s/s versus C70 chain

[Birdseye]

I was reading the interesting anchor chain thread.

In terms of strength, would s/s chain be stronger or weaker than G70 (of the same size, of course).

G70 chain uses material to 700MPa which is 45 tons tensile. A typical austenitic stainless steel after annealing will be about 30 to 35 tons tensile and the act of welding will effectively anneal the material in the weld zone. So no , I would not see stainless chain as being as strong as G70. To get the same strength you would need to increase the wire diameter in the link by 25 %

 

[Roberto]

But if you are considering G70 note that it is very, and I emphasise the very, difficult to find connectors that fit the chain and are sufficiently strong. Simply put - most shackles are not strong enough.

I do not use G70 chain but use this type of link between anchor and chain, I think it may be made of G80 (?), anyway WLL is way above same diameter chain, even G70: the connecting link for 10mm chain has a WLL of 3.2tons, Aqua7 10mm chain has a WLL of 2.2t. I have not checked but I imagine the safety factor for lifting gear should not be lower than that for anchoring chain so the difference in Breaking load might possibly be even higher (?).

Each one is proof tested to 2 SWL, stamped and certified for lifting work.
I have been using one for two years and so far rusting has been very limited.
No problem in changing it often if need be, they cost about 7-8 euro at fishermen cooperatives, they use it for net lifting gear.


There may be a problem if one uses the same rode with different anchors, as it takes longer to open them (need a hammer, etc) than opening a regular galvanised shackle (one that has not rusted, that is )

 

[J Neeves]

Most Google sources of these standards want to sell you a copy at an eye-watering price. However, I have been informed, by a poster here I think (thanks) that you can access East European sites where the standard is displayed for free. Here is one that seems to be Turkish http://www.eginlioglu.com/default.asp?Sayfa=DINEN818_2

The suffixes appear to specify different chain grades.

Thanks Vyv, the only links to the EN standards wanted me to pay lots and lots of cash - so I did not even think about it!

Jonathan

 

[J Neeves]

Roberto,

The devices you picture are called Hammerlocks in America, I'm not sure what anyone else might call them. They come in G80 and G100 strengths (maybe G120) but you can buy weaker ones. I have not seen small galvanised versions but have seen larger commercial sized ones that have been galvanised. I suspect the lack of galvanising is one reason they are not popular in the leisure marine industry. Another reason might be that the pin that holds them together looks very wimpy - even if it is obviously strong. A final reason they may not be popular is that the pin will take a lot of wear, sand in the joint, and you cannot see it (for wear or corrosion) without taking it apart.

These units are very wide and they will not fit in some bow rollers. As with all of these components you really need to try them as bow rollers, chain and anchors are all vary slightly in size.

As you mention the safety factor will not be lower than an anchoring application and much lifting gear, the components, are rated at 6:1 - but again you need to check - some are rated at 4.5:1 and some 4:1. From current reputable, for America Peerless, Campbell etc, and Pewag, Gunnebo and Van Beest etc for Europe, suppliers they are individually Proof Tested and can be sourced from lifting distributors or commercial fishing suppliers. The Chinese seem to have an industry - or it is possible to buy G70 and G80 chain - but if this is a new development I'd watch quality short term (no disrespect - but initial production runs of other 'things' have sometimes been questionable - but they will quickly get it right!).

The Armorgalv process, I mentioned in an earlier post, is perfect (well almost) for these high tensile Q&T components as the process can be conducted at lower temperatures. Gunnebo (the hammerlock you feature) are a licensed processor (coating big chains) and they may galvanise other items using that process (for the fishing industry - so maybe the components will be too big).

There is a whole stack of interesting components used in the lifting industry, chain hooks, swivels and variety of connectors, that are made to G80 or G100 specs that look ideal for marine leisure application - if only they were galvanised (and tested subsequent to galvanising). Van Beest, Pewag and Gunnebo are all European suppliers (and all are playing with or using Armorgalv - even with G120).

I'm in the middle of testing Armorgalv processed products, chain, shackles, 'C' links etc - hopefully the information will hit a UK magazine. I'd not get excited about Armorgalv G30 or G40 chain but anything HT, including G70 (and higher) - interesting opportunities.

Jonathan

 

[Roberto]

they may not be popular is that the pin will take a lot of wear, sand in the joint, and you cannot see it (for wear or corrosion) without taking it apart.

These units are very wide and they will not fit in some bow rollers. As with all of these components you really need to try them as bow rollers, chain and anchors are all vary slightly in size.

As you mention the safety factor will not be lower than an anchoring application and much lifting gear, the components, are rated at 6:1 - but again you need to check - some are rated at 4.5:1 and some 4:1.

Hello Jonathan,
thanks for the reply.

Indeed it's a bit of testing on my side, I have never seen a boat using them for anchoring purposes so I do not know what to expect, obviously I am keeping a close eye, especially about corrosion.

As to their width, indeed it's up to the various setups one finds on different boats.
Just as an example, I have 10mm G30-G40 chain (whatever it is, say regular chandler chain). A 12mm certified "coloured pin" shackle would not easily pass inside my bow roller, so I swapped to a Kong connector, which went smooth inside the davit. The Kong connector sometimes came up locked against the anchor shank in weird positions I did not like; on some instances the anchor/rode came into severe loads and afterwards I did not notice anything worrying; however, when something does not "look" good there is often a reason.
I could not use Vyv's advice to insert a few links of chain between the anchor and the connector as the whole lot would become too long -I have a short distance between the bow roller and the windlass. Eventually, this G-link/Hammerlock is perfect for my setup at the moment, I'll see how it evolves with time.
Knowing it has been tested inside its elastic limits at probably 6+ tons, whereas my regular chain is supposed to break at 5ish tons, well it gives some confidence for a start.

We'll see what happens

regards
r

 

[J Neeves]

Roberto

I've tested Armorgalv coated hammerlocks on the seabed and then tested for strength. So I've abraded them under load. I'm not daring to recommend them but I can find nothing wrong (so I think your solution is more than adequate). They work well, fit in some situations (but may not in others). I'd be looking at them as consumables and as they are so cheap I'd retire as soon as I saw rust developing in the pin. I'd have a spare on board ready. I suspect they might be a real issue taking them off, when the pin has started to corrode - but that is why you carry bolt croppers! Personally I'd use them but I change my anchors frequently, for testing something or other, and needing a hammer and HT pin to knock out the pin is too much hassle.

If you find this all works for you contact Spencer Industries in America - they take G80 hammerlocks of the sizes we use (based on Peerless G80 range) and Armorgalv coat them (for the US Navy). They might sell to you - though having an American company export, anything, is not easy! The other alternative, might be easier as you are based in Europe, is to contact Gunnebo and ask them about Armorgalv coating of small hammerlocks. We have a Armorgalv coating facility here in Oz, and I have them coat items specifically for testing - the process lends itself for very small items, like those hammerlock pins and sleeves (so check the Distekna or Armrogalv website in America and see if there is a licensee near you (and they might then coat for your precise needs). if you follow this route, let us know in the fullness of time.

Jonathan

edit You can galvanise G80 components, normal hot dipped galvanising HDG. But many galvanisers will not process. Those that will galvanise will take special precautions and greater care. They should not acid wash, pickle, but only sand blast (and they need to get all the paint off) you will lose some strength, so maybe HDG a G100 hammerlock to cater for the strength loss. Ideally you want to test, to destruction or just Proof Load to 2 x WLL of your chain to look for deformation. So speak to your local galvanisers and see who is most sympathetic - but try to make sure they know what they are doing - there are members here who galvanise for a living - start a new thread if you want more detail. close edit.

 

[William_H]

I find it surprising that people are concerned about the strength of the chain SS versus mild steel. Surely if the weight of the chain is adequate for the anchoring job then strength will be more than adequate. I would go for SS except for the cost part. Indeed some Mobo at ourt club have SS anchor chain.
I have all stainless steel chain and fittings on my swing mooring. No sign of deterioration or pitting and no sign of wear compared to iron shackles etc. Iron connected to SS is a really bad area of wear/ corrosion and should be avoided. So you will need an SS anchor to go with SS chain. Very shiny but very expensive. good luck olewill

 

[J Neeves]

There is a lot of stainless steel chain around that is not made to a specification, or not one that is obvious to the buyer. It might be heavy (and shiny) but weight, and beauty, is no indication of strength.

But the application of G70 is built on the concept that weight is totally irrelevant. At 30 knots and more all the chain is off the seabed and looks as straight as a billiard queue. Consequently, as someone said, if you could have piano wire at the correct strength it would do the job just as well (as that queue straight chain) for much less weight (and space).

But I would hesitate to look at a MoBo, or the average of a number of MoBos, as examples of good anchor and rode practice. I wonder how many use rated shackles. Most of their anchors seem to be very small and many of the stainless anchors are unbranded and therefore of questionable use at +20 knots. For much less money they could have invested in a reliable galvanised anchor and a Proof Tested chain - but they would be missing the glitz factor. Anchor Right here do say, when asked for a stainless anchor, that their gal anchors are certificated, not so the stainless anchors. Many find certification of little cosmetic value and buy stainless anyway.

Jonathan