Seized nut and bolt

Bought some new stainless M10 nuts and bolts to fix brackets to the rear cross member. Bolted them down no bother. Finger tight first then spanner and socket/wrench to finish. Decided to put a larger diameter washer on them, so unbolted and swapped washers except for one! The nut initially started to wind off no bother, but then quickly developed resistance close to the end of the bolt. Became impossible to move loosening or tightening. Had a few spare nuts, so contemplated using the angle grinder to cut the nut off, but everything is galvanised and didn't want to catch any of it. Soaked it in penetrating fluid, put a socket on each end with longer bars and tried to force it off, but the bolt sheared.
I was loosening it hellish quickly initially before it seized, but no idea what happened. It wasn't cross threaded.

Any ideas anyone?

stainless does that its called galling, it could be poor nut/bolt or just too tight a tolerance on the thread

Is that what it is It was well and truly galled then. Does it fuse together with the friction? I think I unbolted it too fast!

Al2O3 said:

Is that what it is It was well and truly galled then. Does it fuse together with the friction? I think I unbolted it too fast!

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yes ,lube only works if you apply it before ,it friction welds itself

Slowly does it with the stainless from now on.

A friend also had this happen with cheap stainless fasteners. Can be a nightmare when it happens in the wrong place.

jamesmartin said:

yes ,lube only works if you apply it before ,it friction welds itself

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+1 with that stainless bolts/nuts can be a right bitch to work with. Stainless is not a fix all, they have there place. and often people get sticker shock from the price and don't use the correct grade bolt or matching nut

Thor1950 said:

+1 with that stainless bolts/nuts can be a right bitch to work with. Stainless is not a fix all, they have there place. and often people get sticker shock from the price and don't use the correct grade bolt or matching nut

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I could be guilty of this Thor, but I don't know what sticker shock is. I think you've got something with the grade, though I haven't chosen cheaper stuff and accepted lower grade deliberately. The bolts were A2 as were the nuts. However, I have other A2 stainless nuts/bolts that look very different to the offending bolt. The one that seized was a very light grey colour and matt in appearance. Others I have are a dark grey and shiny. If you can get different grades of A2 then my ignorance certainly caused the problem. I paid £4.89 for the 4 bolts (M10 x 110mm)

at work, we have brass nuts on stainless bolts for the ones that are undone and refitted often and they never give a problem. Stainless on stainless often results in the grinder or hacksaw coming out. Some of the storage vessels have had the same brass nuts on them for 10 years+ and have been undone and re tightened dozens of times. Copper slip doesn't always help stainless.

At work we use this stuff its far better than Copper slip.
http://chestertonlubricants.chesterton.com/en-us/Products/Pages/787.aspx

Also once we were doing a job with High Grade Stainless steel tubes in a Nuclear power station. The tubes kept picking up and galling until the Station Engineer/Chemist did some research and got us to use Milk of Magnesia apparently the chalky consitancey was the best thing to stop the galling it did seem to work well none of the threads picked up again.

TorsionBhudda said:

At work we use this stuff its far better than Copper slip.
http://chestertonlubricants.chesterton.com/en-us/Products/Pages/787.aspx

Also once we were doing a job with High Grade Stainless steel tubes in a Nuclear power station. The tubes kept picking up and galling until the Station Engineer/Chemist did some research and got us to use Milk of Magnesia apparently the chalky consitancey was the best thing to stop the galling it did seem to work well none of the threads picked up again.

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I note you refer to Copperslip. It maybe better than the shite products you get from accessory shops going by that name. But maybe falls short of Copraslip which is the proper stuff.

Discokids said:

at work, we have brass nuts on stainless bolts for the ones that are undone and refitted often and they never give a problem. Stainless on stainless often results in the grinder or hacksaw coming out. Some of the storage vessels have had the same brass nuts on them for 10 years+ and have been undone and re tightened dozens of times. Copper slip doesn't always help stainless.

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When I was an apprentice one job I had was to "run down" big pressure vessel nuts and bolts, we put graphite paste on the thread and ran the bolt down and back off again very carefully before it was installed, sometimes the new threads have rough bits on them from the machining and these will pick up this can seize up solid, and then you are buggered.
I have also put a thin wrap of PTFE tape on threads, it make a reasonable anti vibration ( not as strong as Locktite) it keeps out moisture, and it is not a bad lubricant when you want to take the nut off.

wammers said:

I note you refer to Copperslip. It maybe better than the shite products you get from accessory shops going by that name. But maybe falls short of Copraslip which is the proper stuff.

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Generally we don't use any Copper based Anti-siezes anymore in any of the power stations that we work in as it can cause corrosion to studs and bolts we generally use Graphite based anti-sieze also use Nickel based Anti-sieze but companies are moving away from that as its cancergenic. I have never bought Anti-sieze products from shops when better is readily avaliable for free from work (carry it in works van). Only time I use Copperslip (bit like calling all Vacum cleaners - Hoovers) is when applying thin coat to back of brake pads and I have had that tub for over 15 years because I use so little of it.

you generally cant use copperslip (and the various derivatives) on nuclear sites now because its a contamination trap. Theres a coating we apply to the stuff we have made which is chemically bonded to the threads. The name eludes me. Its expensive (so its supposed to be good!) Seems to work though.

I use Molykote at home alot. Only really because I havinched a load of it from Caterpillar when I worked there

Well, from something I thought was an unusual occurrence it turns out to be a fascinating subject. Great responses, gents. Cheers. It's interesting how many of us have spent time working in power stations!

vilguy said:

you generally cant use copperslip (and the various derivatives) on nuclear sites now because its a contamination trap. Theres a coating we apply to the stuff we have made which is chemically bonded to the threads. The name eludes me. Its expensive (so its supposed to be good!) Seems to work though.

I use Molykote at home alot. Only really because I havinched a load of it from Caterpillar when I worked there

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Sorry to digress, but I bought my current Landy from a guy in Kilsyth who worked for Caterpillar!

vilguy said:

you generally cant use copperslip (and the various derivatives) on nuclear sites now because its a contamination trap. Theres a coating we apply to the stuff we have made which is chemically bonded to the threads. The name eludes me. Its expensive (so its supposed to be good!) Seems to work though.

I use Molykote at home alot. Only really because I havinched a load of it from Caterpillar when I worked there

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Molykote is much better than copper slip especially the cheap generic copper copies. In the power stations we had some good things there was a silver graphite spray for hot conditions, and a foliac graphite spray which was good for dry conditions.
You can buy powdered graphite on e-bay I want to try it dry on hot threads i.e. manifold heat shield, and mix some with waterproof grease for wet areas i.e. in the foot wells.

http://www.ebay.co.uk/itm/GRAPHITE-POWDER-200-GRAMS-/121747948420?hash=item1c58be4384