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Stainless Steel Square 1/2" U Bolt Failure
6

Stainless Steel Square 1/2" U Bolt Failure

Stainless Steel Square 1/2" U Bolt Failure

(OP)
Looking for some insight on a failure of a Stainless Steel Square 1/2" U bolt. 3 1/2" legs and 5 3?4" wide inside. Rated for 5000 pounds capacity with a 20% over factor so 7000 pounds.

Background: this is one of 4 U bolts used on the lifting bunks of a boat hoist that hold up the boat on the lifting frame. Overall capacity of the lift is 4000 pounds ( these U bolts are normally used on a 5000 pound capacity rated boat lift) Boat wet weight is 3500 pounds. The U bolts in questions were brand new last year, used for 5 months on a boat lift in fresh water. The U boats and bunks were removed from one lift to install on another lift this year. On the second day of the boat being loaded on the lift the failure occurred on one of the four U bolts about 45 minutes after the boat was put on the lift.

Do you think the tooling mark creases or cuts into the inside corners of the U bolt contributed to the failure? ( since the failure point was at or very near these tooling marks)

Would the angle of the single U bolt when mounted, with the upper and lower portions not being vertically aligned with each other, have any affect on the load contributing to the failure?

Brand new U bolt


One of the three remaining one year old U bolts


Failed U bolt, inside of bend area


Failed U bolt, outside of bend area


Angle of the lifting bunks, U bolts were offset at an angle about 3 1/2" off center due to 5" cross-member tube and 5 7/8" inside U bolt width.

RE: Stainless Steel Square 1/2" U Bolt Failure

affirmative, some testing is required, mfg defect

RE: Stainless Steel Square 1/2" U Bolt Failure

What alloy, 304?
I'll wager that if you use a strong magnet you find the area near the fracture fairly ferromagnetic.
The notch from the forming and the lower ductility from the cold work is not a good combination.
Moving them likely changed the stresses in them (twisted differently or not quite tight enough) and lead to failure.
Hard to tell from your photo but it does not look any deformation adjacent to the fracture.
This really points to Environmentally Assisted Cracking of some sort to me.
Where in the country is this?

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

RE: Stainless Steel Square 1/2" U Bolt Failure

Just a couple of observations ....

1) Was your failed U-Bolt Hardware made in China ?

2) Is the bolt configuration available in larger diameters than 1/2" ?

3) Is there any way you could come up with a weight and test your own purchased hardware ?

4) I do not believe that the age of the hardware or the environmental conditions have anything to do with the failure

Unfortunately, square u-bolts are a bit of a mongrel configuration in the rigging hardware world. There seems to be no standard way to load, configure and test these things. The manufacturer's sales information on maximum loads seems to be just estimates, IMHO ....

ASME has dimensional standards for "round bend" u-bolts, but not square .... as far as I can tell

http://boltingspecialist.com/dimensions/asme-b18.3...

The Portland bolt people offer some guidelines on the minimum required bend diameter of a properly made square u-bolt. You failed U-bolt does not seem to meet these minimum requirements.

https://www.portlandbolt.com/technical/faqs/guidel...

MJCronin
Sr. Process Engineer

RE: Stainless Steel Square 1/2" U Bolt Failure

Note, in the US the lifting device shall have a safety factor from 2-4. If the bolt failed at weight below the rated capacity, it could indicate there was problem during manufacturing.

RE: Stainless Steel Square 1/2" U Bolt Failure

(OP)
Thank you for all your comments and assessments. Besides the $ 1,000.00 plus damage to my one year old boat, I am more concerned with preventing this type of failure for anyone else that may purchase these replacement U bolts from a boat lift parts store like I did. My boat damage can be repaired but had that U bolt failed while lifting the boat up and had someone been to close to or standing on or leaning on the lift during that time it could have been a life changing injury or death!!

I do not know the actual number of the Stainless alloy, trying to find out. Is there a easy way to find that out?

Yes, they were made in China, as confirmed by the US lift manufacturer prior to clamming up and giving me a standard lawyer statement saying they are not liable for use of their component products on any other brands of boat lifts beside their boat lifts. Which is the main problem as I was sold these replacement U bolts by one of their local boat lift distributors to use specifically on a different brand of boat lift.

Yes, there is ferromagnetism when a strong magnet is applied to the fractured area. The outer portion of the failed U Bolt does show some Ferromagnetism but to a much lessor degree than on the inside. On the brand new U bolt pictured the same magnet will not stick to any of the main body of the U bolt but will stick in the crease on the inside of the bend and to the outside of the bend and on the threaded areas.

I do not see any deformations adjacent to the fracture. There are some radial striations in the outer portion of the bends that look like stretching of the metal. I suppose this is normal as that is what is happening to get the bend to form.

This is in southern Michigan in a fresh water in-land lake. Hoist is removed from the water in the winter to avoid damage by ice.

RE: Stainless Steel Square 1/2" U Bolt Failure

You would be better off having a cross bar made with two holes in it, and then using straight bolts.
The cross bar could even have 'shoulders' on it so that it would fit well up against the main structure.
I wouldn't use bolts made this way, it is asking for issues.
There is no easy way to test for the alloy, unless you know someone that has access to one of the hand held XRF analysis guns at work.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

RE: Stainless Steel Square 1/2" U Bolt Failure

hmmm this should be turned in to the governing board to address this safety issue.

shop a round with a more reputable dealer with certifications for the product.

RE: Stainless Steel Square 1/2" U Bolt Failure

Report to consumer protection agency of the state where the purchase was made. Thought you might not be able to get your money back, the agency might investigate, and sanction against the product.

RE: Stainless Steel Square 1/2" U Bolt Failure

Haven't any of you commenters taken a course in strength of materials where stress concentration is discussed? Obviously that sharp interior corner has high stress concentration there. It is not uniformly distributed. You could duplicate this by taking two "U" bolts, one with a smooth corner and the other with that corner containing a notch. Find the cross sectional area of each and compute stress. This is simple text book stuff. Even the unnotched corner looks too sharp.

Do a simple Internet check using "notch radius" and a whole lot of info is out there.

More edit: I'd go to the person that created the system for lifting. The bending of the member and the darned dumb notch is crazy construction. Look at a structural member horizontal under the boat and eye bolts of similar to transfer the load at that lower corner of the bracket to he vertical position. No bending stuff please. With care by welding that corner it may work also.

RE: Stainless Steel Square 1/2" U Bolt Failure

OG, In this case it is even worse. They have a bad geometry, and they have bad material properties from the excessive forming.
Definitely needs to be done differently.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

RE: Stainless Steel Square 1/2" U Bolt Failure

It looks like the angled installation puts a twist load on the ubolt. There would be combined twisting and bending at the bend. The nuts may not have been tightened enough to create enough friction force to carry any the loads. I don't think ubolts carry side loads very well. Their ratings are tensile loads.

Ted

RE: Stainless Steel Square 1/2" U Bolt Failure

@hydtools Yes probably needs eyebolts instead or a bracket bolted to hold the
The weight. No side load.

RE: Stainless Steel Square 1/2" U Bolt Failure

Hi mtgski

All the things that you mention could have contributed to the failure but the one thing that hasn’t been mentioned yet is the ‘u’bolts have been removed and then reused this could be quite a big no no, reusing fasteners of any type can be disastrous particularly if there is no records of what they were preloaded too. So my question how and what preload were those ‘u’ bolts loaded too.

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein

RE: Stainless Steel Square 1/2" U Bolt Failure

mtgski

"Do you think the tooling mark creases or cuts into the inside corners of the U bolt contributed to the failure? ( since the failure point was at or very near these tooling marks)."

Yes - It looks to me like someone is trying to get these square bolts to fit exactly over a square beam / channel / box section. So if the inside edge to inside edge of the U bolt was say 4 inches, then it was designed to fit over a 4 inch wide beam/flange with absolutely minimal clearance. Otherwise any gap between the edge of the beam and the corner you will get a significant bending moment on the inside edge and truly horrendous stress concentrations there. Also as you can see from the failed sections the diameter of the bar is reduced where this notch has appeared.

"Would the angle of the single U bolt when mounted, with the upper and lower portions not being vertically aligned with each other, have any affect on the load contributing to the failure?"

Also yes but that single picture is unclear as to how the boat "lifting bunks?" are actually attached to the frame and how , if at all, these are tightened. Needs more pictures or a drawing / side on view. Are these bunks designed to slide to fit the particualr boat? Is there any tension on the bolt before the boat is lifted out of the water? The existing bolts seem to have scrape marks on them?

I diodn't quite understand this bit "Angle of the lifting bunks, U bolts were offset at an angle about 3 1/2" off center due to 5" cross-member tube and 5 7/8" inside U bolt width. I didn't quite understand this bit " Can you explain / draw what you mean?"

Where is the load path?

Does the bolt go through the holes visible in the lifting bunk to adjust height?

Even if not the load would appear to be concentrated on one side only so I'm far from surprised this broke. The moment from only one side being loaded will create bending forces in the bolt and result in virtually all the weight of the boat being taken in one corner of the bolt. Poor design IMHO. Better to have something in shear than tension like this. Did it look something like this in section?

[EDIT] - NOw incorrect picture - close but see more info from the OP further down the post]



Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Stainless Steel Square 1/2" U Bolt Failure

OK, i think I understand things better now ....

My suggestions:

1) Buy slightly larger diameter quality SS bolts (5/8") without the corner notch and replace the old bolts OR

2) Use TWO 1/2" bolts side-by-side to support your beam and redesign the hardware OR

3) Redesign the support structure where the moment is taken out of the square u-bolt by either a brace or use of two robust flat plates (sandwich) and interconnecting bolts.

My opinions only ...

https://www.sdtrucksprings.com/index.php?main_page...

MJCronin
Sr. Process Engineer

RE: Stainless Steel Square 1/2" U Bolt Failure

In my opinion, the v notch is there to relief stress concentration by design. But I don't know how effective it is. Isn't there any process method can make smooth u-bolt?

RE: Stainless Steel Square 1/2" U Bolt Failure

Quote (retired13)

the v notch is there to relief stress concentration by design

Care to explain this one a bit more?

Any bending moment on that 90 degree angle end will result in high stress concentrations at the root of the V notch. Not to mention reduced diameter of the rod or decrease in torsional strength.

I would say it's not in the slightest bit effective.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Stainless Steel Square 1/2" U Bolt Failure

Tilmore Farm Products uses these bolts in their cross tube clamps. The bolts appear identical with the notch and all. Am I morally required to advise them of our findings?

RE: Stainless Steel Square 1/2" U Bolt Failure

In an application that has no twist or bend to it these are just a little bad, but anything other than a straight pull and these are not to be considered usable.
And never use them anywhere it would be possible to have any exposure to salt.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

RE: Stainless Steel Square 1/2" U Bolt Failure

2
I agree with LittleInch ... The V notches are a defect and not a "product enhancement"

Review the information on the link that I posted above by Portland Bolt.... They take extreme measures to ensure that there is a minimum required diameter at the corners of their products.

The notches are there because some shop in China can more quickly get more bolts out the door if they bend these against a sharp corner. There are no quality standards and they are being paid by the ton ....

Again, square u-bolts are a bit of a mongrel fitting that do not really follow any ASME, ANSI or MSS dimensional, product or quality standards.

MJCronin
Sr. Process Engineer

RE: Stainless Steel Square 1/2" U Bolt Failure

LittleInch,

In my opinion, the purpose of the notch is two fold - 1) easier to bend, 2) the stresses in the remaining area tends to be more smooth.

Stress concentrated at the inner face due to necking.


RE: Stainless Steel Square 1/2" U Bolt Failure

we can all agree that this the wrong tooling to use.
should be an Ibolt or bracket, to prevent moment, that is the main reason it failed.

RE: Stainless Steel Square 1/2" U Bolt Failure

Hi

I think the bend in the ‘u’ bolt is detrimental, with such a sharp bend on the inside it’s likely the outer diameter of the bend would have developed cracks which would reduce the bolts capacity to carry load.

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein

RE: Stainless Steel Square 1/2" U Bolt Failure

When bending round bar, a specified inner radius must be maintained, and the force shall be applied gradually. Bend bolts/bars serve many functions, important thing is to follow manufacture's recommendations in bolt selection and use, pertaining the application. Everything will fail, but what is the percentage and frequency need to be addressed before scrap an idea.

RE: Stainless Steel Square 1/2" U Bolt Failure

Hi retired13

Looking on this site it recommends inside bend radi of a rectangular ‘u’ bolt should be at least twice the diameter of the bar, looking at those pictures here those radi are nothing like 2x dia.

https://www.portlandbolt.com/technical/faqs/guidel...

However the bend radius is only one part of the problem because as already stated in other posts we have suitability for the job, loading on the bolts and the bolts have been re-used so they might of been over stressed the first time they were used which really means they should have been re-placed.

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein

RE: Stainless Steel Square 1/2" U Bolt Failure

desertfox,

I think OSHA only requires inspection on the lifting device by a competent person on each use. The question here is who is competent enough to notice and pick out defects. Un-trained eyes usually won't, so replace after each use maybe is the desirable solution.

RE: Stainless Steel Square 1/2" U Bolt Failure

Hi

Normally lifting devices are tested with a test load, design of lifting rigs are usually to a code of practice so by the time a load test is carried out the design of the lifting rig has under gone various inspections of material certificates, NDT testing Etc, some crackS, flaws Etc cannot be detected by the naked eye that’s why it’s tested but in this case some of the defects are noticeable to the naked eye namely the atrocious bends on the ‘u’ bolts, in addition there seems to be no evidence as yet of any paper work relating to either the design or manufacture of this rig. It would be interesting to know whether the boat repair is being paid for by the insurer cause if I was the insurance agent I would be asking lots of questions, worst still if someone had been killed or badly injured

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein

RE: Stainless Steel Square 1/2" U Bolt Failure

Quote (MJCronin)

1) Was your failed U-Bolt Hardware made in China ?

I think you nailed the ultimate root cause right there.

If I wanted to be philosophical about this I wouldn't say this was a manufacturing defect. The entire idea was so flawed that it can only be described as amateur. They were trying to bend a bar over what was essentially a chisel, instead of a smooth die with an actual radius. There's a fair chance it was cracked when it left the basement, er, factory.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

RE: Stainless Steel Square 1/2" U Bolt Failure

These are bent in a press brake, I've seen the exact same notch in rebar as well. I always wondered why the rebar didn't break, so hey, it must've worked, right?

RE: Stainless Steel Square 1/2" U Bolt Failure

(OP)
LittleInch

Also yes but that single picture is unclear as to how the boat "lifting bunks?" are actually attached to the frame and how , if at all, these are tightened. Needs more pictures or a drawing / side on view. Are these bunks designed to slide to fit the particualr boat? Is there any tension on the bolt before the boat is lifted out of the water? The existing bolts seem to have scrape marks on them?

I diodn't quite understand this bit "Angle of the lifting bunks, U bolts were offset at an angle about 3 1/2" off center due to 5" cross-member tube and 5 7/8" inside U bolt width. I didn't quite understand this bit " Can you explain / draw what you mean?"

Where is the load path?

Does the bolt go through the holes visible in the lifting bunk to adjust height?

Answers Yes, the U bolt goes over the rectangle cross beam and into the holes of the adjustable height bracket. The bunks are adjusted to fit the hull of the boat and then tighten down solid. They do not ( or should not) move once mounted and tightened down to the rectangle cross beam.

By the "Angle of the lifting bunks" I meant that the top of the U bolt is at an angle or offset from the bottom of the U bolt. Since the U bolt is wider than the rectangle cross beam, the bottom of the U bolt does not contact the bottom of the rectangle cross beam unless it is slanted at an angle until the bottom portion of the U bolt contacts the bottom of the rectangle cross beam. Most boat lift bunks mounting brackets are mounted at a slight angle

I believe the load path would be on the shank of the U bolt that is contacting the top and bottom of the cross beam they are bolted to.

Let me know if these photos help or not:





RE: Stainless Steel Square 1/2" U Bolt Failure

Yes that helps hugely - would have been nice at the start....

Anyway - how tight was that U bolt? Or did it vary? I can see that the angle is important to match the boat size, but must have been tightened to stop it slipping sideways? Th scrape marks on the other bolts indicates it has been moved sideways quite a bit.

You can imagine someone really giving that nut some serious torque to clamp the U bolt and lifting frames. Do it too tight on the top angle first and you will get a world of pain at that elbow.

Then unless you get it really well centred you have a moment on the U bolt trying to twist it off the frame.

There is also the distinct possibility that the top of the U bolt is not on the top of the frame at the start, but once the weight increases as you lift the boat out of the water, the frame could easily slip down a few mm but now with shock loading or equally moves under load as the boat lifting pads move under load

At best you get all of the shear stress going through the top angle of the bolt and virtually none on the bottom leg.

Then it gets loosened, moved for the next boat, tightened up again etc etc?? This bolt I would guess wouldn't last 100 such cycles, maybe as low as 20.

Whatever load these bolts were tested to (??) it wouldn't have been in that direction. I can only assume the load is based on a sling along the top bar of the U using BOTH shafts and then lifting something upwards.

This use is totally different so your load strength is meaningless.

In short this is a pretty terrible "design" and to avoid a second or third collapse you really need to re design the connection between the bunks and the frame. IMHO.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Stainless Steel Square 1/2" U Bolt Failure

(OP)
LittleInch

The U bolts & mounting brackets were loosely assembled over the rectangle cross beam, then moved into the desired position, with the top of the U bolt resting on the top of the rectangle cross beam. At that point, the top mounting nuts were very slightly tightened just to the point of a little tension so they would not move so the bottom of the U bolt could be re-positioned at the angle to have contact with the bottom of the rectangle cross beam. Then the bottom nut of the U bolt was very slightly tightened just to the point of a little tension so they would not move. Then both the top and bottom nuts were tightened in an alternating pattern, a few strokes on top then a few strokes on the bottom until the U bolts were tight by hand with the use of a 1/2" drive ratchet wrench with a 3/4" socket. However, no torque wrench was used so the amount of tension on each U bolt nut probably had some variance to the amount of tension.

The scratches you see on the U bolts are not into the metal of the U bolt but actually a "growth" of a hard water type deposit onto the metal surface that easily flakes or chips off with your finger nail with no damage to the metal of the U bolt. The "scrapes" of that growth could have happened during the removal process and/or repositioning during remounting as you can see only a little on the failed U bolt sections. But you may be correct that there is the possibility that the mounting could slip or compress even a couple of mm during the boat lifting.

The U bolt tightening cycle were only cycled two times, tightened once during original install last year and then again this year for the re-install on the different hoist.

I am planning to change the mounting hardware and use normal bolts and a backing plate with the adjustable mounting bar. Should I use grade 8 or grade 5 bolts for extra insurance that I do not have an similar issue again?

RE: Stainless Steel Square 1/2" U Bolt Failure

Hi mtgski

Therein lies the problem in that you have no idea what tension is in those U bolts and even if you replace them with conventional bolts you might encounter the same problem, someone needs to go through the design of that rig, we can’t say it will be okay using this grade or that grade.
Looking at the last picture you posted I would say that the angled arms pointing downwards need to sit on top of that channel section and that way the load path utilises the full channel depth and gives a stiffer joint, the design at present relays totally on the u bolts to transfer the load in shear, if I understand your new proposal Correctly the load path will be no different.

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein

RE: Stainless Steel Square 1/2" U Bolt Failure

Drill out the holes and go with NEW 5/8" SS square U-bolts...Use a locking method on the nuts

Stay away from Chinese U-bolts with sharp notches.....

MJCronin
Sr. Process Engineer

RE: Stainless Steel Square 1/2" U Bolt Failure

Hate to ask that, but how do you verify a parts wasn't made in China? Does the seller provide certificate of origin?

RE: Stainless Steel Square 1/2" U Bolt Failure

I did some more research. It seems the notches may be to "weaken" the bar in just the right locations to get the leg bars at the desired spacing. Similar to the notches sometimes seen at the edges of sheet metal to make sure the metal bends in the right place.
It is "assumed" that the threads define the load limit.

RE: Stainless Steel Square 1/2" U Bolt Failure

Quote (retired13)

Hate to ask that, but how do you verify a parts wasn't made in China? Does the seller provide certificate of origin?

These days that is the working assumption, unless stated otherwise.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

RE: Stainless Steel Square 1/2" U Bolt Failure

(OP)
retire13

The owner of the company of the brand of lift that these u bolts are made for verified that he has them made in China.

RE: Stainless Steel Square 1/2" U Bolt Failure

That notch is a very intentional part of the bending process. You could not get such a sharp bend without it, without tearing occurring on the tensile side of the bend. The overall design the of the boat lift may be flawed, or less than perfect, but that is the way square bends are made.

The whole boat lift is obviously not terribly robust. It is designed to be affordable. Its purpose is to lift a boat slightly out of the water while at dock to reduce maintenance. It is not for overhead lifting. It uses a hand wheel to lift the boat with cables. Most of the lifts I have seen use floats that are filled with air from a blower on the dock. Those have cradles as well that have to be adjusted to each boat hull.

RE: Stainless Steel Square 1/2" U Bolt Failure

Compositepro,

1/2" solid bar is plenty of material to make a robust U-bolt for 5000 pounds rated capacity. That is unless it has been severely compromised by the manufacturing process. Ductility has been exhausted in the material near the sharp notch in this example, and as I said earlier, was possibly even cracked before it was installed.

Carbon steel with suitable coating protection would not have been a bad option here.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

RE: Stainless Steel Square 1/2" U Bolt Failure

mtgski,

Thanks for your feed back. Sadly I was wondering whether there is commercial bolt produced in the US, the percentage, and price.

RE: Stainless Steel Square 1/2" U Bolt Failure

retired13,

Yes there are many US bolt suppliers which manufacture their bolts in the USA.

Two that come to mind are Portland Bolt in Portland, OR and Unytite in Peru, IL. I do not work for either company. Both are good companies to work with.

Jim H

RE: Stainless Steel Square 1/2" U Bolt Failure

Yeah, I forgot Portland Bolt.. Thanks.

RE: Stainless Steel Square 1/2" U Bolt Failure

This is what I would suggest. Anything else including the U bolt puts a whole lot of unknown tension and bending stress on the bolt / U bolt.

Or make your upright out of a pole and use a normal U bolt...

You may just have had a bolt which was particularly bad, but the design isn't great and the bigger diameter you can make your bolt the bigger I would say.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Stainless Steel Square 1/2" U Bolt Failure

If you use the u-bolts the other way around, would there be less mechanical advantage to cause bending/twisting failure at the bend? Insert them through the strut and use a tie plate or short piece of strut material under the nuts.

Ted

RE: Stainless Steel Square 1/2" U Bolt Failure

(OP)
Thanks for all the observations and suggestions. I am planning to go the route similar to what LittleInch diagrammed with 9/16" or 5/8" grade 8 coated regular bolts with a backing plate. But I still plan to pursue contacting a state regulatory agency to get those inferior 1/2" SS U bolts pulled from the boat lift supply stores so no one else goes through what I have!! Thanks again.

RE: Stainless Steel Square 1/2" U Bolt Failure

Good for you mtgski

RE: Stainless Steel Square 1/2" U Bolt Failure

Still think a two pronged support is better but good luck with the bolt idea. Send us a photo when you've done it, we love seeing results even 3 months later.

The notch is a bad idea when that notch is exposed to forces it wasn't expecting. Anything other than a direct pull on both shanks could result in failure.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Stainless Steel Square 1/2" U Bolt Failure

An observation by OG. How's come China got in here anyhow when the design and use had nothing to do with where it came from. My bet if that U-bolt came from Germany no one would bring it up, yet same breakage likely.

RE: Stainless Steel Square 1/2" U Bolt Failure

OG, not really, because no one else would ship ones with sharp inside notches in them.
The structurals that these fit have rounded corners, so the inside of the U-bolt should be rounded as well.
Either these were designed for a special use and then just supplied as generic, or the tooling in FUBAR.
Leaf spring shackles and trailer axle mounts have used squarish u-bolts for ever and they do fine, without sharp inside corners and no angular loads.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

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