Copper Coating of API threads 13Cr110

[Mike Perry]

I am looking for a concise and plausable argument of copper coating API threads (13Cr110) versus just bead blasting. Thanks...

[Gordon]

Hi Mike

to the Surface Engineering Forum.

Copper coating on one connection surface of an API thread (creating
dissimilar surfaces) is used to reduce galling and seizer.

[Mike Perry]

Agree, but can the makeup still be accomplished with just bead blasting. I am into a "beer bet" and we need to make a decison.
I say always copper coat 13Cr.

Thanks again and I enjoy the webpage.

[Stephen Booth]

my guess: (just a guess) glass bead blasting can only increase the surface hardness, and reduce surface stresses. Copper coating is actually and new material in the thread, and the interface (mating surface) will now be copper coating against copper coating. Which on the surface is like to be some oxide facing another oxide. interested in your argument?

[Gordon]

Hi Mike and Stephen

My bet would be for copper coating if we are talking a straight choice between the two systems without complicating factors like corrosion, lubricants etc. I would only consider this though, if only one of the mating surfaces were coated (or bead blasted if we look at the other arguement). A bit like running a steel journal within a bronze bearing. Copper on steel will have much less tendency for forming mutual adhesion together than steel on steel. Copper will also act as a more accomodating soft bearing surface.