What Is a Stud Bolt for Pipe Flanges?

A stud bolt is a threaded rod with two hex nuts used to create secure connections between pipe flanges.

The complete threading along its length sets it apart from standard bolts and enables better pressure distribution.

Two heavy nuts work together on the rod ends to maintain the tight seal needed for safe operation.

Bolts for Pipe Flanges

Flange connections depend on the right bolts to stay secure. The size, number, and type of bolts all come down to a few key factors:

• Flange Size – Larger flanges need more bolts to distribute force evenly
• Pressure Rating – Higher pressure means stronger bolts to handle the load
• Material Compatibility – Using the right bolt material prevents corrosion and failure over time
• Temperature Range – Different materials handle heat differently, with B7 studs rated for up to 800°F

ASME B16.5 sets the standards for flange bolts, making sure everything fits and holds up under pressure.

Types of Stud Bolts

Different jobs call for different stud bolts. Some are fully threaded, whereas others have specific designs for securing equipment.

Full-Threaded Stud Bolts

These are threaded from end to end, allowing nuts to be tightened on both sides. Used in high-pressure flange connections, they apply even force across the joint.

Double-End Stud Bolts

Threaded at both ends but with an unthreaded section in the middle, these bolts are used when one side is permanently fixed into place.

Tap-End Stud Bolts

One side has a shorter thread for screwing into a tapped hole, while the other end holds a nut. These are common for mounting equipment onto flanges.

Stud Bolt Specifications

Stud bolts come in different sizes and materials depending on pressure, temperature, and flange type. The table below covers key specs.

Standard Stud Length

Selecting the correct stud bolt length ensures proper thread engagement and maintains a secure flange connection.

• Overall Length (OAL) – The total bolt length, including any unthreaded sections
• First-to-First (FTF) – The distance between the first full thread on each end
• Thread Engagement – Leave 1.5 to 3 threads exposed after tightening

A properly sized stud bolt leaves 1.5 to 3 threads exposed after tightening. If the bolt is too long, it can corrode or damage the exposed threads.

Installation and Maintenance

Proper installation ensures your stud bolts perform reliably in high-temperature and high-pressure applications.

Always clean threads before assembly and use a calibrated torque wrench when tightening to manufacturer specifications.

Regular inspection of bolt tension and corrosion helps prevent leaks and maintains system integrity.

Conclusion

Understanding stud bolt specifications and installation requirements helps prevent costly leaks and system failures in your high-pressure piping connections.

With various materials, sizes, and types available, choosing the right stud bolt for your specific application ensures safe and efficient system operation.

Take time to research and install your stud bolts correctly, and your flange connections will serve reliably for years to come.

Have questions about flange selections? Visit longanflange.com or explore our ASME and stainless steel options.

Reference

What is a Stud Bolt for Pipe Flanges?