Welding Tips and Tricks

I'm asking for the help of anyone that has experience in heavy structural welding. I have been welding since 1978, as a hobbyist and I now have to fabricate a large frame for a hydraulic press.
The plates are between 1" and 3" thick. The projected working load is around 750 tons.
Questions are:
1- What would be the best welding method to joint these plates (Mig or Stick) I have large Mig and Stick machines .
2- What type of electrode ( 7018, Flux cored, bare wire, dual shield)?
3- What should be the interpass temperature?
4-What type of joint? U, V, J etc
If you have any suggestions where I may find this information it will be greatly appreciate.
This is for a business that I'm trying to start with a friend and the financial resources basically amounts to "sweat equity"
I have to make this work and this is analogous to" I only have one bullet left and the tiger is closing in"
I thank you in advance to anyone that may provide some guidance in this field.

Hi there, if you have a large mig, that is around the 300 amp range, then you should be able to use any one of the machines/processes you listed. Please indicate the types of joints you have to make before we can suggest the joint prep, but remember, the U &J preps are a lot harder to cut, requiring air arc/oxy gouging and grinding or machining. If the material is simple low carbon steel, inter pass temperature isn't as much of a problem as long as you don't keep welding on steel that's glowing orange. The thick plates would benefit from a minor preheat. (50°c or so)- for about 2" around your weld. B just so they don't suck all the heat away from your weld zone.

If stick 7018 electrodes
As big as your machine can handle. Or even 7024 iron powder is its all flat or down hand welding.

I would get an engineer to look at the proposed construction and advise. I don't know how anyone could, at this point, give you an educated response. I also find it surprising and a little disconcerting that you would even be asking for input on best procedure. what type of welding have you been doing for the past 36 years?

Thanks for the initial reply ( weldin mike 27).
The concept is to build a rectangular box that will house the hydraulic cylinders and the cutting assembly ( fixed blade and a moving blade) the actual forces pushing on the ends are projected for around 750 tons with 3 cylinders and we have to leave room in case a 4th cylinder may prove necessary ( total 1000 tons). These would be 16" diameter cylinders

I'm projecting that a lot of welds will be out of position ( vertical and overhead). I don't have the means of lifting the whole assembly. I'm limited to a lifting capacity of around 15,000 lbs therefore the welds will be made as the machine sits on the floor, and not being able to rotate,
For the flat I should be OK, I have used 7024 and the bead comes out very nice. Deposition is very high. I remember a commercial from long ago that they were using a feathered duster to remove the slag. When done right the 7024's would fit the example, however this is for the flat only. I don't know how to select the size for an out of position joint and have proper penetration without dripping all over. I think that I will be using fresh 7018's for everything that is not flat if MIg is not feasible.

The preheat may not be necessary I'm working in South Florida. the sun sometimes heat up the plates to the point that there is some warping. I will have to avoid this problem.

One concern is the speed of deposition, I would think that the MIg should outdo the stick by a large margin.
The Mig setup I have access to is a Maxtron 450 with an M-60 ( if I recall correctly) wire feeder with a 500 amp water cooled gun and a Coolmate. This should be able to handle any Mig approach.

The joints, I don't know what would be better. I have access to an Arcair set up but I don't think that I'm good enough to do it fast and consistently. We were considering ordering the plates and other structural members prepared by the steel supplier. Grinding 2" or 3" plates is a forever endeavor, the time would be absurd. All that I can use are 7"or 9" grinder and I think it just won't be fast enough.
I have no idea what the cost could be but my partner seems to be Ok with ordering the material prepared for welding. Do you have any input on this approach? I just remembered that I can get a Victor cutting machine. I used this machine many years ago to cutoff half of the flange on 36x180 25ft long I-beam and it came out like glass.Do you think that single bevel joint is an option?
How about using corner joints whenever possible? That should cut down the preparation time and costs. Is that assumption correct?
Any inputs on bracing to avoid distortion is greatly appreciated. Do I leave a slightly greater angle, in addition to bracing or just bracing at the desired position and alternating the welds should be enough to control the pull?
Thanks
Don

As far as designing your frame, I'm not much help, as I'm predominantly a welder. As Angus said (though I'm not angry at you) an engineer would give you a big leg up. A mate or a mate of a mate might help out for cheap, or even return of services if money is tight. Another option is adapting an existing machine or buying a second hand one at auction. Surplus government auctions often slip under the radar and have lots of awesome options. A member here, Delraydella has picked up some killer deals.

Thinking of existing presses I have used, yours must be a monster, and what is it used for?

Don,

My personal preference for structure that heavy would be dual-shield. Your MIG should be able to handle at least .052 and likely .080 for anything that can be done flat. (Personally, I prefer .045 for out-of-position, but if you're comfortable with heavier wire it'll go faster.) My preferred joint prep would be a double-vee for any butt welds so the draw is equal. Corner welds, as you suggested, will greatly simplify prep, and I'd suspect that including 2 or 3 degrees in the fit-up to allow for draw would be advised.

Bear in mind that I've not done this on anything thicker than 1.5", so I'm guessing, not citing experience.

I have to agree with Angus, that considering the application it would be wise to consult a welding engineer if possible. If not, I'd search for someone's WPS for sections that heavy... Possibly someone with a shipyard or bridge-building background.

Steve S

In response to Angus.

I'm consulting an engineer, but from the initial conversation with him, I'm not sure that he has ever designed anything like this.
For the past 36 years I learned how to weld on my own by trial and error MIG ( Millermatic 200) then learned stick around 1995probably some 5 years to get any decent results.

I don't weld for others, therefore the frequency of actual welding is not frequent.
My approach is to greatly overbuild to avoid structural failure. This could not work on a commercial environment, but I like welding and I do it for my self, also there are several changes that occur during the project. I think that none of this would be possible with a welding contractor, but then again I'm neither I don't weld for commercial purposes or for another party. I have done many free minor repairs for friends on simple stuff( fixing a crack on a mower deck, a broken table or car seat).
I have done some heavier security re-enforcements for myself ( 3/8" plate).
On the present case I have to try to get it right because I neither have the money to pay someone to do it for me nor do I have the funds to buy the material all over again.
I feel that I have some theoretical knowledge and some experience I should be able to do it with some guidance and checks.

BTW, I once got a certified welder to do a loading ramp for me. At the end I had to do the out of position welds. I don't know what the problem was, but this guy come recommended and I paid him in advance for it.

Another time I decided to rush a project on some heavy doors that I was doing and I just put too much heat into the piece and I don't have to tell you what happened. I called a local company that does welding and sheet metal. These guys have been around since the early 1920's. When their guy came around and after he examined the warping on the door. I asked what could he do to resolve the problem. Not only he said he had no idea, but that he had gotten some ideas form my project. I knew what to do and got it done ( hydraulics, chain, relief cuts etc) So. I don't know how to select someone to do the job and not pay a fortune for it.
I can keep checking my progress , as I weld, and see if it matches the idea or I can stop and try to avoid making a bigger mistake.
That is why I'm asking for help from someone that knows and may be willing to help.
I'm asking these questions because I can't afford to hire someone to do this project.
To anyone willing to put in your 0.02 I thank you for your assistance.

I want to apologize for some of the reply mistakes. I have done this a long time ago and I'm not knowledgeable of the process.
I will try to respond to every point that is raised.

Otto Thanks for the input on the mig wire and options. I thought that was the choice, but there is no harm in running by someone that has more experience in the matter.
I hear you that your limit is 1.5" and I will take that into consideration and try to go from there.

Mike 27 As far as the frame I have a good idea and this is being run by the engineer to validate it or modify. I'm willing to increase the safety factor in a reasonable amount to avoid premature stress failure of the cutting assembly which will be subject to the greatest forces.
As far as I know no such machine is available to the "poor man" or to the rich man.
I'm trying to create something very specific and because of being involved with another party I can't disclose all the details.
I apologize for that
This machine will be used to process scrap.
This is the result of 2 desperate people trying to make a living and if it works creating a better mouse trap ( don't we all hope for that) and get some financial rewards for it.
There are several companies making these machines and their cost is absurd ( to us). We came up with an idea, he has designed several contraptions of one kind or another and I have some knowledge of welding, mechanical processes and scrap.
We are trying to mix all the ingredients, and create a magic mechanical potion nr. 9.
It is also a lack of options, he is in the late 50's and I'm in the 60's we have to try something in the fields that we think we have a minimal chance of success. The clock is not our friend.
To all that have given me inputs, my sincere thanks.

Let me correct my previous statement.
I said that there are several companies that make these machines.
The statement is incorrect because there no machine that actually performs what we are trying to achieve.
The machines perform somewhat similar operations, but it is not what we want to do.

welder 100, are you based out of opa locka. I had guessed it was for recycling scrap and something that size would put you in Miami, tampa or maybe Jacksonville. is it horizontal or vertical. just curious.

along the lines of this? Container shear (CNS 400 K)

http://containerschere.de/en/scrap-shears-cns-400-k.php

welder100,
First welcome to the forum. I was alerted of your post from another member and feel I need to add my two cents. First, as mentioned already, the consult from a structural engineer and possibly a hydraulics engineer is a must. All of us here can tell you how we have built things in the past but unless we are true engineers we will be of no use when it comes to calculating stress and material type needed. Keep this in mind, if we were to tackle this project it would at one point and time pass through at least 3 of our engineers. Also, we build everything with a 5 to 1 safety factor. It sounds like this may be a new concept thus there are no prints exsisting. I highly advise against jumping in on a project this large it you are not experienced in large and highly stressed weldments. No offence is meant whatsoever. Do you know what type of material you will be welding? A36? A500? This will be important to know before hand. This will also determine your filler material. We can advise to use ER70S-6, 71M or E7018 but that would be in error since we don't technically know details.

I am building a testing bed that will see 1.2 million lbs of force through it and our material ranges 3/4" to 4" plate and a vast assortment of material. A500, A992, A514, 4140, etc. All require different procedures and filler materials. We had to certify for every single position and filler as well as trace every nut and bolt. Point I am trying to make is there is a lot of libility in a build of this magnatude. I would also consult a Welding Process/Application Specialist from a reputable company in your area.

The one thing I can tell you, since you asked specifically, I would order as much material processed as you can. The cost savings will be great, especially if you only have and intent to use grinders.
-Jonathan

You have attracted the interest of a number of members but its one of those things that no 1 person can (or should) offer a saving grace over the computer. We would if we could, but its impossible.

I had an idea of adapting or making a frame for static mounting of one of these thing,

http://www.tradeearthmovers.com.au/deta ... duty/15124

I know its dollars, but this is from Australia, so the price will be dramatically higher. But the body of the machine is made, as are the cutting areas, pivots and hydraulic bits, but its only a thought.

Best of luck to you, maybe you will find an out of work or retired engineer that wants to help for the fun or to keep busy.

If you have several full penetration welds on a project that has 1" - 3" thick materials...I would suggest using 3/32" E70T-1, keep in mind that you would need a machine capable of running 420-450a/29-30v (at approx. 150-160ipm). I worked for a structural steel fabricator and this was their main filler size, for everything else they used 1/16" E71T-1, but that size wire is a handful running vert and I felt that .045 was better suited. The bean counters were always looking at pounds deposited per hour, so the heavier deposition wires stayed in place.

I've had success repairing some prehistoric jaw crushers that had frames of three -ish inch thickness by using air carbon arc to vee the cracks out then welded with 7018 using numerous passes. I used no preheat per se but it was plenty hot after all the air arcing. Didn't have any procedures or anything specified, the boss just asked "can you fix it?" So I did. I don't know if that is suitable for the kind of forces your machine will encounter.
It sounds a bit scary to me. Good luck.
Cheers.
-Eldon

Angus
I apologize for not replying sooner, I hadn't noticed that there was a second page.
We are planning something for either Broward or Palm Beach county.
We are designing a shear, my partner is the one that has designed most of it.
Because of non disclosure agreements that were signed ( it is basically his design) I'm being prevented from divulging details of the machine.
I'm the one that will do the welding and I have a fairly good idea of what to do, but I believe that it is always good to check with other people that have experience. No one is foolproof and gets it right 100% of the projects, specially because the financial conditions are very tight we have to make it work on the first try.
It is a shear for scrap metal.

Are you in the scrap business? Have you worked on this type of machines.

I took a look at the machine that you suggested. What do you think of it? Have you seen it in operation?
Thanks
Don

To everyone that has given their input I want to extend my thanks.
I realize that this project is not the everyday welding job and therefore there are questions that aren't so easily answered.
I have considered many alternatives and what I'm leaning towards at this point is a " divide and conquer" approach.
This is in reference to the actual frame "box" that will be subject to the largest loads.
I will somewhat "mimic" the pressure vessel or cylinder cross section. This design is what permits the cylindrical tanks to withstand the inner pressure. The ends are rounded off, or semi-circular and the connecting members between the two ends are just straight. This permits steel to works at its best, which is in tension.
At the ends of the straight members there will be something that would resemble the reenforced flanges of the hydraulic cylinders. There is no questions that hydraulic cylinders are able to support gigantic loads.
This breakdown will permit me to handle smaller segments of the assembly, which in turn is less weight and at that point I can position the pieces so that the numbers of "out of position' weldments are either eliminated or greatly reduced. Final assembly will be done with previously welded members that will be fastened together. I'm considering using structural bolts ASTM grade A490 and 1 1/2" diameter
I think that adding joints that are fastened rather than welded should make easier for future maintenance or change of design, should the initial concept fail or if we find that improvements can be implemented after start of the operations.
If anyone sees a flaw on my reasoning, please offer your opining which is sincerely appreciated.
Again my thanks to everyone who has taken the time to offer their perspective

I work with 25-75t hydraulic cranes on a daily basis and the one thing I can offer is inspect everything that is pre-welded or assembled. As you've indicated, you've had some experience with "professionals" and seem to have a suitably skeptical attitude. I commend that. Good luck.

The one thing I an offer is to make sure you allow for access to all the fittings and hoses that will inevitably fail. Nothing in the world is nearly as much fun as having to disassemble a bunch of heavy things in 5 degree weather to replace some $2 chi-com fitting that failed due to vibration cracking. S/F.....Ken M

Don,
Thanks for the update. Your project has my interest for sure. I would ask that you keep us informed and when you start building start a thread documenting your progress. This will allow us to see what you are doing and be able to continue to help as we can.
-Jonathan