🔷 Overview of ANSI flange bolts

In industrial piping systems, flanges are connected using:

• Bolts (or stud bolts)
• Nuts
• Gaskets

👉 Among these, bolts play a critical role in:

• Providing clamping force
• Ensuring sealing between flanges
• Maintaining connection stability under pressure and temperature

⚙️ Key factors when selecting flange bolts

1. Material standards (ASTM)

👉 The most important factor

• ASTM A193 B7: alloy steel, high strength (most commonly used)
• ASTM A193 B8 / B8M: stainless steel 304 / 316, corrosion-resistant

✔️ Choose based on the working environment

2. Flange pressure class (ANSI)

• Class 150, 300, 600, 900, 1500, 2500

👉 Higher class requires:

• Larger bolt diameter
• Higher strength
• More bolts

3. Bolt size

Includes:

• Diameter
• Length

👉 Must comply with standards such as:

• ASME B16.5 (flanges)
• ASME B18.2.1 (bolts)

4. Bolt types

✔️ Stud bolts

👉 Most commonly used type

• Used with two nuts
• Provides more uniform tightening force

✔️ Hex bolts

• Used for small systems or low-pressure applications

🔧 How to select bolts by application

👉 High-pressure oil & gas systems

→ Stud bolt ASTM A193 B7 + nut A194 2H

👉 Corrosive environments (chemical plants)

→ Stainless steel stud bolts B8/B8M

👉 High-temperature applications

→ B7 or B16 (heat-resistant)

📊 Example of bolt selection by flange

👉 (Actual dimensions should follow ASME B16.5 tables)

⚠️ Common mistakes

• Selecting wrong material → bolt failure or corrosion
• Incorrect bolt length → insufficient clamping force
• Using regular bolts instead of stud bolts → poor sealing
• Improper tightening torque

🔥 Quick selection tips

👉 ANSI systems → follow ASME B16.5 tables
👉 High pressure → choose B7 + 2H
👉 Chemical environments → choose B8/B8M stainless steel
👉 Always prioritize stud bolts

🏁 Conclusion

Bolts for ANSI flanges must be selected based on:

• Material standards
• Dimensions
• Pressure class

👉 Proper selection helps:

• Ensure gasket sealing performance
• Improve system safety
• Prevent leakage and failures

📞 Contact Information

Phuc Minh Engineering Co., Ltd (PM-E) specializes in supplying bolts, nuts, flanges, gaskets, and piping components that meet international standards.

• 🌐 Website: pm-e.vn
• 📧 Email: info@pm-e.vn
• 📱 Hotline: +84 907 450 506 – +84 902 720 814 – +84 979 737 351