Can I trust my new chainplates??

[SKI]

another one for McMaster-carr I just ordered from them today. If you have a 316 S.S. 3/8 bolt it CAN be snapped by standard rachets. As mentioned above get your hands on a torque wrench and torque them to 18-20 FT LB any more is just stretching the bolt and potentially cracking it. I prefer when working with stainless to use anti-seize on the threads as well. This will prevent gaulding together of the nut and bolt when torquing then just use a S.S. lock washer to keep them tight. With stainless the 1 grunt, 2 grunt, tight as possible torque scale usually dosen't work very well.

[Boatguy30]

I think anything with 316 actually stamped in it is BS. It's really disappointing the quality of materials being sold as 316L these days. Just ordered some SS Bar from Online Metals.com for some chainplates for a customer. Will be interesting to see what arrives. Likely whatever came from China last month. I plan to make all composite E-Glass chainplates for my cat.

Jeff

[Cavalier]

Originally Posted by Boatguy30

I think anything with 316 actually stamped in it is BS.

I reacted the same way when I read that. I've never seen 316L stamped into either plate or stock of real 316L - usually just the stock and/or heat number so you have full traceability back to the certs. Same with fasteners : the SS bolt/nut grades I've normally used in my career have rarely been called 316L and definitely wouldn't have that stamped in them.

Could there be a disparity between consumer fasteners and engineering fasteners I've never come across?

[Pauls]

#1. Scrap the bolts.

Understand that substandard fasterners are common and are a plague that has been around for a long time. Back in, I believe, the 80's the US Air Force scrapped something like $800 million worth of fasteners that they concluded could not be trusted.

The aircraft industry employs highly stressed fasteners. They have very specific and rigorous specs, for good reason.

Making high quality bolts is a sophisticated operation and there are a lot of ways to cut corners and produce a substandard product. For something this is genuinely stressed, anything to do with the rig, you want to buy from a thorougly reputable source that can tell you who the manufacturer is. For this appllication I wouldn't touch anything made in a third world country. Get something made in the US, Japan, or Europe.

And after you get good fasteners, install them right. If they don't fit the holes, then fix the holes.

[OrangeCrush]

I'm in full agreement about getting new fasteners, and besides I broke all the other ones anyway. I'll order my new fasteners from McMaster and I'll put them in without over tightening.

I guess that still leaves me a little unsure about the new chainplates. How should I go about researching their source/quality? I can ask the shop that made them for some sort of heat number or cert (as cavalier described). But if they are dismissive or give me a generic answer, will it be necessary to replace them just to make sure they're not from China?

I really appreciate all the help on this one!

Jack

[Wotname]

Originally Posted by OrangeCrush

Thanks for all the help so far, guys.

There was another problem with the bolts, which was that they didn't have quite enough threading on them, so even on the ones that didn't strip from the chain plate I ended up running out of thread before the bulkhead was getting much of a squeeze. This would have been reason enough to get different bolts, but when I found that the easiest way to get them out was to break them, I started getting nervous about all the new stainless.
..............

IMO, this is the most worrying aspect. The chainplates stay in place from the friction between the plate and the bulkhead as much as it does from the shear strength of the bolts. Maybe even more from the friction. The bolts primary function is to supply this compressive load.

[Pauls]

As Cavalier described, when the bar of stainless is made the manufacturer issues a certification. When metal is ordered, by an individual, shop, factory, etc it is an option to request certification. It usually costs a little extra, not much. If the cert is asked for it is shipped with the metal, and it certifies the alloy, condition, etc.

If the shop that made your chainplates got a cert they can show it to you. If not, you could ask them for the order date, company they bought from, etc, and contact that company. They might be able to give you traceability.

Here's my opinion - I wouldn't worry about the strength of the chainplate metal. The truth is that 316 is some of the weakest metal - by that I mean yield strength, available. It's very unlikely your chainplates are not strong enough.

316 is specified because it has good corrosion resistance. If you were given something other than 316 your chainplates will corrode more, they won't look as pretty unless you keep them up more. But they are probably fine as regards strength.

I wish you good luck with your project.

[Cavalier]

Originally Posted by Pauls

- I wouldn't worry about the strength of the chainplate metal. The truth is that 316 is some of the weakest metal - by that I mean yield strength, available. It's very unlikely your chainplates are not strong enough.

I'd tend to agree with this assessment - the original chainplates will be heavily over-engineered wrt utilization factor. They're not the type of item which the original design engineer would have heavily optimized to save material costs or weight. Get your fasteners from a reputable source and ensure they're sized correctly for the hole (to avoid excessive hole-pressure under shear) and bulkhead, don't over-torque them and you'll be golden!
If you're worried about them coming undone, use nyloc nuts w/washers.

[Anonymous7500]

Originally Posted by OrangeCrush

So, are we reaching a consensus that the new plates will be "good enough" if they are made from new 316 plate stock and polished smooth? I trust the steel shop and if they said it was 316 I'm confident that they're not being dishonest.

Thanks for the tip about McMaster-Carr. I guess what I'd be looking for is Grade 9 "Extreme strength" bolts? After a quick look at their site, it seems like these only come "fully threaded" so this may not be perfect for the bulkead connection. Is there another variety I'm not seeing?

Thanks a lot!

First, +1 McMaster-Carr.

Second, the "Grade 9" are not what you want. Look at the "Type 316 Stainless Steel Heavy Hex Head Bolts". By the way, they are available partially threaded.

Third, if you didn't request material certifications when you ordered the part they probably will not have them. If you "polished" the plates, any heat lot markings on the plates are gone. In other words, any certification that is produced will not be able to be verified to the material that you have.

Fourth, all stainless steel, that is purchased as a raw material, should go through a passivation process before being put into service. Without it the material will corrode. Plate and bar are raw materials.

Fifth, purchase a quality torque wrench and install according to manufacture's specifications. Take a look at some military or nuclear assembly instructions. They never say "Do not under tighten", but they often say "Do not over tighten".

[Cavalier]

Originally Posted by Anonymous7500

Take a look at some military or nuclear assembly instructions. They never say "Do not under tighten", but they often say "Do not over tighten".

Actually a torque-range is always specified for load-bearing or critical fastenings, but I agree with your "do not over tighten" point!

[Cheechako]

No not grade 9 bolts! You wont find them in 316 any way. Just good 316 or 304 bolts are fine.

[cdennyb]

In order to properly torque the fastener I believe most if not all reputable mfgs specify using a lube of one kind or another...so... +1 on the Anti-seize because stainless against stainless will gall terribly and you will not get them torqued properly, nor will you get them apart without cutting or breaking them.
Does anyone know if ARP carries stainless fasteners? We get their high grade quality fasteners for our Alcohol Dragster racing business, don't rely on anyone else.
I'm voting for using the new plates, and quality fasteners. Did you say you were going to apply some silicone sealant under the bolt head? I'd be sure to apply some to the hole for waterproofing if nothing else. It won't affect the bolt threads if you apply a small dab to the shank of the bolt after you get the threads started into the hole.

[Vamonos]

I just went back and re-read your original post. It sounds like your main problem is that the holes in the chain plates are slightly undersized. It should NEVER bugger the threads on the bolt. (Sorry if bugger isn't in your vocabulary, I'm from the south)

You need to resolve that issue BEFORE you mess up another set of brand new bolts. (Did I miss where you have already done that?)

Yes, put some anti-seize on the threads before you put the nuts on and thick fender washers if it is in a wood bulkhead. But you do NOT need fancy ARP bolts at $3 each. It's bolted to a plywood bulkhead? Not a rod bolt spinning 10,000 RPM.