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Monel 400 Washers are high-performance nickel-copper alloy fastening components designed for extreme corrosion environments, especially seawater, acidic media, and chemical processing systems. Manufactured from UNS N04400 material, these washers deliver excellent resistance against chloride stress corrosion cracking and maintain structural stability across a wide temperature range from cryogenic conditions up to approximately 480°C. They are widely used in marine engineering, oil & gas refineries, heat exchangers, and offshore equipment where conventional stainless steel grades may fail due to pitting or galvanic corrosion.
Engineered for precision load distribution, Monel 400 Washers ensure bolt tension stability and prevent surface damage in high-vibration assemblies. KK Fasteners supplies these washers to global industrial clients with full material traceability and strict dimensional compliance, supporting critical applications where reliability is non-negotiable.
| Parameter | Specification |
|---|---|
| Material | Monel 400 (UNS N04400), Nickel-Copper Alloy |
| Standards | ASTM B164, ASTM B127, ASME SB164, ISO 7089, DIN 125 |
| Size Range | M3 to M100 / 1/8" to 4" |
| Types | Flat Washers, Spring Washers, Plain Washers, Heavy Duty Washers |
| Hardness | Approximately 70–90 HRB |
| Tensile Strength | Up to 550 MPa (approx.) |
| Finish | Bright, Polished, Pickled, Passivated |
| Thread Compatibility | Metric (M), UNC, UNF fasteners |
| Grade | C | Mn | Si | S | Cu | Fe | Ni | Cr |
| Monel 400 | 0.30 max | 2.00 max | 0.50 max | 0.24max | 28.0-34.0 | 2.50 max | 63.00 min | – |
| Element | Density | Melting Point | Tensile Strength | Yield Strength (0.2%Offset) | Elongation |
| Monel 400 | 8.8 g/cm3 | 1350 °C (2460 °F) | Psi – 80,000 , MPa – 550 | Psi – 35,000 , MPa – 240 | 40 % |
| STANDARD | WERKSTOFF NR. | UNS | JIS | BS | GOST | AFNOR | EN | |
| Monel 400 | 2.4360 | N04400 | NW 4400 | NA 13 | МНЖМц 28-2,5-1,5 | NU-30M | NiCu30Fe |
Bolt Size
|
USS
|
SAE
|
||||
OD (in.)
|
ID (in.)
|
Thickness
|
OD (in.)
|
ID (in.)
|
Thickness
|
|
1/8 (#6)
|
-
|
-
|
-
|
0.375
|
0.156
|
.036/.065
|
5/32 (#8)
|
-
|
-
|
-
|
0.438
|
0.188
|
.036/.065
|
3/16 (#10)
|
0.560
|
0.250
|
.036/.065
|
0.500
|
0.220
|
.036/.065
|
7/32 (#12)
|
-
|
-
|
-
|
0.562
|
0.250
|
.051/.080
|
1/4 (#14)
|
0.734
|
0.312
|
.051/.080
|
0.625
|
0.281
|
.051/.080
|
5/16
|
0.875
|
0.375
|
.064/.104
|
0.688
|
0.344
|
.051/.080
|
3/8
|
1.000
|
0.438
|
.064/.104
|
0.812
|
0.406
|
.051/.080
|
7/16
|
1.250
|
0.500
|
.064/.104
|
0.922
|
0.469
|
.051/.080
|
1/2
|
1.375
|
0.562
|
.086/.132
|
1.062
|
0.531
|
.074/.121
|
9/16
|
1.469
|
0.625
|
.086/.132
|
1.156
|
0.594
|
.074/.121
|
5/8
|
1.750
|
0.688
|
.108/.160
|
1.312
|
0.656
|
.074/.121
|
3/4
|
2.000
|
0.812
|
.122/.177
|
1.469
|
0.812
|
.108/.160
|
7/8
|
2.250
|
0.938
|
.136/.192
|
1.750
|
0.938
|
.108/.160
|
1
|
2.500
|
1.062
|
.136/.192
|
2.000
|
1.062
|
.108/.160
|
1 1/8
|
2.750
|
1.250
|
.136/.192
|
2.250
|
1.250
|
.108/.160
|
1 1/4
|
3.000
|
1.375
|
.136/.192
|
2.500
|
1.375
|
.136/.192
|
1 3/8
|
3.250
|
1.500
|
.153/.213
|
2.750
|
1.500
|
.136/.213
|
1 1/2
|
3.500
|
1.625
|
.153/.213
|
3.000
|
1.625
|
.153/.213
|
1 5/8
|
3.750
|
1.750
|
.153/.213
|
-
|
-
|
-
|
1 3/4
|
4.000
|
1.875
|
.153/.213
|
-
|
-
|
-
|
1 7/8
|
4.250
|
2.000
|
.153/.213
|
-
|
-
|
-
|
2
|
4.500
|
2.125
|
.153/.213
|
-
|
-
|
-
|
2 1/4
|
4.750
|
2.375
|
.320/.248
|
-
|
-
|
-
|
2 1/2
|
5.000
|
2.625
|
.210/.280
|
-
|
-
|
-
|
2 3/4
|
5.250
|
2.875
|
.228/.410S
|
-
|
-
|
-
|
3
|
5.500
|
3.125
|
.249/.327
|
-
|
-
|
-
|
Size |
USS |
SAE |
||||
|---|---|---|---|---|---|---|
Inside Diameter (A) |
Outside Diameter (B) |
Thickness (C) |
Inside Diameter (A) |
Outside Diameter (B) |
Thickness (C) |
|
#2 |
- |
- |
- |
3/32" |
1/4" |
0.020" |
#4 |
- |
- |
- |
1/8" |
5/16" |
0.032" |
#6 |
- |
- |
- |
5/32" |
3/8" |
0.049" |
#8 |
- |
- |
- |
3/16" |
7/16" |
0.049" |
#10 |
- |
- |
- |
7/32" |
1/2" |
0.049" |
#12 |
- |
- |
- |
1/4" |
9/16" |
0.065" |
1/4" |
5/16" |
0.734" |
0.065" |
9/32" |
5/8" |
0.065" |
5/16" |
3/8" |
7/8" |
0.083" |
11/32" |
11/16" |
0.065" |
3/8" |
7/16" |
1" |
0.083" |
13/32" |
13/16" |
0.065" |
7/16" |
1/2" |
1-1/4" |
0.083" |
15/32" |
15/16" |
0.065" |
1/2" |
9/16" |
1-3/8" |
0.109" |
17/32" |
1-1/16" |
0.095" |
9/16" |
5/8" |
1-15/32" |
0.109" |
19/32" |
1-5/32" |
0.095" |
5/8" |
11/16" |
1-3/4" |
0.134" |
21/32" |
1-5/16" |
0.095" |
3/4" |
13/16" |
2" |
0.148" |
13/16" |
1-15/32" |
0.134" |
7/8" |
15/16" |
2-1/4" |
0.165" |
15/16" |
1-3/4" |
0.134" |
1" |
1-1/16" |
2-1/2" |
0.165" |
1-1/16" |
2" |
0.134" |
1-1/8" |
1-1/4" |
2-3/4" |
0.165" |
- |
- |
- |
1-1/4" |
1-3/8" |
3" |
0.165" |
- |
- |
- |
1-3/8" |
1-1/2" |
3-1/4" |
0.180" |
- |
- |
- |
1-1/2" |
1-5/8" |
3-1/2" |
0.180" |
- |
- |
- |
1-5/8" |
1-3/4" |
3-3/4" |
0.180" |
- |
- |
- |
1-3/4" |
1-7/8" |
4" |
0.180" |
- |
- |
- |
2" |
2-1/8" |
4-1/2" |
0.213" |
- |
- |
- |
Monel 400 Washers are used wherever corrosion resistance and mechanical reliability are critical under aggressive operating conditions. They provide stable load distribution and protect joint integrity in demanding environments.
Monel 400 Washers are manufactured using precision cold forging and CNC-assisted finishing to ensure dimensional accuracy and uniform surface integrity. Each batch undergoes controlled heat treatment processes to stabilize mechanical properties and improve corrosion resistance.
Quality inspection includes hardness testing, tensile verification, and surface finish evaluation under strict industrial standards. Every production lot is fully traceable, ensuring compliance with ISO 9001:2015 quality management systems. Additional certifications such as RoHS and REACH compliance are maintained for global export readiness.
KK Fasteners applies multi-stage inspection protocols to ensure that each washer meets exacting tolerances required for critical industrial applications, especially in marine and chemical sectors.
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Monel 400 Washers are corrosion-resistant flat fastening components made from a nickel-copper alloy (UNS N04400). They are designed to distribute load evenly under bolt or nut heads while preventing surface damage and loosening. These washers are widely used in marine, chemical, and offshore environments where standard stainless steel may corrode or degrade.
Monel 400 performs significantly better than stainless steel in high-chloride environments such as seawater. While stainless steel can suffer from pitting and crevice corrosion, Monel 400 maintains structural integrity and resists chloride stress corrosion cracking, making it more reliable for shipbuilding and offshore engineering systems.
Monel 400 Washers are typically manufactured in accordance with ASTM B164, ASTM B127, ASME SB164, ISO 7089, and DIN 125 standards. These specifications ensure correct chemical composition, dimensional accuracy, mechanical strength, and global interchangeability in industrial applications.
They are used in marine engineering, offshore oil rigs, chemical processing plants, desalination units, and heat exchangers. In these environments, Monel 400 Washers provide long-term resistance against saltwater, acids, and extreme temperatures, ensuring joint reliability in critical systems.
A reliable supplier should offer certified material traceability, compliance with international standards, ISO 9001 quality systems, and proven export experience. KK Fasteners supports global procurement teams with inspection reports, test certificates, and consistent quality across large-scale industrial orders.
Monel 400 Washers are essential for industries where corrosion failure is not an option, delivering long-term reliability in aggressive environments. With strict quality control and export-grade manufacturing capability, KK Fasteners supports global industrial procurement needs with precision-engineered fastening solutions.
Request technical specifications or a competitive quotation from KK Fasteners to source Monel 400 Washers tailored to your project requirements.
