Chain Preparation for Welding

[a64pilot]

You don’t want to use either 6010 or 6011 rod on anything important also known as 5P, use low hydrogen, which 7018 is most common. 5P is for dirty, rusty, greasy metal, and is a brittle porus weld.
The first two digits denote strength and you can get low hydrogen up to 110, maybe higher but I used 110 as a welder in 1980 in the oil patch.
I wouldn’t weld chain, boats too important to me, but I won’t join chain either for the same reason.
This morning in the anchorage we are in right now, my Wife saw her first boat “drag” drag as in it went by sideways to the wind going I’d guess about 7 kts in only 35 kts of wind. They didn’t hit anyone and got it under control of course, but it was amazing to see how fast that boat was going, in only 35 kts of wind.

Now imagine middle of a moonless night with you trying to sleep in 50 kts of wind and rain and the chain goes “pop” in a crowded anchorage.
How many boats in the anchorage are you going to take out? How is your Insurence company going or react when they find out you welded your own chain and they have a large claim?
What really stops me is thinking about explaining to someone who’s boat I wrecked that I welded my own chain, and the weld broke. I wouldn’t like looking at myself in the mirror.

Even if you execute a beautiful strong weld, which isn’t hard really, but how are you going to keep that weld from rusting?

[roland stockham]

For any novice welders out there who want to try this - When you weld zinc plating I believe you get some nasty fumes so either grind back thoroughly or wear a good mask

[Adelie]

If using low hydrogen electrodes they should be out of a freshly opened container or they should dwell in an ELECTRIC oven overnight. If they are from a container open more than a year even the baking won’t save them.

Galvanizing should be removed from around the welding area prior to welding, the zinc is a weld contaminant that can reduce strength by up to 50%.

I’m a construction inspector, including welding.

[Simi 60]

Originally Posted by a64pilot

, but I won’t join chain either for the same reason.

We don't all live in a perfect world.

We currently run 80m
When we re galve we will send all that chain off to get done but have no chain for anchoring.

We will buy a second length

If we bought CMP chain (better grade steel, better galv) it only comes in a 64m or shorter length
If we anchor deep, it simply will not be long enough.
What's your solution?

[zstine]

Originally Posted by RaymondR

The reason for cutting on the ends of the links is that it is the place where least tensile loading of the links occurs. Whether or not it's sound, my reasoning is that a poor weld is less likely to fail under shear loading than under tensile.

Shear strength is ~half of tensile strength. So if the steel is good for 60ksi tensile, it will only be good for 30ksi when loaded in shear.

[Reefmagnet]

Originally Posted by Eigenvector

Just to add some engineering to this discussion..........


A)Links are typically welded mid side due to the way high speed chain making machine hold the links during resistance welding.


B) For chain grades such as G70, G40 etc, the 70&40 refer to a maximum tensile strength of 700 N/mm and 400 N/mm respectively. A grade 50 would be approximately 70 ksi which could theoretically be welded with 70 series filler material (ie 7018). This would also assume that the chain is not heat treated alloy.



c) Shear strength is 1/2 the Tensile strength, so putting he weld at the end gains nor looses anything, assuming it's pure shear, which it's not.


But, that was a slick way to cut the links to eliminate having to bend. I'll have to remember that.

C) isn't 100% correct in practice. Weld defects can and do reduce the strength of the weld, sometimes dramatically depending on nature and orientation of the defect and when subject to shock loading. Any undercut or lack of fusion on the outside of the link will make it especially susceptible to failure. The advantage of welding along the side of the link is that the link itself assists in absorbing shock load prior to that shock reaching the weld and the plane of typical weld defects is now perpendicular to the load, reducing the stress concentration around the defect.

[Mike Banks]

I simply get one of those split link joiners, grind off the galvanising where the sides come together, bash it shut into place then braze or silver braze the faces in contact. Do a similar one on a piece of scrap chain then have it load tested just so you will have peace of mind.

[captlloyd]

Originally Posted by roland stockham

For any novice welders out there who want to try this - When you weld zinc plating I believe you get some nasty fumes so either grind back thoroughly or wear a good mask

Absolutely and you will get a much better weld also.

[Eigenvector]

Originally Posted by zstine

Shear strength is ~half of tensile strength. So if the steel is good for 60ksi tensile, it will only be good for 30ksi when loaded in shear.

Correct.


However there are geometries which result in double shear loading. The geometry of a two chain links is not one of them however. A good tight shackle (clevis depending on where you live) connected to a pad eye would be one example. Pin is in double shear and would tear a section of the pin out during failure.

[Eigenvector]

Originally Posted by Reefmagnet

C) isn't 100% correct in practice. Weld defects can and do reduce the strength of the weld
Yes Maybe but Maybe not. there are acceptable amounts of porosity and cracks allowed by code, sometimes dramatically depending on nature and orientation of the defect and when subject to shock loading Nope. Shock doesn't normally come into play except with brittle materials with sharp cracks. Look up glass transition temperature or charpy impact testing. I don't want to get into a fracture mechanics class here. . Any undercut or lack of fusion on the outside of the link will make it especially susceptible to failure It depends if its a stress riser oriented in the principle stress direction. If not, then no. The advantage of welding along the side of the link is that the link itself assists in absorbing shock load prior to that shock reaching the weld and the plane of typical weld defects is now perpendicular to the load, reducing the stress concentration around the defect And a big NOPE. Look up free body diagrams. Shock waves travel at the speed of sound for the given material. Do you really think it stops over a distance of 1 inch or less?..

Look guys. My original comments were just as a very simple education for others that:


A) Don't have multiple engineering degrees
B) Are not Registered Professional Engineers

C) Don't own an Engineering Company
D) Don't do ASME Pressure Vessel Work
E) Don't do API 579 Damage assessment work
F) Don't develop AWS welding procedures
G) Sail better than me.

[Reefmagnet]

Originally Posted by Eigenvector

Look guys. My original comments were just as a very simple education for others that:


A) Don't have multiple engineering degrees
B) Are not Registered Professional Engineers

C) Don't own an Engineering Company
D) Don't do ASME Pressure Vessel Work
E) Don't do API 579 Damage assessment work
F) Don't develop AWS welding procedures
G) Sail better than me.

You might want to knuckle drag yourself down to grass roots level and check the Charpy, Izod and even the "nick break" tests used for weldments, in that case.


Just sayin'

[RaymondR]

It is not a matter of welding being perfect, it is a matter of being better than the alternatives.

[SaltyMetals]

While i admit that a single full length wld be better there are times when i join chain but i only use the Crosby links. I Zn spray the link w 2-3 coats before hand and another 2 afterwards bec i have found that the galv on the chain links tends to be consumed after a few years such that it becomes better to cut out 2-3 links each side and then use another Crosby link. The Zn spray treatment before and after joining seems to have stopped the sacrificial consumption of the galv on neighbouring links. Now is welding (assuming the welder knows what he is doing....) going to be stronger than a Crosby link?
andrew

[col50]

Originally Posted by RaymondR

I needed to join some anchor chain I had had galvanized. I weld my chain to join it because I tend to the opinion that this method gives the best result.

The first image shows an end link being cross cut on the link end. Both ends of the chain are prepared in this manner.

The second image shows the two X cut links.

The third image shows the end links being linked together ready for welding.

I hope you are planning to remove the rust next to the joint before welding.
If you don't, it will contaminate the weld.

[Lodesman]

Originally Posted by Mike Banks

I simply get one of those split link joiners, grind off the galvanising where the sides come together, bash it shut into place then braze or silver braze the faces in contact. Do a similar one on a piece of scrap chain then have it load tested just so you will have peace of mind.

I've been curious about how well that would work. Any issue in the salt water being dissimilar metals?