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Black zinc flange bolts
The head of the flange bolt has a round flange to increase the contact area and disperse the pressure (standard GB/T 5787, GB/T 5789). Common specifications M6-M30, material Q235 or 35CrMo, surface galvanized or blackened.
Description
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Product definition and structure
The head of the flange bolt has a round flange to increase the contact area and disperse the pressure (standard GB/T 5787, GB/T 5789). Common specifications M6-M30, material Q235 or 35CrMo, surface galvanized or blackened.
Core materials and characteristics
Material: Q235 carbon steel (conventional), 35CrMo alloy steel (high strength).
Features:
High sealing: The flange with gasket can enhance the sealing of the pipeline connection;
Shear resistance: The flange design reduces the shear load on the bolt and is suitable for vibration environments;
Standardization: Complies with international standards such as DIN 6921 and ISO 4014.
Functions and applicable scenarios
Function:
Fixed pipe flanges, pressure vessel interfaces and other connections that require high sealing;
Replace flat gasket + bolt combination to simplify installation.
Scenarios:
Chemical pipelines (such as oil cracking equipment), building steel structures (H-shaped steel nodes), automobile engines (cylinder connections).
Installation and maintenance
Installation:
Clean the flange surface to ensure that the gasket fits the flange;
Tighten symmetrically 2-3 times according to the torque standard (such as 8.8-grade bolts refer to ISO 898-2).
Maintenance:
Check the tightness of the flange bolts regularly, and re-tighten them in high temperature environments (>100℃);
Select hot-dip galvanizing or Dacromet treatment in corrosive environments.
Purchase recommendations
Select the coating according to the corrosiveness of the medium: galvanizing for indoor use and hot-dip galvanizing for outdoor use;
Select 35CrMo material for high-pressure pipelines, matching 10.9-grade bolts.
Guide to Comparing and Selecting Sixteen Major Bolts
| Type | 10.9S large hexagonal bolt | 10.9S shear bolt | T-bolt | U-bolt | Countersunk cross bolt | Butterfly bolt | Flange bolt | Welding nail bolt | Basket bolt | Chemical bolt | Hexagonal bolt series | Carriage bolt | Hexagonal electroplated zinc | Hexagonal colored zinc | Hexagon socket bolt series | Stud bolt |
| Core advantages | Ultra-high strength, friction force transmission | Self-checking, earthquake resistance | Quick installation | Strong adaptability | Beautiful concealed, insulation | Manual convenience | High sealing | High connection strength | Tension adjustment | No expansion stress | Economical and universal | Anti-rotation and anti-theft | Basic anti-corrosion | High corrosion resistance | Beautiful anti-corrosion | High tensile strength |
| Salt spray test | 1000 hours (Dacromet) | 72 hours (galvanized) | 48 hours | 72 hours | 24 hours (galvanized) | 48 hours | 72 hours | 48 hours | 72 hours | 20 years | 24-72 hours | 72 hours | 24-72 hours | 72-120 hours | 48 hours | 48 hours |
| Applicable temperature | -40℃~600℃ | -20℃~200℃ | -20℃~80℃ | -20℃~100℃ | -20℃~100℃ | -20℃~95℃ | -20℃~200℃ | -20℃~200℃ | -20℃~150℃ | -40℃~80℃ | -20℃~80℃ | -20℃~80℃ | -20℃~80℃ | -20℃~100℃ | -20℃~100℃ | -20℃~200℃ |
| Typical scenarios | Steel structures, bridges | High-rise buildings, machinery | T-slots | Pipe fixings | Furniture, electronic equipment | Home appliances, cabinets | Pipe flanges | Steel-concrete connections | Cable wind ropes | Building reinforcement | General machinery, indoor | Wooden structures | General machinery | Outdoor equipment | Precision equipment | Thick plate connection |
| Installation method | Torque wrench | Torque shear wrench | Manual | Nut tightening | Screwdriver | Manual | Torque wrench | Arc welding | Manual adjustment | Chemical anchoring | Torque wrench | Tapping + nut | Torque wrench | Torque wrench | Torque wrench | Nut tightening |
| Environmental protection | Chrome-free Dacromet RoHS compliant | Galvanized RoHS compliant | Phosphating | Galvanized | Plastic RoHS compliant | Plastic RoHS compliant | Galvanized | Heavy metal-free | Galvanized | Solvent-free | Cyanide-free zinc plating RoHS compliant | Galvanized | Cyanide-free zinc plating | Trivalent chromium passivation | Phosphating | No hydrogen embrittlement |
Selection suggestions:
Ultra-high strength requirements: 10.9S large hexagonal bolts, matching steel structure friction type connection;
Seismic and anti-loosening: torsion shear bolts, suitable for equipment foundations with frequent vibrations;
T-slot installation: T-bolts, quick position adjustment;
Pipeline fixing: U-bolts, suitable for different pipe diameters;
Surface flatness requirements: countersunk cross bolts, beautiful and hidden;
Manual tightening: butterfly bolts, no tools required;
High sealing: flange bolts, with gaskets to enhance sealing;
Steel-concrete connection: welding nails, efficient welding;
Tension adjustment: basket bolts, precise control of wire rope tension;
Post-anchoring engineering: chemical bolts, no expansion stress;
General connection: hexagonal bolt series, the first choice for economy;
Wooden structure: carriage bolts, anti-rotation and anti-theft;
Anti-corrosion requirements: hexagonal galvanized bolts, the first choice for outdoor use;
Thick plate connection: stud bolts, suitable for different installation spaces.
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