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Thread: Stainless Steel Fasteners

  1. #1
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    Default Stainless Steel Fasteners

    Has anyone used PHEINOX™ R4*™ Multi-Purpose 305 Stainless Steel

    screws from GRK?

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    Default Re: Stainless Steel Fasteners

    I see them at work every day The company I work for has been a GRK wholesaler for 20+ years. I have seen many used and have used them A LOT myself. Never had any corrosion/warranty issues with the stainless. I'm a big fan of the torx head. I used the stainless R4 and the trim head when I built my little fisherman's skiff. They came out with a 316 Marine Grade Stainless that I'd recommend for saltwater use or just that little extra peace of mind.
    “Friendship ... is born at the moment when one man says to another "What! You too? I thought that no one but myself . . .” – C. S. Lewis

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    Default Re: Stainless Steel Fasteners

    Swedishfish

    Thanks for the reply. Getting ready to build Jeff Spira’s “Albion”. I’ll be taking using it in fresh water so the regular stainless will work just fine. I like the torx head as well.

    Thanks again!

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    Default Re: Stainless Steel Fasteners

    I don't think that stainless screw alloys really much care if it's fresh or salt water. I'm not sure where this bit of wisdom that stainless is reliable in fresh water came from. The problem with stainless fasteners is what is known as "crevice corrosion." Crevice corrosion can occur in stainless steel when it is in an anaerobic environment, i.e. no air. If it is wet, there's not much difference between salt and fresh water, although the salt may add a bit of encouragement to the corrosion. Crevice corrosion is wicked stuff because it can start with barely noticeable pit on the surface and then eat its way into the fastener in just about any direction it decides to take. Stainless will corrode very quickly (e.g. through a 3/8" bolt in five years) once it gets started and because the corrosion is localized, the head will look like new while the shaft is severed clean through. It's a function of stainless forming a protective patina of oxidation on the surface. If that doesn't occur because of a lack of oxygen, it corrodes remarkably fast.








  5. #5
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    Default Re: Stainless Steel Fasteners

    Mr. Cleek

    So, are you saying it is best to use some sort of bedding compound or treatment to any screw that’s used?

    if so, what do you recommend?

    Thanks

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    Default Re: Stainless Steel Fasteners

    I think he means don't use stainless steel, use bronze.

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    Default Re: Stainless Steel Fasteners

    I have recently been unearthing SS screws that I stupidly left embedded in an anaerobic environ for over two decades. To my surprise, nary-a-one of the screws is corroded.

  8. #8
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    Default Re: Stainless Steel Fasteners

    Quote Originally Posted by Mo 'Poxy View Post
    I have recently been unearthing SS screws that I stupidly left embedded in an anaerobic environ for over two decades. To my surprise, nary-a-one of the screws is corroded.
    18-8? 304? 316?

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    Default Re: Stainless Steel Fasteners

    Gentelmen,

    I appreciate your wisdom! That's what makes this forum so valuable and interesting.

    I'll be checking out bronze fasteners for my project.

    Chris

  10. #10
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    Default Re: Stainless Steel Fasteners

    Quote Originally Posted by Bob Cleek View Post
    I don't think that stainless screw alloys really much care if it's fresh or salt water.
    This is the only part that I disagree with. Chloride concentration and temperature are important. http://www.ssina.com/corrosion/crevice-pitting.html

    << https://www.cartech.com/globalassets...vironments.pdf
    https://www.cartech.com/globalassets...bluebook12.pdf >>>

    The GRK stainless screws are good, but not all that strong. The heads will torque off and heads will strip much more easily than the regular hardened steel screws. I'm not saying that they aren't good for fresh water, just that they need to be handled more carefully than normal deck screws. They are a lot tougher than bronze. 305 and 304 stainless steel have overlapping chemistry ranges and some mills will certify a heat to meet both. I have had no problems with stainless screws on a freshwater boat.

    Bedding compound? No. They will drive easier with a lubricant, so a bit of wax or wet varnish isn't bad.
    Last edited by MN Dave; 07-12-2018 at 12:59 AM.
    Management is the art of counting beans. Leadership is the art of making every being count. --Joe Finch

  11. #11
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    Default Re: Stainless Steel Fasteners

    Stainless needs consistent exposure to oxygen. Do not use it if you intend to bury it in lumber. Bronze.

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    Default Re: Stainless Steel Fasteners

    Quote Originally Posted by paxtonm View Post
    Do not use it if you intend to bury it in lumber. Bronze.
    Not trying to be funny but aren't ALL wood screws intended to be buried in lumber?
    “Friendship ... is born at the moment when one man says to another "What! You too? I thought that no one but myself . . .” – C. S. Lewis

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    Default Re: Stainless Steel Fasteners

    Quote Originally Posted by MN Dave View Post
    The GRK stainless screws are good, but not all that strong. The heads will torque off and heads will strip much more easily than the regular hardened steel screws.
    MN Dave I agree. I've seen a few heads snap/torque off(especially on the trim #8's) when driven fast into hardwoods or wet treated. GRK tried to compensate for this with the deck screws (R4) by going up to a #10 vs their standard #9 in their coated screw.
    “Friendship ... is born at the moment when one man says to another "What! You too? I thought that no one but myself . . .” – C. S. Lewis

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    Default Re: Stainless Steel Fasteners

    Quote Originally Posted by SCK47 View Post
    Mr. Cleek

    So, are you saying it is best to use some sort of bedding compound or treatment to any screw that’s used?

    if so, what do you recommend?

    Thanks
    Not necessarily. Bedding compound is another issue entirely. If working in wood that is prone to rot, I'd certainly opt for applying a good sealer (e.g. Smith and Co.'s "CPES") to all screw holes, but the better practice is to use wood of a species not particularly prone to decay. I suppose an easier way of saying it is, "Don't use stainless steel fasteners anywhere that matters on a boat." That said, a lot of the performance of stainless steel in the marine environment depends upon the type of "stainless" steel. There are various alloys, some more suitable than others. Not all stainless steel is created equal. It is also of importance to note that whether screws are truly cut when manufactured, as opposed to "rolled," makes a big difference in the ease of driving and their holding power regardless of the material from which they are made. (Holes for cut screws should be drilled with a tapered drill bit.)

    My go-to marine bedding compound is Dolphinite. Such oil-based bedding compounds require that the faying surfaces be well-sealed (CPES or shellac) before bedding the pieces. This prevents the oil in the bedding compound being absorbed by the bare wood and causing the compound to harden and crumble before its time.

    I'll never forget when my most treasured mentor, a master boatbuilder then 80+ years old, was building his last boat, a beautiful 36' sharpie cruiser of his own design. Even though long-retired, he'd work on building the boat "9 to 5" as if it were a regular job, taking an hour off for lunch at noon. I'd often stop by at his "lunch hour" to soak up as much information as I could. While he was a friendly welcoming fellow, he didn't like to have people dropping in on him and distracting him during his "working hours" unless you were there by appointment to lend a hand on the few jobs that he couldn't do alone. Planking was one of those tasks and when it began, I was amazed to see he was using stainless steel screws to hang plank. They were one of the so-called "marine alloys," but stainless all the same. As diplomatically as possible, I asked, "Gee, from what I've heard and read, stainless screws aren't much favored for plank fasteners. Maybe I was wrong about that." He answered, "No, you're absolutely correct, but have you priced Everdur bronze screws lately?" He explained the huge difference in price between "finestkind" bronze and stainless and then said, "For what they are charging for the bronze, I figure the stainless are going to last longer than I will at my age, so I'm saving my money." That was one of the better bits of wisdom I learned from him. He's passed on, but that boat still sails and is maybe twenty years old now. Last I saw her, I didn't see any planks starting, either.
    Last edited by Bob Cleek; 07-12-2018 at 08:07 PM.

  15. #15

    Default Re: Stainless Steel Fasteners

    A quick word about my hull designs. There are no issues if the fasteners corrode. They're there to hold everything in-place until the glue cures, then fill the hole that would be made if you removed it for the rest of the hull's life. No planks will peel or separate. The hulls are a unitized a bonded structure.
    Jeff Spira


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    Default Re: Stainless Steel Fasteners

    Quote Originally Posted by MN Dave View Post
    This is the only part that I disagree with. Chloride concentration and temperature are important. http://www.ssina.com/corrosion/crevice-pitting.html
    Yes. Crevice corrosion is a form of electrolytic corrosion similar to galvanic corrosion. An electrolyte is required, and salt water is an excellent electrolyte, while fresh is not.
    "Where we would wish to reform we must not reproach." -Thomas Paine

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    Default Re: Stainless Steel Fasteners

    Quote Originally Posted by CPF View Post
    Yes. Crevice corrosion is a form of electrolytic corrosion similar to galvanic corrosion. An electrolyte is required, and salt water is an excellent electrolyte, while fresh is not.
    As I said, chloride concentration and temperature are the drivers. Oxygen concentration also plays a major role. Fresh water is a weak electrolyte with a low concentration of chloride. Things still corrode in fresh water. In the figure below, fresh water is on the left.
    https://www.assda.asn.au/43-applications/marine

    Crevice Corrosion

    In situations where crevices exist, such as at propeller shaft glands and bearings where bolts and chainplates pass through the hull or deck, or where barnacles can grow, severe crevice corrosion can occur. As a general rule, crevice corrosion will occur at around 15-20çC below the temperature at which pitting occurs.
    In many cases, grade 316 proves satisfactory. The diagram above shows that crevice corrosion can be expected in grade 316 at temperatures above 10-15çC in seawater, thus making it unsuitable for immersed applications where crevices exist. For this reason, propeller shafts made from 316 are usually galvanically protected. This may be with a separate zinc anode, but a bronze propeller on the 316 shaft could provide the same effect - the bronze slowly corrodes, protecting the shaft and allowing it to perform satisfactorily.
    Management is the art of counting beans. Leadership is the art of making every being count. --Joe Finch

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