Welding fuel tank question

Topic: Welding fuel tank question (Read 1340 times) previous topic - next topic

Re: Welding fuel tank question

Reply #25 – March 02, 2021, 02:06:12 pm

Quote from: markb – March 02, 2021, 01:24:32 pm

Is it that difficult to weld a tank that has held diesel fuel? You know how hard it is to get it to burn let alone explode? Or maybe I'm off my rocker.

We know that when air is compressed, it gains heat and then the diesel explodes when injected. With the heat of an arc, any vapors inside the tank may explode. Sort of like a grain elevator. If a tank exploded when empty with someone next to it, the results could be tragic. Diesel is tough to light on fire when cold but changes character when heated.

Here is a good but short read on the dangers of diesel vapors when the temperature of the liquid exceeds 100 degrees: LCO-47: Diesel Fuel Vapor Hazards

We all remember TWA flight 800 where the vapor exploded. Jet A is not much different than the fuel we use. In fact, our coaches would run just fine on it.

Pierce

Re: Welding fuel tank question

Reply #26 – March 02, 2021, 02:35:35 pm

We have dealt with this issue with marine fuel tanks, many times. One of the challenges is the fact that it will need to be TIG welded. In order to achieve a non porous weld it will be necessay to eliminate any hydrocarbon contamination on top of, or on back side of the weld. Typically that means removing the tank, emptying it, pressure washing it, gotta be clean clean clean. Then the crack can be ground out and a Tig weld done.

You might want to check out one of the epoxy or polymer based patches others have recommended. There is some good stuff of that sort available these days.

Re: Welding fuel tank question

Reply #27 – March 02, 2021, 03:29:04 pm

Shoe Goo?? Just kidding!!

Re: Welding fuel tank question

Reply #28 – March 02, 2021, 03:56:42 pm

A proper purge is easy and quick. I have tig welded
many fuel tanks. I always purge with argon on aluminum tanks and welded. No water or other exotic method... just a good argon purge with the openings taped off except one for the argon to exit.

Re: Welding fuel tank question

Reply #29 – March 02, 2021, 10:47:40 pm

Welding aluminum the aluminum must be clean and use a stainless wire brush, I learned that the hard way.

Re: Welding fuel tank question

Reply #30 – March 03, 2021, 01:07:00 am

We found a welder down by Alamogordo that is going to TIG weld the tank for us. He said that he's TIG welded diesel fuel tanks since the early 80's and that he was not worried about welding the tank as-is, without filling with water or purging the fumes. Who knows... hahaha. The crack is in the weld, a little less than halfway up the tank and is about 4" long. The guy is going to grind out the weld along the crack and re-weld that area. Then he is going to cap that area with a piece of aluminum angle and then weld completely around that. Then he is going to pressure test the tank. He sounded knowledgeable and his outfit looked legitimate, so we're keeping our fingers crossed.

Re: Welding fuel tank question

Reply #31 – March 03, 2021, 09:29:09 am

Quote from: The Soft Boulders – March 03, 2021, 01:07:00 am

We found a welder down by Alamogordo that is going to TIG weld the tank for us.

Congratulations! The tank can be replaced, but it's less expensive to repair it properly.

FWIW an ESAB MiniArc Rogue is $800 less the gas. Then you still need to invest the time and materials to learn how to weld aluminum, and develop the skill to so do. I bet the professional comes in at less than that expense.

Re: Welding fuel tank question

Reply #32 – March 03, 2021, 09:55:19 am

Quote from: Old Toolmaker – March 03, 2021, 09:29:09 am

Congratulations! The tank can be replaced, but it's less expensive to repair it properly.

FWIW an ESAB MiniArc Rogue is $800 less the gas. Then you still need to invest the time and materials to learn how to weld aluminum, and develop the skill to so do. I bet the professional comes in at less than that expense.

The Miniarc Rogue provides a smooth DC (Direct Current) welding power which allows you to weld a variety of metals, such as alloyed and non alloyed steel, stainless steel, and cast iron.
Doesn't mention aluminum. Need ac for tig aluminum and dc- for mig. New millermatic 255 I purchased will mig alum but not tig aluminum. Still keeping my old syncrowave. But it did cost more than $800. Smallest aluminum machine sold with "pulse" capability. $3300 and with the push-pull gun your up to $5500. Paying for the repair will be much , much less.
Scott

Re: Welding fuel tank question

Reply #33 – March 03, 2021, 10:44:48 am

I would love to be able to weld aluminum and make a slick stand like yours in the photo. Attached is my old Millermatic 35. I bought it when they first came out and it welded almost 24/7 from that day on. I do have an argon tank and use it with .023 wire for the thin stuff but mostly .035 for the DOT work and general welding. Argon does make a little flatter bead. It has worked flawlessly from the day I bought it. Think Miller invented it for the 1965 Mustang.

Wish I could add on to it for aluminum.

I was fortunate that two of the guys I worked with were ex-shipyard welders so they took to it like a duck to water. They quickly learned to make nicer looking beads than I could.

Terrific job on the stand!

Pierce

Re: Welding fuel tank question

Reply #34 – March 03, 2021, 11:42:55 am

Quote from: Pierce & Gaylie Stewart – March 03, 2021, 10:44:48 am

I would love to be able to weld aluminum and make a slick stand like yours in the photo. Attached is my old Millermatic 35. I bought it when they first came out and it welded almost 24/7 from that day on. I do have an argon tank and use it with .023 wire for the thin stuff but mostly .035 for the DOT work and general welding. Argon does make a little flatter bead. It has worked flawlessly from the day I bought it. Think Miller invented it for the 1965 Mustang.

Wish I could add on to it for aluminum.

I was fortunate that two of the guys I worked with were ex-shipyard welders so they took to it like a duck to water. They quickly learned to make nicer looking beads than I could.

Terrific job on the stand!

Pierce

Your mail box is full again. Stop by and I'll teach you how to use and set it up in under a hour. World is changing
Scott

Re: Welding fuel tank question

Reply #35 – March 03, 2021, 12:14:50 pm

This is the machine I used to heliarc ski boat tanks in the early 80's Haven't used it in 30 years now. Have helium, argon and co2 tanks. Really messed up the dw's tv when I used HF.

Re: Welding fuel tank question

Reply #36 – March 03, 2021, 12:19:50 pm

Scott and Chuck,

Deleted the letter bombs from the mailbox. Good thing they can't explode or I would look like Wiley Coyote after a run in with Roadrunner.

Chuck, I have deep seated envy after your garage motorcycle photos. I want!

Pierce

Re: Welding fuel tank question

Reply #37 – March 03, 2021, 01:45:54 pm

Quote from: dsd – March 03, 2021, 09:55:19 am

The Miniarc Rogue provides a smooth DC (Direct Current) welding power which allows you to weld a variety of metals, such as alloyed and non alloyed steel, stainless steel, and cast iron.
Doesn't mention aluminum. Need ac for tig aluminum and dc- for mig.
Scott

My bad. But the excuse I offer is that the ESAB is the minimum equipment I need to repair the gas tank and weld in patch panels on the Siata -- If I can't find someone local to do it for less. At work I had a Miller with a spool gun, and avoided aluminum welding as much as I could. Steel is more forgiving.

Re: Welding fuel tank question

Reply #38 – March 03, 2021, 02:31:30 pm

My 40 yr old Miller quit last month. About 150@# of stuff inside . Welded pretty nice. Screwed around dioging it for about 3 hrs. I get 80$ per hr.. No easy fix, looks to be the control board maybe.
Go online for medium power Mig welder. They all are about the same specs at 190 amp /65% duty . etc. Inverter powered , no big transformer. The Miller( Chinese parts) is about 900$ and the E bay Chinese ones are 300$ ish. Same power supply it looks like .
I bought a well regarded 340$ unit. Sun Power 190. The weight is about 30# . the accessories are junk , but swapping some cables a round it works nice. Welds better than the Miller ever did.

Re: Welding fuel tank question

Reply #39 – March 03, 2021, 03:37:05 pm

We have a miller 211 with a spool gun that welds aluminum really well. Pierce I found welding aluminum was easy to learn, give
it a go.

Re: Welding fuel tank question

Reply #40 – March 03, 2021, 04:47:11 pm

Thank you to everyone for the tips. Appreciated. I have gotten fairly good at powder coating now but only after chasing my tail for a while. So, anyone interested, drop me a line.

Pierce

Re: Welding fuel tank question

Reply #41 – March 07, 2021, 01:56:01 am

We got the fuel tank back yesterday and we are very satisfied with the work. The welder said that once he put some heat to the crack it really opened up and was quite a bit bigger than we had thought. He repaired the crack and then capped over the entire area with a piece of angle. The cost was only $106.31 and we didn't have to mess with any water in the tank. The other place quoted me a base price of $175 for a MIG job and a tank full of water. I'd say this project was a win win!

We got the tank reinstalled today and after priming the fuel system, Pearl fired up without a hiccup.

Re: Welding fuel tank question

Reply #42 – March 07, 2021, 08:29:51 am

Quote from: The Soft Boulders – March 07, 2021, 01:56:01 am

We got the fuel tank back yesterday and we are very satisfied with the work.

We got the tank reinstalled today and after priming the fuel system, Pearl fired up without a hiccup.

Congratulations on your successful repair.

Re: Welding fuel tank question

Reply #43 – March 07, 2021, 08:35:52 am

Some of the aluminum fuel tanks in our old coaches are approaching 40 years old. I wonder how many have suffered a mechanical failure. Based on my reading from the time I have spent on the Forum, I would guess not too many. Also wonder if there is any common factor to account for cracks or leaks in some of the tanks. Probably high mileage would figure in, since pretty much everything in the chassis gets shook up pretty good going down the road. Was there a human component? Perhaps one welder at the tank factory was less skilled, or hung over on Mondays?

Just idle Sunday morning musings...

Re: Welding fuel tank question

Reply #44 – March 07, 2021, 04:46:31 pm

glad to hear everything went well

Re: Welding fuel tank question

Reply #45 – March 07, 2021, 04:47:51 pm

I like
Scott

Re: Welding fuel tank question

Reply #46 – March 07, 2021, 07:56:25 pm

Looking at the pictures, it appears to me that the fabricator didn't get the weld balanced between the top and the side More of a weld separation than crack.

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