Description
The ANSI B18.21.1 Spring Washer is a precision-engineered helical lock washer designed to prevent fastener loosening under vibration, torque fluctuations, and dynamic loads. Manufactured in accordance with ANSI/ASME B18.21.1 standards, this spring washer ensures dimensional accuracy, reliable tension retention, and consistent mechanical performance in inch-based fastening systems.
Available in both 304 and 316 stainless steel, this stainless steel washer provides excellent corrosion resistance and long-term durability in demanding industrial, marine, and construction environments. Its split-ring, helical design generates continuous preload (elastic tension) within the joint, increasing friction and helping maintain bolt or nut tightness over time.
The ANSI B18.21.1 Spring Washer is widely used in heavy machinery, structural assemblies, automotive systems, and corrosion-prone installations where fastening security is critical.
Features & Benefits
- Exceptional Corrosion Resistance: Forged from premium 304 or 316 stainless steel, these spring washers offer excellent resistance to rust, oxidation, and chemical exposure. Grade 316 is particularly recommended for marine and high-chloride environments to ensure maximum service life.
- Active Helical Locking Mechanism: The split-ring design creates a "spring" effect that maintains constant pressure on the fastened joint. This active tension effectively resists the self-loosening effects of heavy vibration and mechanical shock.
- High Hardness & Structural Integrity: Engineered for durability, the ANSI B18.21.1 washer features high hardness to resist flattening or permanent deformation under load. This ensures that the locking function remains effective throughout the lifecycle of the assembly.
- Standardized Precision Fit: Fully compliant with ANSI B18.21.1 specifications, these washers guarantee dimensional accuracy for American-standard bolts. The uniform design ensures even force distribution and a stable grip, preventing damage to the mating surfaces.
Specification
|
Thread specification -d |
d |
dc |
h |
h |
||
|
Nominal |
max |
min |
max |
min |
min |
|
|
2# |
0.096 |
0.094 |
0.088 |
0.175 |
0.02 |
0.035 |
|
3# |
0.099 |
0.107 |
0.101 |
0.195 |
0.025 |
0.04 |
|
4# |
0.112 |
0.12 |
0.114 |
0.209 |
0.025 |
0.04 |
|
5# |
0.125 |
0.133 |
0.127 |
0.236 |
0.031 |
0.047 |
|
6# |
0.138 |
0.148 |
0.141 |
0.25 |
0.031 |
0.047 |
|
8# |
0.164 |
0.174 |
0.167 |
0.293 |
0.04 |
0.055 |
|
10# |
0.19 |
0.2 |
0.193 |
0.334 |
0.047 |
0.062 |
|
12# |
0.216 |
0.227 |
0.22 |
0.377 |
0.056 |
0.07 |
|
1/4″ |
0.25 |
0.26 |
0.252 |
0.487 |
0.062 |
0.109 |
|
5/16″ |
0.3125 |
0.322 |
0.314 |
1.583 |
0.078 |
0.125 |
|
3/8″ |
0.375 |
0.385 |
0.377 |
0.68 |
0.094 |
0.141 |
|
7/16″ |
0.4375 |
0.45 |
0.44 |
0.776 |
0.109 |
0.156 |
|
1/2″ |
0.5 |
0.512 |
0.5.2 |
0.869 |
0.125 |
0.171 |
|
9/16″ |
0.5625 |
0.574 |
0.564 |
0.965 |
0.141 |
0.188 |
|
5/8″ |
0.625 |
0.641 |
0.628 |
1.073 |
0.156 |
0.203 |
|
11/16″ |
0.6875 |
0.704 |
0.691 |
1.17 |
0.172 |
0.219 |
|
3/4″ |
0.75 |
0.766 |
0.753 |
1.265 |
0.188 |
0.234 |
|
13/16″ |
0.8125 |
0.832 |
0.816 |
1.363 |
0.203 |
0.25 |
|
7/8″ |
0.875 |
0.894 |
0.878 |
1.459 |
0.219 |
0.266 |
|
15/16″ |
0.9375 |
0.958 |
0.941 |
1.556 |
0.234 |
0.281 |
|
1″ |
1 |
1.024 |
1.003 |
1.656 |
0.25 |
0.297 |
|
1-1/16″ |
1.0625 |
1.087 |
1.066 |
1.751 |
0.266 |
0.312 |
|
1-1/8″ |
1.125 |
1.153 |
1.129 |
1.847 |
0.281 |
0.328 |
|
1-3/16″ |
1.1875 |
1.217 |
1.192 |
1.943 |
0.297 |
0.344 |
|
1-1/4″ |
1.25 |
1.28 |
1.254 |
2.036 |
0.312 |
0.359 |
|
1-5/16″ |
1.3125 |
1.344 |
1.317 |
2.133 |
0.328 |
0.375 |
|
1-3/8″ |
1.375 |
1.408 |
1.379 |
2.219 |
0.344 |
0.391 |
|
1-7/16″ |
1.4375 |
1.472 |
1.442 |
2.324 |
0.359 |
0.406 |
|
1-1/2″ |
1.5 |
1.534 |
1.504 |
2.419 |
0.375 |
0.422 |
|
1-5/8″ |
1.625 |
1.663 |
1.633 |
2.553 |
0.389 |
0.424 |
|
1-3/4″ |
1.75 |
1.789 |
1.758 |
2.679 |
0.389 |
0.424 |
|
1-7/8″ |
1.875 |
1.914 |
1.883 |
2.811 |
0.422 |
0.427 |
|
2″ |
2 |
2.039 |
2.008 |
2.936 |
0.422 |
0.427 |
|
2-1/4″ |
2.25 |
2.293 |
2.262 |
3.221 |
0.44 |
0.442 |
|
2-1/2″ |
2.5 |
2.543 |
2.512 |
3.471 |
0.44 |
0.442 |
|
2-3/4″ |
2.75 |
2.793 |
2.762 |
3.824 |
0.458 |
0.491 |
|
3″ |
3 |
3.304 |
3.012 |
4.047 |
0.458 |
0.491 |
FAQ:
Q1: How does an ANSI B18.21.1 Spring Washer differ from a JIS or DIN spring washer?
A: The primary difference lies in the dimensional standards (thickness and outer diameter) and the specific testing requirements defined by the American Society of Mechanical Engineers (ASME). While they function similarly, ANSI B18.21.1 washers are specifically sized to match American-standard bolt diameters and series (Regular vs. Heavy).
Q2: Why should I choose 316 stainless steel over 304?
A: While both are rust-resistant, 316 stainless steel contains molybdenum. This addition provides superior protection against "pitting" and crevice corrosion, which is essential for marine infrastructure, coastal construction, and chemical processing plants.
Q3: Does this washer replace the need for a flat washer?
A: Not necessarily. In many high-vibration assemblies, a Stainless Steel Spring Washer is used in combination with a flat washer. The flat washer provides a smooth bearing surface to distribute the load, while the spring washer provides the locking tension.
Q4: Can these washers be used in high-temperature applications?
A: Yes, stainless steel spring washers maintain their spring properties better at higher temperatures than carbon steel alternatives. However, for extreme heat (above 800°F), specialized alloys like Grade 321 or Duplex may be required.
Q5: How does a spring washer improve fastening security?
A: The helical split-ring design generates elastic tension when compressed, increasing friction between mating surfaces and maintaining clamp load.
