ASME B18.2.1 is a standard published by the American Society of Mechanical Engineers (ASME) that specifies the requirements for square and hexagonal bolts and screws with coarse thread pitch. This standard covers the dimensional and mechanical requirements for these fasteners, as well as the marking, packaging, and inspection procedures.
The ASME B18.2.1 standard applies to bolts and screws with a nominal diameter ranging from ¼ inch to 3 inches, and a thread pitch ranging from 10 to 24 threads per inch (TPI) for coarse threads. The standard specifies the dimensions and tolerances for the fasteners, including the length, width across flats, head height, head diameter, and thread length.
Uses of ASME B18.2.1
ASME B18.2.1 specifies the requirements for square and hexagonal bolts and screws with coarse thread pitch. These fasteners are commonly used in a wide range of applications, including:
1. Construction: ASME B18.2.1 bolts and screws are widely used in the construction of buildings, bridges, and other structures where reliable and strong connections are essential.
2. Manufacturing: These fasteners are used in the manufacture of machinery and equipment, where they provide a secure and reliable connection that can withstand heavy loads and high stress.
3. Automotive: ASME B18.2.1 bolts and screws are commonly used in the automotive industry for assembly of engines, transmissions, and other components.
4. Aerospace: These fasteners are also used in the aerospace industry, where they provide secure connections that can withstand extreme temperatures and pressures.
5. Marine: ASME B18.2.1 bolts and screws are used in the marine industry for construction and repair of ships, boats, and other watercraft.
In summary, ASME B18.2.1 bolts and screws with coarse thread pitch are widely used in a variety of industries and applications where reliable and strong connections are essential. These fasteners provide a secure and durable connection that can withstand heavy loads and high stress.
Materials of ASME B18.2.1
ANSI/ASME Materials:
• Alloy Steel Bolting Materials for High-Temperature Service, ASTM A193 Grade B7
• Alloy Steel and Stainless-Steel Bolting Materials for Low-Temperature Service, ASTM A320 Grade L7
• Carbon and Alloy Steel Nuts for Bolts for High-Pressure and High-Temperature Service, ASTM A194 Grade 2H
ASTM Materials:
• Carbon Steel Bolts and Studs, ASTM A307 Grade A and B
• High-Strength Structural Bolts, ASTM F3125 Grade A325
• High-Strength Structural Bolts, ASTM F3125 Grade A490
ASME B18.2.1 also specifies the grades or classes of materials that are appropriate for different applications, which include:
Grade 2: Low or medium carbon steel
Grade 5: Medium carbon steel with added elements such as vanadium or manganese
Grade 8: Medium carbon alloy steel with additional elements such as chromium and molybdenum
Class 8.8: Medium carbon steel with a minimum tensile strength of 800 N/mm²
Class 10.9: Alloy steel with a minimum tensile strength of 1000 N/mm²
Class 12.9: Alloy steel with a minimum tensile strength of 1200 N/mm²
Note that these are just a few examples of the materials and standards that can be used to make ASME B18.2.1 fasteners, and the specific material used will depend on the application and engineering requirements. It's always important to consult the specific standards and materials requirements for your project to ensure proper material selection and use.
