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Zinc question


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I'm looking to put my propane forge together this weekend. All I've been able to find around my shop is what I think is stainless but might be zinc. I was going to use them to hold the outside of my brick pile forge together. I wanted to know if there is a safe way to test if it's zinc or stainless? And if it's zinc is it safe to use on the outside of the forge?

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What exactly are you talking about?  "Please tell me if I'm holding a piece of zinc or a piece of stainless in my hand right now!"  Pretty hard to tell with no data right?

If I say it was a piece of milk handling plumbing you could say "if it's metal almost certainly stainless" If I say it was from some household plumbing: more likely zinc plated.

As stainless is very expensive to make items out of; unless we know more about it I would have to guess zinc plated.

Now as to is it safe: Yes, No, Maybe depending on data you didn't supply.  If it will be kept "cool" say under 400 degF then yes. If it will get hot than possibly No.

You know what you have and how you intend to use it---you have to tell or show us, (or both!)

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Here's a *possible* test.  Check with a magnet.  If it is not magnetic it is almost certainly stainless.  If it is magnetic it's probably zinc coated steel, but it could still be stainless.  The 300 series of stainless is not magnetic and a lot of stainless pipe is in that series, but it's not a guarantee.

If there's any chance the pipe will get direct flame or significant heat the safe thing to do is not use anything that is galvanized.  If it will be at least several inches away from anything that gets significantly hot you are probably ok, but the risk is on you.

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In the meantime until you can upload pictures why don't you provide us with some basic information: Do you know what the original use for the metal was? Do you know if it is food grade? does it flake, peel, or have a different color/material underneath the coating? (If it is coated) These can help guide us to the right questions to determine that it is safe to use. Generally if your unsure it is always safer to err on the side of caution and just get something that you can be 100% certain of the material. Chances are if you are using it as the frame of a forge then it will potentially heat up and release fumes if it is Zinc.

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57 minutes ago, Darious said:

In the meantime until you can upload pictures why don't you provide us with some basic information: Do you know what the original use for the metal was? Do you know if it is food grade? does it flake, peel, or have a different color/material underneath the coating? (If it is coated) These can help guide us to the right questions to determine that it is safe to use. Generally if your unsure it is always safer to err on the side of caution and just get something that you can be 100% certain of the material. Chances are if you are using it as the frame of a forge then it will potentially heat up and release fumes if it is Zinc.

These are going to hold plate metal to the angle iron that's holding the fire brick.

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If the fasteners are your only concern you can chuck them in vinegar for a day or so.  If they are zinc plated it will be gone after that.   If there's no change then they are probably stainless, but either way they are safe to use after that.  Make sure you rinse off the vinegar with a neutralizing solution if possible.

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Do you know where Tristan or Jim live? Take it by and ask them of course if you want to drive out I'll take a look. If you bought them take them back and ask. If you do NOT know, the only safe bet is not to use them where they'll get hot.

Frosty The Lucky.

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I think you should follow Frostys' advise and get some face time with experienced people. What I am seeing in your photos is a commercial fastener most likely zinc plated with a zinc chromate treatment. There is nothing wrong with the screws being highly magnetic. The two critical questions are:

From where did you get the screws?

Are there any locations where they will come in direct contact with flame, or with red hot glowing bricks?

This is an exercise in critical thinking, also known as problem solving. Answer the two questions directly and simply, and I predict that we will be able to tell you that the screws will work just fine!

Robert Taylor

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As Buzzkill says strip off the zinc with vinegar if you think there is a chance of them getting hot...presumably they are not actually inside the furnace but will have a few layers of brick or ceramic fibre between them and the flame. However I think the danger posed by the amount of zinc on a few fixings is negligible, even if they did get hot enough to burn the zinc off all at the same time.

If you do not have the furnace in a well ventilated place you should be worrying more about a lack of oxygen rather than zinc fumes from those....if in doubt you could always fire it up to full heat outside for the first few times so any vulnerable or overlooked zinc or other noxious fuming agents are gone before you start using it and standing close by....

Alan

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They were in a junk bin at work being the weren't labeled we could use them. I work for a military contractor on jber. 

They won't come into direct contact with anyfire. There will be soft fire brick between the fasteners and the fire. But they will be holding the t burner the is screwed into a floor flange on the forge. 

It will only be being used out side. Landlord is ok with me blacksmithing just not in the garage. So I'll have plenty of ventilation. 

 

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4 hours ago, Anachronist58 said:

"Military Contractor" increases the risk significantly. they might be Cadmium plated. Others here will chime in soon I expect.

I disagree. It may increase the hazard, but the risk remains the same.

The quantity used..and in the position described...there is still only the same low risk they will reach the temperature required to create any hazard.

Alan

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Alan Evans, hazard, risk? I am fine with your semantic correction. And your assessment is sound.

The screws have a Fastenal head stamp, and the company does apply a cadmium finish to some of its products. I'm only suggesting that the OP be aware of possibilities and educate himself, not call hazmat and the EPA

I have Cad plated items lying about, I simply regard them with a prudent respect.

Robert Taylor

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A substantial amount of time and energy is devoted (wasted)  to producing a "Risk Assessment" for any process beyond scratching your nose over here.

You have to describe the procedure you are about to carry out, identify and list the potential hazards. And then make an assessment for each hazard to quantify the likely risk of it actually occurring, and the steps you will take to prevent it from occurring.

Before I can go on site to install anything I have to send in my Risk Assessment so some clerk with a rule book in the site office can tick the box which says I have assessed the dangers, so they are off the hook. And should anything go wrong the insurance companies have yet more opportunities to get-out of divvying up because I failed to identify the hazard or I failed to correctly predict the risk or my preventive measures were inadequate...what me?...Cynical?

Alan

p.s. I have just looked up the melting points of cadmium 321˚C and zinc 420˚C so I must apologise to you anyway, the risk of fuming if cadmium is indeed increased...given that there is more possibility for the furnace casing to reach the lower temperature than the higher. Still a low risk... and easily resolved with vinegar or any other mild acid....just don't breathe the fumes coming off the pickling pot...

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Note the aircraft hinge section on hatch of this furnace. The cadmium / chromate remains intact in this area even though the door plate has reached peak temperatures a bit above 321° C (609° F), but did not soak long enough to vaporise on this surface. Around the corner is a different story.

I have heavy metals bloodwork done periodically, due to the nature of my work. So far, so good.

No apologies are in order, as I myself am too exhausted to avoid stumbling over every jot and tittle, a harsh situation, as I am quite the pedant. That said, I have read every word you that you have set forth in this thread, and I hold you in esteem.

Finally about the cynicism: I could tell you a harrowing tale from this week at the Rolls Royce Trent factory concerning microscopic titanium plaques on drill margins, but I would prefer to remain employed. maybe I will start a generic thread instead of hijacking this one.

Robert

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