Chromox Duplex (Stainless) chain for rode.

[Muaddib1116]

I've had some questions about SWL before, it seems that there is no standard for what it means. I have speculated that maybe ultimate breaking strength should be the number to care about more, but there are strong arguments for SWL. It is tricky though. With anchor chain, it seems that BBB and G70 use SWL as 25% or UBS, G40 chain uses 33%, and Ketten Walder uses 50%.

It seems like Ketten Walder is a reputable manufacturer of industrial lifting equipment in Germany. It is hard to believe that they are using a poorly conceived criteria for SWL.

I remain unsure of what to think about all this.

[ohthetrees]

I bought a used 2015 Hanse 505 that came with 100m of beautiful 10mm ss chain. I've been unable to determine much about it, and would love to know the manufacturer and the material (316 or 318). Anyone know how to tell? I absolutely love how it performs, never piles up, nice and slippery, cleans easily, no rust, and looks great.

However, I've been getting more nervous lately about how to determine when to retire this chain. I'm not aware of a reliable way to inspect it, and I've been wondering if maybe load testing would be wise. Tough to figure out cruising in Mexico, with no plans to be in the USA for a couple of years. We spend a lot of time at anchor, and it is an important question for us.

We have a short section of the same chain that lives in a locker most of the time as part of our stern anchor setup. I recently found a link with a huge pit in a link, probably eroded 40% of the way through. Yikes! I haven't found anything like that on our main anchor chain, but I haven't inspected every link carefully either.

In summary, I love this chain's performance, but the lack of certainty around life-span, inspectability, and hidden corrosion have got me feeling nervous, and looking for solutions.

[Muaddib1116]

My chain has a few different markings on the links every meter or so. One says "Walder". I then contacted Cromox US, and they told me the easiest check is to use a magnet. 316L is only very very slightly magnetic and 318LN is fairly strongly magnetic, almost as magnetic as mild steel. Those results, with the other markings on the chain, allowed the CromoxUS rep to pretty confidently confirm what my chain was. Later, I actually found the cert form that the previous owner saved.

[SVTatia]

Does anyone know who is the North American distributor for Ketten Waelder Cromox?
I only foud US Stainless, but they re not responding.
I am looking for 8mm 318 LN duplex but can't find anyone who sells on this side of the pond.

[Muaddib1116]

I believe this is their US office, or at least their US distributor.

https://www.cromoxus.com/

I think I communicated with Bruce.

[GRIT]

My quote come from this fellow: jeff@cromox-us.com

Cheers.
Paul.

[pjShap]

I bought from US Stainless 2 years ago.
Bruce Solberg (great guy to deal with)
US Stainless, Inc.
sales at usstainlessinc dot com
Current website is https://usstainless.com/
Phone listed on the site is 804 482 1326 (please leave a voice message).

[B4A]

I just got a quote for 100 meter Duplex L318LN 10mm chain from Cromox Germany.

Does anyone here has first hand experience with this chain? Any feedback?

[Muaddib1116]

I bought my boat a year and a half ago, and it had 10mm Duplex chain on it, installed by a previous owner in 2016, I believe. I have limited personal experience with it, but it was used exclusively in the Med before 2019, when it came over in the ARC to the Caribbean, where the boat was on anchor for a few months due to Covid lockdowns. My use has been a 6 week cruise to Maine last summer. The warm Caribbean waters were probably a much more meaningful test of it's corrosion resistance. As far as I can tell, the chain looks great. I've had all the chain out a couple times and there doesn't seem to be any problems on the end that tends to stay in the chain locker. I like how it looks, how it doesn't castle in the locker, and so far how it performs. I don't plan to worry too much about it until I go south, at which time I'll probably do more strenuous inspections for signs of pitting/corrosion.

[SVTatia]

Originally Posted by B4A

I just got a quote for 100 meter Duplex L318LN 10mm chain from Cromox Germany.

Does anyone here has first hand experience with this chain? Any feedback?

I don't have the expeience, but I did some research as I intended to buy that instead of galvanized. The users are mostly in Europe and the Med and it lasts 10+ years in "cold" water, but I could not find any data or information about the corrosion resistance in tropical waters.

The quote I got from the US distributor also prevented me from going forward...

As Muaddib1116 mentions, the real test will be in warmer climates.

Insteresting conversastion with this materials expert, starting at 17:00.

https://www.youtube.com/watch?v=2g6Is6sf6Vw&t=1027s

[Muaddib1116]

I've watched that video a couple times, and it has some compelling information/arguments in it. I have no reason to think that it is attempting to be deceptive or that the "expert" is not an actual expert of some sort, if not an authority. The PREN numbers that I've found for Duplex steels seem to back up what he says. The 318LN Duplex has a much higher PREN than 316 or 316L, which as he says is only suitable in cold climates. 318LN's higher PREN is supposed to make it suitable for warm waters, which is what the expert in the video above says, and what other things I've read about it indicate. Ketten Walder just recently updated their catalog to indicate they are making 10mm chain in their Super Duplex steel (F255), which was previously only spec'd for 8mm, which is even stronger than 318LN and has an even higher PREN. It's probably even more insanely expensive though.

One other advantage of 318LN chain is that it is stronger than G40. I think it falls about in the middle of G40 and G70. The numbers Ketten Walder has for their 10mm Super Duplex exceeds G70. If money is no object, that would be the chain to go for.

[SVTatia]

Originally Posted by Muaddib1116

I've watched that video a couple times, and it has some compelling information/arguments in it. I have no reason to think that it is attempting to be deceptive or that the "expert" is not an actual expert of some sort, if not an authority. The PREN numbers that I've found for Duplex steels seem to back up what he says. The 318LN Duplex has a much higher PREN than 316 or 316L, which as he says is only suitable in cold climates. 318LN's higher PREN is supposed to make it suitable for warm waters, which is what the expert in the video above says, and what other things I've read about it indicate. Ketten Walder just recently updated their catalog to indicate they are making 10mm chain in their Super Duplex steel (F255), which was previously only spec'd for 8mm, which is even stronger than 318LN and has an even higher PREN. It's probably even more insanely expensive though.

One other advantage of 318LN chain is that it is stronger than G40. I think it falls about in the middle of G40 and G70. The numbers Ketten Walder has for their 10mm Super Duplex exceeds G70. If money is no object, that would be the chain to go for.

Totally agree with you. Even though the high PREN is suitable for warm waters, I still cannot find empirical data.
As to the cost, it is not hard to do the math - suppose Duplex lasts 10 years, this could be 2 or 3 "cycles" for a heavily used galvanized chain, so the initial high cost could be a wash.
This is an industrial (lifting) chain, hence the lack of information for marine use in tropical waters, I hope that will change.

[Muaddib1116]

Depends on what you mean by empirical data. I don't know how the PREN is determined, but if it's in lab conditions or controlled environmental testing, then that's empirical, probably more trustworthy than anecdotal evidence, lacking the absolute wealth of anecdotal evidence we have in regards to galvanized chain behavior. Ketten Walder definitely markets these chains as marine anchor chain, as well as a duplex anchor righting swivel and an interesting looking duplex shackle. It's possible they are just re-marketing existing industrial lifting chain without doing their due diligence, but I think that's unlikely. I think it's likely that the PREN numbers are meaningful and independent of marketing.

I think your cost analysis is basically correct, but the up front cost is the biggest deterrent, that and the limited knowledge of 318LN chain's properties vs the more widespread knowledge that 316 chain is bad. I've said it before, but I think that if the price wasn't so high, a lot more people would be using Duplex anchor chain, and it would be considered by many more people to be the best chain option. I'd be interested to know the price of the Super Duplex 10mm chain. That seems like it is undoubtedly the best option, money aside.

[thinwater]

Originally Posted by GRIT

I was surprised at the breaking strength, and equally surprised that the SWL is 50% of breaking strength. I usually see 25% of breaking strength as SWL, except in the USA where it's often 33%.

Paul.

SWL is derived from both the fatigue limit of the material (50% for this material) plus an allowance for manufacturing tolerances and corrosion. The basis varies with manufacture, but some thing like 3-6 sigma endurance over 100,000 cycles. In this case, they are almost certainly basing it only on the fatigue limit of the alloy, which makes this a dangerous exaggeration. Like other manufactured parts, 25-33% is more realistic.


Because of vulnerability of SS to fatigue and crevice corrosion (which you will not see--it only takes one crack in one weld in one link), the useful life at high load will be similar to galvanized chain in regular use. It will look better and pile better, but should still be replaced in 5-7 years.

[thinwater]

Grit: what is about galvinized chain that did not satisfy you? Corrosion? Piling? Appearance? Mud? Just curious.


One down side of SS chain, seldom mentioned and not relevant to you, is that it is slippery and thus harder to pull by hand. The corollary of why it cleans and piles better.