Tig filler for spot on a diesel tank prone to cracking.

[outdoort]

Hey guys. Havent been on here in a while, but I got this Case 580 super K I need a bit of advice on welding up.

The diesel tank is part of the left hand side frame rail and on these super K backhoes they are very prone to cracking in this one spot where the rear engine mounts are. Its so common that mechanics/dealers reported these cracks happening hours after they left the dealer lot back when they were built in the early 90's. Its not a big crack, but the diesel is leaking and I need it to stop. The Access SUCKS and with a lot of **** covered in oil and grease down there I just dont want to stick weld it even tho I know that would be best.

I want to tig weld it, but seems like these repairs may be prone to cracking again. Nothing is structural. Its just a leak that needs fixed and I want to use a tig filler that will give me the most ductility possible so I don't have to repeat this repair in the future.

Anyone got any filler suggestions? I'm gonna drain the tank to below the crack/leak, probably run my oxyfuel torch over the crack after I grind it out a bit/clean it up as best as I can (using the torch to clean up any contaminants), then tig it up. Would a er70s2 rod be best still, or how about a nickle rod of some kind? Maybe silicon bronze? Like I said, just stoppin the leak and hoping it has some ductility to keep from cracking again. This is not a structural area, just the top of the frame rail near where the engine mount is.

Thanks. Wish the access was better in here fixing this thing.

[William McCormick]

Hey guys. Havent been on here in a while, but I got this Case 580 super K I need a bit of advice on welding up.

The diesel tank is part of the left hand side frame rail and on these super K backhoes they are very prone to cracking in this one spot where the rear engine mounts are. Its so common that mechanics/dealers reported these cracks happening hours after they left the dealer lot back when they were built in the early 90's. Its not a big crack, but the diesel is leaking and I need it to stop. The Access SUCKS and with a lot of **** covered in oil and grease down there I just dont want to stick weld it even tho I know that would be best.

I want to tig weld it, but seems like these repairs may be prone to cracking again. Nothing is structural. Its just a leak that needs fixed and I want to use a tig filler that will give me the most ductility possible so I don't have to repeat this repair in the future.

Anyone got any filler suggestions? I'm gonna drain the tank to below the crack/leak, probably run my oxyfuel torch over the crack after I grind it out a bit/clean it up as best as I can (using the torch to clean up any contaminants), then tig it up. Would a er70s2 rod be best still, or how about a nickle rod of some kind? Maybe silicon bronze? Like I said, just stoppin the leak and hoping it has some ductility to keep from cracking again. This is not a structural area, just the top of the frame rail near where the engine mount is.

Thanks. Wish the access was better in here fixing this thing.

70-S2 is what I would use. If you are not going to clean it well, you can steal a piece of MIG wire which is usually 70-S6, and use it as a TIG filler wire, it has more glass to absorb oxides. You may get a bit of spotty black slag on top which comes off much like ARC welding rod flux. You really should clean it well grind the crack and fill it in with new material. Then if you can figure out why it is cracking there, make something to weld over it if possible to firm up the failing structure there. Just make sure you empty the tank completely or it can blow. You have to de-grease it. Sometimes they refill the tank with water as much as they can before welding as well, to cut down on the size of the pocket of explosive gas possible in the tank.

Sincerely,

William McCormick

[M J D]

Screw that Tig nonsense. Put enough fuel in the tank so it's over the leak and use 6010 or 6011. Even with diesel I wouldn't weld it with vapor in the tank. 6010 or 6011 isnt really affected by fuel or oil like other electrodes.

[Kelvin]

I'd use epoxy and FG and wouldn't weld a used fuel tank on a bet ... but I know people do!

I once tried brazing a loop onto a used metal 5-gallon paint pail to try to pull apart two of them that were jammed together... all I got for my efforts was a big KBOOM and a bucket in the face. Glad I was wearing a face shield!

[duramax-rob]

why don't you forget welding the crack and make a larger patch to cover the crack and weld that covering the crack! or even epoxy the patch on with gas tank epoxy. no chance of kaboom or fire!

[walker]

I would do a patch over it as well. I would steam clean everything first, just because I hate working on oily, dirty stuff.

[SweetMK]

If you want the most ductility that can be TIG welded, I would imagine pure nickel rod would be the answer,,.

BUT, if it was mine to fix, (I did fix a plastic fuel tank on an ATV this way) I would epoxy a sheet of very fine mesh stainless screen over the crack.
(the VERY fine mesh screen is available on eBay,, stainless steel is crazy strong, and screen will flex)

The screen has to come from China, so it takes a couple weeks to get here.
You have waited since 1996, so a couple more weeks should not matter,,

[albrightree]

312 stainless ?

[outdoort]

Alright guys thanks a lot for the suggestions. welding a patch isn't really possible since its in a fillet type joint with other contours of the metal. There was already a fiberglass patch on the thing but I kinda chipped it off stupidly not sure what it was even there for lol. Wasn't leaking prior to me taking a flat blade screwdriver to a certain part of the patch. Oh well. We will see what happens. I should have time this coming week to tackle it. I may weld it and then fuel tank epoxy over the weld area just to be sure... Diesel is pretty safe so I'm not too concerned about Kaboom. I'll purge the tank anyway but I'm gonna leave it filled with diesel below the leak area.

[leightrepairs]

I am not telling you to weld on a tank with any type of fuel in it, but I have welded tanks with diesel in them before and always made sure the fuel level was high in the tank. The liquid is not the issue it is the fumes that cause the problems.

[Meltedmetal]

When you say purge do you mean with argon?

[Josey]

Hi. I have never tried welding or tig. But I have had very good results a few times with brazing a tractor diesel tank.
That's how I would do it.

[12V71]

When you say purge do you mean with argon?

I prefer C02 in the form of dry ice, 1pound of dry ice generates 8 cubic feet of C02 when it evaporates. I'll use a couple extra pounds just to be sure. Break it up and pour it into the tank and set the cap on loosely. No residual water or clean up.

[SweetMK]

I prefer C02 in the form of dry ice, 1pound of dry ice generates 8 cubic feet of C02 when it evaporates. I'll use a couple extra pounds just to be sure. Break it up and pour it into the tank and set the cap on loosely. No residual water or clean up.

I always get freeze burns on my lips,,
the chunks of dry ice are usually too big to fit in the filler neck, so I bite off pieces,,,
That is why I prefer gas in a tank,,,

[12V71]

I always get freeze burns on my lips,,
the chunks of dry ice are usually too big to fit in the filler neck, so I bite off pieces,,,
That is why I prefer gas in a tank,,,

Funny. But a tank explosion is not. I had a vapor whoof once in a hydraulic reservoir, lucky for me it was mostly full and had enough venting to not blow.
After that... always a CO2 purge.

[M J D]

CO2 purge wouldn't work so well when using argon for TIG welding. CO2 coming out of the split would contaminate the argon. If the split isn't too big where the fuel comes out excessively, putting fuel over the level and using stick is the fastest and easiest way to repair that tank.

[12V71]

CO2 purge wouldn't work so well when using argon for TIG welding. CO2 coming out of the split would contaminate the argon. If the split isn't too big where the fuel comes out excessively, putting fuel over the level and using stick is the fastest and easiest way to repair that tank.

True on the CO2, but I don't mess around tigging tanks. I have done them full of fuel or oil above the weld zone using a die grinder to get a groove and then closing the crack tight with a blunt center punch on the air hammer. Works pretty well.

[leightrepairs]

True on the CO2, but I don't mess around tigging tanks. I have done them full of fuel or oil above the weld zone using a die grinder to get a groove and then closing the crack tight with a blunt center punch on the air hammer. Works pretty well.

Just need to be careful that the problem is a split or crack and not corrosion. This is usually only the case on the bottom of a tank. On a few bulk tanks, years ago, I welded 6 inch couplings on the bottom of the tanks due to corrosion, then just screwed caps on the couplings.

[M J D]

True on the CO2, but I don't mess around tigging tanks. I have done them full of fuel or oil above the weld zone using a die grinder to get a groove and then closing the crack tight with a blunt center punch on the air hammer. Works pretty well.

Tig wouldn't be my choice either. I have run into issues mig welding aluminum tanks from fuel residues before. On those I wash the inside out with hot water and soap. Dry them out with air and then slosh around some air brake anti freeze and drain to remove moisture. On those I purge with argon .

[evan]

You guys are crazy

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[JDM Welder]

Diesel is pretty safe so I'm not too concerned about Kaboom.

Diesel being "safe" is an unfortunate misconception that often ends in tragedy. The 100% lower flammability level for gasoline is 1.4% (14,000ppm), where diesel is only 0.5% (5,000ppm). The point at which the atmosphere in the tank becomes explosive is approximately 3X lower with diesel.

People assume diesel is "safe" because you can throw a match on it, and it doesn't ignite like gasoline will. That's because of the higher flashpoint (125-180°F). So if the atmosphere in the tank is under 100°F, it probably won't light. But what happens when you start welding on it? The auto-ignition point is 350-625°F. The fumes in the vicinity of the weld can ignite, setting off a chain reaction that ignites the rest of the fumes in the tank (very explosively).

Cover it with liquid fuel? The fuel can boil in the area being welded, the auto-ignition point is lower than the boiling point, and you can be sure that the vapor you're creating is way above the 5,000ppm LEL.

I used to repair aluminum tanks for F-15 and F-16 fighters (JP8). The ONLY safe way to weld on fuel tanks is by monitoring the atmosphere in the tank. Most standards require an atmosphere of less than 10% of the LEL. In the case of diesel, that would be a maximum of 500ppm. If the atmosphere in the tank rises to 10% of LEL, welding must stop and the cause corrected.

[Kelvin]

Somebody near here got killed cutting open an empty 55 gallon drum that had once contained motor oil...and motor oil has a far lower flash point than diesel fuel!

[SweetMK]

Somebody near here got killed cutting open an empty 55 gallon drum that had once contained motor oil...and motor oil has a far lower flash point than diesel fuel!

That is exactly correct,, and petroleum is not the only hazard,,
getting an explosive mix of "fuel" and air can even be had with oak hardwood with the right conditions,,

Back when wood stoves were popular,, many people experienced opening the door of a smoldering stove,,
the extra air would enter the door opening, and the smoke would burn so rapidly, it was like an explosion,,
It could easily rip the door handle out of your hand.

[Sberry]

I just dont want to stick weld it even tho I know that would be best.

Its hard to help some people

[Kelvin]

Back when wood stoves were popular,, many people experienced opening the door of a smoldering stove,,
the extra air would enter the door opening, and the smoke would burn so rapidly, it was like an explosion,,
It could easily rip the door handle out of your hand.

Interesting excerpt from a white paper on chimney fires:

...One of the more dramatic and potentially dangerous effects of some chimney fires is back- puffing of smoke and sometimes flames from the appliance or venting system. This effect is caused by a series of rhythmic explosions of fuel-rich creosote gases in the confined area of the flue. As the gases burn, they may consume the available oxygen faster than it is supplied. When the concentration of oxygen in the gases reaches the lower limit of flammability, the flame is extinguished, but plenty of heat remains in the flue. Air will re-enter the flue and mix with the gases which then ignite suddenly and explosively. The result is immediate high pressure in the chimney which cannot be fully relieved out the top and smoke and flames may be driven through any opening in the flue or appliance. As the oxygen is again quickly depleted and flames are extinguished, the pressure drops suddenly, drawing in more air to initiate the next explosion. This cycle may be repeated several times a second.

If the flue becomes blocked by fallen or expanded creosote during the fire, a large volume of smoke may spill back into the dwelling. Although the blockage will limit flue gas flow and reduce the air available to sustain the fire, the heat retained in the flue will continue to pyrolize the creosote (which is the source of the smoke) for some time. Rather severe smoke damage to the building and contents has been known to result from chimney fires of this nature...