ASME B 18.31.5 U-Bolts
ASME B18.31.5 U-Bolts are inch-series bent fasteners designed to secure pipes, tubes, cables, and other components to supporting structures. The U-shaped body wraps around the outside of the component, while the two threaded legs pass through a mounting plate, bracket, or other support and are tightened with nuts. This configuration provides a simple and practical way to restrain components against movement while allowing the fastening point to be accessed from one side of the support.
Manufactured in accordance with ASME B18.31.5, these U-bolts are available in different diameters, leg lengths, inside widths, threaded lengths, and bend configurations to match the dimensions of the component being secured. Carbon steel, alloy steel, and stainless steel options are available, with plain, zinc-plated, and hot-dip galvanized finishes for different service environments. U-bolts can also be supplied with matching nuts and washers or produced to customer drawings when specific dimensions or material requirements are needed.
Specification:
ASME B18.31.5 U-bolts are inch-series bent bolts specified by their nominal diameter, leg length, inside width, threaded length, and bend configuration. The standard covers U-bolts in different bend forms, with dimensions defined according to the applicable configuration. We supply U-bolts in carbon steel, alloy steel, and stainless steel to suit structural, piping, equipment, and general fastening requirements.
| Item | Specification |
|---|---|
| Standard | ASME B 18.31.5 |
| Product Type | U-Bolts (Round Bend) |
| System | Inch |
| Size Range | 1/4"-1“ |
| Thread | UNC,UNF |
| Thread Standard | ASME B1.1 |
| Material | Carbon Steel, Stainless Steel |
| Mechanical Property | F1554,ASTM A307, ASTM A193/A193M,SAE J 429,ASTM F593 |
| Surface Treatment | Plain,Zinc Plated,Hot Dip Galvanized,Black Oxidation |
| Hdg Standard | ASTM A2329/F2329M |
| Inspection | Dimensions, Thread,Mechanical Property,Coating |
Dimension Chart of ASME B 18.31.5 U-Bolts:
| Thread Diameter | 1/4 | 1/4 | 1/4 | 1/4 | 1/4 | 1/4 | 1/4 | 1/4 | 1/4 | 1/4 | 1/4 | 5/16 | 5/16 | 5/16 | 5/16 | |
| U04C012 | U04C013 | U04C022 | U04C017 | U04C020 | U04C031 | U04C023 | U04C027 | U04C034 | U04C030 | U04C032 | U05C021 | U05C022 | U05C023 | U05C026 | ||
| Pitch | 20 | 20 | 20 | 20 | 20 | 20 | 20 | 20 | 20 | 20 | 20 | 18 | 18 | 18 | 18 | |
| L | norm. | 1.25 | 1.25 | 2.25 | 1.75 | 2 | 3.125 | 2.25 | 2.75 | 3.438 | 3 | 3.25 | 2.188 | 2.188 | 2.188 | 2.688 |
| max | 1.28 | 1.28 | 2.28 | 1.78 | 2.03 | 3.155 | 2.28 | 2.78 | 3.468 | 3.03 | 3.28 | 2.218 | 2.218 | 2.218 | 2.718 | |
| min | 1.22 | 1.22 | 2.22 | 1.72 | 1.97 | 3.095 | 2.22 | 2.72 | 3.408 | 2.97 | 3.22 | 2.158 | 2.158 | 2.158 | 2.658 | |
| n | norm. | 0.563 | 0.75 | 0.75 | 1 | 1 | 1 | 1.125 | 1.125 | 1.125 | 1.25 | 1.25 | 1.375 | 1.375 | 1.5 | 1.5 |
| max | 0.593 | 0.78 | 0.78 | 1.03 | 1.03 | 1.03 | 1.155 | 1.155 | 1.155 | 1.28 | 1.28 | 1.405 | 1.405 | 1.53 | 1.53 | |
| min | 0.533 | 0.72 | 0.72 | 0.97 | 0.97 | 0.97 | 1.095 | 1.095 | 1.095 | 1.22 | 1.22 | 1.345 | 1.345 | 1.47 | 1.47 | |
| b | max | 0.81 | 0.685 | 1.56 | 1.06 | 1.06 | 1.56 | 1.31 | 1.435 | 2.435 | 1.435 | 1.435 | 1.435 | 1.06 | 1.06 | 1.185 |
| min | 0.69 | 0.565 | 1.44 | 0.94 | 0.94 | 1.44 | 1.19 | 1.315 | 2.315 | 1.315 | 1.315 | 1.315 | 0.94 | 0.94 | 1.065 | |
| Thread Diameter | 5/16 | 5/16 | 5/16 | 5/16 | 5/16 | 5/16 | 3/8 | 3/8 | 3/8 | 3/8 | 3/8 | 3/8 | 3/8 | 3/8 | 3/8 | |
| U05C045 | U05C027 | U05C047 | U05C032 | U05C056 | U05C037 | U06C022 | U06C023 | U06C025 | U06C027 | U06C026 | U06C031 | U06C036 | U06C066 | U06C041 | ||
| Pitch | 18 | 18 | 18 | 18 | 18 | 18 | 16 | 16 | 16 | 16 | 16 | 16 | 16 | 16 | 16 | |
| L | norm. | 4.5 | 2.688 | 4.75 | 3.188 | 5.625 | 3.688 | 2.25 | 2.25 | 2.5 | 2.75 | 2.625 | 3.125 | 3.625 | 6.625 | 4.125 |
| max | 4.53 | 2.718 | 4.78 | 3.218 | 5.685 | 3.718 | 2.28 | 2.28 | 2.53 | 2.78 | 2.655 | 3.155 | 3.655 | 6.685 | 4.155 | |
| min | 4.47 | 2.658 | 4.72 | 3.158 | 5.565 | 3.658 | 2.22 | 2.22 | 2.47 | 2.72 | 2.595 | 3.095 | 3.595 | 6.565 | 4.095 | |
| n | norm. | 1.75 | 1.75 | 1.75 | 1.75 | 2 | 2 | 2 | 2 | 2.5 | 2.5 | 2.5 | 3 | 3 | 3 | 3 |
| max | 1.78 | 1.78 | 1.78 | 1.78 | 2.03 | 2.03 | 2.03 | 2.03 | 2.53 | 2.53 | 2.53 | 3.03 | 3.03 | 3.03 | 3.03 | |
| min | 1.72 | 1.72 | 1.72 | 1.72 | 1.97 | 1.97 | 1.97 | 1.97 | 2.47 | 2.47 | 2.47 | 2.97 | 2.97 | 2.97 | 2.97 | |
| b | max | 2.06 | 1.06 | 3.06 | 1.06 | 3.06 | 1.06 | 1.31 | 1.31 | 1.31 | 1.185 | 1.31 | 1.31 | 1.31 | 3.06 | 1.31 |
| min | 1.94 | 0.94 | 2.94 | 0.94 | 2.94 | 0.94 | 1.19 | 1.19 | 1.19 | 1.065 | 1.19 | 1.19 | 1.19 | 2.94 | 1.19 | |
| Thread Diameter | 3/8 | 1/2 | 1/2 | 1/2 | 1/2 | 1/2 | 1/2 | 1/2 | 1/2 | 3/4 | 7/8 | 7/8 | 7/8 | 1 | ||
| U06C055 | U08C045 | U08C050 | U08C085 | U08C055 | U08C060 | U08C072 | U08C084 | U08C104 | U12C138 | U14C161 | U14C173 | U14C193 | U16C217 | |||
| Pitch | 16 | 13 | 13 | 13 | 13 | 13 | 13 | 13 | 13 | 10 | 9 | 9 | 9 | 8 | ||
| L | norm. | 5.5 | 4.5 | 5 | 8.5 | 5.5 | 6 | 7.25 | 8.375 | 10.375 | 13.813 | 16.063 | 17.313 | 19.313 | 21.688 | |
| max | 5.56 | 4.53 | 5.06 | 8.59 | 5.56 | 6.06 | 7.31 | 8.465 | 10.465 | 13.933 | 16.183 | 17.433 | 19.433 | 21.808 | ||
| min | 5.44 | 4.47 | 4.94 | 8.41 | 5.44 | 5.94 | 7.19 | 8.285 | 10.285 | 13.693 | 15.943 | 17.193 | 19.193 | 21.568 | ||
| n | norm. | 3.5 | 3.5 | 3.5 | 4 | 4 | 4.5 | 5.625 | 6.75 | 8.75 | 10.875 | 12.875 | 14.125 | 16.125 | 18.125 | |
| max | 3.53 | 3.53 | 3.53 | 4.03 | 4.03 | 4.53 | 5.685 | 6.81 | 8.84 | 10.965 | 12.995 | 14.245 | 16.245 | 18.245 | ||
| min | 3.47 | 3.47 | 3.47 | 3.97 | 3.97 | 4.47 | 5.565 | 6.69 | 8.93 | 11.055 | 12.755 | 14.005 | 16.005 | 18.005 | ||
| b | max | 2.31 | 1.685 | 1.56 | 3.06 | 1.56 | 1.56 | 2.06 | 2.06 | 2.06 | 4.06 | 4.31 | 4.31 | 4.31 | 4.81 | |
| min | 2.19 | 1.565 | 1.44 | 2.94 | 1.44 | 1.44 | 1.94 | 1.94 | 1.94 | 3.94 | 4.19 | 4.19 | 4.19 | 4.69 | ||
- RELATED BOLTS LISTS:
- U-BOLTS
- ASME B 18.31.5 U-BOLTS
- DIN3570 U-BOLTS
- STUD BOLTS
- DIN976 STUD BOLTS
- DIN939 STUD BOLTS
- IFI 136 STUD BOLTS
- THREADED RODS
- DIN975 THREADED RODS
- ASME B 18.31.3 THREADED RODS
- FOUNDATION ANCHOR BOLTS
- DIN 529 ANCHOR BOTLS
- JIS 1178 L ANCHOR BOLTS
- JIS 1178 J ANCHOR BOLTS
- ASME B 18.31.5 J BOLTS
- ASME B 18.31.5 HOOK BOLTS
Application of ASME B 18.31.5 U-Bolts:
ASME B18.31.5 U-bolts are commonly used where a component needs to be held securely against a supporting structure without requiring the fastener to pass through the component itself. The U-shaped body provides two points of clamping through the threaded legs, making the fastener suitable for piping, mechanical equipment, structural assemblies, and utility installations.
Pipe and Tube Support
U-bolts are widely used to secure pipes and tubes to steel frames, brackets, channels, and other supports. The curved portion follows the outside of the pipe or tube, while nuts on the threaded legs hold it against the support. They can be used for water, air, hydraulic, process, and other piping systems, with material and surface finish selected according to the service environment.
Mechanical and Equipment Mounting
In mechanical equipment and fabricated assemblies, U-bolts can hold cylindrical or tubular components in a fixed position. They are useful for securing shafts, rods, conduits, tanks, frames, and other components where a wrap-around fastening arrangement is more practical than drilling through the component.
Structural and Utility Installations
U-bolts are also used for securing cables, conduits, tubing, and other services to structural members. Carbon steel and galvanized U-bolts are commonly selected for general structural and outdoor installations, while stainless steel versions can be used where corrosion resistance is an important consideration.