. So far I haven’t. Now that it’s melted I’m leaving the downstairs bathtub tap drooling.

The plumbers I’ve asked about estimates for re-digging the pipe have all said it would be significantly cheaper in the spring. They didn’t say it was because it was easier for the equipment, I suspect it’s because it’s easier for the crew. Since I may pay for it, I would like it to be more reasonable.

Our lawyer isn’t worried about the new driveway, I am.

One last thing to consider. Apparently Silly Putty and PVC have a few qualities in common. This made me glad I gave it time:

http://www.boingboing.net/2005/12/30/how_to_break_silly_p.html


Thanks!
posted by Toekneesan at 1:39 PM on December 31, 2005

It may be too late now, but if you do get a thaw, be sure to install a shut off valve at the well side, with a drain valve (hose faucet will do) just after that. Open faucet in house and well faucet to drain line. Turn it on when you're going to use water, usually during the day. PVC won't be issue because it'll end up bursting at the weld anyway and you can replace it then. You can also run a hose back to the well with a low voltage recycle pump and won't have to shut off water and drain. Put hose through insulation tube. You can even heat part of the line since you'll have the water recirculating. Recirculating pump can be purchased at home depot for about 100.00. When you don't need it anymore you can put it on water heater, to have instant hot water at the tap. Instructions included. Things mentioned are DIY for most.
posted by cjburton at 10:14 PM on October 24, 2006