🔷 What is “Class” in industrial valves?

In the valve and piping industry, Class (Pressure Class) refers to the pressure-temperature rating of valves, flanges, and fittings according to American standards (ANSI/ASME).

The most common pressure classes include: Class 150, 300, 600, 900, 1500, and 2500.

👉 Simply put:

• Higher Class = higher pressure resistance
• However, actual pressure capacity depends on temperature and material

  

⚙️ What do Class 150, 300, 600, 1500, 2500 mean?

Many people mistakenly think that Class equals a fixed pressure value (psi), but in reality, Class is not a fixed pressure number.

Approximate reference values:

• Class 150: ~19 bar at ambient temperature
• Class 300: ~50 bar
• Class 600: ~100 bar
• Class 1500: ~250 bar
• Class 2500: up to ~400 bar

⚠️ Note:
These values are only approximate because actual pressure depends on:

• Operating temperature
• Material grade (A105, F304, F316, LF2, etc.)
• Design standards

📊 Approximate Pressure Chart by Class (at ambient temperature)

📐 Where is Class rating used?

Pressure Class is widely applied to:

• Industrial valves (ball, gate, globe, butterfly valves)
• Flanges
• Pipe fittings
• Bolts and gaskets

👉 All components must match the same Class rating to ensure safe and reliable system connection.

🔥 ANSI Class vs PN rating

👉 Approximate conversion:

• Class 150 ≈ PN16–PN20
• Class 300 ≈ PN40–PN50
• Class 600 ≈ PN100

⚠️ This is not a 100% exact conversion because it depends on temperature and design standards.

🏭 When should you choose a higher Class?

You should select a higher pressure Class when:

• The system operates under high pressure
• High temperature conditions (steam, hot oil)
• Hazardous environments (oil & gas, chemicals)
• High safety requirements

❌ Common mistakes

• Thinking Class equals fixed psi pressure
• Choosing lower Class to reduce cost → leads to leakage or system failure
• Mixing different Class ratings between valves, flanges, and gaskets

🏁 Conclusion

Class 150, 300, 600, 1500, 2500 are important pressure ratings used in industrial piping systems to define the pressure-bearing capability of equipment.

👉 Key takeaways:

• Higher Class = higher pressure capacity
• Always consider temperature + material + working conditions
• Ensure consistent Class rating across all system components

📞 Contact Information

PHUC MINH ENGINEERING – pm-e.vn supplies industrial valves, flanges, gaskets, and bolting materials according to ANSI/ASME standards.

• 🌐 Website: pm-e.vn
• 📧 Email: info@pm-e.vn
• 📱 Hotline: +84 907 450 506 – +84 902 720 814 – +84 902 800 728