Mig welding a fuel cell

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I'm in the process of making a fuel cell for my trail truck. I'm currently planning on mig welding all the seams and would like to know if there is a particular technique or tips that would be helpful in creating an air tight seal and avoid pinholes. ThanksJoel"Stupidity should hurt"
Reply:Got to ask ( I'm just that kind of guy) Why in the world would you be doing this? So many liabilities so much money and time when      * Dorman,    * Goodmark,    * Classic Performance,    * Summit,    * RCI,    * Putco,    * R.J.S. Racing Equipment,    * Rick's Hot Rod Shop,    * Aeromotive,    * ACDelco,    * Show All...all these companies have gone to the trouble of figuring it all out, and then sell them for so little. You can't build them any cheaper unless your time is worth nothing. http://store.summitracing.com/egnsea...nresults=false12 gallon tank aluminum with sending unit for $179.95Well rant over and on to your question. HOT HOT HOTFASTFASTFASTOr the easy way is build it strong and buy a bladder and some foam. TJ
Reply:Two reasons... it needs to be an extremely custom shape to accommodate the area it needs to mount in and I would like to use the stock sending unit and vent lines to retain gauge function and smog. I have researched this for quite a while and have a rock solid shape and baffle design and I understand the potential risk involved (which is rather minimal as long as the proper steps are taken). I also have a hard time paying for something I know I can do myself. In the end, truly understanding the process and better understanding a vital component of my rig is worth more than the time saved with buying a cookie cutter mass production unit. I know I can produce a better product that fits my use perfectly, rather than spending extra time adapting something that will never be perfect and always look like a universal square box in the back of my truck.ThanksJoelLast edited by Just Joel; 12-29-2008 at 02:54 AM."Stupidity should hurt"
Reply:1st Question:  What material Steel, Aluminum, SS?If you already "know" you can build it, what additional information do you really seek?If steel is the material of choice, I'd mig it up and pressure test it.  If leaks appear, I'd go back and wash the welds with tig.If aluminum is the material, I wouldn't think of migging a fuel cell.  Tig it.If SS, warping will be a major problem.Cold starts will be the problem with leaks.  Keep them to a minimum.   Backstep over your starts.2nd Question:  What machine.  No fluxcore I hope.3rd Question:  Experience?  Ever built a fuel cell?Syncro 250 DX Dynasty 200 DXMM 251 w/30A SG XMT 304 w/714 Feeder & Optima PulserHH187Dialarc 250 AC/DCHypertherm PM 1250Smith, Harris, Victor O/ASmith and Thermco Gas MixersAccess to a full fab shop with CNC Plasma, Water Jet, etc.
Reply:I don't know if their is a certain technique or not. I have made several fuel cells over the years and I used my mig for all of them until recent. I have built VW pipe rails for years and made the fuel cells from 1/16 and 1/8 mild steel. From my experience, using a little thicker material makes getting the welds liquid tight a lot easyer while maintaining good penetration and bead profile.. Also try to reduce the stops and starts of the welds.  Make sure you pressure test the tank before putting gas in it. I am currently moving on to custom motorcycle tanks. While doing my home work on this I found that tig it much more preferred when dealing with light sheet metal. I purchased a Lincoln PT225 recently and started using it. All I can say now is that I can see why tig is preferred. The welds and control are amazing. Good luck on the project and post pic'sLast edited by jamlit; 12-29-2008 at 05:19 PM.Miller DVI2Lincoln Precision Tig 225Thermodynamics Cutmaster 38Everything else needed.
Reply:Originally Posted by SundownIII1st Question:  What material Steel, Aluminum, SS?If you already "know" you can build it, what additional information do you really seek?If steel is the material of choice, I'd mig it up and pressure test it.  If leaks appear, I'd go back and wash the welds with tig.If aluminum is the material, I wouldn't think of migging a fuel cell.  Tig it.If SS, warping will be a major problem.Cold starts will be the problem with leaks.  Keep them to a minimum.   Backstep over your starts.2nd Question:  What machine.  No fluxcore I hope.3rd Question:  Experience?  Ever built a fuel cell?
Reply:Hey JoelMake sure  its air tight when your done.  Find a way to test it.  Maybe the water test.  Fill it up and leave over night and see if there are leaks.  Better yet maybe try air instead.Ive never made one personally, mine is from summit, but many of my wheelin friends have made them with no problems using Mig.  Tig would  be easier, but you may not have one to use....right?As far as the welding details ...give us shout when you know what material your going to use.I understand why you would need to make a fuel cell .  Only us crawler guys can relate  Good luck weld it like you own it
Reply:Originally Posted by jamlitI don't know if their is a certain technique or not. I have made several fuel cells over the years and I used my mig for all of them until recent. I have built VW pipe rails for years and made the fuel cells from 1/16 and 1/8 mild steel. From my experience, using a little thicker material makes getting the welds liquid tight a lot easyer while maintaining good penetration and bead profile.. Also try to reduce the stops and starts of the welds.  Make sure you pressure test the tank before putting gas in it. I am currently moving on to custom motorcycle tanks. While doing my home work on this I found that tig it much more preferred when dealing with light sheet metal. I purchased a Lincoln PT225 recently and started using it. All I can say now is that I can see why tig is preferred. The welds and control are amazing. Good luck on the project and post pic's
Reply:Wrap your corners.  Don't just place a tack right on the corners and weld into it.  Weld at least an inch away from the corner, head into it, and wrap another inch right around the side.  This should help minimize the pinhole leaks/cold starts.  That was by far the most common problem I saw when dealing with MIG'd fuel cells.  If you have to do a start/stop mid-way through a seam, grind the end down and feather it in.  This will also minimize leaks, and make it look better to boot by eliminating the bulge of weld metal on the restart.
Reply:Originally Posted by lewrayHey JoelMake sure  its air tight when your done.  Find a way to test it.  Maybe the water test.  Fill it up and leave over night and see if there are leaks.  Better yet maybe try air instead.Ive never made one personally, mine is from summit, but many of my wheelin friends have made them with no problems using Mig.  Tig would  be easier, but you may not have one to use....right?As far as the welding details ...give us shout when you know what material your going to use.I understand why you would need to make a fuel cell .  Only us crawler guys can relate  Good luck
Reply:Originally Posted by SupeWrap your corners.  Don't just place a tack right on the corners and weld into it.  Weld at least an inch away from the corner, head into it, and wrap another inch right around the side.  This should help minimize the pinhole leaks/cold starts.  That was by far the most common problem I saw when dealing with MIG'd fuel cells.  If you have to do a start/stop mid-way through a seam, grind the end down and feather it in.  This will also minimize leaks, and make it look better to boot by eliminating the bulge of weld metal on the restart.
Reply:Also, if when you pressure test it, don't exceed about 3psi maximum, I usually do it with 1-2psi. You will need a 0-10psi pressure gauge and hose barb and some small little parts. I usually take a piece of brake line, attach it to a t connector. The gauge is on one branch of the T and then a ball valve connected to that with an air fiting on the otherside to lock the pressure in once I have filled it with my air compressor. I have used it many time on boat fuel tanks, works like a charm. I'll have to find a picture of it, sounds more complicated then it is.Here we go, not mine but its the same deal to help the visual learners.If you cannot convince them, confuse them.         Harry S Truman
Reply:Weld it up, and after you're done, when you pressure test it, use soapy suds on every weld to test for spot leaks. What can I say?? Any process of weld runs a chance of a leak. The key is to minimize the chances. That's all.And then, after so much work...... you have it in your hand, and you look over to your side...... and the runner has run off. Leaving you holding the prize, wondering when the runner will return.
Reply:Originally Posted by 500HpSilveradoAlso, if when you pressure test it, don't exceed about 3psi maximum, I usually do it with 1-2psi. You will need a 0-10psi pressure gauge and hose barb and some small little parts. I usually take a piece of brake line, attach it to a t connector. The gauge is on one branch of the T and then a ball valve connected to that with an air fiting on the otherside to lock the pressure in once I have filled it with my air compressor. I have used it many time on boat fuel tanks, works like a charm. I'll have to find a picture of it, sounds more complicated then it is.Here we go, not mine but its the same deal to help the visual learners.
Reply:Originally Posted by Rojodiablo The key is to minimize the chances. That's all.
Reply:Originally Posted by Just JoelI'm in the process of making a fuel cell for my trail truck. I'm currently planning on mig welding all the seams and would like to know if there is a particular technique or tips that would be helpful in creating an air tight seal and avoid pinholes. ThanksJoel