API 600 Valve Marking Rules: A Complete Guide

In the valve industry, clear and standardized markings are essential for product identification, safety, and compliance. API 600, the international standard for steel gate valves, defines strict rules for valve markings to ensure that end users, manufacturers, and inspectors can easily verify product specifications.

This blog explains the main API 600 valve marking rules, helping valve manufacturers, suppliers, and buyers understand what information must appear on each valve.

Why Valve Marking Matters

• Traceability – Markings allow users to trace materials, design standards, and manufacturer details.

• Safety – Proper identification ensures that the valve is used in the correct pressure and temperature range.

• Compliance – Without correct markings, valves cannot be certified or accepted in major projects.

Required API 600 Valve Markings

According to API 600, every gate valve must be clearly marked (usually on the body, bonnet, or nameplate) with the following information:

1. Manufacturer’s Name or Trademark

   • Identifies the company that produced the valve.

2. Material Designation

   • The valve body and bonnet material grade (e.g., ASTM A216 WCB, ASTM A351 CF8M).

3. Nominal Size (NPS)

   • Valve size in inches (e.g., NPS 4, NPS 12).

4. Pressure Class (Class Rating)

   • Pressure rating according to ASME standards (e.g., Class 150, 300, 600, 900).

5. API 600 Reference

   • Indicates compliance with the API 600 standard.

6. Heat Number

   • Provides traceability to material test reports (MTRs).

7. Trim Number

   • Refers to the internal trim material (per API 600 trim chart, e.g., Trim 8 = 13Cr).

8. Flow Direction (if applicable)

   • For valves that are not bidirectional, arrows must indicate correct flow.

9. Country of Origin

   • Required in many regions for import/export and end-user specifications.

Example of Valve Marking Layout

A typical API 600 valve body might be marked like this:

4" 600 WCB  

TRIM 8 API 600  

HEAT NO. 12345  

YIXIN VALVE

• 4" → Nominal Size

• 600 → Pressure Class

• WCB → Body Material

• Trim 8 → Trim Material

• API 600 → Standard Reference

• Heat No. → Material Traceability

• Made in China → Country of Origin

Nameplate Requirements

In addition to body cast markings, many API 600 valves also have a stainless steel nameplate fixed to the yoke or bonnet. The nameplate usually repeats the body markings and may include additional data such as:

• Manufacturer’s logo

• Production date

• Serial number

• Operating temperature range

Best Practices for Manufacturers

• Ensure cast markings are legible and permanent.

• Follow API 600 trim number charts precisely.

• Provide MTRs matching the heat number on the valve body.

• Double-check markings during final inspection to avoid rejections.

Conclusion

Understanding API 600 valve marking rules is critical for compliance in oil & gas, petrochemical, and power projects worldwide. Proper markings ensure safety, quality control, and smooth acceptance during inspection.

If you are a valve manufacturer or distributor, make sure your API 600 gate valves are marked correctly to meet international standards and customer requirements.