International Pipe Color Code Differences

International pipe color codes vary significantly between countries and standards. While some services like fire water (red) and compressed air (blue) are consistent worldwide, others—particularly steam, chemicals, and hydrocarbons—differ between ASME A13.1, BS 1710, ISO 14726, and regional standards. These international pipe color code differences create challenges for multinational EPC projects and facilities operating across multiple jurisdictions.

Variations matters for procurement engineers, HSE managers, and piping designers working on international oil and gas projects where multiple standards may apply.

International Pipe Color Code Comparison

Pipe Service	ASME A13.1 (USA)	BS 1710 (UK)	ISO 14726	IS 2379 (India)	DIN 2403 (Germany)	AS 1345 (Australia)
Fire water	Red	Red	Red	Red	Red	Red
Potable water	Green	Green	Green	Green	Green	Green
Compressed air	Blue	Light blue	Light blue	Light blue	Blue (RAL 5015)	Light blue
Steam	User-defined (gray)	Silver-gray	Silver-gray	Silver	Red (RAL 3000)	Silver-gray
Natural gas	Brown	Yellow ochre	Yellow	Yellow	Yellow	Yellow
Nitrogen	Blue	Light blue	Light blue	Light blue	Green	Light blue
Acids	Orange	Violet	Violet	Violet	Orange	Violet
Caustics	Orange	Violet	Violet	Violet	Violet	Violet
Oxygen	Yellow	Light blue with “O2”	Light blue	Light blue	Blue	Light blue
Crude oil	Brown	Brown	Brown	Brown	Brown	Brown
Cooling water	Green	Green	Green	Green	Green	Green

Key Differences Explained

The most significant international pipe color code differences are:

Difference	Detail
Steam: gray vs. red	Most standards use silver-gray for steam. DIN 2403 (Germany) uses red, which creates a direct conflict with fire water in other systems.
Natural gas: brown vs. yellow	ASME A13.1 uses brown (flammable category). BS 1710, IS 2379, and DIN 2403 use yellow.
Acids: orange vs. violet	ASME A13.1 groups all toxic/corrosive fluids under orange. BS 1710 and ISO 14726 assign violet specifically to acids and alkalis.
Nitrogen: blue vs. green	Most standards classify nitrogen with compressed air (blue). DIN 2403 assigns green, which conflicts with water in other systems.
Classification approach	ASME A13.1 uses hazard-based categories (flammable, toxic, etc.). BS 1710 and ISO 14726 use content-based assignments (specific to each fluid type).

Pro Tip

On international EPC projects, always establish a project-specific pipe marking specification during the engineering phase. This specification should define the color code, label format, and placement rules for the specific project, resolving any conflicts between the owner’s standard, the local regulatory code, and the EPC contractor’s practice. Issue this as part of the engineering deliverables early in the project.

Resolving Conflicts

When multiple standards conflict (e.g., a US-designed plant built in Germany, or a project involving contractors from different countries), the following hierarchy is typically applied:

1. Owner/operator specification: the facility owner’s standard takes precedence
2. Local regulatory requirements: mandatory codes in the country of installation
3. International standard (ISO 14726); as a neutral reference
4. EPC contractor standard: default if no other standard is specified

For the complete ASME A13.1 pipe color code chart and detailed label sizing requirements, see the full reference guide.

Read the full guide to pipe color coding