Galvanising a chain is a good practice as it will be cheaper than buying
a new one.. B U T :
Be shure that you chain in in good shape, no "elongated" links, and check that the diameter of the links is not reduced (by rust) to more than 1/10e..
Next but most important point, check that your galvanisation company is using a "vibrating drum" when the chain is lifted out the melted zinc bath.. Vibrations during the cooling
process is a MUST- otherwise several to most of the links could be welded together, and the chain will be galvanised.. but useless..
You can still break the weld by a hamer, but then there is very good chance that you will also at the same time remove the galvanisation..