Incoloy 800H/800HT Washers are high-performance fastening components engineered for elevated temperature environments where mechanical stability and oxidation resistance are critical. Manufactured from nickel-iron-chromium alloys, these washers are widely used in petrochemical processing, heat treatment equipment, and power generation systems where temperatures exceed 600°C.

These washers conform to standards such as ASTM B408 and ASTM B564, ensuring consistent dimensional accuracy and metallurgical integrity across global applications. Their primary function is to distribute load, reduce surface wear, and maintain joint integrity under thermal expansion and cyclic stress conditions.
KK Fasteners supplies Incoloy 800H/800HT washers to international markets with complete material traceability, supporting demanding applications across oil refineries, chemical plants, and thermal processing industries.
| Parameter | Specification |
|---|---|
| Material | Incoloy 800H / Incoloy 800HT (Nickel-Iron-Chromium Alloy) |
| Grade | UNS N08810 (800H), UNS N08811 (800HT) |
| Size Range | M3 to M100 / 1/8" to 4" |
| Standards | ASTM B408, ASTM B564, DIN 125, DIN 9021, ISO 7089 |
| Type | Flat Washers, Plain Washers, Spring Washers, Custom Machined |
| Finish | Plain, Pickled, Passivated, Polished |
| Hardness | Rockwell B 80–95 (Typical) |
| Temperature Resistance | Up to 870°C (continuous service) |
| Thread Compatibility | Metric, UNC, UNF |
| Grade | C | Mn | Si | S | Cu | Fe | Ni | Cr | Al | Ti |
| 800H | 0.05 – 0.10 | 1.50 max | 1.00 max | 0.015 max | 0.75 max | 39.50 min | 30.00 – 35.00 | 19.00 – 23.00 | 0.15 – 0.60 | 0.15 – 0.60 |
| 800HT | 0.06 – 0.10 | 1.50 max | 1.00 max | 0.015 max | 0.75 max | 39.50 min | 30.00 – 35.00 | 19.00 – 23.00 | 0.15 – 0.60ᴬ | 0.15 – 0.60ᴬ |
| Element | Density | Melting Point | Tensile Strength | Yield Strength (0.2%Offset) | Elongation |
| 800H/800HT | 7.94 g/cm3 | 1385 °C (2525 °F) | Psi – 75,000 , MPa – 520 | Psi – 30,000 , MPa – 205 | 30 % |
| STANDARD | WERKSTOFF NR. | UNS | JIS | BS | GOST | AFNOR | EN | OR |
| Incoloy 800H | 1.4958 / 1.4876 | N08810 | NCF 800H | NA 15(H) | ЭИ670 | Z8NC33-21 | X5NiCrAlTi31-20 | XH32T |
| Incoloy 800HT | 1.4859 / 1.4876 | N08811 | NCF 800HT | NA 15(HT) | ЭИ670 | – | X8NiCrAlTi32-21 | XH32T |
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" |
- |
- |
- |
Incoloy 800H/800HT washers are primarily used in high-temperature and corrosive environments where standard stainless steel washers fail to perform reliably.
These washers are produced through precision machining and hot forming processes to maintain metallurgical consistency and dimensional accuracy. Raw materials undergo strict chemical composition verification before production, followed by controlled forging and CNC machining.
Quality checks include dimensional inspection using calibrated gauges, hardness testing, and surface finish verification. Each batch is traceable through heat numbers and inspection records.
KK Fasteners follows ISO 9001-certified quality management systems, ensuring that every shipment meets international compliance standards, including RoHS and REACH requirements where applicable.

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Incoloy 800H/800HT washers are high-temperature resistant fastening components made from nickel-iron-chromium alloys. They are designed to distribute load and maintain joint stability in extreme heat and corrosive environments, commonly used in petrochemical, power generation, and thermal processing industries.
The key difference lies in composition control. Incoloy 800HT has stricter limits on carbon, aluminum, and titanium, resulting in better creep strength and grain stability at elevated temperatures. Incoloy 800H offers reliable performance but is typically used in moderately high-temperature applications.
These washers are manufactured in accordance with ASTM B408 and ASTM B564 material standards, along with dimensional standards such as DIN 125, DIN 9021, and ISO 7089, ensuring compatibility with international engineering requirements.
Selection depends on operating temperature, load conditions, and environmental exposure. For applications above 700°C with prolonged stress, 800HT is preferred. For moderately high temperatures with less demanding conditions, 800H provides a cost-effective solution.
A reliable supplier should provide ISO-certified production, full material traceability, ASTM compliance, and global export experience. KK Fasteners meets these criteria by supplying tested and documented fastening solutions to international markets.
Incoloy 800H/800HT washers play a critical role in maintaining joint reliability under extreme thermal and mechanical stress. With strict adherence to ASTM standards and full traceability, KK Fasteners supports global industries requiring dependable high-temperature fastening solutions. Contact the engineering team to request a quote or discuss custom specifications for your next project.