Cracked boom repair

td25c · Apr 7, 2019

No bigger then that fracture is I would keep using the machine & keep an eye on it .

Stuff cracks over time . If the fracture keeps growing then it's time to do something with it .

Welding from the outside is the quickest & most efficient on a small fracture like that .

lumberjack · Apr 7, 2019

I have no experience with excavator booms, but I welded up several cracks on the boom/superstructure of a loader on my grapple truck as well as other variously unimpressive repairs. If the mfg isn’t helpful with a procedure, my initial thought would be to use the plasma to gouge the crack to good metal end to end, glue it shut, and keep an eye on it.

Nige · Apr 8, 2019

td25c said:
That's what we would do .
Gouge it out & weld it back. Keep an eye on the repair .
As small as that fracture is I aint gonna get to exited over it .

Regarding structural cracks experience has taught me that, like the iceberg that sank the Titanic, it's the 90% you can't see that you should be worried about.
From the outside lovely-looking repairs have been known to come unzipped very rapidly and very catastrophically with no prior warning - see the example below. That's why I'd always cut into the structure and repair from the inside to the outside. YMMV.

Delmer · Apr 8, 2019

If I found a crack like that on something I own, most likely I wouldn't even grind it out before welding. I live in a different equipment universe than Nige, he looks after a fleet of big new stuff that gets run 24/7. If I bought an excavator (don't have one and probably won't) it would do a few hundred hours in the first few years and then probably sit, so that crack wouldn't be an issue. TD25C does a lot more work, but in the scheme of things is closer to my perspective than Nige.

I think a 2013 is going to be expected to work for a while yet so Nige's suggestions are good. Also, a crack that shows up after 30+ years isn't growing as fast, so isn't as likely to turn into the picture above.

Nige · Apr 8, 2019

Good points from Delmer. It's also worth pointing out that our equipment probably works more hours in a year than most construction machines would do from new to disposal if they were owned by a contractor. When the life target for a machine might be approaching the 100,000-hour mark then it's a good incentive to look after structures the best you can. At the end of the day the condition of the structures is what determines whether the machine gets sent to the boneyard prematurely or keeps working. Everything else is bolt-on.

John C. · Apr 8, 2019

My problem with a quick fix on this boom is the location of the crack. It's at the bottom end of the boom and it's started in a corner, ran horizontally to the vertical joint and is now running down the edge of what looks like an interior backing plate. That is exactly the kind of crack that can turn into a catastrophic failure. A crack in the middle or on the ends I've welded up lots of times. I've never seen or repaired a crack in that location. Booms are not supposed to fail throughout the life time of the machine. That is definitely a defect in engineering, material or workmanship and you should give the dealer and manufacturer the time to respond.

td25c · Apr 8, 2019

Nige said:
Regarding structural cracks experience has taught me that, like the iceberg that sank the Titanic, it's the 90% you can't see that you should be worried about.
]

Good Lord Nige !

That's what happens when you let my Old Man run the equipment .

Don't let him anywhere near the controls again . LOL!

Point taken Mate .

I still go from experience & cost effective solutions .

I aint gonna open up a boom for a small crack like this .

CA3AFCD4-3129-4383-ADBB-C32042B9030A[1].jpeg

That would be like a contractor showing up to fix a crack in the basement on the house & cutting a hole though the roof .

No !

funwithfuel · Apr 8, 2019

If men will be positioned beneath the boom stick or bucket that boom needs to be repaired properly from the inside and the outside. A surface Weld and possibly gouging it out might hold might look good might supported for the rest of its life however if somebody were to walk under it and the boom fail who is going to be sued

td25c · Apr 8, 2019

funwithfuel said:
if somebody were to walk under it and the boom fail who is going to be sued

It's an excavator . Stay the hell away form the boom & bucket !

They made for digging .

old-iron-habit · Apr 8, 2019

funwithfuel said:
If you follow td25c's suggestion, which is the quickest, at least drill both ends of the crack to prevent migrating. Still think it best to open it up and weld the inside as well. Especially if you're doing pipe work or anything where men may be under boom n bucket at any time.

It just might be a good time to remind everyone that it is never alright to ever be under a load or a bucket. Its just a matter of time otherwise until someone pays the price.

big ben · Apr 8, 2019

My bet is the inside baffle has broken...you can gouge and reweld but it will crack again. Going to have to open it up, replace the baffle broken in 4 and reweld

big ben · Apr 9, 2019

Here is a pic of a baffle in a boom showing cracks similar to yours

Welder Dave · Apr 9, 2019

It would be great if you could find out what's inside the boom and where from the factory. The location of the crack in relation to the weld makes me think if could be from lack of sufficient preheat prior to welding. The crack isn't right next to the weld but it is a high heat weld and the crack is in the heat affected zone. Heavy sections that cool too quickly can cause HAZ cracks as well. A harder or higher carbon steel would also crack easier. I'd try to get the dealer involved and get some tests done on the steel. It is kind of an odd place for a crack on a low hour machine.

Nige · Apr 9, 2019

big ben said:
My bet is the inside baffle has broken...you can gouge and reweld but it will crack again. Going to have to open it up, replace the baffle broken in 4 and reweld

That's what happened to the stick I posted photos of back on Page 1. It could have been welded on the outside but that would not have fixed it. Thankfully the decision was made to open it up.
Guess what..? - back to the "iceberg syndrome" of what you can't see - again.

Bls repair · Apr 9, 2019

X-ray ,ultrasound the boom?

wornout wrench · Apr 9, 2019

Back in the 90's, Hitachi had an issue with some of the booms on their EX400 series. When they showed up to repair he had a group of drawings that showed where all the baffles were inside the boom complete with explanations of where the cracks could be.

So if your crack was here, this baffle had let go inside. It would then give a set of measurements of where to cut, how big of a hole to cut and the welding procedure.

It was interesting because you had to be pretty exact to determine where the crack was. Hitachi wanted you to cut in on this side of the baffle if the crack was here, that side of the baffle if the crack was there.

Felt sorry for the poor welder. He had to cut a circular hole that was just big enough for his one arm and enough of his head so he could see.

Once fixed, that was the end of the problem. He left the drawings behind so that if I had another crack we could tell if it was a broken baffle again.

Having said that, I have worked for companies that would chase boom cracks for years without ever opening the boom up, gouge and fill, gouge and fill

Nige · Apr 9, 2019

Amen to that ...........

Welder Dave · Apr 9, 2019

wornout wrench said:
Felt sorry for the poor welder. He had to cut a circular hole that was just big enough for his one arm and enough of his head so he could see.

Really??? Nobody EVER feels sorry the welder. It's more like it's the welders fault it broke in the first place and they have to bend and contort themselves anyway they can to fix it yesterday!

Bls repair · Apr 9, 2019

You cut it out ,why do I have to pay you to put it back

td25c · Apr 9, 2019

Hey ….. The way I look at it is " it aint my fault " that the fracture started to begin with .

I did not build or design this thing but customer wants it taken care of .

Do my best to deal with it & move on to the next task .

It's an excavator boom ……

We aint sending it to the moon …. LOL!

Cracked boom repair

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