Steel to aluminum

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how much thicker material do you go with if building a 90 foot sprayer boom (2 45 foot sections )out of aluminum that was previously steel ? My thoughts were double the thickness on everything , but my boss opted to just go about 25 percent heavier . His opinion is it does not need it because as a whole it is a lot lighter . What are your opinions?
Reply:25 seems like a good number. less weight so less strength is needed to support it....Just a couple welders, big hammers, grinders, and torches.Work will free you.Men in dirty jeans built this country, while men in clean suits have destroyed it. Trump/Carson 2016-2024
Reply:Was the original booms 1/8" wall steel?If so I would think 3/16" alumuinum would be adaquateJust a couple welders, big hammers, grinders, and torches.Work will free you.Men in dirty jeans built this country, while men in clean suits have destroyed it. Trump/Carson 2016-2024
Reply:Hello Miller Guy, I would say that it depends on how the booms are fabricated. Are they of a truss type construction, do they need to be self supporting? Pictures, dwgs., or more details would certainly help with supporting a particular oversize on your aluminum material use. More information about specifics should get you some information that might be more valid. Best regards, Allanaevald
Reply:Originally Posted by aevaldHello Miller Guy, I would say that it depends on how the booms are fabricated. Are they of a truss type construction, do they need to be self supporting? Pictures, dwgs., or more details would certainly help with supporting a particular oversize on your aluminum material use. More information about specifics should get you some information that might be more valid. Best regards, Allan
Reply:Millerguy, as mentioned in previous posts- the structure pretty much makes this impossible to define; without images/descriptions/details but.. a Rule of Thumb that takes aluminum and steels relative wt.s and strengths into account is that 1/2 the wt. in aluminum is equal strength to the original steel. Where steel is both stronger and heavier, and aluminum lighter and weaker; make an aluminum structure about half the weight of the steel and they're about the same strength in performance. Not a solution but commonly used in many structures for approximation; (where) welding joints, location and type of joints and the materials (alloys) chosen are all factors to be considered.Hope this helps in some conversational estimations about the relative masses as fabricated structural comparison.Cheers,Kevin MorinKenai, AK
Reply:Pay an engineer to do the math.  It may run you a few $100 but this sounds like a decently large project with a total cost in the 1000's.
Reply:Question would be are you building this just like what was there or is this a new design?
Reply:Building the trusses for the booms will be the easy part.  Keeping everything together at the hinges and where the hydraulic cylinders attach will be the weak link.  Making pivots, hinges and pin eyes from steel and bolting that to the aluminum structure might help.  Then you will have the issue of bolts wanting to work loose and let the connections slip and start wollaring out holes.  Look at the weak spots on the steel structure you have now, then think to you self about how aluminum will hold up in the same application.Dan D.Manipulator Of Metal
Reply:I'm not a metallurgy expert but I know enough between the two to say go heavier, those booms take alot of abuse when they go bouncing up and down across a field when the operator decides to run fast to get the job done.
Reply:Can't remember ever seeing an aluminum spray boom. From the things I've done tho I think you will need both thicker wall and larger dimension.Yeah, I know, but it'll be ok!Lincoln Square wave 255Miller Vintage mig30a spoolgunThermal Dynamics Pacmaster 100xl plasmaSmith mc torchEllis 1600 band saw
Reply:It would be really cool to see the finished boom in aluminum.   If I were you guys I would probably get some engineering involved simply because.. Aluminum is a great metal for the right application.....just like steel is a great metal for the right application.  Aluminum is much less forgiving and has no real elasticity in its modulus....if you bump it it will dent and if you overload it....it fails quick....harmonics also screw with many aluminum projects.  On the commercial boats and Yachts we build the hull out of steel and the super-structure out of aluminum.  You can do exactly what you want with the right aluminum pipe schedule and I am sure you guys can get it to work.  If I was doing the job I would be sure to give my joints gussets with plate and leave an opening in the gussets which will allow for some flexing.  I mean aluminum can be brittle when overloaded where steel seems to "handle overloaded stresses better by showing some elasticity before shearing or bending"  Just some thoughts about aluminum.   Are you using 3 pipe with 1/2 plate? 6061?  Will the booms need to be painted?  I have some great coating experience if you need any help.  Thanks and hope it helps.