How to test tank for leaks?

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Hello everyone, my friend is going to build me and diesel transfer tank but we are both wondering how we can test it for leaks before we install it?  We don't want to fill it with diesel at almost $3 a gal and don't want to use water because we are worried about it rusting.  How should we test it?Thanks
Reply:Put it in a large tank of water and fill it with compressed air?
Reply:Could try pressurizing the tank with air and spraying the seams with soapy waterI'm not a welder, but I do sit next to one at the bar.
Reply:Originally Posted by sanford02Could try pressurizing the tank with air and spraying the seams with soapy water
Reply:wrap all the openings in the tank with elecrician tape (or something else) except two small ones. Then you put a balloon (yes leftovers from your kids birthdayparty!) onto one of the ends. Use tape on that one too. in the last hole you put the airgun from your compressor. Now you fill air in the tank till the baloon rises, then you have enough air to spray on some dishwasher soap and water on the outside. If it leaks you will have bubblesThe reason for the baloon is that you dont want too much air in the tank. If theres too much pressure in the leaks, there will be no bubbles, the soap just blows off.The other reason is too much pressure in the tank can destroy it.( Rip it, deshape it)This way you also check that you have enough air to do a good test. If the baloon doesnt fill, you need more air in the tank.Good luckGaute
Reply:go easy with the pressure, you can bulge that thing like crazy if it is a flat-walled vessel.  If you have a 12x48 panel that would be 576 in^2 and 10 psig will put 5760 lbs of force on the panel
Reply:The problem with pressure testing is - it doesn't take a lot to deform the tank.  Let say you pressurise to 50psi.  if the tank is 10 x 10 x 10 inches, each side would be hold 5000 lbs.  If you are testing something bigger than a shoe box, the pressures increase by the square of the dimensions.   2x as big, 4x the forces.Some automotive repair shops check for things like vacuum leaks with a smoke generator.Something like this:http://www.amazon.com/Vacutec-EVAP-D.../dp/B000X29W7MDon't discount water yet...The problem with testing with water isn't so much the rust (if it was an issue, moist air would already be a problem for you) - its more that water won't go through some cracks that other fluids or gasses will.  Probably OK for testing for diesel fuel leaks.  If you are really worried, maybe you can fill with a gallon of diesel and coat the inside of the tank, then add water.Con Fuse!Miller Dynasty 350Millermatic 350P-Spoolmatic 30AMiller Multimatic 200Hypertherm PowerMax 1000G3Miller Maxstar 200DX
Reply:Have actually had the problem con_fuse9 is talking about.Diesel has lower surface tension than water and will find the pinholes that water doesnt find.I tig welded a alutank and tested with air and soap. no holes:-)When we mounted it in the boat and the customer filled it up with diesel he found a VERY small hole.The hole caused a diesel smell in the engine compartment and the customer demanded it fixed, so we pulled the tank back out, and we had to fill it with diesel and leave it standing on paper for a whole weekend to find the leak..
Reply:Originally Posted by alutigHave actually had the problem con_fuse9 is talking about.Diesel has lower surface tension than water and will find the pinholes that water doesnt find.I tig welded a alutank and tested with air and soap. no holes:-)When we mounted it in the boat and the customer filled it up with diesel he found a VERY small hole.The hole caused a diesel smell in the engine compartment and the customer demanded it fixed, so we pulled the tank back out, and we had to fill it with diesel and leave it standing on paper for a whole weekend to find the leak..
Reply:Air will come thru where diesel, water, gasoline won't, especially when you have a little positive pressure behind it.   You just have to be careful enough, and diligent enough, with the soapy water spray.This is what I use when pressurizing a tank, plenty of reducers so I can fit it into anything, seal and cap off the tank, low pressure gauge lets me know immediately when I have pressure.   Depending on the type of tank and the size, 2 psi is generally enough.   No way, no how, will I pressurize a tank, without a correct gauge on it. Attached Images
Reply:And by the way, checking for pressure changes over time, is not a valid test.   Temperature changes in a limited space, the pressure will also change, for better or worse.   Every gas line I put in a house, code calls for holding "x" pressure for 15 minutes, that's all.  Any longer, temperature changes can distort your readings/conclusions.
Reply:Put some CHCl3 (Chloroform), CCl4 (Carbon Tetrachloride), Freon (134a works) or similar compound in it and then pressurize it, using an accurate gauge as jsfab mentioned.Then use an electronic halogen detector of the type used by refrigeration people; they detect leaks of a fraction of an ounce per year of Freon, so should pick up the halogen in any vapors escaping from your tank due to a leak.Here's a link to one which has specs. listed; I don't know the brand or if it's a good unit, but you get the idea:http://www.sourcingmap.com/automatic...aign=usfroogle Here's another well-known brand at a bit higher price; no specs listed, however:http://www.amazon.com/Robinair-16600.../dp/B000JFL8Q6
Reply:Like everyone else said, weld a threaded fitting into the tank, screw in a pipe with T fitting, a low pressure air gauge and the air hose from your compressor.  Fill to about 5 psi.  Stand back while filling and watch for any bulging.  It will groan and bang while filling.  Stop at 5psi and watch the gauge to see that it doesn't drop.  Also listen for leaks.  Any hissing, check it with soapy water.  I used this method to test the aluminum pontoons I built for a house boat.  Found a couple leaks and repaired them, re-tested.  The boat is still floating.MM350P/Python/Q300MM175/Q300DialarcHFHTP MIG200PowCon300SMHypertherm380ThermalArc185Purox oaF350CrewCab4x4LoadNGo utilitybedBobcat250XMT304/Optima/SpoolmaticSuitcase12RC/Q300Suitcase8RC/Q400Passport/Q300Smith op
Reply:I want to say that the smaller (less than 1000 gallons) fuel oil tank I've purchased for our plants were tested with ~5 psi air.  Apply a water/soap solution as others have said.  I've done a few myself that way, but be careful as I also bought two 25K gallon fuel oil tanks.  The the local manufacturer checked all the welded seams by just applying pressure to the welds only with special equipment.
Reply:Originally Posted by sanford02Could try pressurizing the tank with air and spraying the seams with soapy water
Reply:Years ago I worked in a fab shop where we built various size dust collectors and various tanks. We used a 2 part chemical application to find pin hole leaks. We would spray or paint one chemical, red, on the interior seams and the other, white, on the exterior. The red would draw to the white, revealing and leaks. I tried to find this test product a while back but had no luck. Does any one else know of this?Miller TrailBlazer 251Miller HF-250-1Miller MaxStar 150 STLHyperTherm PowerMax 380 plasmaLincoln PowerMig 180Millermatic 252Miller Diversion 180
Reply:Here's a case of a buddy that's going to whack together a tankof unknown materials, unknown design, unknown constructionand weld quality......and folks are bantering about all kinds ofpressure reccomendations--without any knowledge of the above.5#--is for DOT engineered tanks, quality construction/design....and even some of those are restrained in cradles during the testing.How much??Stop prior to permanent deformation, which can occur at 2# or less,depending on all sorts of things. I've previously posted items on pressure testing--with safety in mind;and you don't see me picking pieces of tank out of my body, or the wallsand roof.Hydrostatic testing with soapy water inside (the soapy water has much lesssurface tension, to seek out leaks) is another, safer alternative than air testing.Blackbird
Reply:Originally Posted by waginYears ago I worked in a fab shop where we built various size dust collectors and various tanks. We used a 2 part chemical application to find pin hole leaks. We would spray or paint one chemical, red, on the interior seams and the other, white, on the exterior. The red would draw to the white, revealing and leaks. I tried to find this test product a while back but had no luck. Does any one else know of this?
Reply:How NOT to check an oil tank for leaksI wanted to check a motorcycle oil tank for leaks. It was the style that  had a press-in filler plug.It was easy enough to scrounge up some plugs for the threaded openings but the fill hole was more involved.I threaded a chunk of aluminum to accept a Schrader valve and then I epoxied the aluminum to the filler hole. The result was a sealed oil tank.I took the wife's floor washing bucket and filled it with water. It was big enough to hold the oil tank so I could check for bubbles after filling the tank with air. It was winter time so I filled the bucket with hot water and headed to the garage.I hooked an air line to the tank and filled it with ten pounds of air pressure and stuck the tank into the bucket. No bubbles....Good. Try twenty pounds....Still no bubbles....Good again. Now try thirty pounds....The bucket was on the floor and I was standing over it. At thirty pounds of air pressure, the thought...air bubbles...just barely entered my  mind when....WOOOOSSHHHHH....the epoxied plug blew through the side of the bucket.  Most of the water went straight up,soaking me from nutsack to noggin. This all happened just as the wife was walking down the driveway toward the garage.As I stood there soaking wet in the middle of the frickin' winter, steam pouring off me, she said "What the hell did you do to my bucket?".The moral of this   story, Ten pounds of pressure is enough. Thirty is too much.....and you'll have to buy a new bucket.
Reply:Originally Posted by small_e_900How NOT to check an oil tank for leaksI wanted to check a motorcycle oil tank for leaks. It was the style that  had a press-in filler plug.It was easy enough to scrounge up some plugs for the threaded openings but the fill hole was more involved.I threaded a chunk of aluminum to accept a Schrader valve and then I epoxied the aluminum to the filler hole. The result was a sealed oil tank.I took the wife's floor washing bucket and filled it with water. It was big enough to hold the oil tank so I could check for bubbles after filling the tank with air. It was winter time so I filled the bucket with hot water and headed to the garage.I hooked an air line to the tank and filled it with ten pounds of air pressure and stuck the tank into the bucket. No bubbles....Good. Try twenty pounds....Still no bubbles....Good again. Now try thirty pounds....The bucket was on the floor and I was standing over it. At thirty pounds of air pressure, the thought...air bubbles...just barely entered my  mind when....WOOOOSSHHHHH....the epoxied plug blew through the side of the bucket.  Most of the water went straight up,soaking me from nutsack to noggin. This all happened just as the wife was walking down the driveway toward the garage.As I stood there soaking wet in the middle of the frickin' winter, steam pouring off me, she said "What the hell did you do to my bucket?".The moral of this   story, Ten pounds of pressure is enough. Thirty is too much.....and you'll have to buy a new bucket.
Reply:i was fearing an explosion story, glad it was only the plug blowing out.miller syncrowave 250hobart handler 140home made 400 amp engine driven in progress...
Reply:That size of tank, 2 psig is plenty for soapy water test.
Reply:Originally Posted by WHughesYes and put a gauge on it to check if it will hold pressure for xxx amount of time.