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rust-proofing tapped holes
5

rust-proofing tapped holes

rust-proofing tapped holes

(OP)
I have tapped holes 1/4-20 in steel that are getting rusty. Apparently the supplier cant Zn plate because they are blind and it's an air lock. One thought was to put stainless inserts. But is there a good product that can be applied to prevent rust?

RE: rust-proofing tapped holes

Oil or grease are pretty effective. Be careful with grease in a blind hole. You can crack steel with the hydraulic pressure created by the screw compressing trapped grease. There are also greases designed to protect electrical connections from corrosion that contain zinc powder.

RE: rust-proofing tapped holes

There are oils that have rust preventatives in them, RP oils.
Contact someone like CorrTech or Edco.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

RE: rust-proofing tapped holes

I'm a big fan of anti-seize.
A low strength thread locker might work too.

RE: rust-proofing tapped holes

How permanent of a solution are we looking for here? Grease packed in the holes is standard practice to keep them from rusting until delivery. If it needs to last the life of the item, consider using a plug.

RE: rust-proofing tapped holes

Hi Chopper

Have you considered putting a small pilot drill hole through prior to drilling and tapping the hole, that way the hole isn't blind anymore and plating might be an option.

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein

RE: rust-proofing tapped holes

It’s not just a question of appearances. If untreated rust can completely decimate an entire structure.

RE: rust-proofing tapped holes

If this is only a concern while the part is in transit or stored prior to use, have the supplier but wooden golf tees or the soft foam disposable ear plugs in place

I wouldn't grease the threads without figuring out the impact to the applied torque on the mating fastener

RE: rust-proofing tapped holes

If you where to plate the holes then likely you would have to be machining them oversize to compensate for the coating, else you would be breaking bolts and or not starting them.
It depends on the shelf life as to what kind of oil or rust preventative to use.

RE: rust-proofing tapped holes

Candle wax. I once used this in an emergency and it worked. These were bees wax candles that came from an old church.

RE: rust-proofing tapped holes

Let's not overthink this. How about putting a piece tape over the holes? You know, the good stuff like a little circle of FEP tape or something.

RE: rust-proofing tapped holes

I'm a big fan of Loctite PST applied to the male threads.

Mike Halloran
Stratford, CT, USA

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