The 67/548/EEC Directive contains the regulations for the labelling, classification, and packaging of dangerous substances.
Labels used on pipes must be visible at the most dangerous points, such as valves and joints and at reasonable intervals. The dimensions of the pipe markers must be proportionate to the labelling surface.
Hazardous materials flow through miles of piping in many industrial, commercial and manufacturing facilities. Just like hazardous materials in other situations, piping systems should be appropriately labelled to make people aware of the materials they carry.