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Thread: 304 vs 316 stainless

  1. #1
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    304 vs 316 stainless

    I have a customer who always asks for 316 stainless, saying it can't be 304 because it's for exterior use, the problem is that 304 is available in a lot of different shapes and sizes, whereas 316 is not,

    I've never had a problem with 304 rusting outside, I did a brushed 304 railing about 100 ft from the ocean, and it held up just fine,

    What should I tell him, does the additional molybdenum make 316 that much more corrosion resistant? I know it makes it a lot more expensive.

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    304 vs 316 stainless

    316 is more corrosion resistant in certain cases. Maybe the customer needs it. Maybe it is overkill. Maybe he just needs passivation.

    304 is used in kitchen utensils, and holds up in the dishwasher just fine. But once a rust spot shows up, it can be difficult to passivate again.

    In places where oxygen may be depleted (crevice corrosion situations), 316 is far superior.

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    Re: 304 vs 316 stainless

    Quote Originally Posted by MetalMan23 View Post
    I have a customer who always asks for 316 stainless, saying it can't be 304 because it's for exterior use, the problem is that 304 is available in a lot of different shapes and sizes, whereas 316 is not,

    I've never had a problem with 304 rusting outside, I did a brushed 304 railing about 100 ft from the ocean, and it held up just fine,

    What should I tell him, does the additional molybdenum make 316 that much more corrosion resistant? I know it makes it a lot more expensive.
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    Re: 304 vs 316 stainless

    Quote Originally Posted by MetalMan23 View Post
    I have a customer who always asks for 316 stainless, saying it can't be 304 because it's for exterior use, the problem is that 304 is available in a lot of different shapes and sizes, whereas 316 is not,

    I've never had a problem with 304 rusting outside, I did a brushed 304 railing about 100 ft from the ocean, and it held up just fine,

    What should I tell him, does the additional molybdenum make 316 that much more corrosion resistant? I know it makes it a lot more expensive.
    I used to live on the coast, 304 does rust, just takes a while. 316 doesn't. Yes, it is a better alloy, you are getting what you pay for if corrosion is the deciding factor.

    some shapes it's only a little more expensive, depends a lot on the customer base your supplier serves. If you are near a lot of marine industry or chemical industry, 316 is easier to find and only a little more expensive.
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    Re: 304 vs 316 stainless

    Quote Originally Posted by MetalMan23 View Post
    I have a customer who always asks for 316 stainless, saying it can't be 304 because it's for exterior use, the problem is that 304 is available in a lot of different shapes and sizes, whereas 316 is not,

    I've never had a problem with 304 rusting outside, I did a brushed 304 railing about 100 ft from the ocean, and it held up just fine,

    What should I tell him, does the additional molybdenum make 316 that much more corrosion resistant? I know it makes it a lot more expensive.
    IMHO the spec for 316 is extreme overkill unless you are installing railing in a chemical plant or where corrosive chemicals are used. I believe this is a case where a little knowledge is jut showing stupidity. I would tell him to find someone else to do the job. The extra cost of the 316 material will make the project cost prohibitive as well as make fabrication harder. I would passivate any fabrication involving SS. I would bet that once he see what it will cost it will be a no go anyway.

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    Re: 304 vs 316 stainless

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    Re: 304 vs 316 stainless

    304 railing that I mentioned being close to the ocean, I've never had a call back on that so, what I did was I rubbed wax on the stainless steel after I finished installing it. That has been at least 5 years ago, guarantee if it was rusted I would have got a call back by now , I actually did drive by in a couple years ago and look at it and it wasn't rusted from what I could see

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    Re: 304 vs 316 stainless

    Quote Originally Posted by MetalMan23 View Post
    I have a customer who always asks for 316 stainless, saying it can't be 304 because it's for exterior use, the problem is that 304 is available in a lot of different shapes and sizes, whereas 316 is not,

    I've never had a problem with 304 rusting outside, I did a brushed 304 railing about 100 ft from the ocean, and it held up just fine,

    What should I tell him, does the additional molybdenum make 316 that much more corrosion resistant? I know it makes it a lot more expensive.
    304 is perfectly fine outside, unless your on the coast. then its a risk of it slowly rusting.
    i would simply give them the price of both. most people will take the risk with the cheaper 304.
    however some people want the best and are not afraid to spend the $$.
    don't think your doing them a favor by using cheaper materials. thats a trap for any tradesman.

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    Re: 304 vs 316 stainless

    Like others said 316 is more corrosion resistant and generally recommended for areas near the coast/saltwater outside whereas 304 is recommended for outside away from the coast. But I would highly recommend either passivation, or electropolishing if you want it really shiny too. But if the customer really wants 316, then give it to him and charge extra for the material. But i would still passivate it, at least.
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    Re: 304 vs 316 stainless

    So if I put 304 stainless posts for a cable rail near the ocean am I screwing myself?

    Should I clear coat them? should I passivate them?

    Or should I just buy a kit of stainless steel cleaner and passivator and tell the customer that it needs to be done once a year

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    Re: 304 vs 316 stainless

    Passivating is done in an acid bath at an industrial metal finisher, it isn't really something you can have a customer do with a squirt bottle (though there are solutions you can get like that for small areas). Passivating also gets rid of any weld discoloration, if done properly. Electropolishing does all that plus makes it very shiny.

    Again 316 is recommended in those installations, but it is up to you and the client. I know 316 is pricier but i don't know how much more in your area. Material cost may not be a huge factor in these things.
    -Dave
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    Re: 304 vs 316 stainless

    In the end though,,, if you tell him something other that what he's specified will work just fine, it might come back to haunt you

    304 is what exhaust tubing in your truck is made from. It does get surface rust....

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    Re: 304 vs 316 stainless

    My 304 tubing has rusted outside in the pnw. Just surface rust tho

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    Re: 304 vs 316 stainless

    Quote Originally Posted by BaTu View Post
    In the end though,,, if you tell him something other that what he's specified will work just fine, it might come back to haunt you

    304 is what exhaust tubing in your truck is made from. It does get surface rust....
    Pretty sure factory SS exhausts are 400 series, but I know people have used 304 also.
    -Dave
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    Re: 304 vs 316 stainless

    Quote Originally Posted by davec View Post
    Pretty sure factory SS exhausts are 400 series, but I know people have used 304 also.
    Correct. 316 is used in better exhausts. 316Ti is often specified for stainless that needs to take such heats and not corrode.

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    Re: 304 vs 316 stainless

    I realize this Q is 4 weeks old but....
    We never use 304 externally , fine internally .
    It "Tealeafs" far too quickly and does corrode .
    Additionally we actively discourage satin externally as opposed to gloss. Gloss definitely stains much slower.
    We are based in Sutherland Shire in Sydney a coastal Shire and do only balustrading , some parts of Greater Sydney are upto 40-50 kms from the ocean but even then we would still use 316.
    I have no experience "Inland" .
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    Re: 304 vs 316 stainless

    If the customer is asking for it, why not give it to him?
    I realize 316 isn't as common or easily attainable but if it's being requested, I have a hunch the customer knows what he wants or he wouldn't be specifically asking for it.
    What does he want made?

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    Re: 304 vs 316 stainless

    When a customer wants 316, I have learned to just price both 304 and 316. Most of the time, they will take the 316 quote as they know what they want.

    If the material is not standard stock locally, most will switch to 304.

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    Re: 304 vs 316 stainless

    Quote Originally Posted by MetalMan23 View Post
    304 railing that I mentioned being close to the ocean, I've never had a call back on that so, what I did was I rubbed wax on the stainless steel after I finished installing it. That has been at least 5 years ago, guarantee if it was rusted I would have got a call back by now , I actually did drive by in a couple years ago and look at it and it wasn't rusted from what I could see


    Is this the one your working on now?

    316 on average is about 25% more expensive than comparable 304 square tube. On angle, sometimes 316 is actually cheaper, I don't know why. It pays to shop around at different suppliers, some specialize in more exotic metals, and forms. Just for the sake of comparison Mcmaster/Grainger gets about $40 a 1-1/2"x1-1/2"x .18" 304 square tube, and $60 for a 1-1/2"x1-1/2"x .18" 316 square tube, about 20 dollar difference for 3ft lengths. If you did about 20 posts the difference would be about $400 for the posts alone. Signifigant, but not absurd.
    What shape of 316 were you having trouble finding ?

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    Re: 304 vs 316 stainless

    If the customer has sense enough to request 316SS specifically then he should already know its going to be expensive. We try not to do any marine fabrication in 304ss. We service the marine industry, food industry and lab settings and pretty much all stainless needs to be passivated after fabrication and put into service. All marine or residential railings are also high polished with Walter compound. Luckily most marine fittings and tubing come EM polished. If you are doing stainless railings I believe King Metals carries a line of 316 ss components.
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    Re: 304 vs 316 stainless

    Both 304 and 316 and hastalloy fittings will rust,I saw first hand when working on Johnston Atoll on the JACADS site.The 304 and 316 pipe came polished and it still rusted that salt air environment rusted everything,but that was a good job anyway.

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    Re: 304 vs 316 stainless

    Was it passivated or electropolished after welding/fabrication? That is the first big item...

    But also remember it is called stainLESS not stainFREE. Just LESS staining, not none of it! It is better at resisting rust than any plain steel but it is not impervious to it under the right conditions.
    -Dave
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