Non-destructive leak detection methods?

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Hey I'm a welder/fabricator at a place that makes brewery systems. Recently we have been having problems with pressurized jackets that go around the tank leaking. We test them with 15 psi of air and use a bubble solution which allows us to see the medium sized leaks. The big leaks just shoot the bubble soultion around the area and don't actually make the bubble bigger. This isn't a huge problem because you can feel the air rushing out. The big problem is the extremely small leaks, I'm talking like the tiniest bit of porosity. The bubble solution often dries up before we can even see the bubbles grow. So my question to you people is "do you know any non-destructive leak detection methods that are better than the bubble solution method?"http://specific.net
Reply:15 psi is enough to do a lot of damage, Perhaps you could use Liquid Penetrant.I forgot how to change this.
Reply:Soap doesn't hold a bubble well. They make solutions that form bubbles and keep them visible much better. Something like Sherlock 5 second http://www.wintonproducts.com/id21.htm Or Seamtest http://www.wintonproducts.com/id23.htm
Reply:It's not actually soap it's a leak detection liquid.. it just sucks.. lolhttp://specific.net
Reply:Originally Posted by guy-finniganIt's not actually soap it's a leak detection liquid.. it just sucks.. lol
Reply:Calgon leak detector is a viscous, soap based-used for AC. I've used that,but regular, full strength dish soap-not diluted works as well for the lettle,bitsy, teeney-weeney, tight-microscopic leaks (bubbles the size of a small pin prick).These little ones are normally found under higher pressure testing--100# and uP.There may be more high-end leak detection methods that sniff the pressurizedtest gas for minute amounts.I've tried and have ultra sonic testing, but that requires enough air flow and pressureto create sound that registers on the test meter. There's UV flourescent dyes used for AC checks and oil leaks that could be used withpressure test medium--if injecting liquid is okay.Finding the leaks will be easier than improving your weld process to stop them in the first place.Decent joint design, good prep practices, no cold starts/stops/craters......andthe weldor paying close attention to just how the puddle's wetting/flowing/workinggoes a long ways towards minimum leak problems--paying the same care andattention to the weld as pressure and pipeline weldors do.Almost without exception--every time I've found a leak--the cause has becomeevident--we learn how to weld seal tight.Blackbird
Reply:they make sonic inspection equipment for finding voids and stress cracks, might work on pin holes and leaks too.
Reply:Why not hydro at a low psi?
Reply:I found a leak in an acetylene manifold that was slow enough that it would not make a bubble, and I found a leak in a tire off a rubber tire dozer that was only losing 5 psi a week using airborne ultrasound.  My machine is an old Ultaprobe 9000.................but if it were me, I would use Dye Penetrant as others have already advised.6 Miller Big Blue 600 Air Paks2 Miller 400D6 Lincoln LN-25's4 Miller Xtreme 12VS2 Miller Dimension 812 4 Climax BW-3000Z bore welders Hypertherm 65 and 85Bug-O Track BugPair of Welpers
Reply:I use liquid penetrates as well but be careful because most of the cleaners that are used with the dyes contain chlorinated slovents. Tig welding and chlorinated solvents are a big no no. Hopefully you have a post weld/fab cleaning process that will take care of any possible contaminants.
Reply:I have used food colouring in the past when dealing with minute leaks. It helps trace the origin and I also found if the liquid used evaporates the stain remains. I use it on stainless steel food vessels as I am loathe to use anything too chemical for that application.
Reply:Windex glass cleaner..Turns to foam where there is a leak....zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:Die pen. test.  It smells horrid, but it works good!  Spray the die inside and let it sit overnight and then spray the developer on the outside.  Leaks will stand out like a sore thumb.
Reply:Dye penetrant is a lot safer than pressurized air..A "safer"  home made leak checker can be made with mineral oil & food coloring.  (not quite as good as magnaflux)Buy American, or don't whine when you end up on the bread line.
Reply:If you are able to pressurize with CO2, you might want to consider our AccuTools eL-720 CO2 leak detector:http://www.accutools.com/index.php?p...&subpage=el720Full disclosure:  I am the owner of Core Enterprises, Inc., the manufacturer of the AccuTools product line.
Reply:Originally Posted by joeydcIf you are able to pressurize with CO2, you might want to consider our AccuTools eL-720 CO2 leak detector:http://www.accutools.com/index.php?p...&subpage=el720Full disclosure:  I am the owner of Core Enterprises, Inc., the manufacturer of the AccuTools product line.
Reply:We used to use a similar soap based product called Snoop Leak Detector when i worked in semiconductor industry. I know it's a pressure vessel, but if you can pull a vacuum on it and hook up a millitorr gauge, you can easily find pinhole leaks with a squirt bottle of isopropol alcohol. The solvent will cause a definite vacuum loss indication on the gauge.For high vacuum leaks, we used helium leak detectors attached to the vacuum chamber while blowing small amounts of helium near suspected leak areas.PapaLincoln Idealarc 250 (circa 1962)Lincoln Weldpak 155 w/Mig KitLincoln Squarewave TIG 175
Reply:Thanks for all the suggestions I'll let my boss know about them.. He said we can't really use dye penetrant cause of the cost.. We have 30' x 4' sheets with hundreds of dimples in them with holes in the dimples to weld to the other sheet so that's a lot of dye penetrant but some of the other ideas may be more suitable.http://specific.net
Reply:Reply to 'guy-finnegan' at the end of the list here.  4'x30' sheets with dimples, Well, that simplifies my thoughts, as you can't use too much pressure for testing. How large are the weld-holes? I'd concentrate on the TIG procedure maybe, instead of finding problems. I've done a good deal of this stuff in heat exchangers, pressures from 15-100+ PSI. Weld the outer edge of holes, then 'tail-out' the bead off of the area. If you're working with any sort of Stainless, this is about the only way.  Automotive AC test gear will find the tiniest leaks, but won't be cheap. I'm talking a gas detector type unit, but when you look at time wasted finding and fixing leaks, it might be the best way to go.   Picture here is 1/2", 035" wall tubing on a 3/4" thiick header. Attached ImagesDougspair
Reply:Actually anything over 15 psi will cause the metal to "bloat" as it's a 12 gage shell on the tank with a 14 gage jackethttp://specific.net
Reply:Originally Posted by zapsterYou do realize this is borderline spam don't you?Maybe you should send the Admins a request for this before we make it vanish.....zap!
Reply:hat do person do with large transformer tanks, 150 tons capacity, filled with virgin oil to test, or say to test at the fabrication stage before shotblast and paint, cost effective, but practical. I moved from a armour manufacturing background of 24 years an 10 years from pressure vessels total 38 years, welding/NDT/quality management, we manufacture transformer assemblies from 5KVA to 79 5MVA . With KPA to reduce, minumize leaks, these warm oil has more capillary action than liquid peneterant red. I have variuos auspices under me; qa,qc,ndt,design, etch on the R&D technolology group and bu setting standards ISO  3834 comprehensive level 2 and high end building/fabrication standard EN 15085 for grade CLI welding for transformers on rail truck. Discussion please with suggesdtions, practical and cost effective. Attached Images Attached ImagesMbombe pic.pdf (60.2 KB, 7 views)
Reply:sorry, i did not excecute the spell check!!
Reply:I've tested pressure vessels before using mains water under pressure with a gauge and then isolated, left for a day and then i can see any leaks or loss either by visual inspection, ie drips, seepage etc, or a loss of reading from the pressure gauge
Reply:Originally Posted by Gerry1964I've tested pressure vessels before using mains water under pressure with a gauge and then isolated, left for a day and then i can see any leaks or loss either by visual inspection, ie drips, seepage etc, or a loss of reading from the pressure gaugeWe use small hand hydro pumps and distilled water in the Navy for our jacketed kettles.
Reply:I am of the opinion that if you get your welding parameters down pat and produce welds that will not leak, you have your problem solved.There is no better leak prevention method than appropriate joint prep and welding execution.The hydro hand pump mentioned above by Wade is a great and simple tool.....