Double-Ended Bolt

Double End Studs (Double-Ended Stud Bolts): Overview

Material:

• Common materials:
  • Carbon steel (Grade 5/8.8/10.9) for general and high-strength applications.
  • Stainless steel (304/316) for corrosion resistance in chemical or marine environments.
  • Alloy steel (ASTM A193 B7/B16) for high-temperature/pressure systems.
• Surface treatments: Zinc plating, hot-dip galvanizing, Dacromet coating, or Xylan® for corrosion and wear resistance.

Manufacturing Process:

1. Cold Heading: Forms the stud body from steel wire with threads on both ends.
2. Thread Rolling: Precision rolling of threads (metric/SAE) using dies to ensure uniformity.
3. Heat Treatment: Quenching and tempering (for high-grade steel) to achieve required hardness (HRC 22-34) and tensile strength.
4. Surface Finishing: Electroplating or coating for environmental protection.
5. Straightening: Ensures stud straightness within tolerance (e.g., ≤1mm per 300mm length).

Key Production Considerations:

• Thread symmetry: Both ends must have identical pitch, diameter, and alignment.
• Material integrity: Avoid internal voids or cracks during cold heading due to extended length.
• Coating uniformity: Critical for corrosion resistance across the entire stud surface.
• Stress relief: Post-heat treatment to minimize residual stresses in long studs.

Applications:

• Piping systems: Flange connections in oil/gas pipelines, refineries, and chemical plants.
• Automotive: Engine blocks, cylinder heads, and exhaust manifolds.
• Machinery: Pump housings, compressors, and hydraulic systems.
• Construction: Anchor systems for heavy equipment and structural frameworks.
• Power generation: Turbines, boilers, and heat exchangers.

Installation:

1. Thread preparation: Clean and inspect threads on both ends and mating components.
2. Alignment:
   • Through-hole method: Insert stud through aligned components.
   • Tapped-hole method: Screw one end into a pre-tapped hole.
3. Fastening:
   • Use two nuts (jam nut method) or a stud tensioner for precise preload.
   • Apply manufacturer-specified torque sequentially to ensure even load distribution.
4. Sealing: Apply thread sealant (e.g., PTFE tape) in high-pressure fluid systems.
5. Inspection: Verify stud tension via ultrasonic testing or torque audits for critical joints.

Note:

• Load distribution: Ensure equal engagement length on both ends to prevent uneven stress.
• Corrosion prevention: Use anti-seize compounds in high-temperature or dissimilar metal applications.
• Reuse limits: Discard studs with thread damage, bending, or coating degradation.