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Alternative to Woods strike on 316 SST before high phos Electroless Nickel plate


November 9, 2016

Q. I need to get high phos electroless Nickel on the inside of a welded pipe with elbows.
The electroless nickel plate step is not a problem for the plumbing, but the woods strike is a major issue. We cannot effectively fish an anode through the 1/4" ID and around all the bends.

Is there an alternative to the woods strike that will allow the electroless Ni to adhere properly? (Something that does not require an anode on the ID).

Why does SST need the woods strike, but not aluminum?
I assume it is more than just removing the native oxide?

Would a pre-nitride (Or nitrocarburized) layer do it?

Chris Gage
- Campbell, California USA
  ^- Privately contact this inquirer -^


November 2016

A. Hi Chris. Although aluminum substrates don't require Wood's Nickel for activation, they do require a zincate activation step (which will not work for stainless steel). I'm personally not aware of any method of activating stainless steel except a nickel strike.

If it's going to be electroless nickel plated anyway, why can't it be plain steel instead of stainless?

Alternately, how about electroforming it out of nickel instead of starting with a stainless pipe?

Regards,

pic of Ted Mooney
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


November 9, 2016

Q. This is a high purity gas line with VCR seals.
These fittings are generally only available in 316 SST.
Any deviation from 316 could be difficult.

What kinds of steel alloys could be plated without an anode?

So there is no way of plating 316 without an anode?

The purpose of the NI plate is corrosion resistance to a particular chemical.

The interior is electropolished.

Chris Gage [returning]
- Campbell, California USA


November 2016

A. Hi again. Nothing can be electroplated without an anode, but the electroless nickel plating which you mentioned does not require an anode. The problem is that it won't adhere to stainless steel, but it will adhere to low carbon steel. I'm not saying there is no way of plating electropolished 316 SST without an anode, but I don't know of any.

Regards,

pic of Ted Mooney
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


simultaneous November 10, 2016

A. Chris

If this is a new part, I'd talk to the designer/engineer to see what he they had in mind for how to accomplish the plating.

With regards to "effectively fish an anode", it suggests you can but it makes the process time-consuming, awkward, difficult, all of the above. Sounds like you could command a premium for it.

Willie Alexander
- Green Mountain Falls, Colorado


November 10, 2016

A. I think that an electroless nickel strike (special alkaline EN) might work on a properly activated material.
Check with different vendors.

James Watts
- Navarre, Florida


November 15, 2016

Q. Willie,
We are the engineers.... Just trying to get Nickel on the inside of our 316 SST parts.

James,
My 'go to' plating shop is pretty good.
What should I ask them to look into specifically?

I assume we need to properly strip the oxide and activate the surface, then keep it "wet" before dropping into an Alkaline electroless Nickel tank?

Chris Gage [returning]
- Campbell, California USA


November 15, 2016

A. You might get sufficient activation prior to EN with a simple HCl dip.

Clean in alkaline/detergent (get a good one from a plating chemical supplier).

Rinse, well.

HCL, 20%, perhaps 60 seconds. You will need to keep this fresh and clean.

Rinse.

Rinse.

Immediately into EN plate.

It may take some experimentation as to HCl strength and time.

jeffrey holmes
Jeffrey Holmes, CEF
Spartanburg,
      South Carolina


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