Pipe color codes according to UNI 5634-97

Here are the main options for the UNI 5634-97 standard, i.e. the colours used to differentiate the pipe labels:

Redwith white lettering. This red label with white lettering is used for all fire-extinguishing liquids, such as water;

Greenwith white lettering. A green label with white lettering indicates that the pipe contains potable water. It could be used for cooling, boilers, or even fountains or sinks;

Greywith black writing it refers to steam or heated water;

Blueorsky bluewith black lettering. Blue labels with black lettering are used for hoses carrying compressed air;

Brownwith white characters. This option is valid for all combustible and flammable liquids and mineral oils;

Yellowochre with black characters. This option is used for all pipes containing gases in the gaseous or liquid state (excluding air);

Orangewith white lettering. Orange labels with white lettering are for toxic or corrosive liquids. Most acids will require this type of tube marking;

Violawith white writing it refers to all alkalis;

Blackwith white writing for all other fluids;

Yellow with black writing for other hazardous fluids;

Whitewith black writing for comburents.

ANSI/ASME Standard Pipe Color Codes

Unlike the UNI standard, ANSI/ASME pipe color codes also provide several user-defined pipe color combinations. This is important because it allows facilities to plan for certain pipes that don't fit into the standard standards. It's important to remember, however, that whenever user-defined pipe markings are used, untrained personnel won't know what they mean.

The user-defined color options are:

• Purple with white writing;
• White with black writing;
• Grey with white writing;
• Black with white writing.

One of the most effective ways to ensure that people in the facility always know what each color label means is to post pipe color code diagrams.