# Material Compatibility for Silver Processing - Stainless, PVC, etc



## snoman701 (Nov 28, 2016)

I've checked the compatibility charts and done some searches, and most are consistent that using Nitric Acid at 50% or less concentration shows no attack on 304 series stainless. 

I'd like to use a couple of tanks that I have similar to:

https://www.mcmaster.com/#41665k18/=158h8mr

The EPDM seal is out, but I am able to get a flouropolymer seal for it. 

The biggest reason for a tank like this is ease in fume capturing, and, I've already got a couple of them. I'll be able to get away with a very small fume handling system, while processing larger batches of material. Working in open glassware requires either a larger vacuum top, or a large hood. 

My concerns are largely all the other chemicals. Silver Nitrate, Copper Nitrate, NOx, etc. Does anyone have any experience that would suggest that 304SS, PVC, Flouropolymer, etc are not compatible with all of the chemicals encountered throughout the refining process?

I've also noticed that some of you have built really nice PVC refining cells. Is there any reason you've chosen sheet PVC over stainless? Simply fabrication costs? Concerns about shorts between wall?


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## Lou (Nov 28, 2016)

Either stainless or PVC work fine. I prefer HDPE/PP for tanks that don't get hot.

Fluoropolymers are way over kill.


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## snoman701 (Nov 28, 2016)

Lou said:


> Either stainless or PVC work fine. I prefer HDPE/PP for tanks that don't get hot.
> 
> Fluoropolymers are way over kill.


The flouropolymer is just for the seal....only options are buna n and flouro. 


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## snoman701 (Nov 28, 2016)

How are you joining the hdpe/pp??


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## Lou (Nov 28, 2016)

Hot air gun is fine on it. Put filler rod in. Standard plastic welding prep and procedures apply.

For you, I'd just make them out of plywood and use a marine grade fiberglass resin.


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## snoman701 (Nov 28, 2016)

In real life I'm a self employed fabricator/machinist. I'd make a huge mess with sawdust and sticky stuff and probably be itchy for a week. Whereas with ss sheet, I'll be pouring acid in by the time I would have located the table saw.

Never actually used the plastic welders...do you find it difficult?

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## Barren Realms 007 (Nov 28, 2016)

snoman701 said:


> In real life I'm a self employed fabricator/machinist. I'd make a huge mess with sawdust and sticky stuff and probably be itchy for a week. Whereas with ss sheet, I'll be pouring acid in by the time I would have located the table saw.
> 
> Never actually used the plastic welders...do you find it difficult?
> 
> Sent from my iPhone using Tapatalk



Welding plastic is not too difficult. It is a lot slower than steel. And it does take patience to do the job correct.


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## snoman701 (Nov 29, 2016)

Thanks! I'll have to look in to it.


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## MKEGold (Jul 24, 2019)

This thread helped me find my new stainless tanks that I'll be using for recovery. I've been wanting to get a large multi purpose stainless vessel and I recently picked up a couple of the 30gal tanks for only $150! These are usually $300+. They also have 50gal tanks and I might pick up another as well.

30 gallon - https://www.ebay.com/itm/123777536069
50 gallon - https://www.ebay.com/itm/123843744192


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