Welding crack on dump truck box frame

[IslandHD]

Hello,

I have this crack that I would like to weld. I know how to weld but lack experience to know the best way to weld this crack.

Do I Weld all sides of it? Do I Need to fish plate it? If so where

This pictures are not the greatest. I took them in a rush and didn’t check them.

This crack is a few inches from where the box pivot pin is installed. The pictures went sideways when uploading don’t know how to fix this!!

thanks in advance

[SweetMK]

Never run any beads perpendicular to the length of the frame,,
only run weld beads parallel to the length of the frame.

Since no welds will be going the direction of the crack,, you will need fish plates.

AND,,, Welcome to the forum!!

[farmshop]

Vee out the crack and weld it. I would personally put a fish plate inside the channel with the ends cut at an angle

[smithdoor]

The good news about cracks is it crack again 👏 repeat work.
It is a engineering error keeps welders working.

FYI More engineering is thought and pray 🙏 it works. .Then let's save money cut back on steel more work for welders.

Dave

Just look at metal buildings well engineer. Just look at base plate.
Then custome building I have seen 2" base plate the metal building company used 1/2" plate.

Ever part of metal building manufactur is engineered
The custom building uses a outside engineer and not ever part was calculated we just guess. Good luck in a earthquake 😳 ok run fast

Hello,

I have this crack that I would like to weld. I know how to weld but lack experience to know the best way to weld this crack.

Do I Weld all sides of it? Do I Need to fish plate it? If so where

This pictures are not the greatest. I took them in a rush and didn’t check them.

This crack is a few inches from where the box pivot pin is installed. The pictures went sideways when uploading don’t know how to fix this!!

thanks in advance

[BillE.Dee]

hello Island and welcome. I can't tell which part is which in the pic, but it looks like the crack is headin to parts unknown. Try to find the end and drill a stop hole in it, vee it out, weld it, grind the weld flush then fish plate it. My opinion anyway. No such thing as a 15 minute weld job.

[Leogl]

I would grind it out get a good v joint jack both sides of crack up till frame is straight weld it with low hydrogen put fishplates in on both frame rails in the same spot weld them in let jacks down

[IslandHD]

hello Island and welcome. I can't tell which part is which in the pic, but it looks like the crack is headin to parts unknown. Try to find the end and drill a stop hole in it, vee it out, weld it, grind the weld flush then fish plate it. My opinion anyway. No such thing as a 15 minute weld job.

here I added some better pictures

[IslandHD]

So I should weld the crack on all sides up the sides, and the flange area. Then do I just fish plate the web(side) do I do anything to the web? And do I do this on both sides?

[whtbaron]

So, if I'm looking at this right side up, you aren't actually welding a crack in the frame of the truck, the crack is in the bottom rail of the box where it pivots at the back, right?

[IslandHD]

That is correct not on the truck frame. Box rail/frame

[IslandHD]

So, if I'm looking at this right side up, you aren't actually welding a crack in the frame of the truck, the crack is in the bottom rail of the box where it pivots at the back, right?

correct

[Woznme]

You might need to clean that up and use some dye penetrant to find the real end of the crack.

[farmersammm]

With channel, there's a "good" side, and a "bad" side. The good side is where you can access it with a grinder.........the bad side is where you can't access it with the grinder.

V the crack from the good side. Just deep enough to leave a bit of a land to keep your dimensions intact. A full V will cause the thing to contract too much when you weld it. This is a place for a full penetration weld.............but not from the get go. It has to be done in stages.

Now that you've V'd the good side, grab some 7018 and put a nice surface bead on the bad side. This weld will stay there when you're done, and doesn't need to be ground down.

After you've welded, you'll see where the slag shows through on the good side you V'd. Use your grinder, with either a narrow wheel, or a razor wheel, and grind down to the bottom of your V until you reach clean metal. This will be the backside of the surface bead you placed on the backside. You've now reached full penetration.

Then, just fill the V from the good side, and you're good to go. A fish plate is optional. If the welding is done right, you shouldn't need one.

This was done back in 2017 when I could still see.



The bevel is ground leaving some material to keep the original dimensions when the crack was forced closed

A weld was placed on the backside. You can see the bit of dark line. That's the slag from the backside weld. The bevel is then made deeper to hit that slag line, and then deepened to get to clean metal (your weld you placed on the backside). At this point, you know you have full penetration.

Then simply fill the bevel, and you gotta full pen weld. I like 7018, but any good Charpy rated wire will also be fine.

So, anyways.........this is the blueprint for getting it done in a good manner. The work I'm putting out these days isn't up to the stuff I could do when the eyes were still functioning right, so don't take recent posts as evidence of the type of stuff I do. Things have changed.............but the principles haven't.

[farmersammm]

The thing about fishplates is................they stiffen an area, and transfer the stress to the ends of the fishplate. We all know that. Sometimes that isn't an optimal thing.

In your case, it appears that a flange failure caused the crack in the web. There's no real gain in reinforcing the web, when it's been a failure in the flange that caused the problem.

The stress at the pivot caused a fatigue crack in the flange, and it will probably do so in the future. The base of the pivot probably should have been longer to spread the stress out over a longer portion of the channel. Or, a cover plate should have been welded to the flange where the pivot attached.

[farmersammm]

I'm assuming you're working with channel because I can't see a flange through the crack. Beam would be the same fix though, just a bit more of a PITA if you have to use a burr to V it.

[whtbaron]

I agree with Sam's idea of a repair, but I would still fishplate it on at least one side to spread the force of the hinge over a longer length of the beam. Trying to fishplate both sides might just put excess heat into it. Somebody has been loading that hoist over it's rated capacity ( I'm sure that doesn't surprise you) and if they continue to do so, the other side will likely crack too. Inspect it closely. Check around where the cylinder (or cylinders) push against the beams as well.

[farmersammm]

I agree with Sam's idea of a repair, but I would still fishplate it on at least one side to spread the force of the hinge over a longer length of the beam. Trying to fishplate both sides might just put excess heat into it. Somebody has been loading that hoist over it's rated capacity ( I'm sure that doesn't surprise you) and if they continue to do so, the other side will likely crack too. Inspect it closely. Check around where the cylinder (or cylinders) push against the beams as well.

Oh, I suppose

[Leogl]

Well I am going to guess but you have little or no experience welding so don’t do something you cant handle having fixed a lot of these don’t make it to tough on the next guy to fix trust me if you don’t know how to fix a truck frame DONT !

[shortfuse]

You don't know sammm..............

[whtbaron]

Well I am going to guess but you have little or no experience welding so don’t do something you cant handle having fixed a lot of these don’t make it to tough on the next guy to fix trust me if you don’t know how to fix a truck frame DONT !

Sam wasn't the OP. The OP did state that he is an experienced welder, he's just in new territory. He isn't welding a truck frame, it's the beam on the hoist that sits above the frame. I've seen them welded before, and it isn't as sketchy as welding on frame rails.