burst a water line on my tig torch

[craig]

i just installed an sr 20-25 water cooled torch on my dialarc-hf. homemade water cooler running at 20-25 psi. went to try it out around 200-225amps. welded for 15-20 seconds and heard a loud pop followed by an unidentifiable sound. stopped welding and lifted the hood to find water shooting everywhere from about a foot behind the torch. shut everything off and inspected the burst. the power cable was warm. the actual wire inside the power cable was only about 1/8" or so in diameter, is this normal? has anyone else ever done this? should i have had more pressure in the lines?

[Franz]

Need more information on your setup.
Are you running a cooler?
Was it the tube containing the wire that burst?
If so, have you run the water path thru the solonoid valve?
Did you confirm water flow thru the torch prior to beginning to weld?
Is this the initial startup on the machine?
Does the split appear that the conductor insode the tubing melted the tubing?
Can you post a picture?

Increasing water pressure only increases problems.

[DrIQ]

Craig, Did you have the torch hooked up so the water (coolant) goes to the torch first and then back the hose with the power cable to the power block?

The pressure you have set could be a little higher but if you blew the line behind the torch I wonder if you had coolant flow through the torch before you started welding if not 15-30 sec. will destroy the power cable.

[craig]

yes i did confirm there was flow thru the torch. it is setup to flow thru the power block then the torch. it just flat out burst a hole in the line going to the torch. maybe the conductor melted it but it just looks like a burst. i had the pressure up to 40-45psi during testing of my homemade cooler and it didn't burst then. maybe the torch head clogged and the pressure spiked? i'm just using a simple adjustable bypass right after the pump with a gauge on it. i'm going to take the torch apart tomorrow and blow air backwards thru it to see if i get any debris out of it. anything else you guys can think of?

[Franz]

If it was the line containing the wire, chances are you developed an air pocket, and the wire melted thru, or at least softened the line sufficient for the water pressure to burst it.
I'm absolutely against the solonoid being in the liquid circuit when a cooler is used, and in my opinion, your pressure is too high. Without restriction in the fluid circuit, you shouldn't be acheiving that pressure thru a torch.
The bypass valve method of pressure regulation you're using is the same as mine, and it is possible your bypass malfunctioned, but rather unlikely.

[DrIQ]

Reverse your coolant flow, always cool the torch head first and the power cable is the return line. That probibily didn't cause the line failure but will reduce the life of the torch.

[craig]

franz, i'm not using the solenoid, i didn't see a point in it. is the coolant supposed to go thru the torch, then the power cable or power cable then the torch? the only restriction i have in the circuit is the torch and again when it happened i was only running 20-30psi. i hate to put a new cable on it and have it happen again, so i want to fully understand what heppened the first time.

[dseman]

If this scenario is going to be replayed in your lifetime, then you should install a fuse block. If there is no coolant pressure or flow, the fuse blows---with as little as 5 or 6 amps.

http://www.welding-direct.com/saffusforwat.html

http://www.ckworldwide.com/Fuse_block.htm

Here is how the torch should be setup:

http://www.ckworldwide.com/tech-2.pdf

-dseman

[craig]

yeah i had the flow wrong.makes sense, the heat from the conductor warms the tubing making it softer and weaker. any pressure can then blow a hole in it. duh

[aircraft]

Yea I checked mine it has only 10psi.

[Franz]

I think the key to understanding this failure would be seeing the failure rather than trying to rely on representations.
A water fuse is certainly a good idea when using a cooler, and the fuse links are a lot cheaper to replace than torches and components.
Coolers do have the drawback of not always maintaining the liquid circuit full of coolant, especially if the torch is hung above the cooler for storage, and it is possible to get an air pocket in the torch circuit. I have clear vinyl tubing in my return from the torch to the tank, and try to remember to look at the tube and confirm flow before striking the arc.
Depending on the torch brand, most real welding distributors should have replacement tubing in stock, and while it's a pain in the a$$ to retube the current carrying lead, it can be done.

[craig]

ok i found it. i'm a complete dumbass!!! i had pressure but no flow. it would flow upon startup then stop a few seconds after. the pressure would remain though. started rechecking things and found one of the fittings i used was not hollow all the way thru. (carb fuel filter fitting) the coolant would go thru the circuit but couldn't go from the transmission cooler i'm using back to the tank. it's always the simple things. now the pump can only generate a max of 30psi whereas before it was deadheading at 50-60psi. now i just need to replace the cable and i'm good to go.

[aircraft]

Most store bought coolers have a pinwheel to indicate flow, the few home-made ones that I have used had a window in front of the return line on the tank to be able to confirm the flow. You need to confirm the flow before welding do not assume you have flow.

[dseman]

I have a powerwave 450 cooler. It has a small pressure switch on the return line before the coolant is dumped back into the tank. Depending on the welder it's connected to, it can be used to control an arc-disable signal which would prevent any arc from being struck if there was a blockage or low-flow situation in the path. At the very least, the pressure switch could be connected to a buzzer to let you know not to strike an arc until the problem was resolved.

-dseman

[DrIQ]

I've burn't my share of torch leads over the years. On my current system I have a flow switch on the return line that is wired inline with the foot control contactor circuit, if I don't have coolant flow the contactor circuit is opened by the flow switch.