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Jim constantino
11-15-2004, 12:12 PM
I work for a water utility that is considering the purchase of a welding machine to thaw frozen water services. I have several questions:

1. Is it safe to use a welding machine to thaw a frozen water service?

2. What welding machine is best to use to thaw a frozen water service?

3. Is there a max amperage that can be safley applied to a frozen water service? The pipe materials would be 3/4" to 2" copper tube and galvanized steel.

4. What are the potential dangers?

5. Is there some type of published guideline on this procedure?

6. Who should do this work and what training or certification should be required?

Thank you in advance,
Jim

hankj
11-15-2004, 12:25 PM
Jin,

I you don't get an answer here (doubtfull, BUT possible!) post your question on the AWS buliten board at www.aws.org

Hank

Sberry
11-15-2004, 01:41 PM
I have used up to 400A machines to do this and DC is the best. I like a clamp on amp probe. There are some dangers. The main one being thawing lines with multiple houses with electric service from the same transformer and city water systems. If there is a high resistance connection such as a rusted galvanized coupling in the line the current path may follow the electric grounding that is connected to it. Since the neutral is bonded to the ground at main entrance panels the use of high currents may overheat a ground wire that is within or passes thru a wall somewhere. It could even start a fire in another house, not just the one you are working on. What I usually do is discnnect the ground to plumbing bond at the house I am working on, use rubber gloves in case of currents on the ground wire when disconnecting. You should be then able to get some idea with an ohm meter if it is bonded elsewhere or it may show some reading thru a ground rod, maybe Terry L can help some here, but the idea is to seperate it so that electric currents cant be carried via the neutral line and using it as the conductor isteaf of a pipe. Nice thing about rolled copper lines, reduces this a lot. After a while instinct plays a part in how much to heat but an amprobe is usefull in setting heats and making sure its working right. Using less than a couple hundred A makes it slow (the reason to use 40 or less is that it wont overheat a number 6 ground wire) You need to keep an eye on the machine to keep it from overheating, not so bad as winter temps help. You need to keep pressure on the line and it melts a small film of water on the inside of the pipe and when it starts to flow the water will melt the ice plug out. Good heavy leads help. Now, having said some of this,,, insurance companies have a fit about doing this because of a few horror stories, there is nothing inheriently wrong with thawing lines provided its done correctly. Miller doesnt reccomend doing it any more due to the conditions they describe, I guess they figure the amount of machine sales due to this are not worth the grief. If you dont understand this ask some more or get an electrician to help explain it,, I am not saying to do it,, but it can be done. Galvanized steel heats quicker than copper. Its a strange thing sometimes,,, have heated away,,, nothing,, take welder off for 10 mins, hook up and heat again and it works,,, ha. Usually a 3/4 copper line 75 ft about 30 mins @ 200A depending on a couple of factors. I like to avoid heating thru soldered copper joints when I can unless I am sure they are full of water.

Roger
11-15-2004, 04:39 PM
You can only thaw pipes at less amps than your welder is rated for 100% duty cycle. I think the Lincoln tombstone AC welder is rated about 40 amps for 100% duty cycle. It has a line with circle or dimond at 100% duty cycle point. Now days they only recomend doing this on pipes isolated from buildings.

Sberry27 did great job covering the rest of the story .

Thomas Harris
11-15-2004, 04:42 PM
Fix them so they do not freeze again. Kinda like the ice dams. Everyone goes apesh)t over them in the winter, but nobody takes the time to eliminate the cause of the problem. And guess what... they come back next year! I suppose if you're a maintenance worker that does keep some hours availible for you.

Sberry
11-15-2004, 06:48 PM
Most of the tombstones are rated 70A and some of the older ones had "pipe thaw" right on the label. Its a little slow at that power but it does work. I have even put them on in the morning and came back in the afternoon when using those machines. Used some old number 6 electric service entrance wire for cables,, ha. I like the muffler clamp U bolt idea. On small lines I use Vise Grips and connect to it or make last connection on a heavy fittling or lead connector. You wouldnt want to arc a hole in a copper line.

Smitty
11-15-2004, 08:46 PM
Ridgid makes a tool desgined for this called a KT 200 with 300 amps output,no duty cycle and works on a 15 amp circuit.Right tool for the job!

Sberry
11-15-2004, 08:59 PM
This I woud like to see. maybe 30 A???

abooker
11-15-2004, 09:16 PM
Here is a link to the KT200 (http://www.ridgid.com/Tools/KT190-KT200-Pipe-Thawers/) , seems like a nice tool to have.

Terry Lingle
11-15-2004, 09:44 PM
sberry covered the dangers and hazzards involved pretty well. When all pipes were galvanized iron and power distribution was simpler this was a standard practice for water mains but even more for fire hydrant stubs . I worked for the works department when I was in school and we used to test each hydrant every saturday. These are deep taps with drainback provisions and they must work.
Frost would hit 7-8 feet under the paved streets due to the clearing the insulating snow . we would thaw up to 15 stubs a day in cold weather , Nowadays with copper pipes , plasiic house plumbing and all the complex grounding issues I doubt if you could get a licenced conteractor to try this a second time.
The last time i did this was on as feed from a well to the house . I unpluged the pump, disconnected the grounds, ( hydro ,phone and cable feeders all have separate grounds clamped to the water pipe in the same area), then unsrewed a union iin the house two feet above the concrete .
When I was about 10 min into the thaw I looked up at the power drop on the pole and saw steam coming from the neutral tie point. I shut off all breakers in the house except the 220 feeding my welder and finnished the thaw then called hydro to get the bad connection repaired.

The point here is that I did everyting possible to isolate the pipe from the electrical side and still had problems with ground currents even with the thaw current held to under 60 amps .

If you or your employer go forward with this confirm the insurance limits before you start .


If I remember correctly from 40 years ago there was a chart on the power source that gave recomended setings . I think we used 5 volts for every 100 feet of 3/4 pipe in the thaw loop that gave us 75 to 100 amps depending on the condition of the pipe. That works out to 3.75 to 5 watts per foot .just enough to raise the temp above freezing.
For copper pipe with its lower resistance you will need less voltage and get more current to get the same watts per foot ,
The ground problem is independant of the power source and is the biggest concern here .
Good luck
Terry

Smitty
11-15-2004, 11:13 PM
The reason the kt 200 only draws 15 amps is that its output voltage is 4.5 volts instead of 20 like a welder which not only makes it safer,but more efficient because current generates heat-not voltage.

Terry Lingle
11-16-2004, 01:28 AM
Well er heat is the product of current times voltage so it really takes both
watts = volts times amps
or watts = amps sqared times ohms or
watts = volts squared divided by ohms
All formulas derive from ohms law .

The problem here is that to thaw pipes you must put current through them. To do that you need voltage proportional to the circuit resistance. The longer the pipe the more voltage needed.
It is the unintentional I squared R power in . ground wires that causes the problems.


You should not use a constant voltage machine to thaw pipes because it will not limit the current if the connected load decreases in resistance.

Assume for the sake of discussion that a particular frozen pipe needs 200 amps to thaw it .
A constant current welder may have a 400 amp capacity and 80 volt open circuit voltage. If you set the current to 200 amps and connect it across a pipe the voltage from one pipe connection to the other pipe connection will be 200 X 200 X pipe resistance. The welders terminal voltage will be controlled by the internal design of the welder to that value plus cable loss. .
Tthis means that if the kt 200 can put 200 amps into that particular pipe the voltage wiill be exactly the same as the welders loaded terminal voltage assuming that the same cables and connection points are used for both machines . On the other hand if the kt does not have enough voltage to push 200 amps into the pipe then it will not thaw the pip[e , The welder on the other hand will rsise the voltage untill 200 amps flows and thus it will thaw the pipe.
Terry

Sberry
11-16-2004, 09:38 AM
I dont know much about electricity but it seems you are only going to be able to get 1800 watts out of the wall and there isnt any more.

Terry Lingle
11-16-2004, 11:31 AM
I dont know much about electricity but it seems you are only going to be able to get 1800 watts out of the wall and there isnt any more.
Not even that much. that is the must trip level.
The actual continiuous output of a 15 amp receptacle at high rated ambient is about 1320 watts. This ambient is the temperature in the breaker box not the outside ambient. That is why you get toasters ,kettles microwaves ect designedfor 1300 watts.
Terry

Sberry
11-16-2004, 12:15 PM
Yes, that was what I was actually thinking, it would have to be rated to run continious on a 15A circuit. I dont remember the readings on the last one I heated, it seems it was about 200A at 22v or so maybe a little less. It was at a casino and we had half the maint crew standing around and they had just got a new meter. I had a couple poor lead connects and they really show up laying in the snow,, ha. I had a couple of 100 ft 1/0 leads I lost in a fire and everytime I thaw now I wishing I had them back instead of piecing 50's. I should redo connectors before I need them this winter. Burning a couple small electrodes you dont notice but heating you do. I have done as much as 400 ft of 1 1/2 galv and it took about 2 hrs or less which is kind of amazing.

Portable Welder
11-16-2004, 03:43 PM
Back in 1994 approx. The city of Southlyon, MI. had their Main freeze up Thinking back it was probally a 4" main on a dead end street with about 6 Houses on it.
Something you guys forgot to mention if you are going to do this is dont forget to warm up your welding machine to operating temputure, shut it down and then quickly start it up and dont exceed the duty cycle.
I was using a Miller big 40 when I did it and I think it was 400 amps and 300 amp at 100% duty cycle. I had my machine on it all night long and the next morning with no luck, not untill they added their little lincholn to help did it finally work.
I noticed that my machine was never the same after that, I had to change my normal setting up about 10 amps to weld with the same rod as I use to, and my motor had a miss in it when it warmed up, I think I hurt the valve seat.

I will no longer thaw pipes for this reason.
Help me under stand How the fire happens, If there is a bad connection on the pipe joints the possitive lead will send power the other way seeking out a ground.
I also did a few houses after, and what I did was attatch my lead to the key at the road and then go in the house before the meter and hook my lead up, so in my mind I could not have caused a , but I think you guys are telling me the power could have went the other way. Please explain. one of the shops in my area did burn down a house, pipe thawing but I was never able to find out what he did wrong.

Sberry
11-16-2004, 04:41 PM
The current went thru the neutral wire on the electric system. Neutral and ground are bonded to the water system at servie entrance. He likely overheated a ground wire going thru a wood wall somewhere, one that bonded the electric service to the water service. This is a big danger pimarily with houses sharing the electric from the same transformer and connected to city water, If you have an eletrician friend have him draw a sketch and he can explain it very easily.

uncrichie
11-16-2004, 05:48 PM
I also agree with the 1300 watts continuous duty on a 15amp receptacle. You must also remember that is input power. Unless this unit establishes a 100% efficiency rating, NOT, the output is probably more like 75-80%. Now your looking at approx 1050 watts, not very impressive is it. I would imagine you have to have this unit pluged in forever for it to work. Another issue is the difference in the two models, almost a 100 amp difference using the same 115v 15 amp circuit? Very questionable unless the smaller unit is more like 600 watts output. Plus there is only a difference of 4 lbs between the two, smells fishy to me. Uncrichie...

Smitty
11-16-2004, 11:00 PM
Why is it that you can plug in a 15 amp chop saw or jackhammer,1875 watts and hammer or chop till you are blue in the face.I've stalled out chopsaws from load and that is the peak current and never had the breaker flip once.The only time it has kicked out is if someone is using the drillpress that is also on the same circuit. Furthermore, voltage does not create heat,voltage is the force that drives electrons (current) down a conductor.If you compare electricity to water, voltage is force (water pressure),Amperage is flow of electrons (Gallons per minute), Resistance is impedeing the flow of electrons.Watts has nothing to do with heat except for it is the amount of power you have consumed and are going to have to pay on your next bill.Welders are all rated in amps because this is the amount of heat produced for fusion- the higher the amps,the more heat. The reason for 400 amps is 1875 watts consumed is 400 amps x4.68 volts.Amperage is going to go down with ineffiecency so the smaller unit probably has a cheaper transformer with less windings.

Sberry
11-16-2004, 11:44 PM
Watts are the actual units of energy. As for tripping breakers my chop wont even start on a 15. It will snap the breaker every time. In fact I run it on a dedicated 30. But you double the voltage and you double the wattage at the same amperage.

Smitty
11-17-2004, 12:14 AM
Of course if you double the voltage (force) you are going to double the wattage (energy consumed),But by doubling your voltage and keeping your current constant you have actually Halved the heat from resistance and can use a lower guage conductor because it is forcing electrons down the conductor twice as fast.The lower the voltage for this intended purpose would be better because is there would be a less chance or arcing thus making it safer.BTW what kind of chop,I use makita.

david_r
11-17-2004, 01:10 AM
Portable,
Was that shop using an engine drive like you were? If you read through the thread on engine drive grounding, I don't see how the grounding/grounded wire could be an issue.

Terry Lingle
11-17-2004, 10:13 AM
Of course if you double the voltage (force) you are going to double the wattage (energy consumed),But by doubling your voltage and keeping your current constant you have actually Halved the heat from resistance and can use a lower guage conductor because it is forcing electrons down the conductor twice as fast.The lower the voltage for this intended purpose would be better because is there would be a less chance or arcing thus making it safer.BTW what kind of chop,I use makita.

Smitty heat or watts is volts X amps the volts are what drive the amps through the load
If you do not have enough volts available you cannot get the amps. it matters not what you use as a source the voltage across the load will bet the same for a given current flow.

The heating problem is not arcing but excess current for the wires size. The cause is you forcing current across the water pipe upsetting the voltage distribution in the ground circuit which BTW is not supposed to have any deliberate current in it. This can cause excess local current loops to form causing heatiing in the affected wires.

Your tools are rated at peak watts and only achieve them near stall . toasters ect are pure resistive loads and always draw full rated power when on.
what sberry said tells me that one of three things are true.
! his breakers may be more sensitive to current peaks than yours.
2 his machine may be more powerfull than yours ( most likely cause) thus it has a higher starting current
3 his machine may be faulty this is not likely as I believe it is a near newe millwalkee and they are pretty rugged.

Terry

Jim constantino
11-17-2004, 10:33 AM
Hey Guys,

Thanks for the responses. Its getting a little over what I can understand. Our boss wants to pruchase a welding machine and have our publics work staff trained to operate it and thaw frozen water services. This seems to be a risky service to provide without the experience you guys seem to have. Can you confirm this? Can you suggest what training and who should provide it? I have noticed that the major welding machine suppliers DO NOT RECOMMEND USING A WELDING MACHINE TO THAW FROZEN WATER SERVICES. If welding machines are not reccommended by the suppliers and our water utility wants to go ahead with using a welding machine what should we purchase and how and by who should we be trained? Any other horror stories? Can the person doing the thawing be injured by working with the grounds? Who should actually touch the graounds?

Thanks Jim

Sberry
11-17-2004, 11:58 AM
The main personell saftey issue would be disconnecting grounding from the water system as there could be stray currents or faults carried on it. A pir of runner gloves and boots shoud take care of this and you could put an amp probe on the ground wire to see if any large currents are on the line or use a jumper cable with insulated handles, disconnect the bond and then disc the cable.
I am not sure how sophisticated the utility you work for is? I would have an electrician review this thread and then have him on the spot or train sufficiently the operators. Even if he isnt familiar or have experience with this particular process he would be able to come up to speed with it from reading this.
Moe, I have had 2 or 3 saws and get the best most powerful motor on them I can. I am using SQ D QO breakers and (long time ago) when I had them on an old Federal panel it didnt trip them. The Federals didnt want to trip on heat well unless it went to short circuit. There were some problems with those and I trashed those panels as it was a common problem. There are a couple of older brands that didnt work so well. Also my electric sevice is good, very good and they really snap on when you pull the trigger. They usually didnt snap the breaker for the first half a dozen starts untill it ratched up a bit and new wheels made it a little worse than a worn smaller one. I overheated a Skil model I had by making too many continious cuts in some 4 inch pipe without letting it cool. It was my own fault for not paying attn and it would still be working if it wasnt for that. That is a downside of breakering them up,, but,, you have to be able to start it. I now check motor heat with my hand over the motor exhaust when making real heavy cuts and keep an eye on it.

Portable Welder
11-17-2004, 12:54 PM
david R, I dont know what the other company was using, I just Assumed it was a portable welder, This was approx. 13 years ago when the house burned down.

To Sberry, The way I under stand it is that if I'm using a portable welder and I stay inside my loop from the key at the road to the base of the meter I will be OK.
the problem would be if I were to use a buzz box connected to the house power and hook up inside the house past the meter where the grounds are connected to the water pipes is where I would have a potential problem.

Sberry
11-17-2004, 03:13 PM
No, it has nothing to do with what type of machine you are using. The ground to the wiring of the machine is non operating part of the circuit. In theory if you are connected at the street and inside it should be ok,,, but, this is where the problem arises. You would need to disconnect the meter and any ground wires going to that piping that led underground. It is the welding current that can cause a problem. It could take an alternate route, instead of going thru the pipe (most cause would be such as a rusted coupling) it would circulate around from house to house on the electric system. Ground wires are only number 6, 4 at best and even as small as number 8 on 100A services. High welding currents may turn this small wire red hot and if it passes thru a wall its like putting a toaster element in there. You can see how fast a 1/8 electrode heats if you stick it and short it out, will turn it orange in a few seconds. With electric services they are required to be bonded to water systems, 2 houses connected by the same transformer and bonded to the electric, the current goes from the ground wire, to the panel, up the neutral wire, across to the next house down the neutral to the ground wire and back to the water system. With these interconnected systems you are never sure the path the current is going to take unless you isolate the line at the point you are working on. If you had a wrench so you could turn the water off, take the meter and any ground jumpers out, thaw line and when it started to trickle, shut off water and re-install the meter and hook ground back up, then open water main again and let the water finish melting the plug out you would be ok. Do you have someone helping you wire your building,, have him sketch this on the bench with a soapstone. Maybe someone could post a drawing?

uncrichie
11-17-2004, 03:16 PM
Smitty, your mixing apples and oranges. When your heating a pipe to melt the water in it you are talking wattage. Volts x amps = watts period. if I were to take 1000 volts on a line and allow 1 amp of current to flow the outcome would be 1000 watts. The reason welders do not use 1000 volts on the electrode is because of shock hazzard issues. I could melt the same amount of ice in that pipe with 1000 volts and 1 amp as you could with 1000 amps and one volt. heat is heat. This is why you can weld with some welders that use scrawny transformers and use hurendous capacitors. Uncrichie...

Sberry
11-17-2004, 03:19 PM
Here is a pic, lets see how it goes. The pink line is the welder current and you hope thats how it travels. If for some reason there is less resistance in the electric system than in the piping, a bad coupling say, it will follow the yellow line and cook the wires that hook the electric to the water system. What makes that Ridgid tool so safe is that in a home the smallest ground wire you would find is a 14 and that tool wont overheat one of them by accident as its limited by the incoming power. It uses huge secondary leads because they want no resistance there, they want all the energy being put into the water line. Its going to be slower than the second coming. If you had several and a bunch of lead you could connect them to customers water lines and come back the next day and remove them but a welding machine makes so much more power that its fast and you can do one right after another or while you are waiting, 30 minutes and its done in some cases, move on to the next one or go home. Anytime you can double the heat it takes probably 1/4 the time. (maybe someone can verify this number?)

uncrichie
11-17-2004, 03:53 PM
SBerry27, "slower than the second coming" great phrase, I haven't heard it used in awhile. I agree the Ridgid would take forever to resolve the problem. I believe with the ratings listed it should be called an appliance. Uncrichie...

Sberry
11-17-2004, 05:29 PM
I wonder why they made the voltage sooooo low? Did they figure like smitty mentioned arcing? Or potential to ground? Or less likely to find ground loops?

Terry Lingle
11-17-2004, 06:18 PM
There would be two reasons for welding machine manufacturers to not recommend there machines to thaw pipes . the first reason is potential damage to the machine if you exceed the duty cycle when thawing..Thawing is 100 % duty cycle operation.
The second reason would be potential liability if any damage occurs .

Sberry your pic is good but the yellow should be red.
With todays added communications grounds the complexity is even greater.

portable welder
Even if you carefully control your loop things hidden in the ground will come into play to give unexpected results some of the time.
It must be pointed out that most of the time no problem will occur. When a problem does happen it most often will be at the house you are thawing so you stand a good chance of spotting it before it becomes serious.
Occasionaly the problem will affect a different premise one that you are not concentrating on so you may not notice it at all. At some time (If you damage the ground system but do not cause a fire it may be weeks later) it will be noticed and then the legal problems start.

Be very cautious thawing pipes and be sure to reconnect the grounds removed properly when finished
Terrry

Sberry
11-17-2004, 07:12 PM
Ya, I used a highliter marker for the first one and thought of the paint program when I got to the second. The only thing I really know how to do well on the puter is flirt with girls on ICQ. ha,, Did you give any thought as to why Ridgid made the V so low on that unit? I am sure there s a good logical reason that I am missing. Seems it would have made secondary conductor sizing so much easier with a little higher V. My understanding of electrical theory is so poor I usually have to ask when it comes to things I dont deal with on a regular basis. Most common wiring installations are mostly mechanical that I can deal with it and there is always code to follow so I manage and just a certain amount of sheer repetition is helpful as well as being able to remember facts and just enough curiosity to find out why when I am wrong. One reason for a little study was the seemingly constant quoting of hearsay as to what code was in so many situations and I have so much stuff I had to be able to add and customize circuits on a continious basis. One of the first or seond things a guy should learn when getting a welding machine is how to run a basic welder circuit properly. Enough babble, back to work for a while, fun, rusted truck frame for a customer.

enlpck
11-17-2004, 09:54 PM
I wonder why they made the voltage sooooo low? Did they figure like smitty mentioned arcing? Or potential to ground? Or less likely to find ground loops?

Well.... The voltage is so low for a couple of simple reasons.

1) minimal risk of leakage current. This is key. The ground is a poor conductor. It is also not a true resistance--it doesn't follow Ohms law exactly. At below two volts, the resisance is a good bit higher than at 10 or more volts. Railroad track signaling voltages used to be in the 2 to 4 volt range for this reason--essantially no leakage, even with wet ground. Very important in the case of a poor joint--significant current won't leak through the ground to nearby conductors. Wet ground is somwhat better, than moist or dry, as a conductor, especially if there is a high content of soluble mineral, but leakage is still better controlled at low voltage.

2) power delivery--high current is needed to heat the pipe, and with large work cables providing minimal loss in the machine, a high current can be achieved in the pipe with a low power from the supply, so a higher voltage isn't needed to push the current. using a welder wastes much of the power in the machine itself (my Lincoln motor-generator will blow 80% of the generated power in the welder on a dead short at the output. Transformer machines are about as bad)

3) minimal risk of personal injury and fire

at 4 volts secondary, a 15A, 120v primary will provide over 400A to the pipe--this is a lot of heating capability with steel pipe.

Terry Lingle
11-17-2004, 10:49 PM
Enlpic
The trap here is that the resistance of the pipe limits the length that can be thawed .The useable continuous power from a 15 amp circuit is about 1320 watts any more and the breaker will heat trip. so at 100 % efficiency you could get 330 amps. At a more reasonable 90% efficiency you could get about 300 amps. The working limit for 300 amps at 4 volts will be the length of pipe and leads that has a total resistance of.013 ohms. the lead length is assumed to be about the same as the pipe length .
The resistance of 4/0 wire is.005 ohms /100 ft so the total max wire is about 266 feet if it is all 4/0 copper wire a more reasonable working length given the nature of pipe and the cost of wire would be 25 to 50 feet of pipe and the same amount of # 2 wire at .0159 ohms/100 ft.. so this unit might thaw a frozen outside tap through the wall but not much more .
For comparison A cc welder hooked up to the same 25 foot pipe and set for 300 amps would have the same terminal voltage as the 115 volt machine and deliver the same current 300 amps. what happens if you want to thaw 100 feet of pipe ? With that machine you would get about 75 to 100 amps as most of your voltage woud be used on the wire. the pipe probably would not thaw untill spring. . The welder on the other hand would drive the voltage up until 300 amps flowed. or about 10 to 15 volts. The pipe would thaw in about double the time for 25 feet. the difference is that you have to thaw lfor more time on the longer pipe before flow starts. Once you get water flowing the water finishes the job.

The fire risk is independant of the supply machine. If you drive enough current into the pipe to thaw it you drive enough to seriously heat a # 6 ground wire if it becomes the path due to resistance problems in the pipe connections. All the meter testing in the world can not determine if the resistance shown is through the pipe or through a shunt path.Unless you have access to all possible shunt connections and the time and knowledge to set up a proper testing scheme to check and eliminate them you will not know for sure .
Terry

Smitty
11-18-2004, 01:21 AM
There is a owners manual/operating guide on the bottom of the rigid page that can be applied to whichever machine you intend to use.What i meant by watts has nothing to do with heat was i was refering to the input and output watts because energy can get consumed by ineffiecenties in different products.The reason you can weld with a scrawny transformer and a enormous cap is that a cap stores current and all the transformer does is step up/down voltage, the cap stores current (power) to stabilize the arc.

enlpck
11-18-2004, 08:34 AM
Note that I make no claim that the machine is particularly good for the purpose. I don't know if it is or not, but I wouldn't suspect that it is real useful for long pipe runs. I only conjectured as to the reason for the 4 volt output.

I think that you may have hit the pipe on the thread with "thaw an outside tap", tho. That is probably all the thing is really good at.

As a side note: Should I point out that if the burried line is close enough to the surface to freeze, there is a design flaw? (stated knowing that when I lived up north, I never had a pipe freeze, other than in the house when the heat was out, despite several months of below freezing, and typically a month or more of -20 to -30C. Those ppes were DEEP) Of course, one I moved to Jersey....


Enlpic
The trap here is that the resistance of the pipe limits the length that can be thawed .The useable continuous power from a 15 amp circuit is about 1320 watts any more and the breaker will heat trip. so at 100 % efficiency you could get 330 amps. At a more reasonable 90% efficiency you could get about 300 amps. The working limit for 300 amps at 4 volts will be the length of pipe and leads that has a total resistance of.013 ohms. the lead length is assumed to be about the same as the pipe length .
The resistance of 4/0 wire is.005 ohms /100 ft so the total max wire is about 266 feet if it is all 4/0 copper wire a more reasonable working length given the nature of pipe and the cost of wire would be 25 to 50 feet of pipe and the same amount of # 2 wire at .0159 ohms/100 ft.. so this unit might thaw a frozen outside tap through the wall but not much more .
For comparison A cc welder hooked up to the same 25 foot pipe and set for 300 amps would have the same terminal voltage as the 115 volt machine and deliver the same current 300 amps. what happens if you want to thaw 100 feet of pipe ? With that machine you would get about 75 to 100 amps as most of your voltage woud be used on the wire. the pipe probably would not thaw untill spring. . The welder on the other hand would drive the voltage up until 300 amps flowed. or about 10 to 15 volts. The pipe would thaw in about double the time for 25 feet. the difference is that you have to thaw lfor more time on the longer pipe before flow starts. Once you get water flowing the water finishes the job.

The fire risk is independant of the supply machine. If you drive enough current into the pipe to thaw it you drive enough to seriously heat a # 6 ground wire if it becomes the path due to resistance problems in the pipe connections. All the meter testing in the world can not determine if the resistance shown is through the pipe or through a shunt path.Unless you have access to all possible shunt connections and the time and knowledge to set up a proper testing scheme to check and eliminate them you will not know for sure .
Terry

Terry Lingle
11-18-2004, 08:50 AM
Normally everybody in frost country burys pipes below the frost line but sometimes the situation changes .
I have found that the main reason that pipes start to freeze even if buried to the proper depth is a change in the surface useage . If you later put a driveway or an unheated structure over the pipe the ground freezes deeper because you lose the snow's insulating effect in these areas. such changes are made by new owners that are unaware of pipe locations. the other causee is a really bad cold snap before the snow builds up to a resepectable depth.
Terry

Meach
11-19-2004, 09:47 PM
While I dont claim to be a master welder, I was a Master Plumber and HVAC contractor for over 10 years. Every year houses are burned to the ground from people using welders, battery chargers and torches to thaw frozen pipes. As one of the other posts mentioned, there is a pipe thawing machine on the market, readily available and they work very well and are very fast. I earned tens of thousands of dollars with them. Please dont mess around. Get the right tool for the job. Thank You :D

Sberry
11-19-2004, 10:03 PM
Feel free to enlighten us on these machines. You have used this ridgid? How fast does it work?

toolaholic
11-19-2004, 11:25 PM
30 years ago my welder mentor, told me a sad tale. he had a new machine cooked,
unfreezing water pipes. he hadn't even made one payment on it.

he bought a used machine and made the payments on the anchor weight.

Smitty
11-20-2004, 10:07 AM
Hey meach,but did you ever try welding with one!!!!

Meach
11-21-2004, 09:27 AM
Hey meach,but did you ever try welding with one!!!!
No I had a good welder at the time.
In Reno Nevada code calls for 36" bury of water pipes. Most frozen pipes occur from some deviation from code or some other condition such as no heat in the home. For some reason plumbers seem to want to do things the easy way instead of the right way and then some customers want the cheapeast way regardless of what is proper. I feel that is where the responsibility of the true professional comes into play. Refuse a job if they dont want to do it according to proper practice or code, however some feel if they dont do it the next guy will so the money may as well be in their pocket. Just my 2 cents.
The ridgid pipe thawing machines work quickly and are a god send. I had 100' of I think 1/0 welding cable put on all 3 of my machines. Most homes dont have a straight run of over 50-60 feet and you never really knew where the freeze was. Usually you have to use common sense and start where it was most likely to freeze and work from there. A water pipe under a house that runs by a foundation vent will freeze sometimes. A pipe run inside a wall that is on the perimeter of the home could freeze. A main line coming into the home sometimes is run closer to the surface as it comes through the foundation or is brought up above ground too close to the foundation perimeter. If the homeowner goes on vacation and leaves the heat off or if their furnace breaks down.You kind of get the idea. In most cases I hooked up the machine, turned it on and started writing the bill. The water would be running before I got the invoice finished. We had a 1 hour minumum and I can not remember ever charging for over the minimum on a thawing call.
I have seen welders used as thawers heat the copper pipe so hot it melted the solder joints! I have over 10 years experience thawing pipes and I would not even consider using anything but a pipe thawing machine. Even on my own home!

bjdenommee
11-22-2004, 05:20 AM
Guys, I run the General thaws units, last year up here it was -40oF for 2 weeks we were thawing almost all of the time. With the generals units they work great on any line under 2", I try to isolate as much of the pipe as possible, as to keep the charge from getting out of the loop, I have run machine also to thaw and again you have to have a picture of that pipe taken out of the system and its sitting on the ground, connected to nothing else but the machine. Thats the way I tell the guys isolate as much as possible, so as to make the current run were you want it.
I dont know how much it works, and or how well but my dad use to wrap the cables a few turns on each end, His reason was it made the current flow a little better, I have tried it and can only say each frozen line is defferant than the other.

Also if you ever end up thawing heat lines in houses, beware of TVs screens they and the magnetic field can cause chaos with them (Keep your cables away from them)

They also get hot, keep them off of the rugs.

Bernie

enlpck
11-22-2004, 08:54 AM
I dont know how much it works, and or how well but my dad use to wrap the cables a few turns on each end, His reason was it made the current flow a little better, I have tried it and can only say each frozen line is defferant than the other.



Only works with AC welders, but works reasonably well. Turns the pipe into a single turn secondary for the welding lead multi-turn primary. Major league current with a low current welder. Good for spot heating, like welding preheat at a pipe joint. Watch for overheating, as even a fairly low power welding machine can put in a LOT of heat to a small area rapidly.

Meach
11-22-2004, 08:56 AM
Its amazing how people never learn. In Reno we had two one week periods of -30 degree weather a week apart. Even though we told people after we thawed their pipes to leave them running a trickle we ended up thawing the same peoples pipes twice! We also thawed in smaller sections isolating sections of pipe to be sure we knew or at least had a **** good idea of where the current was flowing. Even after several houses were burned to the ground, people still thawed with torches! Unbelievable

AKPlumber
12-06-2005, 07:10 PM
Hi, this is my first post to this awesome board (was referred here by a plumbing board) so thanks for lettin me in!

I was going to just lurk awhile lol but I really can't stay shut-up to this thread. :D

Meach, I think you're over-reacting and just a tad paranoiac about thawing. That said, here in Alaska, frozen pipes are a fact of life everyday in winter, and if you're going to do service work it greatly enhances your chances of staying in business if you offer this service. Turning it down is an option, and so is seeing your competition get every other job around you because they have a welder on a trailer. I do service work and i don't want to get involved in it myself but I've worked for guys who do and I've done lots of it, both electric and steam.

The little buzz boxes like the Ridgid are great for my uses, which are primarily now just the occasional frozen heat loop or water line (along with all the inevitable soldering for bursts). But on many, many jobs, it simply can't be done with one. There are homes built with little to no insulation, lines running under slabs or barely accesible crawl spaces covered over with floorings and crossing and touching one another, on and on. It takes you half the day just to find where the lines or loops are running much less making accessibility to them. I have thawed boiler loops simply by cutting the return to isolate and clamping on to the return and supply right off the boiler thawing the entire loop, done in 20 minutes and I'm putting the cable away and writing the invoice while the customer has heat back. I would DARE you to tackle some thawing jobs we get around here with a little buzz box. And it's fine to say you would turn those down, but the fact is these people need their services restored NOW they have no heat and the longer you let the system freeze the worse shape it's gonna be in. What is your solution, move them into a hotel until spring?

Also, there are many times a short, simple run can be quickly and easily thawed with a small torch, such as in crawl spaces or attics or whatnot, and just as with repairing a line by soldering, you have to use common sense and just do it safely. There are even asbestos rags and such one can use to avoid lighting materials on fire. It's just common sense.

hankj
12-06-2005, 09:15 PM
Alaska Plumber?

Wow. Welcome to the board.

I guess a plumber's job in AK might be OK in the short summer (depending on where you are), but an AKplumber in winter is a tougher dude than I'll ever be! I've onlt visited a few Alaskan cities on te inland waterway, but is is an incredibly beautiful part of North America.

I'm not into thawing pipes. California (my part) isn't that cold yet.

Again, welcome!

Hank