How to best weld stress/fatigue crack in end dump trailer.

Does the DOT allow you to weld the frame? From priory lurking in groups I thought that they did not allow welding to be done on a commercial frames. Now it is someone elses turn to answer your question.

Rusted,
Some manufacturers recommend against welding to their frames 'cause they're heat treated. The welding HAZ messes that up.
The DOT doesn't allow you to weld up a rim. And it would stand to reason they wouldn't let you weld a cast part such as a spring hanger, or a hardened part, such as a spring. All for very good reasons. But I don't think there's a problem with a trailer frame. After all it is a WELDED construction.
Vernon

snip
The biggest problem with scantily clad wimmin around here is they tend to get wicked flash burns and then you get no peace.
Can modern truck frames be field welded? In my limited contact with large rolling stock (mostly oggling the metalwork in passing on the highway) I remember seeing prominent signs of "Heat Treated Frame. Do Not attempt to weld or drill" on everything recent.
Bob

I ran into a very similar problem with a car-hauler. We were legally (DOT and Illinois Safety inspection passed) - we took a pair of 1/2" thick gussets, drilled holes in a 30deg off center pattern placed ten grade 8 but&bolts over the crack and got a 6 month extension as it was not on a load bearing principal of the structure when loaded with a 3200lb car with the steel sandwich in place. After the expiration we scrapped the trailer. If you look at DOT regs Part 16 for exceptions and corrective measures they might have part of your answer there. I know hydro formed frames and heat treated frames are never to be touched via torch. I really don't understand why this is but if someone could answer the root question of why no torch I'd like to know for my own knowledge.
All the best,
Rob
Fraser Competition Engines Chicago, IL.

Bob,
That's true. While others can opine with way more authority than I can, I've always presumed this trend is a result of using heat treatment to get the most strength from the stingiest amount of steel.
This trailer is OLD. And the trunnion frame (or whatever you call it) is welded to the frame. Replacement suspension systems are to be had. And THEY are welded to the frame.
And even if this trailer had a heat treated frame (which I cannot imagine in my wildest dreams) the crack in question is in the trunnion mount.
None of the above addresses whether the DOT prohibits this repair but I'll wager a bag of beer nuts to a bag of deer nuts that it's a non-issue in this case.
What do "beer nuts" and "deer nuts" have in common? They're both under a buck.
VT

I've welded on a few truck frames, it's no big deal as long as you're really staying on the ball. Don't drill the ends, grind it back and be sure you're getting weld all the way to the back of the piece. Don't stand the beads up real high as this will cause strain next to the weld.
I say don't fishplate it 'till you've had a chance to see it in action, it won't fail right away 'cause it hasn't yet and it's best to not fishplate if you can avoid it.
Another poster mentions welding on spring hangers.. they're great stuff to weld on, they're cast steel and very friendly. They're often welded onto the frame.
DOT issues.. I've welded on heavy trucks for major truck lines, if there were a DOT issue they'd probably have told me so- I'm pretty certain there isnt'.
John

John,
Thank you for your good advice. There's no substitute for hearin' from somebody who's "been dere and dunn datt".
Vernon

we weld trailer frames for repair at work every day , the weld shop just wrapped up re-sliding a
huge dovetail trailer today , the truck itself is a different matter , absolutely no welding on the frame
rails of any sort
all of the highway trucks use heat treated hydroformed rails made by one of two companies
the company guarantees the frame to the truck maker for so many miles , last I heard they have not
replaced one under warranty for over 25 years, we have a local peterbilt plant here and they treat
those frames like gold ,

I'd just vee out the crack about half way through with a grinding disc where I could reach and a carbide burr on a die grinder for the rest. Fill in the groove then put a proper fillet weld in. For the crack on the plate just fill the grove and leave a slight buildup in the region of 1/8 inch max. 1/16th would be ideal. Wire brush and paint. If the thing starts to crack again the paint will crack showing the problem appearing again. Of course fill all craters at the end of your beads and make sure you have no undercut. If you can, use E 7018. Some frame stock is made out of low alloy plate like Corten. For thicknesses of a quarter and under you don't need preheat in the summer but '18 is wise. Randy

I missed some important points that Randy picked up.. use 7018. And, as he said, if you put some good paint on it, you'll see trouble a lot sooner than if you don't.
It's really not a big deal, it's just "attention to detail" and being willing to judge your work objectively.
John

Randy,
Could you translate that to Texan?
Specifically, as to veeing out the crack, are you saying just grind it open and weld it shut? If so, then out with it man! ... Seriously, I think I understand "Fill in the groove" but I don't get "then put a proper fillet weld in". I thought a fillet weld was two pieces in a T... Yes?
If so, it just may be that you're talking about the trunnion to rail joint, and have detected a crack that I haven't noticed.
It would be just like you.... you.. you... you eagle eyed nit picker!
Yur texas buddy

Don't grind all the way through! Your weld metal is stronger plus the buildup should match strengths. I am thinking that the narrow stain down the length of that fillet weld is a crack.... I may be wrong but it sure looks suspicious. "Course water may do wierd things in Texas. Up here when it makes a straight line of rust that means something.
It's my Germanic heritage.... Deal with it :')))) The other half is Scot. I'm cheap too. As always you bring a smile to my face, Randy

Randy,
I looked back at the picture. And I'm sure you are correct. This po' ole trailer now has one leg in the scrap heap. The axles are shot. The suspension is toast. It's a popular brand (Reyco) but an obsolete model. Nobody has parts for it anymore.
Last week, when I got the news, I decided to look around for a dump truck. I went to a nearby town to look at one I saw in a "Thrifty Nickle", a sales tabloid that is also published on the internet.
The dump truck seemed not such a deal since it had a bad engine. But while I was there I was telling the guy about my worn out suspension. He exclaimed "Let me show you something" and we both drove back inside his yard (as in commercial).
He had some kind of equipment trailer back in the weeds. We tromped over to the rear of it and began kicking down the growth. Sure enough I got a glimpse of a nicely painted, rust free, single point suspension system.
I say a "glimpse" because within about 4 seconds this BASKETBALL of bees came boilin' up from under the trailer. The guy started running away and swatting. The basketball followed him. But the dribblers continued to keep me company.
About that time Alma walked up. I whispered "bees!". Turn around and slowly walk back to the van".
Meanwhile, "Steve" and "the basketball" got into HIS truck. We made it back to the van without a single sting. The guy only got hit about 3 times. So it coulda BEEn shitty.
As a result, I barely got a look at the trailer. I vaguely remember a large but well painted heavy frame missing any kind of deck. There's an excellent chance I'll buy it tomorrow for a kilobuck.
But he'll have to keep the bees.
V