Have you tried to contact the manufacturer?

Peter,

WELCOME TO THE AWS WELDING FORUM!!

Now, Al and Nick made good points.  I would like to expand on both a little.

First, D1.1 is a good starting place for work on heavy equipment, but the code you really want to reference is D14.3.  It covers pretty much all applications for machinery such as trackhoes, earthmoving equipment, log stackers, etc.  I don't have one anymore, haven't worked for LeTourneau for many years, but I'm pretty sure it would have what you need for considering box tube booms and repairs that need to be made to a broken member.

Second, having worked on many such pieces of equipment, Nick made a good suggestion.  If you open up your root a bit, take a piece of flat bar and attach a small diameter (1/8" 7018 electrode or the like) rod to it at one edge you can slip it in the crack and line it up to give you a backing.  Tack it in place and then snap the rod off.  Now you can get your CJP with no questions asked and a minimum stress riser. 

My favorite method for accomplishing this is to set the bevel groove as I want it and then on the 90* surface from where I am working I make a slot that the backing will fit into.  Cut it to a proper length so it goes to the opposite corner but is short enough it lets me weld the slot back in.  Attach a rod to the center of the backing bar to hold it up tight against the root and work it into place.  Tack it and then snap it off.  Again, a CJP with backing. 

One of my customers called me a couple of years ago with a trackhoe boom that had snapped around 3 sides and part of the 4th and was at a rediculous angle from being straight.  It had a heavy duty chopper on it for clearing brush including small trees from under 1000's of miles of power transmission lines across AZ.  The operator had been using it with way to much side pressure applied and as a means of relocating the machine on very steep hillsides.  When it snapped it went almost all the way.  The manufacurer told them it could not be repaired successfully.  They and others had tried and they would be lucky if it lasted a couple of days.  So, they wanted to charge them a terrible price for a new boom member and total replacement.  I laughed so hard I started to feel sorry for the guy.  I hate incompetence and the excuses people use for lack of knowledge and proper training and experience.  But it does mainly come down to not wanting to risk their poorly trained people having to stand behind a product that they know is going to fail.  So, money and insurance are the bottom line with more profit coming from selling a new part and not having to worry about it's structural integrity.

So, I used the machines power to push it back around to close to straight.  Had to do some removing of material because of the way the box tube stretched around the edges of the tear.  Prepped it with my bevels, put backing in place, and used strongbacks and come along to pull it into position straight, both side to side and up and down.   Then, with plenty of root gap and backing in place I welded it out.  That was two to three years ago and last time I saw him it was still going strong. 

Repeat business!!  I prefer my repeat business to be from a reputation of success and repairs needed in a different location and even different machine.  Not that the same machine FINALLY broke again in the same place.  I have my own structural ideas on repairs on heavy equipment so they don't break again in the same place or even close to my repair.  Not because I relocated stress risers and it broke there.  Not because my HAZ caused it to break further away.  Etc.  New break with it's own problems. 

And BTW, I ALMOST NEVER use SCAB or, as you called them, phishplates.  In most cases they are an excuse for not doing the actual repair properly and very few people know how to design them to get the stresses properly distributed and you have a worse problem that takes even longer to repair because now you have both a scab plate and the original material to deal with. 

Another thing, gussets, edges of welds, corners of the box tube, etc need to be very smooth in their transition.  Stress risers created at these points are critical. 

Have a Great Day,  Brent

I've done so.e repairs like you are talking about. And the owner told me to just fix it and get it back to work. The boom got bent I had to cut out the bent section. Build and weld in place a new section about 8' long and then fish plated it too took me a weekend tl do it. Before I started I told him ill do it but I will not guarantee nothing. He said fix it as far as I know it is still in operation today. There was not a WPS or a inspector I welded it with 5/32 lohi and jet rod he was very impressed

pre heat do a 6010 6011 root, fill with 7018 or equivelent wire install a reinforcing patch and your off to to the races. have posted lots of pics on the site but you will have to go back a way's to find them. all the machines I have used this method on are still in the field today some have been there for 14+ yrs.

Thanks for they reply. I understand what you mean about D1.1 I have had many customers demand that the repair be sufficient enough to not need phishplating. I understand there is only so much I can do on my end while not making it a bigger project than it needs to be. I have developed a technique of my own, but I am no official source. I have done  quite a few without phishplates that are still holding to this day and they were welded many seasons ago. So I can assume I may have found a good way of doing it with careful prep when gouging and how I do weld it out. I can understand where the construction companies are coming from tho, most of the repairs, I have seen done by others look pretty atrocious and they don't want that on their machines after all, they did pay a lot of money for them. As my boss would put it, "no phishplate you get no guarantee on the work" I guess that's just how it is. I was just looking for something that would provide a little bit more of a middle ground with the customer. I understand what is being stated, and the reasons why here, the problem  comes trying to explain this to a customer who knows nothing about welding and fabrication.

Thank you for the reply.