Copper grease on bottle screws

[oldsaltoz]

Just make sure the copper based grease is removed from the boat, if it ever gets pumped into the prop shaft casing you will have a real problem, the water removed the grease but not the copper.

 

[Topcat47]

In the nuclear industry we do(did?) have special SS/Monel transitions. Admittedly we were dealing with high temperatures and pressures in the primary cooling circcuits, but I have seen test pieces done in workshop conditions fail under test at very much smaller reduced loads than design. We operated a strict ban on copper in ant form coming into contact with SS and I've kept to the rule ever since. I've spent an hour or so unsuccessfully hunting for my metallurgy notes regarding the risk and I have a feeling it was related to the chromium content of the SS rather than the temperature and pressure, although these may well be contributory to the ultimate failure mechanism.

The fact that riggers use bucketloads of copper grease means little to me. I've seen "craftmen" bodge a lot of things, secure in the knowlege that they'll be far away when the **** hits the fan. I did a five year marine engineering apprenticeship before attending uni and I'm well aware of what passes for "skilled labour" in the boat industry.

 

[GrahamHR]

I vaguely remember lectures relating to intergranular corrosion of stainless steel at high temperatures ( over 30 years ago at Uni). I personaly use a colloidal nickel product on any threads on my boat; some stainless steels contain nickel in any case, so I figure it can't do any harm.

Graham

PS probably expensive stuff, but it was a free sample from a potential supplier many years ago that was going to be binned, before I intercepted it!

 

[Ubergeekian]

In the nuclear industry we do(did?) have special SS/Monel transitions. Admittedly we were dealing with high temperatures and pressures in the primary cooling circcuits, but I have seen test pieces done in workshop conditions fail under test at very much smaller reduced loads than design. We operated a strict ban on copper in ant form coming into contact with SS and I've kept to the rule ever since.

I spent a few years of my life working on stainless steel / copper composite materials - as conductors for high-field pulsed magnets. Very strong stuff it was, thanks largely to the cold welded intermetallic bond at the interface. Mind you, running at 77K helped a fair bit too.

 

[William_H]

Turnscrews

I make a point of unwinding all of my rigging screws each winter. I apply a bit of grease on reassembly but it is only axle grease. it seems to last a season OK. i have had many turnscrews come to me stuck and it really is difficult to get them to move once they grow together. So frequent unscrewing is I think the answer. olewill

 

[TradewindSailor]

Would an anti-seize product be better than grease? If so which one?

I had to unload my rigging via the furler's turnbuckle as the cap shroud turnbuckles were seized at the normal rig tension. De-tensioning the rig via the forestay did the trick. I used Permatex® Anti-Seize Lubricant when I re-assembled the turnbuckles ...... but it is a blend of graphite, aluminium, and copper lubricants. Would the aluminium neutralise the possible galvanic potential of the graphite?

 

[vyv_cox]

I personaly use a colloidal nickel product on any threads on my boat; some stainless steels contain nickel in any case, so I figure it can't do any harm.

PS probably expensive stuff, but it was a free sample from a potential supplier many years ago that was going to be binned, before I intercepted it!

Probably the best of the thread lubricants, nickel based ones came to the fore when it was found that molybdenum disulphide based ones caused stress corrosion cracking in very high strength steel bolting. There have been various 'scares' about copper based lubs in the oil industry but little in substantiated facts other than a few very high temperature ones. Just to make sure, which the oil industry likes to do, all other thread lubricants were being phased out in favour of nickel based ones. That was six years ago, no idea how it has gone.

 

[Marsupial]

The fact that riggers use bucketloads of copper grease means little to me. I've seen "craftmen" bodge a lot of things, secure in the knowlege that they'll be far away when the **** hits the fan. I did a five year marine engineering apprenticeship before attending uni and I'm well aware of what passes for "skilled labour" in the boat industry.

So how many rigging screw failures have you seen as a result of using copper grease? is it nearly one?

the bodgers in the rigging industry are the ones who use nothing and wait for the "my bottle screws have galled" cry!

Thanks for the tip about "skilled labour" and apprenticeships in "marine industry" - I ll steer well clear of any time served marine engineers in furure.

 

[VicS]

all other thread lubricants were being phased out in favour of nickel based ones. That was six years ago, no idea how it has gone.

Nickelslip, like Copaslip and Alumslip from MOLYSLIP