Choosing between pipe markers
Pipe markers are specified by pipe diameter as much as by material, because letter height is tied to the size of the pipe and a marker sized for a small line is unreadable on a large one. The colour scheme follows the hazard characteristics of the contents and is deterministic once the contents are known, so the real decisions are size, legend, and attachment. Adhesive markers suit clean, dry, accessible pipe. Insulated, hot or dirty lines take strap-on carriers, because adhesive on lagging fails and adhesive on a hot line fails faster. Outdoor runs need UV stable stock, since the colour is carrying the message and a faded marker misinforms rather than merely fading.