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New boat - Stainless fitting rusting?

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New boat - Stainless fitting rusting?

Old 02-11-2016, 09:32 AM
  #41  
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Default You are trying hard. Good luck. They are pretty dead set

Originally Posted by finsleft258 View Post
Even if it is 316L it can and will rust if not bedded properly. Even if the fasteners are 316L and the studs were welded with the correct filler rod. IF STAINLESS GOES ACTIVE IT WILL RUST, CORRODE, PIT, OR CRACK!!!

The problem is the perception of what the alloy is/was designed to do. It also has to do with the tooling that the metal was exposed to. There are common stories listed about how the quality of metals has dropped; they haven't. In fact, the are more uniform now than they were before (albeit, the ratios are so closely monitored that it is possible to have a slightly "worse" alloy of 304 or 316 than decades ago simply because the controls are so much better).

Consider this as well, if the metal is cleaned with a polishing tool (wire brush, Scotch pad, etc.) that was previously used on steel or is made of a lesser alloy of steel, the surface will rust due to contamination.

I have tried to explain this in person on a guys almost new high end boat. He would not believe me.

! 1 All stainless steel including 316 has 60% carbon steel or Iron steel that can be brought to the surface very easily. Most all rust removing cleaners will cause the fitting to rust even faster in the future.
Watch the Gem Video in the beginning of the thread that many on here refuse to believe??

If it is not installed properly. saltwater gets under it. It works and works and eventually causes rust to form.

Too strong of a cleaner will cause the best grade of stainless to rust. Fact

Good luck finsleft258. Its a tuff crowd. You have all the facts. But, its not enough around here.
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Old 02-11-2016, 05:10 PM
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Am I being totally naive in asking....... If you wash your boat with soap and water really good and then dry with a chamois would this still happen? Is there a fine misting spray that you could us to help prevent this?
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Old 02-11-2016, 05:37 PM
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Originally Posted by billinstuart View Post
Stainless is a class of steel which contains Chromium, and sometimes molybdenum and/or nickel. These added metals tend to make stainless likely to oxidize, among other properties they impart to the steel.
This guy knows what he speaks! Yes, 316 is more but better, on the other hand cost plays a part at retail?
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Old 02-11-2016, 05:50 PM
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Originally Posted by billinstuart View Post
Not all stainless is rust proof. In particular, "chinese stainless" is an oxymoron.
Stain less is not stain proof.

In defence of the Chinese they probably have the skills to make some of the best stain less steel known to man.

Someone here in the USA more than likely specified the particular SS alloy in question. To save a buck.

We have met the enemy. He are us.
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Old 02-11-2016, 08:28 PM
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collinite wax will remove the rust and help protect against further rusting
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Old 02-12-2016, 04:33 AM
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Proper bedding of hardware from Gemlux. http://www.gemlux.com/aboutgem/properinstallation
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Old 02-12-2016, 07:33 AM
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Well my new Edgewater has SS hardware rusting, they sent me some new hardware so I will take the advice on this post and also use a marine sealant to create a gasket between the hardware and surface. Thanks to all posting this has been very helpful to me.

Jim
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Old 02-12-2016, 09:07 AM
  #48  
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Originally Posted by jshadow View Post
Good luck finsleft258. Its a tuff crowd. You have all the facts. But, its not enough around here.
Finsleft does have all the facts, and I'm willing to bet he also has signs of rust on his boat as well.
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Old 02-12-2016, 09:30 AM
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I'm surprised that some of you folks with metallurgy backgrounds haven't discussed re-passivation of stainless steel with citric or oxalic acid. While proper bedding of stainless steel hardware is essential for minimizing crevice corrosion and staining of the adjacent fiberglass, folks who already have some rust need to know a few things about cleaning it up without encouraging more corrosion.

As already explained, the rust resistance of stainless steel is determined largely by the chromium content, which allows a thin layer of chromium oxide to form on the surface of the steel when it Is exposed to oxygen. When the oxide layer is exposed to chloride or chlorite ion (from saltwater, hydrochloric acid, or bleach) in the absence of oxygen, the protective oxide layer is destroyed and rust forms.

While strong acids such as muriatic (hydrochloric acid) or phosphoric will rapidly remove rust, they can leave components on the surface that will encourage more corrosion. That's why nitric acid is historically used in the original passivation process at manufacturing facilities. But nitric acid is being replaced by the use of less toxic organic acids, typically a 10% citric acid solution. Besides not containing any chloride, citric acid is a chelating agent that binds the oxidized iron (rust) and keeps it in solution where it can easily be rinsed away.

You can re-passivate stainless steel parts by using a cleaner that contains citric acid such as Spotless Stainless (http://spotlessstainless.com/), but the trick is that you need to let the cleaner stay in contact with the steel for at least 30 minute before rinsing it off. There are other products sold for cleaning and re-passivating stainless steel. Just look for the ones that contain citric acid.

I've used Spotless Stainless successfully to restore deck fittings after removing them and soaking them in Simple Green to first remove grease and dirt. I used a toothbrush to clean off the loose stuff. After rinsing, I soaked them in Spotless Stainless overnight. The product does not work as quickly as they show in their advertisement, but it does remove the rust with a little more scrubbing. After rinsing and drying the fittings and re-bedding them with Boatlife Lifeseal, I've not gone 2 years without visible rust.

The only downside of citric acid cleaners is that they react with concrete. I have a couple holes in my driveway where I spilled some Spotless Stainess and didn't rinse until 30+ minutes later.
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Old 02-12-2016, 09:53 AM
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I've been using a citric based cleaner on my S&W 629 for years and agree with DocStresser. Shows a little rust from storage and I let the cleaner sit on there and it's like new.
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Old 02-12-2016, 10:13 AM
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Couple more points relevant to some of the information in this thread.

There are a number of broad classes of "stainless" steels out there - austinitic, ferritic, and duplex. Austinitic and ferritic refer to the crystal structure in the metal alloy, and are most easily determined with a magnet. Austinitic stainless steels are non-magnetic, Ferritic stainless steels are magnetic (note that carbon steels also have a ferritic structure). Duplex stainless steels are a more exotic mix (in the grain structure) of ferritic and austinitic steel in the same material. There are other classes of stainless such as precipitation hardening stainless steels, but they're typically not used on marine parts.

Simply stated:

300 series steels are austinitic, non magnetic, and generally used in marine service fittings and hardware. More resistant to corrosion than 400 series. Strain hardening (hardened by stretching the material), can't be hardened by heat treating.
400 series steels are ferritic, magnetic, and generally used where higher yield strengths are required (think structural stuff). Can be hardened by heat treating. (For reference most stainless firearms are made with 400-series stainless because of the heat treat/strength requirements and resistance to galling, which is a whole 'nother topic.)
Duplex is pricey exotic stuff generally only used in industrial process equipment (think great big seawater pumps, industrial chemical pumps, etc).

If you have a cup holder that holds a magnet, it isn't 300-series stainless. Likely 400. You got boned.

As stated earlier 316 is preferred over 304 for improved resistance to chlorides. Chlorides induce an intergranular cracking mechanism which is different from rust. Usually this is a really big problem in thin cross section items (like tubing or sheet/stamped goods).

the "L" versions of 300 series stainless steels are low carbon primarily for weldability. The carbon in the non-L versions does not cause rust in a properly annealed chunk of metal, but when welded, the rapid heat/cool cycle will cause the chromium and carbon to form carbides (called carbide precipitation), depleting the local metallurgy of chromium. Once chromium content falls below about 12%, the rust sets in.

Translation - non "L" versions, when welded, will be more susceptible to rust in the weld region.

As noted above by DocStressor and others, residual (ferritic) carbon steel embedded in stainless steel will also cause rust (typically sudden emergence of little spots of rust). The source of carbon steel is the tooling used to make the part. On properly manufactured stainless parts, a passivation step is included after all metal cutting and forming operations are complete. A proper milspec passivation involves dunking the part in a heated (iirc 180F) Nitric acid solution for an hour or two. That nitric preferentially eats away the carbon steel, leaving a clean stainless surface which forms a clean undisturbed passive layer that is then ready for service.Parts that have been passivated can still be contaminated with free iron by poor handling and installation practices. Run a carbon steel file, steel wool, wire brush, etc. across the part and you just did it.

These kinds of threads are hard because people try to make sense of little snippets of information handed down by welders, engineers and material science folks, and then try to piece that information together. People spend entire careers becoming expert on material science. The armchair efforts generate a lot of misinformation and half truths that result in bad practice. Just how it is. Innoculate yourself. In general, marine fittings should be made of 316L, properly passivated and installed in a way that doesn't introduce free iron.

Last edited by JiminAZ; 02-12-2016 at 10:36 AM.
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Old 02-12-2016, 11:22 AM
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Originally Posted by TTB View Post
Finsleft does have all the facts, and I'm willing to bet he also has signs of rust on his boat as well.
NOPE I am working on my new one now. There will be very little visible hardware for this exact reason. I will post a thread in a few months when it is completely finished.

Another note on passivation as others have mentioned--most marine hardware is electro-polished, which will also remove foreign contaminates in the material. Simple chemical passivation will do little to help welds where the chromium was burned off (too hot of a weld) or in terms of long term stability of the weld. It is also not going to remove embedded solids.
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Old 02-13-2016, 10:33 AM
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Originally Posted by rocketman1 View Post
Proper bedding of hardware from Gemlux. http://www.gemlux.com/aboutgem/properinstallation
I think this says it all and probably OP root cause. No need for more metallurgy class.
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Old 02-13-2016, 10:59 AM
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Originally Posted by Pioneer180 View Post
I think this says it all and probably OP root cause. No need for more metallurgy class.
Agree, watch the gemlux video!!
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Old 02-14-2016, 06:37 AM
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Micro cell corrosion I think but as to the cup holder why not just use plastic? Very cheap and when it looks bad in several years just change it out.
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Old 02-14-2016, 06:53 AM
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Originally Posted by billinstuart View Post
Not all stainless is rust proof. In particular, "chinese stainless" is an oxymoron.
There is very little stainless being cast in the USA. It's thankless dirty labor that few Americans would stand for these days.

Getting quality out of China is the same as getting quality of an American factory. Inspect and hold your imports to high standards. Don't choose your factories based on price alone. "Made in China" by itself is meaningless. Your iPhone is made in China. Gemlux does not have a casting factory here in Florida.
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Old 02-14-2016, 07:05 AM
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Have you tried Spotless Stainless? I applied 2 months ago, and it did a good job removing the rust off a neglected cc. I wanted to try it because there is no acid in the formula, does not require scrubbing or buffing and claims to leave a protective layer. Fine for fiberglass too. 2 months later, and the new look of the stainless is still there.

However, I doubt it will work were the rust has piled thick into those crevices. That is a bedding issue that has been well covered by other members.

http://spotlessstainless.com/
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Old 02-14-2016, 08:53 AM
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See my post above. Spotless Stainless contains citric acid. This is not a strong acid, so you don't need to wear gloves. But it will eat a hole in your driveway unless you rinse it off right away.

But as you suggest, it doesn't get in and remove crevice rust. You need to disassemble the parts, clean them, and reinstall with proper bedding.
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Old 02-14-2016, 09:35 AM
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Ah, yes, good post.

Originally Posted by DocStressor View Post
See my post above. Spotless Stainless contains citric acid. This is not a strong acid, so you don't need to wear gloves. But it will eat a hole in your driveway unless you rinse it off right away.

But as you suggest, it doesn't get in and remove crevice rust. You need to disassemble the parts, clean them, and reinstall with proper bedding.
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Old 02-14-2016, 10:14 AM
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If you ask key west boats, it's all the dissolved iron in your wash water.
Same reason your irrigation system makes rust stains on your house.

(Not kidding, that's their explanation)
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