Escavator boom

Hello gawelder, if you will refer back to Al's post you will notice a statement that he made concerning "completely" excavating the crack as opposed to simply grinding or gouging partially before welding it back in. A couple of points for you to consider, using 11018 will not necessarily solve the cracking issue, it may make it worse, the material that boom is made of is very likely A-36, you would just end up over-welding the repair and causing the stress to be shifted and crack again outside of the weld area, likely right along side of it. Secondly, a more important item and the one that Al was more specifically referring to, you need to completely take the cracked area out all the way through the thickness of the material. A carbon arc gouging unit is best suited for this. Definitely gouge the entire crack the length of it and slightly past both ends and completely through the thickness of the material. When you are done you will have the edges slightly beveled and you will be able to "see" into the boom, be sure to grind and clean this excavation well before proceeding. Next, cut a piece of backing material of 1/4" to 3/8" or so in thickness that could be turned sideways and fished into the crack and then pulled back up tight against the inside of the boom. This can be accomplished by stubbing a rod out against the backing piece and will allow you to hold onto and position it from the outside while you are putting it into place. Once you have gotten this inside the boom and pulled back up against it, tack it into position as required and then remove the rod portion and properly clean the backer and any tacks before proceeding with the weld-out of the excavated area. Preheat would be a good idea, 200F to 250F should be sufficient. To further understand why Al made his statement about partial penetration versus complete penetration you could do a simple test for yourself on some scrap material. take a couple pieces of flat bar, bevel their edges about halfway through, butt them up tight and weld them together. Then place this piece into a vice and clamp it slightly below the weld, using a hammer apply blows to the side of the plate that doesn't have the weld on in and watch how easily it will break. The un-welded portion of the joint will provide the notch that will allow the weld to break rather readily. Do this same test again, yet in this one make the weld on the side with the bevel and then use a grinder to grind the un-welded portion of this same joint out and then weld that in. Now put this part in the vice the same way and try to break it. It will likely bend but not break, this is how the repair to the boom can react when it has only a partial penetration repair as opposed to a full penetration repair. Hope this post can be of some use to you. Best regards, aevald