Product Definition & Industry Terminology
In industrial fastening terminology, stud bolts are threaded rods without a head, designed to be installed with nuts on both ends. Key configurations include:
| Term | Description |
|---|---|
| Double Ended Stud Bolt | Threaded at both ends with an unthreaded center section; typically with equal or unequal thread lengths |
| Full Thread Stud Bolt | Continuously threaded along entire length (fully threaded rod) |
| Tap End Stud | One end with longer thread for screwing into tapped holes; opposite end accepts nut |
| Continuous Thread Stud | Uniform thread pitch across full length; also known as fully threaded stud |
Critical Applications & Specific Locations
| Industry | Application | Specific Location / Component |
|---|---|---|
| Machinery | Heavy equipment assembly | Bearing housings, gearbox flanges, motor mounts |
| Engineering Structures | Steel connections | Structural joints, bridge components, foundation anchors |
| Pumps | Pump casing assembly | Bearing brackets, flange connections, seal housings |
| Petrochemical | Pressure vessels | Flange connections, heat exchanger covers, valve bonnets |
| Power Generation | Turbine assembly | Bearing caps, casing splits, foundation bolts |
| Marine | Engine mounts | Bearing supports, propulsion system flanges |
| Oil & Gas | Pipeline flanges | Flange joints, riser connections, wellhead equipment |
Specific Application: Bearings
In bearing applications, stud bolts serve critical functions:
Bearing Housing Clamping: Secures bearing caps to housings, maintaining preload under dynamic loads
Bearing Retainers: Fastens bearing retainers and lock nuts in rotating assemblies
Pump Bearing Brackets: Provides secure mounting for pump shaft bearings, ensuring alignment
Motor Bearings: Fastens bearing end covers in electric motor assemblies
Material Grades & International Standards
| Material | Standard | Grade | Tensile Strength | Typical Application |
|---|---|---|---|---|
| Carbon Steel | ASTM A193 | B7 | 860 MPa | General industrial, pumps, compressors |
| Carbon Steel | ASTM A193 | B7M | 690 MPa | Sour service, reduced hardness |
| Carbon Steel | ISO 898-1 | Class 8.8 | 800 MPa | Machinery, structural |
| Carbon Steel | ISO 898-1 | Class 10.9 | 1,000 MPa | High-strength, heavy equipment |
| Carbon Steel | ISO 898-1 | Class 12.9 | 1,220 MPa | Maximum strength applications |
| Alloy Steel | ASTM A320 | L7 | 860 MPa | Low-temperature service (-100°C) |
| Stainless Steel | ASTM A193 | B8 (304) | 515 MPa | General corrosion resistance |
| Stainless Steel | ASTM A193 | B8M (316) | 515 MPa | Marine, chemical, high corrosion |
| Stainless Steel | ASTM A453 | Grade 660 | 895 MPa | High-temperature, aerospace |
International Standards Compliance
| Standard | Scope | Common Applications |
|---|---|---|
| ASTM A193 | High-temperature alloy steel studs | Pressure vessels, flanges, pumps |
| ASTM A320 | Low-temperature service | Cryogenic, refrigeration, cold climates |
| ASTM A453 | High-temperature stainless | Turbines, exhaust systems |
| DIN 976 | Metric threaded studs | European machinery, industrial |
| ISO 898-1 | Mechanical properties of fasteners | General engineering |
| ASME B18.31.2 | Continuous thread studs | Flange connections |
Surface Treatments & Coatings
| Finish | Standard | Corrosion Resistance | Application |
|---|---|---|---|
| Zinc Plating | ASTM B633 | 72–120 hrs salt spray | General industrial, indoor |
| Zinc-Nickel | ASTM B841 | 500–1,000 hrs salt spray | Automotive, outdoor, high corrosion |
| Xylan / PTFE | Customer spec | 300–500 hrs salt spray | Low friction, anti-galling |
| Geomet / Dacromet | ISO 10683 | 500–1,000 hrs salt spray | High-strength, no hydrogen embrittlement |
| Hot Dip Galvanized | ASTM A153 | 1,000+ hrs salt spray | Structural, outdoor, marine |
| Passivation | ASTM A967 | 500–1,000 hrs salt spray | Stainless steel corrosion enhancement |
| Phosphate & Oil | MIL-DTL-16232 | Moderate | Oil-retaining, break-in applications |
| Parameter | Double Ended Stud | Full Thread Stud | Tap End Stud |
|---|---|---|---|
| Diameter Range | M6 – M100, 1/4″ – 4″ | M6 – M100, 1/4″ – 4″ | M8 – M64, 5/16″ – 2 1/2″ |
| Length Range | 40 mm – 1,200 mm | 300 mm – 3,500 mm | 50 mm – 600 mm |
| Thread Type | Metric, UNC, UNF | Metric, UNC, UNF | Metric, UNC, UNF |
| Thread Tolerance | 6g (metric), 2A (UNC) | 6g (metric), 2A (UNC) | 6g (metric), 2A (UNC) |
| Material Grades | B7, B7M, L7, B8, 8.8, 10.9, 12.9 | B7, 8.8, 10.9, A2, A4 | B7, 8.8, 10.9, 316 |
| Surface Finish | Zn, Zn-Ni, Geomet, Xylan | Zn, Zn-Ni, Geomet, HDG | Zn, Zn-Ni, Geomet |
| Tensile Strength | 515–1,220 MPa | 400–1,220 MPa | 515–1,000 MPa |
| Hardness | 22–35 HRC (depending on grade) | 22–35 HRC | 22–32 HRC |
| Proof Load | 80–95% of yield | 80–95% of yield | 80–95% of yield |
| Certification | EN 10204 3.1 | EN 10204 3.1 | EN 10204 3.1 |
Mechanical Properties Verification
Each production lot undergoes comprehensive testing to ensure high-strength performance:
| Test | Standard | Acceptance |
|---|---|---|
| Tensile Test | ASTM A370 / ISO 6892 | Meets grade requirements |
| Hardness Test | ASTM E18 / ISO 6508 | Within specified range |
| Proof Load | ASTM F606 | No permanent set |
| Impact Test | ASTM A320 (low temp) | Charpy V-notch requirements |
| Thread Gaging | Go/no-go gauges | 100% on critical dimensions |
Quality Documentation Provided
EN 10204 Type 3.1 Material Test Report
Heat number traceability
Dimensional inspection report
Coating thickness & adhesion certification
Third-party inspection available upon request
High-Strength Grades for Critical Applications
| Grade | Yield Strength | Tensile Strength | Application |
|---|---|---|---|
| Class 8.8 | 640 MPa | 800 MPa | General machinery, pumps |
| Class 10.9 | 900 MPa | 1,000 MPa | Heavy equipment, bearing housings |
| Class 12.9 | 1,100 MPa | 1,220 MPa | Maximum strength, critical flanges |
| ASTM A193 B7 | 725 MPa | 860 MPa | Petrochemical, pressure vessels |
| ASTM A320 L7 | 725 MPa | 860 MPa | Low-temperature service |
A pplication | Recommended Stud Type | Material | Surface Treatment |
|---|---|---|---|
| Bearing housing assembly | Double ended stud | Class 10.9 / B7 | Zinc-nickel |
| Pump casing flanges | Double ended stud | ASTM A193 B7 | Geomet / Dacromet |
| Structural steel connections | Full thread stud | Class 8.8 | Hot dip galvanized |
| Petroleum pipeline flanges | Double ended stud | ASTM A193 B7M | Xylan / PTFE |
| Marine pump bearings | Tap end stud | A4 (316) stainless | Passivated |
| High-temperature turbine | Double ended stud | ASTM A453 Grade 660 | As machined |
| Low-temperature equipment | Double ended stud | ASTM A320 L7 | Zinc-nickel |
