Copper ease on aluminium

[OceanSprint]

Just removed the masthead light unit. The two screws into the aluminium fitting came out with much grinding and white ally powder. I was thinking of putting a smear of copper ease when i fit them back - but does copper and aluminium react?

Thanks

 

[macd]

does copper and aluminium react?

Yes. Better to use Duralec.

 

[VicS]

Just removed the masthead light unit. The two screws into the aluminium fitting came out with much grinding and white ally powder. I was thinking of putting a smear of copper ease when i fit them back - but does copper and aluminium react?

Thanks

Logic says dont use a copper based anti-seize compound on aluminium.

Use Duralac, (barium chromate paste) or Tefgel, a teflon based compond. No problems then

 

[Mistroma]

+1 on Duralac. A tube is quite expensive from Chandlers so try other sources first (specialist garage?). Fortunately, it lasts for ages so don't buy a lot. I've probably given away as much as I've used myself and the small tube is still about 80% full after 5 years. It does tend to get on clothes if you aren't very careful (just seems to creep out of the tube when you back is turned).

 

[OceanSprint]

Is copper ease ok for stainless bottle screws? Or duralac better?

 

[VicS]

+1 on Duralac. A tube is quite expensive from Chandlers so try other sources first (specialist garage?). Fortunately, it lasts for ages so don't buy a lot. I've probably given away as much as I've used myself and the small tube is still about 80% full after 5 years. It does tend to get on clothes if you aren't very careful (just seems to creep out of the tube when you back is turned).

Tef gel is much less messy than Duralac ITYWF. A good choice for close fitting joints as it works by keeping water out. Duralac may be better for pooly fitting joints.

 

[VicS]

Is copper ease ok for stainless bottle screws? Or duralac better?

Duralac is not an antiseize/ antigalling compound. It is used to prevent corrosion between dissimilar metals such as stainless steel and aluminium.

 

[lpdsn]

Is copper ease ok for stainless bottle screws? Or duralac better?

Yes, copper grease is what you'd use where there is a lot of pressure between the surfaces, such as on bottle screws.

As VicS says, Duralac (a.k.a canary ****) is to isolate dissimilar metals to prevent galvanic corrosion.

Completely different materials for completely different purposes.

 

[Bobobolinsky]

On stainless, better off using one of the nickel based anti seize. Copper slip et al may cause galling

 

[ccscott49]

On stainless, better off using one of the nickel based anti seize. Copper slip et al may cause galling

Not true, we use copper based grease for stainless steel drill collars in the oilfield and the larger ones are torqued up to 78 k/ftlbs and they done gall, also I have used copper grease on stainless fittings for 30 years and only time I had a stainless fitting seize, is when I forgot!

 

[lpdsn]

On stainless, better off using one of the nickel based anti seize. Copper slip et al may cause galling

Can you expand? I'm genuinely curious and keen to learn. As I understand it, galling is caused by the protective Chromium Oxide layer being scraped off and the exposed stainless steel surfaces corroding together. Everything I've been told is that Copper grease prevents the high levels of friction removing the Oxide layer. Other greases are more easily squeezed out. So I've relied on the belief that Copper grease is good enough.

 

[Bobobolinsky]

Not true, we use copper based grease for stainless steel drill collars in the oilfield and the larger ones are torqued up to 78 k/ftlbs and they done gall, also I have used copper grease on stainless fittings for 30 years and only time I had a stainless fitting seize, is when I forgot!

And what's the thread on a drill collar.

I had corrosion coupons galled on a platform (Tartan?) Can't remember, flogged em for two days, then the platform engineer brought out his new toy, a battery powered impacter. Thought it was a bit of tonka, but it ripped out the coupon holders quick quick.

 

[ccscott49]

And what's the thread on a drill collar.

I had corrosion coupons galled on a platform (Tartan?) Can't remember, flogged em for two days, then the platform engineer brought out his new toy, a battery powered impacter. Thought it was a bit of tonka, but it ripped out the coupon holders quick quick.

Large collars, not the largest, 9 1/2 say 7 5/8 regular. But never seen a thread for collars larger than 8 5/8 regular.
Tartan?? Did most of the pre-drilling and conductor pre-setting on there!

 

[cryan]

If you don't want to use copperslip, which I have to say I have never had an issue with, then there are lots of non metallic and aluminium based anti seize compounds on the market. Molykote are famous for their graphite based stuff and Loctite do a whole range of antiseizes.
http://hybris.cms.henkel.com/medias/sys_master/catalogsync/8802960932894.pdf Page 116 is the start of the anti seize
https://www.cromwell.co.uk/MLK7031000T
http://www.neverseezproducts.com/neverseez.htm

 

[vyv_cox]

Can you expand? I'm genuinely curious and keen to learn. As I understand it, galling is caused by the protective Chromium Oxide layer being scraped off and the exposed stainless steel surfaces corroding together. Everything I've been told is that Copper grease prevents the high levels of friction removing the Oxide layer. Other greases are more easily squeezed out. So I've relied on the belief that Copper grease is good enough.

Galling is adhesive wear, effectively the welding of adjacent surfaces. Anything that can prevent heavy sliding contact of the two metal surfaces will help to prevent it. Molybdenum disulphide is probably the best palliative but nickel and copper thread lubricant also work well.