Din 6921 Hex Flange Bolt
Product:HEX FLANGE BOLTS
Standard: DIN6921 ISO4162 EN1665
Raw material: Q235,35K, 45K 40Cr, 35CrMo, 42CrMo stainless steel (304/A2, 316/A4), etc.
Surface: Plain,zinc plated,black oxide,H.D.G,etc.
Specification Range: M8–M64; INCH: 1/4”–2 1/2”
Property Class:4.8, 5.6, 8.8, 10.9, 12.9 A2-70, A4-70, A2-50, A4-50
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Product Introduction
Product:HEX FLANGE BOLTS
Standard: DIN6921 ISO4162 EN1665
Raw material: Q235,35K, 45K 40Cr, 35CrMo, 42CrMo stainless steel (304/A2, 316/A4), etc.
Surface: Plain,zinc plated,black oxide,H.D.G,etc.
Specification Range: M8–M64; INCH: 1/4"–2 1/2"
Property Class:4.8, 5.6, 8.8, 10.9, 12.9 A2-70, A4-70, A2-50, A4-50
Mechanical Properties (Typical Grades)
|
Characteristic |
Carbon Steel 8.8 |
Carbon Steel 10.9 |
Stainless Steel A2-70 |
Stainless Steel A4-70 |
|
Minimum Tensile Strength |
≥800 MPa |
≥1000 MPa |
≥700 MPa |
≥700 MPa |
|
Minimum Yield Strength |
≥640 MPa |
≥900 MPa |
≥450 MPa |
≥450 MPa |
|
Hardness Range |
235–302 HB |
302–363 HB |
- |
- |
Product Overview
Flange bolts are specialized fasteners designed for secure and leak-proof connections in flange joints, widely utilized across industrial piping systems, machinery, and equipment. Compliant with international standards such as DIN EN 1665, ASTM A193/A194, and ISO 4162, they integrate the functions of a bolt and a washer-featuring a built-in flange under the bolt head that eliminates the need for separate washers, enhancing installation efficiency and connection stability.
Key Specifications
Category Details
Raw Materials Carbon steel (Q235,35K, 45K), alloy steel (40Cr, 35CrMo, 42CrMo), stainless steel (304/A2, 316/A4), etc.
Surface Treatments Plain, zinc plating (clear/color passivated), black oxide, hot-dip galvanizing (H.D.G), Dacromet, Geomet, Teflon coating, phosphating, etc.
Specification Range Metric: M8–M64; Imperial: 1/4"–2 1/2"
Property Classes Carbon steel: 4.8, 5.6, 8.8, 10.9, 12.9; Stainless steel: A2-70, A4-70, A2-50, A4-50
Product Characteristics
Integrated Flange Design:
The one-piece flange under the bolt head provides a larger bearing surface, distributing pressure evenly across the flange joint to prevent deformation and leakage.
Diverse Material Options:
Carbon steel variants balance cost and basic strength; alloy steel (8.8–12.9 grade) offers high tensile and yield strength for heavy-load applications; stainless steel (304/A2, 316/A4) ensures excellent corrosion resistance in harsh environments.
Reliable Sealing Support:
Works in tandem with gaskets (rubber, metal, PTFE) to form a tight seal, suitable for high-pressure, high-temperature, or corrosive medium transmission systems.
Easy Installation:
Eliminates the need for additional washers, simplifying assembly and reducing the risk of component mismatch.
Application Fields
Piping Systems:
Oil and gas pipelines, chemical pipelines, water supply and drainage systems, heating ventilation pipelines, etc.
01
Industrial Equipment:
Flange connections in pumps, valves, compressors, turbines, boilers, and pressure vessels.
02
Energy & Power:
Thermal power plants, nuclear power plants, wind turbines, and hydraulic/pneumatic systems.
03
Marine & Offshore:
Ship hull flanges, offshore platform piping, and seawater treatment equipment (prioritizing 316/A4 or H.D.G coating).
04
General Machinery:
Industrial machinery housings, flange-mounted motors, and heavy-duty equipment joints.
05
Usage Precautions
Installation:
Use a torque wrench to tighten bolts in a crisscross, symmetrical sequence (in 2–3 stages) to ensure uniform preload and avoid uneven flange stress.
Select the appropriate bolt length: Ensure 1–3 threads extend beyond the nut after tightening, avoiding insufficient engagement or excessive thread protrusion.
Environmental Adaptation:
For humid, outdoor, or corrosive environments (e.g., chemical, marine), choose stainless steel (316/A4) or hot-dip galvanized/Dacromet-coated carbon steel to prevent rust and corrosion.
For high-temperature (＞300℃) or high-pressure (＞10 MPa) scenarios, select alloy steel 10.9/12.9 grade bolts with heat-resistant gaskets.
Maintenance:
Regularly inspect for loosening, corrosion, or gasket aging; retighten or replace components promptly to avoid leakage.
Clean threads before installation to remove oil, rust, or debris that may affect preload accuracy.
Critical Taboos:
Do not mix bolts of different grades, materials, or surface treatments to prevent strength mismatch or galvanic corrosion.
High-strength bolts (10.9/12.9 grade) are not reusable after disassembly-fatigue damage may compromise structural safety.
Main Sales Markets
North America, Europe, the Middle East, Southeast Asia, and domestic industrial hubs.
Packaging and Logistics
Packaging Options: Small plastic bags, cardboard boxes, cartons, wooden pallets, and iron drums. Customized packaging (e.g., labeled with specifications, moisture-proof packaging) is available upon request.
Order Flexibility: Supports bulk and small-batch orders; transportation terms (FOB, CIF, EXW) and delivery schedules are negotiable to meet project timelines.
Certification and Quality Assurance
Certified to international quality standards including ISO9001:2015 and IATF16949:2016.
All products undergo strict dimensional inspection (thread gauges, calipers) and mechanical performance testing (tensile, hardness) before delivery.
Provide long-term quality guarantees and professional after-sales support, including technical consultation and replacement of defective products.
FAQ: Key Differences Between Flange Bolts and Standard Hex Bolts
Structural Design:
Flange bolts have an integrated flange (built-in washer), while standard hex bolts require separate washers for pressure distribution.
Application Focus:
Flange bolts are specialized for flange joints, prioritizing sealing and pressure distribution; standard hex bolts are general-purpose for non-flange connections.
Sealing Performance:
Flange bolts' larger bearing surface and compatibility with gaskets make them more suitable for leak-proof requirements; standard hex bolts rely on washers for basic pressure distribution.
Bearing Capacity:
The flange design of flange bolts provides better load dispersion, reducing the risk of joint deformation compared to standard hex bolts with washers.
Established in 2005, our company has evolved over two decades of continuous development into a leading regional enterprise in the fastener industry with fully automated end-to-end production. With an annual output value exceeding RMB 130 million, our product range covers diverse market segments from mid-range to high-end and is distributed worldwide
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