Welding - I want to learn ..need advice.

[Dan W]

Hee Hee Hee... on my last job as a fabricator, a trucker brought in a fuel tank for a tractor trailer to be tig welded, I wouldn,t touch it!

Here is an interesting real life story?hen I was much younger, working as a heavy equipment mechanic in the Yukon, a bunch of guys were working indoors on a 48 ft fuel tanker. The complete rig was in the shop, tractor and 4 axle trailer. Some guys were doing a quick brake adjustment before the rig continued its trek down the Alaska Highway; others were welding various cracks on the tank. All were "older" and much smarter than most ... anyway, make a long story short, one mechanic heard a strange rumbling noise coming from inside the (empty) tanker, everyone left the shop except the oldest obviously smartest guy in the shop and then the tanker exploded ? blew the rear end off the tanker, it went through the shop doors and the rest of the tractor/trailer was driven through the opposite front shop doors the bang was heard clear across Whitehorse
Exciting to say the least, other than the smart guy who wouldn稚 stop welding on top of the tank (he lost his hearing permanently) no one was hurt
My two cents worth ? Steam-clean inside the vessel, fill with inert gas and work outdoors
All the best to every one for Christmas...
Dan

 

[Dan W]

This is the same Crap that Edison started back when he was fighting with Tesla in the great "Battle of the Currents". Basically Edison wanted the electrical infrastructure to run on DC. DC required burying HUGE cables and power stations to be located within only a mile or two of the locations serviced. When Tesla invented AC and distribution transformers that would allow much smaller wire to be used on transmission lines which run at extremely high voltage and are then converted to lower voltage and high current by transformers at each residence.

AC and DC are just about equally dangerous at equal voltages. Neither one can penetrate dry human skin until a certain voltage is reached. The 60-hz frequency of AC makes it a tiny bit more dangerous because the particular switching frequency is almost the perfect frequency to confuse the nerves that drive the heart and cause them to shut down. So AC can stop your heart easier than DC, but if you get an AC shock that stops your heart a defibrillator or CPR done quick enough can usually get it going again. If you get a DC shock that is strong enough to do stop your heart, it's usually going to be because the DC has cooked your muscles from the inside out. No amount of CPR or defibrillation is going to undo that damage.

Most welders don't produce voltage high enough to penetrate skin. Now, that can change if you're hot and sweat and manage to get yourself across the leads. That much current flowing from hand to hand directly across your heart is going to kill you regardless of whether you're using AC or DC.

It's not voltage that kills, it's current. (Actually a combination of both since you don't get penetration without enough voltage) You mention the VanDeGraff generator operating at 50,000 volts... Yea, that's relatively safe because it is a potential. There is no flow. Now consider this: The 1970's movie "The Entity" had special effects where a possessed woman shot lightning bolts from her hands. Those effects were produced by having the woman stand on the output terminal of a Tesla Coil producing AC voltage in excess of 1,000,000 volts and channeling the power through her body and out metal thimbles placed on her finger tips. The machine was built by a man named William "Bill" Wysock. The machine was perfectly safe because even though it operated at extremely high voltages it produced almost no current in the output streamers. (And no contrary to popular belief it wasn't due the the so-called "Skin Effect" of the RF energy in the output. That part is a bit of a myth/misunderstanding.)

Right on the money Brent ... I love this site, I whish I would have known about it years ago ... Thanks
BTW, I used to build some huge Tesla coils when I was a kid, drove them with a train transformer (120/18VAC if memory serves me right) and we'd jump a spark gaps of about 3/4"
Dan

 

[ben2go]

When we weld fuel tanks,we drain them,and take them to a radiator shop to be cleaned out.I have left tanks sitting empty for a couple weeks before welding them.My friend,who is a certified welder,welds them if their full.I usually leave the shop when he does,but stand by with an extinguisher.

 

[Egon]

My friend,who is a certified welder,welds them if their full.I usually leave the shop when he does,but stand by with an extinguisher.

I surely hope you are standing by about a block away.

 

[jayste]

Going back to when I was in highschool welding class, we used to build cattle feeders from 55 gal drums. Usually this required us to cut the end out of most of the drums. We would always take out the bungs and fill the drum with water. Leaving the bungs out we would use an OA torch and cut the first end out. After that we'd not have a problem with the second end. This kept the drum from having any trapped fumes or whatever that could ignite.

Jay

 

[JB4310]

Going back to when I was in highschool welding class, we used to build cattle feeders from 55 gal drums. Usually this required us to cut the end out of most of the drums. We would always take out the bungs and fill the drum with water. Leaving the bungs out we would use a OA torch and cut the first end out. After that we'd have not problem with the second end. This kept the drum from having any trapped fumes or whatever that could ignite.

Jay

Wasn't gonna go into detail but that's How I almost lost my head, cutting into a smaller 35 gallon drum. Neighbor had one behind his barn, he had brought home from the shop where he worked. I was an up and coming contractor wanna be with a hand me down O/A torch outfit.
I wanted to be like the big contractors who had drums for garbage and burn barrels, so I proceeded to cut the top off. The drum said right on it "SOLVENT" but was old and rusty and dry sounding inside, I wanted to vent it by removing the bung but it wouldn't budge.
Anyway, started at it with the torch, just as it was getting red and I was ready to hit the blower, I thought to myself, HMM, I wonder if this could blow up and I just kinda leaned my head back away from directly over the top, and BOOM!!! sounded like a Navy 20" Gun!

I was peppered with rusty buckshot, blew my glasses off, ears where just ringing as I was regaining my senses, I was feeling around my head with my hands, since my head was all numb and I couldn't hear or see to well I thought for sure I must be missing some parts

This was 6:30 am. My younger sister came running out of the house to check on me, clutching her hands over her heart. Miraculously I had no serious injuries except singed hair and light burns on my arms. The top had come off clean at the seam, the bottom looked like a jiffy pop popcorn thing. if that drum split on the side I might not be here typing this. Just told this long storey to maybe help some one in the future to respect any type of sealed/pressurized container.
Oh yeah, the top was never found.

And almost forgot, before starting that storey, I just wanted to show some pics of me welding today on my snow plow, with the DC welder I'm finally able to show some of my beads
This is 3/8 to 1 inch material, 1/8" 7018 EP ~140amps DC.



JB.

 

[dcyrilc]

And almost forgot, before starting that storey, I just wanted to show some pics of me welding today on my snow plow, with the DC welder I'm finally able to show some of my beads
This is 3/8 to 1 inch material, 1/8" 7018 EP ~140amps DC.
JB.

Nice weld, youv'e had some practice.

 

[David Devuono]

I wanted to build an extended range tank for a 4x4. As I was starting from scratch fuel vapor was not an issue. I got tired of filling it with water to find leaks and then emptying it to reweld. I found that I could weld it while full of water, going over any spots that weeped and it work great. Probably could transfer that to a fuel tank repair, IE fill it with water and weld up any pin hole leaks???

 

[ben2go]

I wanted to build an extended range tank for a 4x4. As I was starting from scratch fuel vapor was not an issue. I got tired of filling it with water to find leaks and then emptying it to reweld. I found that I could weld it while full of water, going over any spots that weeped and it work great. Probably could transfer that to a fuel tank repair, IE fill it with water and weld up any pin hole leaks???

When I do a tank,I fill it with 10psi of air,and spray the welds with soapy water.Then fix any that bubble up.Then I let it sit over night with 10psi and check it the next morning.If it's lower than 8psi,I air it up and recheck the welds.

 

[mjncad]

Nice welds JB and I'm glad you weren't seriously hurt by your drum welding experience.

To quote Mythbuster Adam Savage, "Am I missing an eyebrow?"

To quote Mythbuster Jamey Hyneman, "I always enjoy seeing Adam in pain."