Incoloy 800H/800HT bolts are engineered nickel-iron-chromium alloy fasteners designed for extreme thermal environments where conventional stainless steel fasteners fail due to creep, oxidation, or structural weakening. These bolts maintain mechanical integrity in temperatures typically exceeding 600°C, making them essential for heat-intensive industries such as petrochemical processing, power generation, heat treatment furnaces, and nuclear engineering systems.

Manufactured in compliance with international standards such as ASTM B564 and related nickel alloy specifications, these fasteners offer a balanced combination of high-temperature strength and resistance to carburization and oxidation. The addition of controlled carbon, aluminum, and titanium stabilizes the alloy microstructure, improving long-term creep rupture strength in demanding conditions.
KK Fasteners supplies these high-performance bolts to global EPC contractors and industrial OEMs, ensuring full traceability, dimensional accuracy, and material certification for every production batch. For engineers working in thermally aggressive environments, these fasteners are not optional—they are critical to system reliability and safety.
| Parameter | Specification |
|---|---|
| Material | Incoloy 800H / 800HT (Nickel-Iron-Chromium Alloy) |
| Grades | 800H (High Carbon), 800HT (Controlled Ti/Al for creep strength) |
| Size Range | M6 to M100 / 1/4" to 4" diameter |
| Thread Types | Metric (ISO), UNC, UNF, BSW |
| Standards | ASTM B564, ASTM B408, DIN 933, ISO 4014, ASME SB specifications |
| Surface Finish | Bright, Pickled, Passivated, Polished |
| Fastener Types | Hex Bolt, Stud Bolt, Heavy Hex Bolt, Socket Head Bolt |
| Tensile Strength | ≥ 500 MPa (varies with heat treatment condition) |
| Grade | C | Mn | Si | Fe | S | Cr | Al-Ti | Ni | |
| Incoloy 800H | min. | 0.05 | – | – | 39.5 | – | 19.0 | 0.15 | 30.0 |
| max. | 0.1 | 1.5 | 1.0 | – | 0.015 | 23.0 | 0.60 | 35.0 | |
| Incoloy 800HT | min. | 0.06 | – | – | 39.5 | – | 19.0 | 0.85/0.25 | 30.0 |
| max. | 0.1 | 1.5 | 1.0 | – | 0.015 | 23.0 | 1.20/0.60 | 35.0 | |
| Grade | Tensile Strength (MPa) min | Yield Strength 0.2% Proof (MPa) min | Elongation (% in 50mm) min | Hardness | |
| Rockwell B (HR B) max | Brinell (HB) max | ||||
| Incoloy 800H/800HT | 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 |
All measurements in millimeters
NOMINAL SIZE (D) |
BODY DIAMETER |
BOLT HEAD THICKNESS |
ACROSS THE FLATS |
ACROSS CORNERS |
||||
|---|---|---|---|---|---|---|---|---|
D (MAX) |
D (MIN) |
H (MAX) |
H (MIN) |
F (MAX) |
F (MIN) |
C (MAX) |
C (MIN) |
|
m10 |
10.00 |
9.78 |
6.63 |
6.17 |
17.00 |
15.73 |
18.48 |
17.77 |
m12 |
12.00 |
11.73 |
7.76 |
4.24 |
19.00 |
17.73 |
20.78 |
20.03 |
m14 |
14.00 |
13.73 |
9.09 |
8.51 |
22.00 |
20.67 |
24.25 |
23.35 |
m16 |
16.00 |
15.73 |
10.32 |
9.68 |
24.00 |
23.67 |
27.71 |
26.75 |
m20 |
20.00 |
19.67 |
12.88 |
12.12 |
30.00 |
29.16 |
34.64 |
32.95 |
m24 |
24.00 |
23.67 |
15.44 |
14.56 |
36.00 |
35.00 |
41.57 |
39.55 |
m30 |
30.00 |
29.67 |
19.48 |
17.92 |
46.00 |
45.00 |
53.12 |
50.85 |
m36 |
36.00 |
35.61 |
23.38 |
21.63 |
55.00 |
53.80 |
63.51 |
60.79 |
m42 |
42.00 |
41.38 |
26.97 |
25.03 |
65.00 |
62.90 |
75.06 |
71.71 |
m48 |
48.00 |
47.38 |
31.07 |
28.93 |
75.00 |
72.60 |
86.60 |
82.76 |
m56 |
56.00 |
55.26 |
36.2 |
33.80 |
85.00 |
82.20 |
98.15 |
93.71 |
m64 |
64.00 |
63.26 |
41.32 |
38.68 |
95.00 |
91.80 |
109.70 |
104.65 |
m72 |
72.00 |
71.26 |
46.45 |
43.55 |
105.00 |
101.40 |
121.24 |
115.60 |
m80 |
80.00 |
79.26 |
51.58 |
48.42 |
115.00 |
111.00 |
132.72 |
126.54 |
m90 |
90.00 |
89.13 |
57.74 |
54.26 |
130.00 |
125.50 |
150.11 |
143.07 |
m100 |
90.00 |
99.13 |
63.9 |
60.10 |
145.00 |
140.00 |
167.43 |
159.60 |
| MM THREADS AS PER IS 1363/67 | ||||||||||
| APPROXIMATE WEIGHT IN KGS FOR 100 NOS | ||||||||||
| LENGTH | DIAMETER | |||||||||
| M 5 | M 6 | M 8 | M 10 | M 12 | M 14 | M 16 | M 18 | M 20 | M 22 | |
| 16 mm | 0.448 | 0.743 | 1.590 | 3.211 | ||||||
| 20 mm | 0.598 | 0.812 | 1.711 | 3.411 | 4.892 | |||||
| 25 mm | 0.660 | 0.897 | 1.871 | 3.660 | 5.252 | 8.170 | ||||
| 30 mm | 0.737 | 1.010 | 2.070 | 3.912 | 5.574 | 9.690 | 10.707 | 18.657 | ||
| 35 mm | 0.804 | 1.120 | 2.271 | 4.223 | 5.974 | 10.000 | 11.416 | 16.026 | 19.608 | |
| 40 mm | 0.881 | 1.230 | 2.470 | 4.533 | 6.410 | 10.288 | 12.107 | 16.667 | 20.747 | |
| 45 mm | 0.958 | 1.340 | 2.671 | 4.840 | 6.859 | 10.504 | 12.821 | 17.241 | 21.739 | |
| 50 mm | 1.030 | 1.450 | 2.870 | 5.155 | 7.299 | 11.261 | 13.624 | 17.857 | 22.727 | 28.409 |
| 55 mm | 1.560 | 3.071 | 5.464 | 7.740 | 11.628 | 14.409 | 18.868 | 23.810 | 30.120 | |
| 60 mm | 1.670 | 3.270 | 5.774 | 8.183 | 12.255 | 15.244 | 20.000 | 25.126 | 32.051 | |
| 65 mm | 1.781 | 3.472 | 6.083 | 8.621 | 12.626 | 16.026 | 21.008 | 26.455 | 34.014 | |
| 70 mm | 1.890 | 3.671 | 6.394 | 9.058 | 12.987 | 16.835 | 22.124 | 27.778 | 35.461 | |
| 75 mm | 2.000 | 3.873 | 6.702 | 9.506 | 13.228 | 17.606 | 23.256 | 29.070 | 39.063 | |
| 80 mm | 2.111 | 4.072 | 7.013 | 10.000 | 13.889 | 18.248 | 24.510 | 30.303 | 40.000 | |
| 90 mm | 4.472 | 7.634 | 10.917 | 14.925 | 19.841 | 26.042 | 33.113 | 41.667 | ||
| 100 mm | 4.873 | 8.251 | 11.820 | 16.340 | 21.459 | 27.778 | 35.714 | 46.296 | ||
| 110 mm | 8.881 | 12.723 | 17.730 | 23.041 | 31.250 | 38.168 | 47.170 | |||
| 120 mm | 9.506 | 13.624 | 18.797 | 24.631 | 32.895 | 40.984 | 50.000 | |||
| 130 mm | 10.101 | 14.535 | 20.000 | 26.316 | 34.722 | 43.478 | 52.632 | |||
| 140 mm | 10.707 | 15.432 | 20.833 | 27.933 | 35.461 | 46.296 | 55.556 | |||
| 150 mm | 11.312 | 16.340 | 22.222 | 29.412 | 37.594 | 48.544 | 58.824 | |||
| 160 mm | 11.905 | 17.241 | 24.272 | 31.056 | 40.984 | 50.505 | 61.728 | |||
| 170 mm | 12.500 | 18.116 | 32.680 | 53.191 | 64.935 | |||||
| 180 mm | 13.123 | 19.011 | 26.882 | 34.247 | 55.556 | 67.568 | ||||
| 190 mm | 13.736 | 19.920 | 35.971 | 58.140 | 70.423 | |||||
| 200 mm | 14.327 | 20.833 | 29.586 | 37.594 | 49.020 | 60.976 | 73.529 | |||
| 220 mm | 15.528 | 22.624 | 40.650 | 65.789 | 79.365 | |||||
| 240 mm | 16.722 | 24.510 | 43.860 | 71.429 | 84.746 | |||||
| 250 mm | 17.301 | 25.381 | 45.455 | 74.627 | 87.719 | |||||
| 260 mm | 17.921 | 26.316 | 47.170 | 76.923 | 90.909 | |||||
| 280 mm | 19.157 | 28.090 | 50.505 | 81.967 | 98.039 | |||||
| 300 mm | 20.325 | 29.940 | 53.763 | 87.719 | 104.167 | |||||
| 320 mm | 31.646 | 56.818 | 92.593 | |||||||
| 340 mm | 33.557 | 60.241 | 98.039 | |||||||
| 360 mm | 35.211 | 63.291 | 104.167 | |||||||
| 380 mm | 37.037 | 66.667 | 108.696 | |||||||
| 400 mm | 39.063 | 69.444 | 113.636 | |||||||
| Class 150 Flanges ASME B16.5 (Stud bolt sizes) | Length of Stud Bolts | |||||||
| NPS | Outside Diameter of Flange | The diameter of Bolt Circle | The diameter of Bolt Holes | Number of Bolts | Diameter of Bolts | Raised Face 0.06 in |
Ring Joint | |
| 1/2 | 3 1/2 | 2 3/8 | 5/8 | 4 | 1/2 | 2 1/4 | – | |
| 3/4 | 3 7/8 | 2 3/4 | 5/8 | 4 | 1/2 | 2 1/2 | – | |
| 1 | 4 1/4 | 3 1/8 | 5/8 | 4 | 1/2 | 2 1/2 | 3 | |
| 1 1/4 | 4 5/8 | 3 1/2 | 5/8 | 4 | 1/2 | 2 3/4 | 3 1/4 | |
| 1 1/2 | 5 | 3 7/8 | 5/8 | 4 | 1/2 | 2 3/4 | 3 1/4 | |
| 2 | 6 | 4 3/4 | 3/4 | 4 | 5/8 | 3 1/4 | 3 3/4 | |
| 2 1/2 | 7 | 5 1/2 | 3/4 | 4 | 5/8 | 3 1/2 | 4 | |
| 3 | 7 1/2 | 6 | 3/4 | 4 | 5/8 | 3 1/2 | 4 | |
| 3 1/2 | 8 1/2 | 7 | 3/4 | 8 | 5/8 | 3 1/2 | 4 | |
| 4 | 9 | 7 1/2 | 3/4 | 8 | 5/8 | 3 1/2 | 4 | |
| 5 | 10 | 8 1/2 | 7/8 | 8 | 3/4 | 3 3/4 | 4 1/4 | |
| 6 | 11 | 9 1/2 | 7/8 | 8 | 3/4 | 4 | 4 1/2 | |
| 8 | 13 1/2 | 11 3/4 | 7/8 | 8 | 3/4 | 4 1/4 | 4 3/4 | |
| 10 | 16 | 14 3/4 | 1 | 12 | 7/8 | 4 1/2 | 5 | |
| 12 | 19 | 17 | 1 | 12 | 7/8 | 4 3/4 | 5 1/4 | |
| 14 | 21 | 18 3/4 | 1 1/8 | 12 | 1 | 5 1/4 | 5 3/4 | |
| 16 | 23 1/2 | 21 1/4 | 1 1/8 | 16 | 1 | 5 1/4 | 5 3/4 | |
| 18 | 25 | 22 3/4 | 1 1/4 | 16 | 1 1/8 | 5 3/4 | 6 1/4 | |
| 20 | 27 1/2 | 25 | 1 1/4 | 20 | 1 1/8 | 6 1/4 | 6 3/4 | |
| 24 | 32 | 29 1/2 | 1 1/4 | 20 | 1 1/4 | 6 3/4 | 7 1/4 | |
| Class 300 Flanges ASME B16.5 | Length of Stud Bolts | |||||||
| NPS | Outside Diameter of Flange | The diameter of Bolt Circle | The diameter of Bolt Holes | Number of Bolts | Diameter of Bolts | Raised Face 0.06 in |
Ring Joint | |
| 1/2 | 3 3/4 | 2 5/8 | 5/8 | 4 | 1/2 | 2 1/2 | 3 | |
| 3/4 | 4 5/8 | 3 1/4 | 3/4 | 4 | 5/8 | 3 | 3 1/2 | |
| 1 | 4 7/8 | 3 1/2 | 3/4 | 4 | 5/8 | 3 | 3 1/2 | |
| 1 1/4 | 5 1/4 | 3 7/8 | 3/4 | 4 | 5/8 | 3 1/4 | 3 3/4 | |
| 1 1/2 | 6 1/8 | 4 1/2 | 7/8 | 4 | 3/4 | 3 1/2 | 4 | |
| 2 | 6 1/2 | 5 | 3/4 | 8 | 5/8 | 3 1/2 | 4 | |
| 2 1/2 | 7 1/2 | 5 7/8 | 7/8 | 8 | 3/4 | 4 | 4 1/2 | |
| 3 | 8 1/4 | 6 5/8 | 7/8 | 8 | 3/4 | 4 1/4 | 4 3/4 | |
| 3 1/2 | 9 | 7 1/4 | 7/8 | 8 | 3/4 | 4 1/4 | 5 | |
| 4 | 10 | 7 7/8 | 7/8 | 8 | 3/4 | 4 1/2 | 5 | |
| 5 | 11 | 9 1/4 | 7/8 | 8 | 3/4 | 4 3/4 | 5 1/4 | |
| 6 | 12 1/2 | 10 5/8 | 7/8 | 12 | 3/4 | 4 3/4 | 5 1/2 | |
| 8 | 15 | 13 | 1 | 12 | 7/8 | 5 1/2 | 6 | |
| 10 | 17 1/2 | 15 1/4 | 1 1/8 | 16 | 1 | 6 1/4 | 6 3/4 | |
| 12 | 20 1/2 | 17 3/4 | 1 1/4 | 16 | 1 1/8 | 6 3/4 | 7 1/4 | |
| 14 | 23 | 20 1/4 | 1 1/4 | 20 | 1 1/8 | 7 | 7 1/2 | |
| 16 | 25 1/2 | 22 1/2 | 1 3/8 | 20 | 1 1/4 | 7 1/2 | 8 | |
| 18 | 28 | 24 3/4 | 1 3/8 | 24 | 1 1/4 | 7 3/4 | 8 1/4 | |
| 20 | 30 1/2 | 27 | 1 3/8 | 24 | 1 1/4 | 8 | 8 3/4 | |
| 24 | 36 | 32 | 1 5/8 | 24 | 1 1/2 | 9 | 10 | |
Incoloy 800H/800HT bolts are used in high-temperature and corrosive industrial environments where long-term mechanical stability is critical. These fasteners are commonly selected for systems operating under thermal stress, pressure cycles, and chemically aggressive atmospheres.
The manufacturing of Incoloy 800H/800HT bolts involves controlled hot forging followed by precision machining to achieve required dimensional accuracy. The alloy is solution-annealed to stabilize its microstructure and enhance high-temperature performance. CNC threading ensures compliance with ISO and DIN tolerances.
Quality inspection includes dimensional verification, hardness testing, tensile strength evaluation, and surface integrity checks. Each batch undergoes heat number traceability to ensure full material certification compliance.
KK Fasteners implements strict quality control aligned with ISO 9001 standards, ensuring every fastener meets global engineering expectations. Additional compliance with RoHS and REACH ensures suitability for international industrial supply chains.

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Incoloy 800H/800HT bolts are nickel-iron-chromium alloy fasteners designed for high-temperature service. They maintain strength, oxidation resistance, and creep stability in environments above 600°C, making them ideal for petrochemical, furnace, and power generation applications where conventional steel bolts fail.
800H contains higher carbon content for improved tensile strength, while 800HT includes controlled titanium and aluminum additions that enhance creep rupture resistance. 800HT is preferred for long-duration high-stress thermal applications, whereas 800H suits moderate exposure conditions.
These bolts are commonly manufactured under ASTM B564 for forgings and related ASME specifications for nickel alloys. Dimensional standards include DIN 933, ISO 4014, UNC, and UNF thread series depending on application requirements.
They are used in petrochemical reactors, thermal power plants, heat exchangers, furnaces, and chemical processing equipment. Their high-temperature strength and oxidation resistance make them suitable for continuous thermal and corrosive industrial environments.
Buyers should evaluate material traceability, ISO certifications, compliance with ASTM standards, and testing capabilities. A reliable supplier provides mill test certificates and consistent quality control. KK Fasteners supplies certified fasteners with full documentation for global industrial projects.
For high-temperature critical applications, material reliability is non-negotiable, and Incoloy fasteners play a decisive role in system safety and uptime. With controlled alloy chemistry and precision manufacturing, KK Fasteners delivers bolts engineered for demanding industrial environments with full export documentation and engineering support.
Request technical drawings or a quotation today to source application-ready Incoloy 800H/800HT bolts for your project specifications.