ASME/ANSI B18.2.1 Hex Flange Bolts
ASME/ANSI B18.2.1 Hex Flange Bolts feature an integral flange beneath the hexagonal head, providing a larger bearing surface than a conventional hex head bolt. The flange helps distribute clamping force over a wider area of the joint and can reduce localized pressure on the connected material. Because the flange is formed as part of the bolt, no separate washer is required where the joint design permits its use.
The hexagonal head provides standard wrench or socket access, while the integrated flange remains fixed to the bolt throughout installation. This one-piece configuration can simplify assembly and reduce the number of loose components required in a fastening joint. These bolts are manufactured in inch-series sizes and can be supplied in carbon steel, alloy steel, or stainless steel, with the applicable material and mechanical requirements selected according to the intended application.
Specification:
ASME/ANSI B18.2.1 primarily defines the dimensional requirements and general data for inch-series hexagon head fasteners, including flange head configurations. Material and mechanical requirements should be specified separately according to the selected material and strength grade.
For carbon and alloy steel versions, SAE J429 may be used for mechanical and material requirements, while applicable ASTM specifications can be used for specific material grades. Stainless steel versions may be supplied according to ASTM F593, where applicable. Mechanical testing can be performed according to ASTM F606/F606M when required.
| Item | Specification |
|---|---|
| Product Standard | ASME/ANSI B 18.2.1 |
| Product Type | Hex Flange Bolt |
| Head Style | Hexagon Head with Integral Flange |
| Thread System | Inch |
| Thread Pitch | UNC/UNF |
| Thread Size | 1/4"-3/4" |
| Mechanical Proerty | Steel: SAE J 429 Stainless Steel: F593 |
| Material | Carbon Steel, Alloy Steel, Stainless Steel |
| Surface Treatment | Zinc Plated,Black Oxidation,Bright Finish,Passivation |
| Test Standard | ASTM F606/F606M |
- RELATED BOLT LISTS:
- ASME B 18.31.5 HRA Hook Bolts
- ASTM A394 HDG Tower Bolts
- ASTM A354 Hex Bolts
- ASME B 18.2.1 Square Head Bolts
- ASME/ANSI B 18.5 Round Head Square Neck Bolts
- ASME/ANSI B18.5 T- Head Bolts
- ASME/ANSI B18.2.1 Hex Head Flange Bolts
- ASME/ANSI B18.5 80°Slotted Countersunk Head Bolts
- ASME/ANSI B18.2.1 Hex Cap Bolts
- A307 Hex Head Bolts
Dimension Chart of ASME/ANSI B18.2.1 Hex Flange Bolts:
The ASME/ANSI B18.2.1 dimension chart provides the key measurements needed to select an inch-series Hex Flange Bolt, including the nominal diameter, thread pitch, bolt length, head dimensions, and integral flange diameter. These dimensions determine thread compatibility, wrench access, and the bearing area available beneath the bolt head. When selecting the bolt size, the thread diameter and length should match the joint requirements, while the head and flange dimensions should be checked against the available installation space and seating surface.
| Thread Diameter | 1/4 | 5/16 | 3/8 | 7/16 | 1/2 | 9/16 | 5/8 | 3/4 |
| P | 20|28|32 | 18|24|32 | 16|24|32 | 14|20|28 | 13|20|28 | 12|18|24 | 11|18|24 | 10|16|20 |
| ds max | 0.25 | 0.3125 | 0.375 | 0.4375 | 0.5 | 0.5625 | 0.625 | 0.75 |
| ds min | 0.245 | 0.3065 | 0.369 | 0.4305 | 0.493 | 0.5545 | 0.617 | 0.741 |
| s max | 0.375 | 0.5 | 0.5625 | 0.625 | 0.75 | 0.8125 | 0.9375 | 1.125 |
| s min | 0.367 | 0.489 | 0.551 | 0.612 | 0.736 | 0.798 | 0.922 | 1.1 |
| e max | 0.433 | 0.577 | 0.65 | 0.722 | 0.866 | 0.938 | 1.083 | 1.299 |
| e min | 0.409 | 0.548 | 0.618 | 0.685 | 0.825 | 0.895 | 1.034 | 1.234 |
| dc max | 0.56 | 0.68 | 0.81 | 0.93 | 1.07 | 1.19 | 1.33 | 1.59 |
| k max | 0.28 | 0.32 | 0.39 | 0.46 | 0.51 | 0.57 | 0.62 | 0.73 |
Application of ASME/ANSI B18.2.1 Hex Flange Bolts:
Pumps, Compressors and Power Equipment
Used for pump housings, compressor assemblies, generator mounts, motor bases, equipment covers, and other serviceable mechanical components where inch-series fastening is specified.
Agricultural and Heavy Equipment
Suitable for tractors, agricultural machinery, loaders, excavators, and other heavy-duty equipment using UNC or UNF threaded connections. The integral flange provides a larger seating surface beneath the bolt head.
Material Handling and Industrial Machinery
Used in conveyors, lifting equipment, industrial carts, machine assemblies, and equipment frames where standardized inch-series bolts are required for component fastening.