You learn something every day.

Submitted: Thursday, Aug 15, 2013 at 08:40
ThreadID: 103770 Views:2522 Replies:9 FollowUps:13
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I put a 38 ltr poly water rank on the dmax a while ago and decided to do a few adjustments the other day.

Took one of the stainless steel locknut and bolt off did the adjustment and put it back on.

Well , only got it half way on and decided the adjustment wasn't quite right, so I tried to undo the nut,,,,,,it wouldn't move tried every thing, cursing swearing and occasionally the two spanners.

Took it to a mechanic and the rattle gun wouldn't get it off, that made me feel better,
a long bar and a socket finally snapped the bolt.

Now to finish this long winded story. The mechanic said that stainless nuts and bolts are normally a big no no as they will bind together, like mine did.

He said it was better to have a stainless steel bolt with non stainless nut or vise versa other wise the same problem will occur.



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Reply By: Member - Boo Boo (NSW) - Thursday, Aug 15, 2013 at 08:41

Thursday, Aug 15, 2013 at 08:41
Oh for an edit button.

Spell checked the content did not look at heading, should be day not say!
AnswerID: 516431

Follow Up By: ModSquad - Thursday, Aug 15, 2013 at 10:02

Thursday, Aug 15, 2013 at 10:02
Hello

For minor edits such as this just use the "alert moderator" button and we will fix it. We have changed "say" to "day" for you.

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Follow Up By: member - mazcan - Thursday, Aug 15, 2013 at 11:53

Thursday, Aug 15, 2013 at 11:53
hi boo boo
yes ive run into this problem too
when I customized/altered several things on my camper trailer
I used st/st bolts
just before easter this year a tried to undo some of them to replace an item and I finished up twisting the bolts off with a large socket bar and two came undone so far
then luckily i was able to buzz them off with the 4inch cutting disc

i spray them with grease now and it stops the binding
at first I though I must have x-thread them
but that wasn't so
the above thread imfo confirms that there is a problem with st/st material
thanks also for the enlightenment
cheers
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Follow Up By: fisho64 - Thursday, Aug 15, 2013 at 18:15

Thursday, Aug 15, 2013 at 18:15
the reason this happens is that ss bolts stretch easier than steel.
When a bolt stretches the pitch of the thread changes and the thread "galls", especially if there is a bit of anything hard there such as grinding dust etc.
Once it picks up no amount of force will get it off intact.
Anti sieze helps but SS bolts shouldnt ever be used for load bearing applications. There are high grade SS alloys for this sort of use but for general use, dont use SS.
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Reply By: Erad - Thursday, Aug 15, 2013 at 08:55

Thursday, Aug 15, 2013 at 08:55
Stainless steel on stainless is a no-no. I had a tech officer tighten a pipe fitting in the office BY HAND, and he couldn't get it undone. The instructions were to use a lubricant when tightening it up. Another example I heard of was a hydraulic gate in the US which was suspended on a SS chain. When they raised the gate, the chain came straight up instead of wrapping over the pulley. That was simply minor vibrations and the roller chain links had welded themselves together. The I had a turbine bearing fail in PNG and the stainless runner seals welded themselves together. The list goes on....

You can get away with it if you have a significant difference between the hardness of the nut and the bolt (eg using a 400 series bolt with a 300 series nut), but you are still risking it welding together, especially if there is a minor relative movement between the components.
AnswerID: 516432

Follow Up By: tg123 - Thursday, Aug 15, 2013 at 12:34

Thursday, Aug 15, 2013 at 12:34
Usually only a problem when SS threads are an interference fit ie when you are trying to both create a joint and also seal it using threads only. NPT taper and BSP taper are good examples of this. Hence the use of Teflon tape or liquid thread sealer - not only does it fill in the gaps between the threaded components to create the seal, it also provides lubrication between the threads to stop binding. Parallel threads usually don't bind as they are not an interference fit (ie they have a bit of 'slop') and are used to hold the joint together whilst any sealing is done elsewhere eg 'O' ring, crush washer etc
Cheers
TG
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Follow Up By: Shaker - Thursday, Aug 15, 2013 at 13:47

Thursday, Aug 15, 2013 at 13:47
Ha ha, tell that to the marine industry!

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Reply By: Chris (Qld) - Thursday, Aug 15, 2013 at 08:58

Thursday, Aug 15, 2013 at 08:58
BooBoo,
Using a steel nut or bollt kind of defeats the purpose of using stainless steel in the first place. Your mechanic would have been better off advising that when you use stainless on stainless, to use a thread anti-sieze, or just grease would do, to prevent the threads 'picking up'.
Chris
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AnswerID: 516433

Reply By: Member - Duncan W (WA) - Thursday, Aug 15, 2013 at 09:59

Thursday, Aug 15, 2013 at 09:59
Well I've just learnt something I never knew about. BooBoo your missery our gain.

Cheers

Dunc.

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AnswerID: 516435

Follow Up By: OBT46 - Thursday, Aug 15, 2013 at 23:56

Thursday, Aug 15, 2013 at 23:56
Me too.
Cheers
Ian
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Reply By: olcoolone - Thursday, Aug 15, 2013 at 10:45

Thursday, Aug 15, 2013 at 10:45
It's called "galling" and is common on alloys that oxidise, never seize will fix the problem.

AnswerID: 516436

Follow Up By: Member - Boo Boo (NSW) - Thursday, Aug 15, 2013 at 13:03

Thursday, Aug 15, 2013 at 13:03
Thanks fellas

Reading through the replies I've learnt a bit more.

Olcoolone, you must be a mind reader! I've just come in from putting a corrosion inhibitor/lubricant on gal fittings for a boat lifter I put on the tinnie a few months ago.

Just a tiny bit of 'green' under the washers.

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Follow Up By: olcoolone - Thursday, Aug 15, 2013 at 17:04

Thursday, Aug 15, 2013 at 17:04
What you may be referring to is the reaction between two dissimilar metals, galling is similar but it is caused by oxidation of similar metals.

And then you have electrolysis thats different again..... so really you can have three types of corrosion and each is treated differently.

With stainless you can pickle the metal to stop corrosion.

This is one of the reasons you have to have a shield of Argon or a mixture depending on what you are welding to reduce oxidation, aluminium is the worst and will start oxidising with in 5 seconds of being cleaned.
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Reply By: gbc - Thursday, Aug 15, 2013 at 13:41

Thursday, Aug 15, 2013 at 13:41
Yep, never sieze or good industrial lanolin is awesome. I used to build staino towers (nav aids, lighthouses, radar bases etc) and had lots of fun with galling. There is a BIG difference in the standard 316 (maybe) stuff you get at the hardware or the boat shop, and proper 304 staino bolts/nuts. The cost is a fair bit different too though.
AnswerID: 516440

Follow Up By: Member - Boo Boo (NSW) - Thursday, Aug 15, 2013 at 13:46

Thursday, Aug 15, 2013 at 13:46
The s/s bolt and zinc loctight nut replacement was bought from a nut and bolt place for $1.40.

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Follow Up By: Sand Man (SA) - Thursday, Aug 15, 2013 at 18:50

Thursday, Aug 15, 2013 at 18:50
gbc,

Not sure I understand your comments re the two grades of stainless steel.
304 grade is the "standard" stainless steel and in some applications requires a coating to stop surface oxidisation. Most commonly used in the food industry and architectural applications.
316 is marine grade and as the name suggests is much more resilient to pitting of the surface.

Bill


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Follow Up By: Member - johnat - Friday, Aug 16, 2013 at 22:05

Friday, Aug 16, 2013 at 22:05
Not sure there is sich a thing as "standard" stainless steel.
Fact is (and I trained as a metallurgist some few years ago) there are a number of grades of SS, and each is intended for a specific purpose.
The numbers 304 and 316 are simply shorthand identifiers for the particular grade of stainless.
As mentioned, 316 is commonly referred to as "marine" stainless, and this indicates that it is intended for use in environments where it will be subjected to intermittent (or possibly constant) immersion in seawater, or brine.
304 SS is a steel (so mainly iron and carbon) with the addition of 18% Chromium, and 8% Nickel - it is also known as an 18/8 stainless for that reason.
316 SS is a 16/10/2 stainless, being steel with 16% chrome, 10% nickel and 2% moly (hence sometimes referred to as chrome/moly)

Much too much information is available at http://www.assda.asn.au/types-of-stainless-steel for anyone interested in the detail - lists upwards of 70 different stainless steel grades.
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FollowupID: 795901

Reply By: ray j4 - Thursday, Aug 15, 2013 at 13:47

Thursday, Aug 15, 2013 at 13:47
Hi Boo Boo,

As everyone are saying you will have to put some lube on the threads to stop binding. I work in an environment where we use thousands of stainless bolts and nuts a month. We use anti seize on all of the bolts. Another thing is never use a impact gun on the bolts and it just loves to bind them up. As soon as you feel the nut tightening on the thread and you haven't taken up the slack in the thread, stop and try to undo the nut. MIGHT be lucky, if not get out the hack-saw or cutting disc on the grinder. I think even doing up the bolts by hand causes heat in the bolt and nut and with the fine tolerance is what causes the nut to bind. All in all good material won't rust. Drilling stainless is another matter, all I can say is use a low speed and use cutting oil and when started use the same pressure and don't stop until you have drilled through the material.

Regards Ray.
AnswerID: 516441

Follow Up By: Member - Boo Boo (NSW) - Thursday, Aug 15, 2013 at 13:55

Thursday, Aug 15, 2013 at 13:55
Ray

Thankfully the situation I am using the s/s and zinc nut is not critical, ie not a high rust area.

The next time I use s/s I'll use anti freeze or similar.

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FollowupID: 795797

Reply By: bluefella - Thursday, Aug 15, 2013 at 15:08

Thursday, Aug 15, 2013 at 15:08
Stainless steel contact with zinc = corrosion, pretty sure that's the case.
AnswerID: 516443

Follow Up By: greywiki - Thursday, Aug 15, 2013 at 16:51

Thursday, Aug 15, 2013 at 16:51
Stainless steel regardless of grade mixed with zinc or hot dipped galvanize is definitely a no no and it won't take long before electrolysis and corrosion occurs. Never seize and quality marine grade stainless is best answer.
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FollowupID: 795800

Reply By: Garry S3 - Thursday, Aug 15, 2013 at 23:51

Thursday, Aug 15, 2013 at 23:51
wow.. I would never imagine this would happen. it might have explained some of the nuts I haven't been able to undo. I thought that was just my problem. thanks guys
AnswerID: 516467

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