Valve Tagging

I have always had ID tags on valves. Today, I was asked to provide the regulatory requirement for this and I can not find it. Does anyone know if there is a regulatory requirement and can reference it?

Don’t believe there is a requirement. Valve regs are 46 CFR 56.20

Fire fighting valves (CO2) have to be labelled.

Most labels one finds fitted are associated with the client’s build specification.

Color coding as seen is often per ISO stds.