ASME B18.2.1-2012 is the latest active version of the standard for inch-series bolts and screws. It specifies dimensions, tolerances, terminology, and quality requirements for a wide range of imperial fasteners used in mechanical engineering, manufacturing, assembly, and industrial projects worldwide.
Compared with the widely used ASME B18.2.1-2010 edition, this 2012 version provides clearer definitions, expanded product coverage, and improved structural standard separation.
What’s New in ASME B18.2.1-2012?
ASME B18.2.1-2012 introduces several key updates and additions compared to the 2010 edition, as confirmed by the official standard’s table of contents:
New Fastener Types Added
The 2012 edition expands the scope to include three new fastener categories that were not covered in the 2010 version:
- Askew Head Bolts (Table 4)
- Hex Flange Screws (Table 8)
- Lobed Head Screws (Table 9)
These additions provide comprehensive specifications for modern fastening applications not addressed in the previous edition.
Structural Bolts Relocation
Notably, heavy hex structural bolts have been completely removed from ASME B18.2.1 2012. These fasteners are now specified exclusively under ASME B18.2.6, the dedicated standard for structural applications, eliminating confusion between general-purpose and structural fasteners.
Enhanced Technical Specifications
The standard now includes detailed new sections for critical design parameters:
- Maximum and Minimum Length Limitations for Short Screws Threaded Full Length (Table 11)
- Maximum Grip Gaging Lengths, LG, and Minimum Body Lengths, LB, for Screws Except Flange Head (Table 12)
These additions support larger-diameter applications and provide clearer guidance for engineers and manufacturers.
Improved Formatting and Definitions
All tables, notes, and technical definitions have been revised in accordance with ASME B18.12.1, ensuring consistency and readability. Lag screw threads have also been redefined to align with other fastening standards.
Products Covered by ASME B18.2.1-2012
Based on the official table of contents, ASME B18.2.1-2012 covers the following inch-series fasteners:
- Square Head Bolts (Table 1)
- Hex Bolts (Table 2)
- Heavy Hex Bolts (Table 3)
- Askew Head Bolts (Table 4)
- Hex Cap Screws (Table 6)
- Heavy Hex Cap Screws (Table 7)
- Hex Flange Screws (Table 8)
- Lobed Head Screws (Table 9)
- Square Lag Screws (Table 14)
- Hex Lag Screws (Table 15)
- Lag Screw Threads (Table 16)
Important Note: This standard does not cover heavy hex structural bolts, which are now governed by ASME B18.2.6.
Download ASME B18.2.1-2010 & ASME B18.2.1-2012
For reference, you may also review details of the previous widely used edition:
https://www.zzsteels.com/knowledge/asme-b18.2.1-2010.pdf
For the latest specifications, you can access the full document of the active edition: