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  #41  
Old 04-09-2016, 10:43 AM
sandmanred sandmanred is offline
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Default Another leak test

I decided it seemed too good to be true that I found no leaks on my first test. I had used a balloon connected to the outlet provide the pressure and soapy water to try to find the leaks.

Second test using more pressure indicates a number of pinhole leaks.

I don't want to use the tank sealants, they sound like they all eventually fail.

So, to fix the pinholes do you think I need to drill them out or just re-weld over them? Any suggestions welcome.
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  #42  
Old 04-09-2016, 01:25 PM
AllyBill AllyBill is offline
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Jeff,

just pop a 1/8th hole through and weld it up again. Purge the inside of the tank with argon first.

Will
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  #43  
Old 04-09-2016, 01:59 PM
sandmanred sandmanred is offline
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Jeff,
Purge the inside of the tank with argon first.

Will
If I didn't purge with argon for the original fab not sure why I need to purge now?
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  #44  
Old 04-09-2016, 02:26 PM
AllyBill AllyBill is offline
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just habit, I always purge tanks when welding them, especially if they've ever contained anything remotely flammable, but if you didn't then you don't need to now. Purge the next one and you'll get fewer leaks.

Will
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  #45  
Old 04-09-2016, 07:10 PM
sandmanred sandmanred is offline
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This one has never had anything in it. I have the stuff I need on the way to purge so I might as well. Just didn't think it was necessary with aluminum.
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  #46  
Old 04-09-2016, 08:26 PM
AllyBill AllyBill is offline
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Originally Posted by sandmanred View Post
This one has never had anything in it. I have the stuff I need on the way to purge so I might as well. Just didn't think it was necessary with aluminum.
Hi Jeff, It could be argued that it isn't necessary as it's easy enough to make a tight tank without purging but as these are welds you can't get onto from behind once the job is done I see no sense in allowing the back side to burn away in an oxygen rich environment potentially causing problems that can be avoided, especially with aluminium because it likes to absorb all sorts of nasties when hot and you get more complete penetration with a back-purged weld so no leaks to chase out. I would normally spot the parts together then close the seams with making tape then purge gently as I weld, removing the tape as I go and wiping down with isopropanol to remove any residue. I stuff a wad of paper towel into the filler with the hose through the middle.

Will
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  #47  
Old 04-12-2016, 10:21 PM
sandmanred sandmanred is offline
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I got impatient and went ahead without argon purge. Used a burr to get close to the bottom and then rewelded. Found probably 20 pinholes, mostly pinhole from craters due to poor tapering technique at the end of a bead. All patched up and ready to go.
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  #48  
Old 04-13-2016, 05:14 AM
AllyBill AllyBill is offline
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Quote:
Originally Posted by sandmanred View Post
I got impatient and went ahead without argon purge. Used a burr to get close to the bottom and then rewelded. Found probably 20 pinholes, mostly pinhole from craters due to poor tapering technique at the end of a bead. All patched up and ready to go.
Good work... What's the next project?

Will
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  #49  
Old 04-13-2016, 08:19 AM
Seanpd Seanpd is offline
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Allybill, what is making tape?
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  #50  
Old 04-13-2016, 01:00 PM
sandmanred sandmanred is offline
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Good work... What's the next project?

Will
Good question...

I will be getting the bike this tank is for on the road. After that it could be an alternate tank or maybe front fender for the same bike.

IMG_0858.jpg
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Last edited by sandmanred; 04-13-2016 at 01:04 PM. Reason: add pic
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