Useful Life of Stainless Steel Hardware

[silverp40]

I just read on stainless fabricator's website that "with proper care, stainless hardware will have a 10-15 year useful life. Stainless steel made in the 60s and 70s will last longer". This company primarily fabricates rails, davits and the like.

Now, it all depends on the quality of the stainless fitting (316, 304, 316L, etc), country of origin and it's application. A stainless turnbuckle or mixing chamber will undergo a lot more stress than a stainless flagpole for example. Chinese knock-offs are always suspect, especially when in a hi load situation (ss anchor shackle).

Given the relatively young age stainless steel has in the pleasure craft industry (about 40 years) it is hard to determine if this is a true statement or not.

Any opinions/experiences would be greatly appreciated.

Shipshape are you out there and how is your ABYC marine corrosion certification faring??



Cheers

[roverhi]

The SS fittings on my Westsail 32 circa 1975 are still going strong except for the chain plates. The whisker stay, boomkin, and bowsprit tangs are all doing fine even though they've been constantly exposed to salt water. Haven't talked to the owner to see how the gudgeon and pintles are holding up but they were fine after 20 years of constant salt water corrosion. The shroud chain plates did suffer from crevice corrosion and had to be replaced at around 15 years. SS has an indefinite life on a boat as long as crevice corrosion or electrolysis doesn't end it's life prematurely.

[James S]

Originally Posted by roverhi

The SS fittings on my Westsail 32 circa 1975 are still going strong except for the chain plates. The whisker stay, boomkin, and bowsprit tangs are all doing fine even though they've been constantly exposed to salt water. Haven't talked to the owner to see how the gudgeon and pintles are holding up but they were fine after 20 years of constant salt water corrosion. The shroud chain plates did suffer from crevice corrosion and had to be replaced at around 15 years. SS has an indefinite life on a boat as long as crevice corrosion or electrolysis doesn't end it's life prematurely.

I have similar experience with my 78 vintage boat...the only real failures I've seen have been chain plates and bolts and a couple welded brackets.

[silverp40]

Yep, also similar experience with our 79 Pearson -chainplates had to be replaced and the forward pipe berths had extensive crevice corrosion where the canvas laid up against the steel. All stainless screws are still in great shape, inside and outside...


The official argument goes like this however: back in the 70s, the metallurgy of ss was not as exact as it is today so more nickel and chromium were added "just to make sure". Hence, ss 304 from the 70s is more like ss 316 from today more or less.

[ShipShape]

Originally Posted by silverp40

Shipshape are you out there

Bwahaha! Yes, I'm "out there", and I should be going up my mast right now to retrieve the CDs I put at the top so the birds would have a more interesting place to sit while they poop on my boat, not drinking coffee and surfing CF. And of course I could not resist a thread about stainless steel hardware.

As you have already discovered, quality control was not as precise in the 60s and 70s as it is now, so manufacturers erred on the side of safety, whereas now products are formulated on the edge of their chemical content definition. THAT is what substantiates the fabricator's claim. But legal liability and the endless unknowns of raw material supplies and manufacturing processes (think Cheap Chinese Crap) preclude easy or definite claims, or answers.

Once it leaves the store, the history and environment of the SS piece must also be considered. SS often appears to fail without warning, similar to aluminum, but probably if you look close there is a reason for the failure. SS "works" because of a chromium oxide skin, and any break in that skin means trouble - the skin acts as an anode and inside the scratch acts as a cathode and now there is a little galvanic cell and the SS starts eating itself. That is why it is important not to scratch SS, and to clean up corrosion (rust) and keep it polished. And welding is a different story - the heat changes the SS around the weld so technically you have two different metals that used to be the same, and galvanic action gets going that way too, there is a specific name for it, maybe Weld Corrosion.

So if you have something under stress like davits, you've got the edges of sleeve fittings scratching their male inserts, bolts wiggling around in their holes scratching inside the hole and at the head and washer or nut, welds, dings and scratches from the everyday life of a davit, salt water, fresh water, acid rain .... Looking at it from the beginning with the raw materials to your boat years later, the variables are endless and essentially unknown. The piece may have a life of 100 days or 100 years, it all depends on __________. There really isn't anything better that can be said than to make a blanket statement of "10-15 year useful life." It is neither true nor false, it is just a generalization that can be backed up by statistical averages. It is easier and safer to just renew important hardware than to have it fail while underway. When you get into expensive custom stuff like chain plates though, that is when you take the time to remove it, clean it up, and inspect it for crevice corrosion. But nobody is going to do that for fasteners. Well, nobody I know.

There is a lot I haven't said, and I love this stuff and could go on all day, but interestingly enough the past few months I have been renewing all the SS fasteners through my deck and cabin top and only have a few days to transform my construction zone back into a sailing vessel. Wow, I get to go sailing! Gah, gotta go aloft now and retrieve those CDs....

[silverp40]

Thanks shipshape for all that great info...

May I make a suggestion:

"And welding is a different story - the heat changes the SS around the weld so technically you have two different metals that used to be the same, and galvanic action gets going that way too, there is a specific name for it, maybe Weld Corrosion." this could likely be IGC, intergranular corrrosion, where the chromium gets burned off by the heat??

I just built a new bowrail and sternrails out of 1" 304 tubing, had my friend Tig it with 316L rod, polished the welds and now there is rust around the edges of the welds- most likely IGC??

Shipshape, can you tell me if I polish these out, will the rust be a constant issue here?

Hope you get the CDs before the birds get to steal the good ones....

[roverhi]

A well done weld that is properly polished will not cause any problems with corrosion. Gudgeons and pintles on W32 were welded 304 and stayed brighter than the stainless that wasn't always under water. If the weld isn't done well, otherwise too much heat, it can cause the alloys in the metal to separate. In your case, I'd think it was more the 304 SS which is notorious for bleeding rust. Continual polishing with Barkeepers Friend will eventually get rid of most of the rust.

[silverp40]

Thanks roverhi

Do you still have the P35? I am familiar to the boat and sailed my friend's many a times - good sailing boat, especially off the wind with the board up....

[roverhi]

Yes, did a solo TransPac this summer to Kona. 15 days 4 hours, 2020 miles from the Golden Gate to anchored in Radio Bay, Hilo. A rather easy downhill slide. Ran wing and wing for 11 days with one jibe. Pretzeled the whisker pole on the second day but luckily also have a spinnaker pole. Biggest problem was didn't hit warm weather till the 8th day. Good thing I was alone as my longies and layered clothes were getting a bit ripe by the time it warmed up enough to wash down.

[ShipShape]

Originally Posted by silverp40

"And welding is a different story - the heat changes the SS around the weld so technically you have two different metals that used to be the same, and galvanic action gets going that way too, there is a specific name for it, maybe Weld Corrosion." this could likely be IGC, intergranular corrrosion, where the chromium gets burned off by the heat??

I just built a new bowrail and sternrails out of 1" 304 tubing, had my friend Tig it with 316L rod, polished the welds and now there is rust around the edges of the welds- most likely IGC??

I should have said "welding is an ADDITIONAL story". I checked Nigel Calder and you are correct, it is called "intergranular corrosion", but the "weld" part got in my head from another name used, "weld decay".

Somewhere in the back of my mind I kinda remember that the weld stick MUST be the same as the material being welded. I took a semester welding class in 1995, and have read a *few* things since then, but without looking into it again I can't say that the different stick is the cause of your corrosion. Similar to what roverhi said, a well done, properly polished weld should not have major corrosion problems - and you said your bow and stern rails are new....

Nigel Calder also wrote, "heating the metal in the area of the weld causes the chromium to combine with carbon in the steel, removing the chromium from its passivating film-forming role". Given that your friend used a low carbon stick, it seems that he knows what is up. When I took the welding class, we were given a thick handout with settings and sticks to use for different metals and applications - there was no need to guess anything. Ask your friend why he chose the stick he did instead of 304, and go over the recommended settings for his welder. You can probably research the settings and stick options on the internet and confirm his choices.

As for those CDs, I think the birds knew they were just blank CDs, it looks like I need to use something obnoxious, like a Barry Manilow CD, or maybe put a picture of Colonel Sanders up there. My neighbors are trying to give away their cat....

[silverp40]

The reason we used 316L is only because I found a bunch of rod at a metal recycling place cheap - $2/lb vs about $20/lb and it was stamped, not labeled. I figured that if there is a difference in metal composition, I would rather the welding material be superior than the tube.

I priced 316 and 316L schedule 40 and it's really steep so 304 would have to do.

Also polished out a few areas and will see how they do. BTW, a Dremmel with a polishing attachment and rubbing compound or rouge is very fast and I did all the welds for each rail in about 1 hour.

I have an excellent book on marine corrosion called the Boatowner's guide to Marine Corrosion by Everett Collier. It deals with virtually every aspect of corrosion on a boat - highly recommend checking it out!
Oh and the Cds - maybe a Black Crowes album would keep away the fertilizers...

Cheers

[silverp40]

Here is a pic of the rail, total cost of materials and labor $365 vs $3500 as quoted by a stainless fabricator. Of course, all labor was mine ($0.10 per hour) plus the paid welder and bending time ($40 per hour).

[GordMay]

Originally Posted by silverp40

Here is a pic of the rail ...

Are your Nav' Lights mounted parallel with the fore and aft center line of the boat, or toed in?

[hellosailor]

Welding problems are something else again. I was watching a documentary that mentioned the oil pipeline welders on rigs at sea, and the way the companies require something like 10 years of experience before they'll hire a pipeline welder--but that even then there's an incredibly high amount of rework after the welds are inspected. Welding is easy, like playing poker. Good welding, a bit more difficult.

the guys at your local stainless fabricator? Who knows.

[harryrezz]

Most of the SS on my 33 year old gal is still fine, tho I did pull all the chainplates, clean them up, replace any that were bad and put in all new bolts (several of which broke off in the removal process).
So far as keeping things cleaned up, the best product I've found is Wichard's "Wichinox". It's a paste that cleans and repassifies stainless. Pricey, but it works.
>> My neighbors are trying to give away their cat.... <<
So take the cat, tie it to the top of the mast, and if it's quick enough you'll have both a clean boat and a well fed cat. Then again, there's the litterbox issue, so maybe its not such a good idea after all ......