ENGINEERING TOOL
M22 Bolt Torque Chart: Specs, Values & Settings
Class 8.8 · Target preload (kN) 135.7
| Dry / Black | 597 N·m 538–657 |
| Electro Zinc | 508 N·m 448–597 |
| Hot-Dip Galv. | 657 N·m 538–747 |
| Oiled | 388 N·m 358–448 |
M22 bolt torque spec: class 8.8 dry is 597 N·m (440 ft·lb). Values cover six property classes across five friction states — dry, zinc, HDG, oiled and anti-seize. K-factor method, basis fully disclosed.
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Torque by Property Class and Friction State
Quick answer: class 8.8 · dry / black ≈ 597 N·m (538–657); other classes and friction states below.
| Class | Rp0.2 (MPa) | Target preload (kN) | Dry / Black K 0.18–0.22 · N·m | Electro Zinc K 0.15–0.2 · N·m | Hot-Dip Galv. K 0.18–0.25 · N·m | Oiled K 0.12–0.15 · N·m | Wax / PTFE / Anti-seize K 0.08–0.12 · N·m |
|---|---|---|---|---|---|---|---|
| 4.8 | 340 | 72.1 | 317 286–349 | 270 238–317 | 349 286–397 | 206 190–238 | 159 127–190 |
| 8.8 | 640 | 135.7 | 597 538–657 | 508 448–597 | 657 538–747 | 388 358–448 | 299 239–358 |
| 10.9 | 940 | 199.4 | 877 790–965 | 746 658–877 | 965 790–1097 | 570 526–658 | 439 351–526 |
| 12.9 | 1100 | 233.3 | 1027 924–1129 | 873 770–1027 | 1129 924–1283 | 667 616–770 | 513 411–616 |
| A2-70 | 450 | 95.4 | 420 378–462 | 357 315–420 | 462 378–525 | 273 252–315 | 210 168–252 |
| A4-80 | 600 | 127.3 | 560 504–616 | 476 420–560 | 616 504–700 | 364 336–420 | 280 224–336 |
Cell shows the typical value; the small line below is the range (min–max).
References
- ISO 898-1:2013 — Mechanical properties of fasteners made of carbon and alloy steel
- ISO 3506-1:2020 — Mechanical properties of corrosion-resistant stainless steel fasteners (A2/A4)
- GB/T 3098.1-2010 — Mechanical properties of bolts, screws and studs (CN national standard, official full text)
- GB/T 3098.6-2014 — Mechanical properties of stainless steel bolts, screws and studs (CN, official full text)
- ISO 16047:2005 — Fasteners: torque/clamp force testing (K-factor measurement method)
- Machinery's Handbook (30th ed.) — empirical K-factor ranges
- Machine Design — anti-seize compound friction test (K≈0.10)
Fine-Thread Torque Matrix
Fine-thread series (M22 × 1.5 mm) target preload and tightening torque ranges, same basis as the coarse chart; the fine-thread stress area As follows ISO 898-1:2013 Table 6 (this page takes M22 As = 333 mm²).
| Class | Rp0.2 (MPa) | Target preload (kN) | Dry / Black K 0.18–0.22 · N·m | Electro Zinc K 0.15–0.2 · N·m | Hot-Dip Galv. K 0.18–0.25 · N·m | Oiled K 0.12–0.15 · N·m | Wax / PTFE / Anti-seize K 0.08–0.12 · N·m |
|---|---|---|---|---|---|---|---|
| 4.8 | 340 | 79.3 | 349 314–384 | 296 262–349 | 384 314–436 | 227 209–262 | 174 139–209 |
| 8.8 | 640 | 149.2 | 656 591–722 | 558 492–656 | 722 591–821 | 427 394–492 | 328 263–394 |
| 10.9 | 940 | 219.1 | 964 868–1061 | 819 723–964 | 1061 868–1205 | 627 578–723 | 482 386–578 |
| 12.9 | 1100 | 256.4 | 1128 1015–1241 | 959 846–1128 | 1241 1015–1410 | 733 677–846 | 564 451–677 |
| A2-70 | 450 | 104.9 | 462 415–508 | 392 346–462 | 508 415–577 | 300 277–346 | 231 185–277 |
| A4-80 | 600 | 139.9 | 615 554–677 | 523 462–615 | 677 554–769 | 400 369–462 | 308 246–369 |
Cell shows the typical value; the small line below is the range (min–max).
Basis of Calculation & Sources
Calculation basis
- Torque follows the K-factor (nut factor) method T = K·D·F: D is the nominal diameter and F the target preload = 70% of Rp0.2 × thread stress area (M22 As = 303 mm²).
- Yield strengths are published values from ISO 898-1 (carbon/alloy steel) and ISO 3506-1 (stainless A2/A4).
- K follows published empirical ranges per friction condition (Machinery's Handbook; the wax/PTFE/anti-seize band K≈0.10 follows Machine Design test data).
- The grease/MoS₂ band (K≈0.11) nearly overlaps anti-seize and is available in the calculator instead of a separate column.
Stainless note: A2/A4 austenitic thread pairs gall easily under frictional heating. Always apply anti-seize and follow the Wax/PTFE/Anti-seize column (K≈0.10).
Scope & limits
- This chart is a simplified K-factor estimate, not a full VDI 2230 analysis (which accounts for joint resilience, embedment and assembly method).
- Friction is the dominant variable — no single torque value exists without its friction state.
- Always follow the design specification or manufacturer torque table.
Cite this chart
YAXIIO. M22 Bolt Torque Chart: Specs, Values & Settings. https://www.yaxiio.com/en/tools/bolt-torque-chart/m22 (accessed 2026-10-29).
Free to cite and embed — attribution required: “YAXIIO” + a link to this page.
FAQ
What is the target preload for an M22 bolt?
At 70% of Rp0.2: class 4.8 ≈ 72.1 kN, 8.8 ≈ 135.7 kN, 10.9 ≈ 199.4 kN; stainless A2-70 ≈ 95.4 kN and A4-80 ≈ 127.3 kN.
Can I use carbon-steel torque values for stainless M22 (A2-70/A4-80)?
No. The classes have different yield strengths (A2-70 = 450 MPa, A4-80 = 600 MPa), so target preloads differ; and stainless thread pairs gall easily — always apply anti-seize and follow the Wax/PTFE/Anti-seize column (K≈0.10).
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Related References
Bolt Torque Calculator
Interactive version: fine threads, imperial, stud bolts, custom K and torque check — this size is pre-filled.
M22 Hex Bolt Weight Chart
Per-piece and per-1,000-pcs weights across the full length series of the same size.
M22 Hex Key Size Chart
Which hex key (Allen wrench) fits a socket head cap screw of the same size: socket width across flats, key long and short arm lengths, and unit weight on the GB/T 70.1 + GB/T 5356 basis.
Tap Drill for the Thread Being Tightened
The hole under the bolt: rule tap drill value plus the nearest drill bit in the set, stated ahead of the torque tables.
Disclaimer: This chart is an engineering estimation for selection and budgeting only. It does not constitute assembly instructions or acceptance criteria.