Resistance to Ferric Chloride

[swall]

Anyone have thoughts on either a base metal or coating that would offer resistance to ferric chloride fumes at ambient temperature? This would be for a constant force type spring (i.e. clock spring).

 

[metengr]

Look at Hastelloy C-22 or similar.

 

[swall]

Metengr--I was afraid you would say that.

 

[metengr]

swall;
One other thought, Elgioly. Although, the only reference I found is below for 10% ferric chloride solution @ 75 deg F;

http://books.google.com/books?id=Ie...&resnum=1&ved=0CBUQ6AEwAA#v=onepage&q&f=false

 

[unclesyd]

If my memory serves me well Titanium is good up to 50% and boiling in Ferric Chloride Solution.
I believe this ins in the old Timet Corrosion Tables if anyone has them.

 

[swall]

Thanks for the responses. I am in a classic situation of having to fix a project that the client has already quoted (they quoted 301ss for the app). So, basically the client does not have a viable program at this point. Oh, well.

 

[moltenmetal]

Fumes only? Ambient temperature? Could you not get away with a nonmetallic coating? Spray applied PFA for instance? Depends on how big the spring is.

 

[swall]

moltenmetal--it may that a suitable coating exists, but given the potential liability of a ferric chloride spill (the spring is used on a transportation vehicle hatch closure)and the lack of time/resources for testing, the only safe route is to go with something bullet proof.

 

[TVP]

swall,

For bulletproof, I agree with metengr (Hastelloy C-22 or similar) and unclesyd (titanium). A coating seems like a really big risk unless the entire process from manufacturing through assembly to end use is optimized.

Here is a link to the product bulletin for HASTELLOY® C-22® alloy:

http://www.haynesintl.com/pdf/h2019.pdf

Here is a link to the Timet corrosion info:

http://www.timet.com/pdfs/corrosion.pdf

 

[unclesyd]

Is this spring like the torsinol springs seen on a lot hatches?

if so when we had a process that used Ferric Chloride there we some components of 316 SS that would occasionally see what little vapor there is. I believe the 301 SS steel might work if it would have only brief exposure to the liquid and rinsed off after the exposure.

 

[swall]

Yes, unclesyd--from what I have been told it is a hatch cover spring. Were I the manufacturer of this device, I might be inclined to proceed as you suggest, as I would have some control over the testing necessary to validate such as an approach. But as the supplier of a component spec'd by others of unknown technical competence, I put my company at risk by suppling something less than bullet proof.

 

[EdStainless]

If this a spring, and at spring hardness and stress, then a "C" alloy (22, 686, 59) or Elgiloy or MP35N are about the list.
Ti makes bad springs since they have to be over twice as large due to the low modulus.

= = = = = = = = = = = = = = = = = = = =
Plymouth Tube

 

[unclesyd]

If this spring is external as they are normally are I can see exposed to is a little splash which would be washed off prior to shipping. Our standard procedure on covers of this type is to fill, close, and rinse off where you have a waster drain. We got a fine years ago because there was white stuff reported around a cover on a tanker truck. This was recorded as a leak when in reality it was material that wasn't rinsed off and was reacting with CO2 in the air.

What is the container made of?

Could you post a picture of the hatch and cover?

edStainless,
Normally this is a very big spring probably weighing around 10-15 pounds so making it from any of C-22, Elgiloy, or MP35N would be extremely expensive $450 US ea. for a 1 1/2" by 3/4" dia. of .016 wire for use in a pump in Cupric Bromide service. The order was for 10 springs.