Stripped Thread on Brass Nut

You might check PI (Vespel®) type bolts....

http://extreme-bolt.com/applications-high-temperature.html

http://www.professionalplastics.com/professionalplastics/content/Vespel_datasheet.pdf

great post,good story too

Del

Thanks!

It's nice to know that a educational story of how things were done the old school common sense way can be appreciated. It's getting rare these days.

On a farming forum, I got run off from this week no less for repeatedly trying to educate idiots (and embarrassing a bunch of 'know it all' fools too with bonehead obvious and simple solutions to a few problems), I did one on how to make very nice custom gaskets for odd components (because someone said that making a large gasket for a tractor rear end was a all all day project when it's not if you actually know what you are doing) of any size, only to be attacked and trolled to shreds by every suposed experienced farm machinery service tech on the forum, plus several old farmers, to who claimed that gasket making is never ever done in service shops regardless of what the situation is and if they ever caught someone hand cutting a gasket for a tractor they brought in they would sue the company for gross negligence on their repairs.

One hell of butthurt bulshyte storm exploded all over me having showing how making a gasket of most any size that is neat, clean and accurate even for a large complex part can be done quickly and easily using little more than a utility knife and the fasteners related to the components at hand.

BTW, according to them, engineers and technicians should never ever be allowed to work on machinery because they are all stupid and don't know anything aobut how to properly fix stuff and any shop mechanic or person who has ever met one knows that. (Never mind the fact that those are the types of people who both design the machines and develop those actual service procedures that every shop mechanic uses.)

Yeah, I can remember making gaskets for a Lambretta out of cornflake boxes when I couldn't get a replacement! And a plumbing gaskets from an old wellington boot.
They guys who made the first engines couldn't buy gaskets so they must have made 'em.
I get all sorts of BS on archery forums from people with all the gear and no idea.
Del

Yep. The old school professor I had for that class even told us about how boiling different papers and thinner cardboards stock in various natural and petroleum based waxes was how many non leather based gaskets were first made.

Same concepts for making waxed rope type shaft seals.

I've never purposely boiled any paper in wax to make a gasket but I did make a gasket for a antique brass gear pump out of a wax kitchen paper once. Worked perfect!

As for the farmers forum I rather got the impression that most felt that just throwing money at things until it was someone else problem then complaining about how poor they are was best.

It always bewildered me to hear guys complain about $200+K a year repair bills and have zero personal shop or mechanic of their own in place because they don't feel it worth it to do their repair work at home on their own time.

I don't get it. That's not how the farmers I grew up with and still associate with work.

Jeez, don't those guys know how use a ball peen hammer and a crochet hook?

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(To fish the punchings out from the bolt holes.)

We used to make all our own gaskets....we had sheets of various materials for whatever the application was...just cut the material to size and go around the profile with a ball peen hammer, or trace it out on paper....Working in the field on critical systems you don't have time to order or wait for gaskets all the time....

And People look at you as if you were joking about making a gasket.

Wish I would have had you guys in my corner in that discussion.

You need to get your link on....

https://www.hemmings.com/magazine/hsx/2010/04/Gasket-Making-101/3012301.html

Gasket cutter kits....

Gasket materials...

Video instruction how to...

On a farm you had to be resourceful... gaskets from cereal boxes. And that was the minor task... you may have to Mae, it twice, because the first try failed.

the other thing is when you still have 10 acres of hay down and thunderstorms on the horizon. The knotter in the baler is out of adjustment. Neighbor never could figure that out, and they'd call the implement dealer and wait as their hay got rained on.

And the experience served me well, was never afraid to try anything... twice.

Thanks for the feedback. I will look to set up a trial, but will have some difficulty simulating the operating temperature.

The brass nuts are used to prevent galling which would occur if stainless nuts were used. If you know the grade of the stainless studs, you might get away with using a different grade for the nuts. Alternatively, you could re-tap the nuts to take Nitronic 60 Helicoils which are made to prevent galling on stainless at high temperatures.

Yer I agree I am looking into using a 304grade nut but didn't consider a helicoil, Thanks

Concerned about SS galling?

Bostik, Loktite and others have a plethora of anti sieze formulations that solve that problem, Bostik Never Seez pure Nickel is a likely candidate, and it will easily handle the temperature.

It has an added advantage of reducing required tightening torque for the same or better clamping force and you get a more consistent and accurate torque, but be a bit careful you don't exceed the fastener's proof load when using this stuff. You can also use a simple Graphite powder such as lock/key lube if you're stuck.

Also be cognizant of health regs if this is a food environment.

Another trick is to use different grades of SS for the bolt and nut as this can reduce galling tendency, and do turn the nuts down by hand first so that heat build up doesn't destroy the passive layer as this is where the galling begins.

How are the threads formed? It looks like the threaded rod, they are roll formed, as the threads major diameter is larger then the rod. Assuming it has not been turned down. As for the brass nut, how are the threads cut? Was a thread forming tap used. Also torque specs for 3/8-16 is 192 inch-lbs= 22 Nm, possible you are over torquing?

The 192 in lb is for brass, 316 stainless is 247 in lb.

The st/st stud is turned. And the brass nuts are made as per BS 1083:1965.

I think this may be the case and they are being torqued to high.

Any nut will strip if the torque is <...to[o] high...>. The torque needed needs re-evaluation.

Good point. Usually, one flogs it up until the stud breaks, then backs it off half a turn. Brass being softer than stainless, the nut goes first.

You show what appears to be brass studs [you say nuts] I am a little confused by your description.?

I do not know if it is practical but change your studs to stainless steel and use double diameter depth brass nuts.

The studs are stst, they look the colour they do due to heat tint (temper) as the operating temps are high.

In that case use monel for your nuts it has a high toughness, certainly do not use stainless steel.

<...corrosion resistant...> to what fluid, please?

The main concern being oxidation due to atmosphere, the environment is high humidity and temp.

Brass is routinely used in water fittings, however, bronze might be better for elevated temperatures.

A grade of silicon bronze is used in electrical connections, should be somewhat easy to find, bolts and nuts, not too much galvanic potential with stainless steel, and zinc, if memory serves. Used on outdoor substation fittings and connectors, but local supply houses were able to find them also.

I believe that your fastener failure is at least partially due to usage at high temperature. (you state 280C -- 536F)

Most codes and guidelines recommend that brass piping and bolting materials not be used above 250F

Brass materials should have never been originally specified for this high temperature application.

If you need information related to brass fasteners like brass nut, bolt screws you can visit at http://www.siddhagirimetals.com/brass-manufacturer-supplier.html

Brass Nuts Information