NR-26 Pipe Color Coding

NR-26 & ABNT NBR 6493: piping color identification

Brazilian regulation NR-26 (Safety Signaling) works alongside the technical standard ABNT NBR 6493 to pin a base color on each fluid running through industrial piping. The point is that a worker or an emergency team can read what's inside a pipe without opening anything. The core palette goes like this: red marks fire-fighting water or foam, yellow (sometimes yellow-ochre) flags combustible gases, green covers cold industrial water, black is sewage and effluents, orange signals acids, violet is for alkalis, white means steam, and grey is reserved for vacuum lines.

You can paint the whole pipe or just apply bands. Band width follows the rule w ≈ D, scaling with the pipe's outside diameter D, and you repeat it near valves, branches, walls, and every 10–20 m along long straight runs. Arrows show which way the fluid moves. When two substances would otherwise share the same hue, the fluid name and pressure have to be written next to the color so nobody confuses them.

Applications

Refineries, chemical plants, food and beverage facilities, hospitals, water-treatment stations, HVAC plant rooms — they all lean on the code for day-to-day operation, lockout-tagout, hot work, and emergency response. A maintenance crew reads the bands to figure out what to isolate. Firefighters follow the red lines straight to hydrants and sprinkler risers.

FAQ

Is NR-26 color coding mandatory? Yes. The Ministry of Labour enforces NR-26, and if you don't comply you risk fines and even having the plant shut down.

What about gases like oxygen or nitrogen? NBR 6493 sets aside specific shades for them — light blue for oxygen, grey for nitrogen — backed by a written legend. Check the current revision of the standard before you commit, since the shades can change.

How often should the painting be renewed? Once the color fades to the point someone could misread it. Indoors that's usually every 3–5 years; outdoors, or anywhere chemically aggressive, expect to repaint sooner.