304 or 316 Stainless Steel
304 or 316 Stainless Steel
(OP)
I was curious as to a method (simple if possible) that can test for 316 as apposed to 304 stainless steel.
A test that possibly could be done on-site would be the most advantageous.
Thanks
A test that possibly could be done on-site would be the most advantageous.
Thanks





RE: 304 or 316 Stainless Steel
RE: 304 or 316 Stainless Steel
RE: 304 or 316 Stainless Steel
1) long term purchase - get a portable alloy analyzer (NITON, SpectroAnalytical, etc.) - be prepared to spend some money though (in excess of $30,000 usually) - reason to purchase is frequent checks, fast results.
2) short term purchase - alloy spot checking kit (wet chemistry) - inexpensive, usually under $1000 - reason to purchase is infrequent checks, budget prohibits larger purchase.
3) no purchase - hire a metallurgical or NDE analysis company to provide the service on a contractural or per need basis.
We use a NITON II (portable, handheld, looks like a phaser from Star Trek) where I work. It has been fairly reliable and provides a good quick analysis (from power up to results usually in less than 2 or 3 minutes). The only drawback is distinguishing between the same type of metal that has differing carbon or sulfur contents.
~NiM
RE: 304 or 316 Stainless Steel
a) Place equal drops of concentrated hydrochloric acid and concentrated nitric acid on the metal surface. Allow 3 to 4 minutes for reaction and transfer 2 drops to a spot plate.
b) Add 2 drops of 10% potassion thiocyanate.
c) Add 25% sodium thiosulfate dropwise stirring until the red color begins to disappear. A violet color will appear if molybdenum is present.
However, you can purchase a chemical spot test kit form Koslow or Systems Scientific Labs.
RE: 304 or 316 Stainless Steel
There is a simple electrochemical verison also that uses a battery and an electrolyte to drive the same reaction.
= = = = = = = = = = = = = = = = = = = =
Corrosion never sleeps, but it can be managed.
http://www.trenttube.com/Trent/tech_form.htm
RE: 304 or 316 Stainless Steel
The purpose does not warrant the cost of equipment and the test kits are possibly the way to go - however I was hoping to do the test in the next day o r so at a plant that was being decommissioned.
I have found some information that suggests the use of Sulphuric Acid or HCL.
The Sulphuric acid on 304 - Strong attack - green crystals and dark surface
The HCL on 304 -Fast attack - gas formation
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The Sulphuric acid on 316 - Slow attack - tan surface turns brown
The HCL on 316 - Very slow attack
Any thoughts on this form of testing.
Regards
RE: 304 or 316 Stainless Steel
In your situation, I would call on a metallurgical lab and have the PMI performed on site using a portable alloy analyzer, as NickelMet stated in option 3 of his post. This can be done quickly, and probably for less than a couple hundered bucks (travel time for a tech).
RE: 304 or 316 Stainless Steel
Take a 50/50 HCl/Water, V/V, solution and saturate it with S02. The solution requires periodic re-saturating. Work outside or in a fume hood.
Slightly abrade the suspect material and a known and add one drop of the solution and let the reaction stop. Rinse in cold water and look form a purple color, molybdenum disulfide.
You may have to slightly tilt the test piece to see the color.
The only real interference is 303 SS where a black smut forms.