How would you repair this crack in aluminum tube?

[Noidea87]

You need more heat. Turn your volts around 20-21 and if using .035 wire, around 370 ipm

It's 035 wire, it was on about 5.5 for voltage and 60 for wire speed. Door chart said 7 and 80 but that was burning through almost immediately

[Noidea87]

You need more heat. Turn your volts around 20-21 and if using .035 wire, around 370 ipm

This is at about 6.25 and 70 for wire speed I have trouble filling in the crater at the end without burning through. On steel i usually go slightly past and come back and hold for a beat and it fills in. If I try that it just burns through. I had a little success giving a couple of bursts at the end. I assume the extra spatter is from too much stick out? It reduced significantly once I got a little closer. It is wild how fast it heats up I will see the puddle start widening way out and then have to increase travel speed a lot or stop to prevent burn through. We have some 1/4" laying around, but we don't have a 240v outlet in our shop so I can't practice on that. I figure if I can get it down on 1/8" then 1/4" should be much easier.

[shovelon]

This is at about 6.25 and 70 for wire speed I have trouble filling in the crater at the end without burning through. On steel i usually go slightly past and come back and hold for a beat and it fills in. If I try that it just burns through. I had a little success giving a couple of bursts at the end. I assume the extra spatter is from too much stick out? It reduced significantly once I got a little closer. It is wild how fast it heats up I will see the puddle start widening way out and then have to increase travel speed a lot or stop to prevent burn through. We have some 1/4" laying around, but we don't have a 240v outlet in our shop so I can't practice on that. I figure if I can get it down on 1/8" then 1/4" should be much easier.

You need to send that arc into spray, so looks like the door chart is more on point. If you burn through you are not moving fast enough. This is the deal with alum mig. The massive spatter is a good indication of lack of spray. Everytime it short arcs you loose continuity. This is nothing like steel.

So if you have to move faster and stop after a couple of inches. Or just figure out how to move. There is no bacon sound like steel. It is more like a hiss from the spray transfer. Alum mig is always spray, remember that.

[Noidea87]

You need to send that arc into spray, so looks like the door chart is more on point. If you burn through you are not moving fast enough. This is the deal with alum mig. The massive spatter is a good indication of lack of spray. Everytime it short arcs you loose continuity. This is nothing like steel.

So if you have to move faster and stop after a couple of inches. Or just figure out how to move. There is no bacon sound like steel. It is more like a hiss from the spray transfer. Alum mig is always spray, remember that.

I think I'm getting the hang now. I had to turn the wire speed to 50 and the volts at 7 and it is a hiss with no popping.

[Welder Dave]

Sometimes you have to know your own limits and when you need to call in someone more experienced. There's no shame in that and your boss should respect you for being honest.

[shovelon]

I think I'm getting the hang now. I had to turn the wire speed to 50 and the volts at 7 and it is a hiss with no popping.

Definitely better. On the termination to fill the crater, stop to let solidify a tad, then hit the trigger to spot weld and fill it up a bit.

[Noidea87]

Definitely better. On the termination to fill the crater, stop to let solidify a tad, then hit the trigger to spot weld and fill it up a bit.

Thanks, yeah I did eventually figure that part out today too. I spent a couple of hours just filling up these little plates with beads.

[Yofish]

Looking at your welds, I'd say better off using hose clamps. I get the 'I gotta do it' thing but c'mon man, hire a weldor for a one hour job with even a coffee break in there...

[William McCormick]

I don't think and aluminum extruder would take the time to engineer a customer's problem on a super small quantity requirement. That is the job of the engineer of record for this structure. I think it would be easy enough to bolster this design at the weak link. Could also be just a bad section of tube. I personally think the liability of repair repairing this is too much without engineering input. The design is 90% effective and doing the wrong thing could make it worse. Interesting though that the structure still stands even with this damage.

You cannot use a square sharp corner architectural tube in anything marine, that tower is next to the water. Corrosion starts in the inside and outside sharp corners, architecture tube is for a pretty in-home design or light commercial office art. When you flex a sharp corner architectural tube, the opposing faces of the tube one being stretched and one being compressed, tend to bow inwards, and then outwards as the force subsides, this starts the crack in the sharp inside corner of the architectural tube, which you cannot even see until it is too late. Add a little corrosion and it goes quickly. The extrusion marks add to the crack starting as well.

Years ago this never could have happened but most of the engineers today do not apprentice. Anyone who apprentices will tell you they got most of what they know from an old tool and die guy, an old welder, an old machinist, a guy in a race shop, an old tool supplier, an old guy at a marina, and occasionally an old architect. The structural round corner square tube avoids the stress because of the radius in the four corners. The problem is that book smart Wattson comes along and looks at the specs and says "look the yield on the square corner architectural tube is higher than the round corner tube so it must be better for structural use." When that is the furthest thing from the truth. In fact the stronger it is the worse the effect is in the corner upon flexing. This is exactly what we were saying to OPUS about the square end cap on his pressure vessel. Flex and Square sharp corners are not acceptable engineering.

You really should not call yourself an engineer after a construction like that until you make it right.


Sincerely,

William McCormick

[Noidea87]

Looking at your welds, I'd say better off using hose clamps. I get the 'I gotta do it' thing but c'mon man, hire a weldor for a one hour job with even a coffee break in there...

Lol, ok man hose clamps eh? Sounds like I can save a lot of money and time then. Thanks!

[shovelon]

You cannot use a square sharp corner architectural tube in anything marine, that tower is next to the water. Corrosion starts in the inside and outside sharp corners, architecture tube is for a pretty in-home design or light commercial office art. When you flex a sharp corner architectural tube, the opposing faces of the tube one being stretched and one being compressed, tend to bow inwards, and then outwards as the force subsides, this starts the crack in the sharp inside corner of the architectural tube, which you cannot even see until it is too late. Add a little corrosion and it goes quickly. The extrusion marks add to the crack starting as well.

Years ago this never could have happened but most of the engineers today do not apprentice. Anyone who apprentices will tell you they got most of what they know from an old tool and die guy, an old welder, an old machinist, a guy in a race shop, an old tool supplier, an old guy at a marina, and occasionally an old architect. The structural round corner square tube avoids the stress because of the radius in the four corners. The problem is that book smart Wattson comes along and looks at the specs and says "look the yield on the square corner architectural tube is higher than the round corner tube so it must be better for structural use." When that is the furthest thing from the truth. In fact the stronger it is the worse the effect is in the corner upon flexing. This is exactly what we were saying to OPUS about the square end cap on his pressure vessel. Flex and Square sharp corners are not acceptable engineering.

You really should not call yourself an engineer after a construction like that until you make it right.


Sincerely,

William McCormick

Won't argue that the area that failed was not the best application of this tube. But this structure was designed and engineered and to this point has stood. The question here is how to repair and reinforce to move forward. I am super curious as to the root cause of the failure as opposed to just saying this should never have been built. What was done is done. Personally I think this material is adequate for the majority of the structure, but beams may have been better at the base. The cutouts may have caused stress risers that led to the fatigue.

[Mac's Crew]

No matter the material we use for structure, I always add a weep hole. For Aluminum it is required to get a decent 100% weld, and on steel it allows condensate to escape. Water is the Debil!

Sent from my SM-G960U using Tapatalk

[123weld]

[QUOTE=Noidea87;8804704]Th We have some 1/4" laying around, but we don't have a 240v outlet in our shop so I can't practice on that. I figure if I can get it down on 1/8" then 1/4" should be much easier.

your doing great, keep it up. u should have some 230v, it shouldnt be too hard to rig something hanging out the panel temporyily to get through this at the least. u'll want 240 in the future anyway. ur gonna see that that the heat is gonna run and act much different on that tube, than ur these skimpy practice plates, or even .250 practice plates. i know we talked about preheat, but really, u gonna want 230v

[Noidea87]

[QUOTE=123weld;8804907]

Th We have some 1/4" laying around, but we don't have a 240v outlet in our shop so I can't practice on that. I figure if I can get it down on 1/8" then 1/4" should be much easier.

your doing great, keep it up. u should have some 230v, it shouldnt be too hard to rig something hanging out the panel temporyily to get through this at the least. u'll want 240 in the future anyway. ur gonna see that that the heat is gonna run and act much different on that tube, than ur these skimpy practice plates, or even .250 practice plates. i know we talked about preheat, but really, u gonna want 230v

I plan to run it off our generator so I will have 240v with that I just have to buy the right pigtail to go from the generator plug to the machine. I had assumed it would be easier to control on the 1/4" wall tube so I figured practicing with thin stuff would help. Should I just stick to practicing with 1/4" wall tubing sections? My thought process was if I can fill a small gap between 1/8" plates surely I could make it work easier on 1/4" since burning through would be more difficult.

[Welder Dave]

You cannot use a square sharp corner architectural tube in anything marine, that tower is next to the water. Corrosion starts in the inside and outside sharp corners, architecture tube is for a pretty in-home design or light commercial office art. When you flex a sharp corner architectural tube, the opposing faces of the tube one being stretched and one being compressed, tend to bow inwards, and then outwards as the force subsides, this starts the crack in the sharp inside corner of the architectural tube, which you cannot even see until it is too late. Add a little corrosion and it goes quickly. The extrusion marks add to the crack starting as well.

Years ago this never could have happened but most of the engineers today do not apprentice. Anyone who apprentices will tell you they got most of what they know from an old tool and die guy, an old welder, an old machinist, a guy in a race shop, an old tool supplier, an old guy at a marina, and occasionally an old architect. The structural round corner square tube avoids the stress because of the radius in the four corners. The problem is that book smart Wattson comes along and looks at the specs and says "look the yield on the square corner architectural tube is higher than the round corner tube so it must be better for structural use." When that is the furthest thing from the truth. In fact the stronger it is the worse the effect is in the corner upon flexing. This is exactly what we were saying to OPUS about the square end cap on his pressure vessel. Flex and Square sharp corners are not acceptable engineering.

You really should not call yourself an engineer after a construction like that until you make it right.


Sincerely,

William McCormick

I think you might mean Motolife313's pressure vessel not OPUS's.

[Welder Dave]

[QUOTE=Noidea87;8804911]

I plan to run it off our generator so I will have 240v with that I just have to buy the right pigtail to go from the generator plug to the machine. I had assumed it would be easier to control on the 1/4" wall tube so I figured practicing with thin stuff would help. Should I just stick to practicing with 1/4" wall tubing sections? My thought process was if I can fill a small gap between 1/8" plates surely I could make it work easier on 1/4" since burning through would be more difficult.

Practice on similar material to what needs to be repaired. The material you're using looks pretty clean and hasn't been outside weathering in high humidity (possibly salt water) conditions. It sounds like you're going to attempt the repair regardless what anyone says but do you have a plan B if it goes South? If you make a mess might have no choice but to replace the cross member. The other thing to consider is a qualified weldor may decline the job it if you mess it up worse.

[Noidea87]

[QUOTE=Welder Dave;8804916]

Practice on similar material to what needs to be repaired. The material you're using looks pretty clean and hasn't been outside weathering in high humidity (possibly salt water) conditions. It sounds like you're going to attempt the repair regardless what anyone says but do you have a plan B if it goes South? If you make a mess might have no choice but to replace the cross member. The other thing to consider is a qualified weldor may decline the job it if you mess it up worse.

Next time I'm in the office I plan to practice on some old aluminum scrap we have that had been installed out on a platform for probably 10 years around salt water. Try my cleaning method out and see how it works.

The back up plan is to replace the whole cross member. The more I think about it that might actually be easier than trying to repair these cracks. We are meeting with our engineers for suggestions here soon. They may recommend just replacing the whole cross member instead of repairing. He was surprised to see it fail like this. Thought maybe it was bad section of tube from the get go. If we do go that route I'm trying to figure out a good way to rig up a temporary support. Any ideas there?

[William McCormick]

Won't argue that the area that failed was not the best application of this tube. But this structure was designed and engineered and to this point has stood. The question here is how to repair and reinforce to move forward. I am super curious as to the root cause of the failure as opposed to just saying this should never have been built. What was done is done. Personally I think this material is adequate for the majority of the structure, but beams may have been better at the base. The cutouts may have caused stress risers that led to the fatigue.

That is not an engineered structure because he chose an ornamental square corner tube for a project that requires structural radius corner box tubing. You cannot see the damage in the other members yet. As I mentioned when you bend an architectural square tube all the inside corners go acute less than 90 degrees that compresses the inside of the corners and expands the outside of the tube right next to the corners. When the flex force is removed the inside corner is stretched and the outside of the tube compressed. At that point it is just a ticking time bomb. He should make right on that. This was known sixty years ago just like we knew and still know an aluminum structure liquifies in a small fire faster than a wood structure fails.

Sincerely,

William McCormick

[shovelon]

That is not an engineered structure because he chose an ornamental square corner tube for a project that requires structural radius corner box tubing. You cannot see the damage in the other members yet. As I mentioned when you bend an architectural square tube all the inside corners go acute less than 90 degrees that compresses the inside of the corners and expands the outside of the tube right next to the corners. When the flex force is removed the inside corner is stretched and the outside of the tube compressed. At that point it is just a ticking time bomb. He should make right on that. This was known sixty years ago just like we knew and still know an aluminum structure liquifies in a small fire faster than a wood structure fails.

Sincerely,

William McCormick

I built a structure some 20 years ago that was fully engineered and speced the same material in 6061 alloy. It met all of the load ratings and safety factors, codes and insurance requirements. The installation went into an NFL football stadium. Met AWS D1.2 weld qualifications as well.

[William McCormick]

I don't think and aluminum extruder would take the time to engineer a customer's problem on a super small quantity requirement. That is the job of the engineer of record for this structure. I think it would be easy enough to bolster this design at the weak link. Could also be just a bad section of tube. I personally think the liability of repair repairing this is too much without engineering input. The design is 90% effective and doing the wrong thing could make it worse. Interesting though that the structure still stands even with this damage.

A structural square tube with radiused inner and outer corners is readily available. The problem is that engineers and architects look at the strength or yield load of the structural tube and it is less than the same sized architectural tube for a one-time load, maybe. But if you flex the architectural tube it will start to crack so you may never know what you have, and therefore you only have an ornamental tube, not a structural tube.

For custom tubes, it is a rather simple calculation something like two times the wall thickness for the inner radius and I do not recall what it is for the outer radius in order to call it structural. When we weld up custom shapes we always try to use that formula. The extruders will bend over backward to help you out if you want to go there.

Sincerely,

William McCormick

[William McCormick]

I built a structure some 20 years ago that was fully engineered and speced the same material in 6061 alloy. It met all of the load ratings and safety factors, codes and insurance requirements. The installation went into an NFL football stadium. Met AWS D1.2 weld qualifications as well.

I fully understand what has been allowed to be built with ornamental tubing. However, and this is paramount if that tube flexes it will develop a similar crack as the original poster displayed to us. It is poor architects or engineers looking in the catalog and saying this aluminum tube with square corners has the strength necessary to do what I need to do. The problem is he is in the ornamental part of the book, not the structural part of the book, but does not know it. So if what you build in a stadium will never flex and is an ornamental piece more power to the engineer. But if this device flexes, perhaps when the whole stadium flexes as people are running from a fire, that will be the day that you realize just how poor a group of engineers we are.


Sincerely,

William McCormick

[shovelon]

I fully understand what has been allowed to be built with ornamental tubing. However, and this is paramount if that tube flexes it will develop a similar crack as the original poster displayed to us. It is poor architects or engineers looking in the catalog and saying this aluminum tube with square corners has the strength necessary to do what I need to do. The problem is he is in the ornamental part of the book, not the structural part of the book, but does not know it. So if what you build in a stadium will never flex and is an ornamental piece more power to the engineer. But if this device flexes, perhaps when the whole stadium flexes as people are running from a fire, that will be the day that you realize just how poor a group of engineers we are.


Sincerely,

William McCormick

Yes there is different criteria to be met between cyclically loaded structures and statically loaded structures. I only get involved in meeting welding specs. I leave the modeling, load testing, and failure testing to the engineers. If square cornered tube meets the needs, then use the KISS approach.

[shovelon]

I fully understand what has been allowed to be built with ornamental tubing. However, and this is paramount if that tube flexes it will develop a similar crack as the original poster displayed to us. It is poor architects or engineers looking in the catalog and saying this aluminum tube with square corners has the strength necessary to do what I need to do. The problem is he is in the ornamental part of the book, not the structural part of the book, but does not know it. So if what you build in a stadium will never flex and is an ornamental piece more power to the engineer. But if this device flexes, perhaps when the whole stadium flexes as people are running from a fire, that will be the day that you realize just how poor a group of engineers we are.


Sincerely,

William McCormick

The bright spot is that the only defect is where the hole is at the base. The rest of the structure including all of the welds show no signs of failure. Could be the OP is right, that a defect was inherent in only that section of tube. Something looks to be installed behind that crack.

[Spectator]

Long time lurker here and have been in the marine rigging business all my life. I say keep it up, give yourself a little more time to do you're homework (which your doing), to think about the repair process and practice a bunch more on similar condition sections (slice open practice welds afterwards to inspect your work) and to think about if this is the right solution and what can happen if things go wrong during the operation?

Sounds like some people here sitting at their desk being critical and demanding idealistic perfection instead of helping out more with your task at hand, its your property and project that you want to see out and complete yourself, sounds like you understand the impact and responsibility of doing it yourself. Having a good contingent plan B is a really idea if Plan A goes south and sounds like you already have done that. My only advice is to think about more what could go wrong during your welding repair, if it will fix the issue and what the impact (costs) it will have on the tower and its usage if things don't go according to plan?

Based on the very limited pictures and info, there is some additional work on the tower you can do afterwards that can hopefully help mitigate more failure like the one you're dealing with now to make the tower last longer, a lot more info, specs & pics is needed about what's on top but that's for a later conversation and more overall pics are needed but as of right now you first have to deal with this specific spot and repairing it.

[Noidea87]

Congratulations on the want to learn. Too bad you didn't mark the break to see IF it is still growing as you stated that the pics are a year old. As stated by other folks, once you get welding the aluminum, there is no break ... keep moving and MOVING is for real. Also, as William Mc stated, it does appear that the structure in the pic is architectural tubing. Once you make a repair and add some extra support to that area, you will be placing force somewhere else, BUT, since the structure is going to be replaced, the repair is viable. I and I'm sure the others in here wish you well. Keep us posted.

Do you mean you aren't supposed to stop with aluminum until you finish the joint? I was able to stop and restart in my test piece once I figured out how to get the crater to fill. Or do you just mean you can't slow down? I definitely figured that out haha, I got the feel for watching the puddle and figuring out when I should stop completely or start moving fast to keep from burning through