Brass Collar around cylinder necks.

Afternoon all.

I have an old (OK very old) cylinder with a tapered valve, which has a
brass collar around the neck of the cylinder, onto which the cylinder
data is stamped.

That brass ring has a crack in it (actually cracked all the way
through).

Does the brass collar form an integral part of the strength of the
cylinder, or is it just somewhere to stamp the data?

Out of interest, it had a hydro test in November of this year, and has
only stood in my garage since, so I assume the ring was cracked at the
time of test, but wheter it was either overlooked, or noticed and not
relevant to the test, I know not.

TIA

David