Aluminum Tower cracked at weld, how to fix.

909MARIO

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If you have an aluminum T-Top with a crack, many people will tell you that welding the crack is a temporary fix until it cracks again. They are probably correct. Replacing a Tower is $$$$. So I hope this repair saves someone from having to scrap a tower and drop a few grand on a new one.

I repaired a crack near a weld over a year ago and is still holding up. I found a crack on a welded joint of a main vertical support of my T Top over a year ago. The crack was 1-1/2" long. Replacing the tower would cost $7K or more. SO I hired a mobile welder to TIG weld the crack.$200! He told me it probably would not last long due to heating of the metal and fatigue. I did not want to trailer the boat to a weld shop for fear of making the crack bigger.

My solution after the weld repair was done was to sleeve the inside of the tube with West Systems 206 epoxy mixed with a filler for added strength.

Before you can add the epoxy to the inside of the tube you need to first find a way to keep the epoxy in the tube and not flow down and out of the tube through some other hole. One solution is to use a can of expanding foam that can be bought at any hardware store. "Great stuff" is one of many brands. The goal is to create a plug with foam. Drill a hole below the crack low enough so that when it expands it does no go up the tube and over the cracked area. You can use a 3/8" bit for this. Shoot enough into the hole to block the tube. Tape the hole shut and allow it to harden.

Once your foam plug is hard you can drill your next hole above the welded area. I would go at least 6". Drill a hole about 1/2" to 3/4" in diameter using a stepped drill bit. Find a spot where people won't likely see the hole. This is the hole the filler will be poured into. Now drill a smaller hole (any size) above the larger hole to allow air to escape as resin flows into the tube. This will keep your funnel from burping and allow your resin to flow smooth.

Find a cheap plastic funnel that fits in your hole. Buy a quart of "West Systems 206 epoxy" which gives about 20 minutes of working time. Its not cheap but it is great stuff and it wont eat through the foam plug like Polyester Resin will. Buy 1/4" chopped fiberglass and add small amounts to a cup of resin. How much resin to use is really up to you. Do not mix more than you can work with. I would say 1 cup resin is about max. It may take multiple batches to fill the tube. Mix the resin and chopped glass until you get a thickness that will flow through your funnel. Then add the hardener and mix well. When done mixing have someone hold the funnel while you pour. You will know when its full when it overflows so be prepared to tape and cover anything you do not want resin on. Have acetone and a rag handy for clean up of spills.

That is about it. Once it hardens it will be sleeved on the inside and very strong. This same concept can be used multiple ways to sleeve aluminum towers after welds have been made. Hope this saves someone a few thousand $$$.
 
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a238killfish

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I thought the weld would be sufficient as long as metal is not contaminated I guess it depends on where the crack is. I have a crack on a cross support btween port side forward post and post on port side that connects to center console. had it for 3 years. haven't dealt with it yet.
 
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dcarlisle

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I wouldn't recommend epoxy due to the fact you will never be able to weld that area again due to contamination. I would repair the weld and then add extra support using a rather large gusset at the 90 deg. angle areas both sides.
What he said. If it cracks in a particular place, it is one of two reasons. Either the weld quality wasn't sufficient or the bracing wasn't sufficient. Assuming the weld was sufficient, as most tower builders are very good welders, the bracing needs to be beefed up.
Adding and insert will probably help for a while, but you just moved the stress point to the edges of the insert. This will likely be stronger as it should be solid tube at each end of the insert , ie no welds, but still doesn't negate that there is a higher than normal load area there.
The best thing to do Is add more bracing after the original weld is corrected.
 
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MATTANZA

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in order for epoxy to stick to aluminum, it must be etched with alodine and alumiprep. i think the 2 dissimilar materials will let go, and west sys cracks.I had tom at pyt {long drive}, reweld the cracks in my t-top , and they've held up for 3 years so far.
 
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c-goat

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You need to terminate the crack before welding.You drill a small hole at both ends of the crack and then you weld it.A welder told me that,makes sense to me.
 
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909MARIO

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I wouldn't recommend epoxy due to the fact you will never be able to weld that area again due to contamination. I would repair the weld and then add extra support using a rather large gusset at the 90 deg. angle areas both sides.

Sounds good but expensive. I called around and got many quotes. Gusseting and welding according to my welder is not a sure thing either.

The area that is damaged can be welded again, you would have to cut out the old section with epoxy and weld in a new section of pipe. Just depends on where the crack is.

My fix was for the budget minded guy. If money is no option then weld it up. But
If your looking to fix it under $300 then your solution probably wont work. Most welders will charge much more than $300 to Tig that and gusset it.
 
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909MARIO

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in order for epoxy to stick to aluminum, it must be etched with alodine and alumiprep. i think the 2 dissimilar materials will let go, and west sys cracks.I had tom at pyt {long drive}, reweld the cracks in my t-top , and they've held up for 3 years so far.

It cracks, but so does Aluminum. It takes over 7,000 psi to crack the West systems Epoxy. Should be fine, it wont see those loads. As for adhesion, i think being inside the tube it wont go anywhere. Thanks for the suggestion.
 
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Second Lair

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Anyone have suggestions for repairing the pipe when it contains your wiring so it will not burn the wires ?

I can’t get the wiring out it’s corroded in there
 
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karlow

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Hum, interesting. Here is a thought. The aluminum will mainly crack from fatigue. This is the result from cycles of flexing. Its a boat, right lots of bouncing about. If it doesn't move, it doesn't flex, it doesn't fail. Simple, right!
So most of the failures are the result of bad design. Not enough gussets bracers and material. Or A-holes that just run too fast and too hard. Its the same reason that those light weigh aluminum boats are such a great idea for our West Coast! Hell you can get 8 MPG in an 18ft AL boat! The problem is each time you hit a swell it bends a bit, your Tee Top bends a bit right. With each bend, the metal is just a bit harder and more brittle. You can see how this ends. So you go to get it welded, the welding process relives the stress in the heat effected area only. Back in service, it's just like new except the whole Tee Top is stiffer from work hardening except the recently welded section.
 
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stairman

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"from work hardening except the recently welded section"
the solution for that is being a much larger section up to temp to reset the flexibility
 
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Gil Marlin

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You'll have to pull new wires, run them on the outside in a bundle. Holes drilled in the tubing just weaken the pipe anyway...
 
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duckbutter6a

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No you just melt it back together again and maybe add some filler metal to reinforce.

No need to drill it out.

Just clean the surface really well and turn the area of the crack into a puddle with a AC TIG welder. Once there's a good puddle the metal will flow back into one piece again. Then add make a second pass adding filler metal to reinforce.

Option two if you are worried about heat fatigue is to grind away the old weld and weld it back together again with new filler.

Buy a Lincoln Square wave and learn to weld :D it will pay for its self in fun and making whatever you can imagine for your boat.
 
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909MARIO

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2 YEARS LATER, JULY 2018 AND STILL HOLDING STRONG. NO CRACKS. :)
If you take note my repair also includes fiberglass chop mixed with West systems epoxy. Quarter inch chop mixed with epoxy is freaking strong. If you want to do a little experimenting you can fill a PVC tube with the same mix you're going to use and wait a day or two then take a hammer to it and see if you can break it.

You can also use G-FLEX 655, Its a thickened epoxy made by West Systems with a strength of 150,000 psi. :)https://www.westsystem.com/specialty-epoxies/gflex-655-thickened-epoxy-adhesive/
 
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rowdyrosco

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WS is pretty idiot proof stuff with many uses, but in no way, shape, or form does it compete with a welded joint. Fix the crack, figure out why it cracked, then correct the design flaw.
 
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karlow

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Well now if you think about it, you had aluminum tubing that is about 1/8" thick or less. Its rated at about 10,000 psig, Now you plug it with epoxy rated at 7000 psig. You likely over 20 times as much material in the epoxy as the AL. The epoxy is a lot more brittle but it's reinforced with short glass fibers and contained inside the tubing. Add the part about the tubing being rough inside and epoxy sticks to everything. Are u smelling what he is cooking here! The good news is no way it will fail in that location. The repair is heavy and will damping any vibrations in the tubing. U fished with glass fishing poles for years, u should have some idea how strong that stuff is. The down side is your repair its not very repairable and it might fail adjacent to your current repair, and drilling holes in the tubing did not help.
 
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909MARIO

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WS is pretty idiot proof stuff with many uses, but in no way, shape, or form does it compete with a welded joint. Fix the crack, figure out why it cracked, then correct the design flaw.
Why not? Why doesn't it compete with a weld. Doesn't it depend on the application ? Welding is not perfect either buddy . Yeah I agree you should correct the design flaw . But even well designed towers that are built by pros have cracked. Every weld creates a weak spot. Heat applied during welding changes the structure of the metal on a molecular level. WS used in certain applications can perform much better than a weld. But if you want to be stubborn and keep arguing that welding is always better you go right ahead
 
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Wefish

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gogMario, you the man. I'm going to use West System epoxy to finally try to stop the tower cracks. Welding and bracing has not worked.
 
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909MARIO

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