There are as many types of chain as there are uses for it — everything from jewelry to ship anchors and all have specific criteria to meet with generally a very limited amount of maintenance to keep them working.
Choosing chain
There are only about five things to consider when choosing a chain: grade, finish, link size, length and use.
Grade: All chain is graded. Common coil chain, that I have seen advertised as ‘proof chain,’ is the lowest grade of 30 which is determined by tensile strength. For grading, as the number goes up so too does the strength and price. By choosing a heavier grade you can reduce the link size which can reduce the cost of the additional hardware you need to put it to use such as clevis/pin,
Left is a link replacer which replaces the broken link and is then hammered flat. Quick links (threaded) come in a wide selection of sizes and are quick and easy to use
anchor shackle, eye hook, grab hook, slip hook, quick link or bolts for permanent fixes. As an example, a grade 70, 1/4 inch size chain is rated at a safe load of 3150 lbs which well exceeds a grade 30, 3/8 inch size at almost half the price.
Unlike bolts that have hash marks on the head to reveal their tensile strength, one of the unfortunate things about chain is that the grade is not stamped on it anywhere. If you go to purchase a new chain you will be able to check its grade marked on the end of its container before you measure what you want. I have a selection of chains in the shop and do not know what any are graded at.
Generally for farm use, the bigger the load the bigger the chain you should use is what comes to
Grab hooks have to be matched to the chain link size to be effective
mind. I have one chain fitted on both ends with grab hooks (a slot that the chain link fits into) and another chain fitted with a grab hook on one end and a slip hook on the other (allows the chain to slip through). I did this for versatility. The chain with grab hooks has a large enough link size to allow the use of quick links.
If the grade is crucial then you may want to spray paint a portion of one end to identify it or stamp the # on the hook.
Finish: Choices are self-coloured or bare metal, plated and galvanized. Most of the chain in use is in its raw state as it was manufactured, which is what all my chains are. If a chain is to be applied primarily for submerged use, than a galvanized finish would be the call. With the added galvanized finish, the link will be enlarged and subsequent hardware should be fitted before purchase to ensure fit. And to keep everything proper all hardware should also be galvanized.
Link size: Choosing a size of chain (link) that will accommodate your use is directly related to the next heading. You are going to be adding attachments and knowing what they are will determine how large the link has to be. Something worth considering here is if your chain length will change for say, towing logs. You may want to look at a link large enough to accommodate an anchor shackle or clevis and pin rated to the load expectation. Either can be quickly moved and securely attached with the minimum of effort.
Use: Your use may affect what grade you have to buy. Jurisdictions may require a certain grade of chain for transport of product on public roads. Overhead lifting requires a heavier grade than 30 for the obvious built-in safety margin. Galvanized coating for use in constant moisture to prevent rusting is another consideration.
Maintenance
About the only maintenance here is I wipe off any grit and try to store it dry to prevent rust. The only alteration I’ve ever made to one of my chains was the removal of a grab hook and installation of a chain slip hook. Links that break or become damaged can be replaced with a matched link replacer or quick link. I carry a couple of these in the tractor tool box just for the occasion but primarily for slack adjustment. For load tightening I acquired a small load binder which has proven an excellent choice as chains have a way of simply falling apart it the load shifts or twists; I found it on the side of the road.
For storage, I have a heavy box that they get placed into, not the best for organization, but the box is sitting on a wheeled dolly that I can just move up to the loader and drop it in. Works for me. I saw one farmer use large nails driven into a beam with his selection of chains wound around each nail; this is good, it allows the chain to drip dry and debris to self clear.
Load binders kind of go hand in hand with chain. If you try to tow something using just the hooks, inevitably they will come apart and at the worst time. I do not rely on those Mickey Mouse clips on the hooks to hold anything in place; I find them more of an interference than help.
Load binders are all load rated as well, not only for their capacity in pounds but for link size. There are generally two types, a simple offset lever type and the ratchet version. Once tightened down the ratchet version is pretty well on for the ride. The lever type has a hole in the end of the handle which is used to wire the handle to a link in the closed position as they can bounce free. A piece of pipe can be used over the handle to lock the lever binder in place but caution should be used here as too much pipe could over stress the handle to failure.
Note: all hardware, quick links, bolts, shackles, hook and links should be matched to or exceed the grade of the chain, hence the saying ‘weak link’.