ASME / ANSI A13.1 Pipe Marking Standard: Color Code Chart & Sizing Guide
The definitive engineering breakdown of the ASME A13.1-2020 / 2026 standard for industrial pipe identification. Master the exact color assignments, minimum letter heights, marker lengths, flow directional arrows, and recommended Brady vinyl formulations.
1. Official ASME A13.1 Color Code Chart
ASME A13.1 establishes 6 mandatory primary color combinations based on the inherent hazard of the fluid contents, plus 2 user-defined combinations.
2. Pipe Sizing, Marker Length & Letter Height Matrix
ASME A13.1 dictates exact minimum letter heights and marker field lengths based on the Outer Diameter (OD) of the pipe, including insulation.
| Pipe Outside Diameter (OD) | Min. Marker Length | Min. Letter Height | Brady Standard Style | Continuous Vinyl Width |
|---|---|---|---|---|
| 0.75 in to 1.25 in (19 to 32 mm) | 8 inches (203 mm) | 0.5 inches (13 mm) | Style 1 Roll Form / Snap-On (0.75" – 1.375" OD) | 91200 / B-595 Continuous Tape (1.0" W) |
| 1.50 in to 2.00 in (38 to 51 mm) | 8 inches (203 mm) | 0.75 inches (19 mm) | Style 2 Snap-On / Wrap-Around (1.5" – 2.375" OD) | 91210 / B-595 Continuous Tape (1.5" W) |
| 2.50 in to 6.00 in (64 to 152 mm) | 12 inches (305 mm) | 1.25 inches (32 mm) | Style 3 Strap-On / Self-Adhesive (2.5" – 6.0" OD) | 91230 / B-595 Continuous Tape (2.25" W) |
| 8.00 in to 10.00 in (203 to 254 mm) | 24 inches (610 mm) | 2.5 inches (64 mm) | Style 4 Heavy-Duty Strap-On Marker (8" – 10" OD) | 91240 / B-595 Wide Tape (4.0" W) |
| Over 10.00 in (> 254 mm) | 32 inches (813 mm) | 3.5 inches (89 mm) | Style 5 High-Visibility Large Diameter Marker | 91250 / B-595 Wide Tape (4.0" W / 8.0" Multi-Line) |
3. Recommended Brady Technical Materials for Pipe Identification
Industrial pipes endure UV exposure, steam washdowns, and chemical leaks. Selecting the proper Brady formulation ensures zero peel-off and permanent readability:
All-Weather Indoor / Outdoor Vinyl Tape
Conformable vinyl with aggressive ultra-tack acrylic adhesive. Adheres to rough, textured, and curved pipe surfaces. Temperature range: -40°C to +82°C (-40°F to 180°F).
View B-595 Engineering Specs & SKUsPremium Industrial Pipe Marker Vinyl Film
High-gloss printed film with pressure-sensitive permanent acrylic adhesive. Engineered specifically for pre-printed pipe markers and directional flow arrows.
View B-946 Engineering Specs & SKUs4. Mandatory Marker Placement Rules
Place markers within 3 feet of all valves, flanges, pumps, and major branch connections.
Label pipes on both sides where they pass through floors, ceilings, and bulkheads.
Install markers every 25 to 50 feet along continuous straight pipe runs for continuous line-of-sight.
Wrap directional arrow banding tape around both ends of every text marker to indicate fluid flow.
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