ENGINEERING TOOL
M14 Stud Bolt Torque Chart
Target preload and tightening torque for M14 stud bolts (full-thread double-end studs) at three nut factors (K 0.12 / 0.15 / 0.20), across six property classes. K-factor method, basis fully disclosed.
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Torque by Property Class and Nut Factor K
Quick answer: class 10.9 at K 0.15 ≈ 159 N·m (typical stud bolt / flange torque); other classes and K values below.
| Class | Rp0.2 (MPa) | Target preload (kN) | K 0.12 N·m | K 0.15 N·m | K 0.20 N·m |
|---|---|---|---|---|---|
| 4.8 | 340 | 27.4 | 46 | 57 | 77 |
| 8.8 | 640 | 51.5 | 87 | 108 | 144 |
| 10.9 | 940 | 75.7 | 127 | 159 | 212 |
| 12.9 | 1100 | 88.6 | 149 | 186 | 248 |
| A2-70 | 450 | 36.2 | 61 | 76 | 101 |
| A4-80 | 600 | 48.3 | 81 | 101 | 135 |
Each K column shows the tightening torque at that nut factor (N·m). K combines thread and bearing-surface friction: 0.12 ≈ well lubricated (MoS₂ / assembly paste), 0.15 ≈ normal assembly oil (typical default), 0.20 ≈ unlubricated or plated surfaces. Select by your actual lubrication condition; verify on site for critical joints.
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 (M14 × 1.5 mm) target preload and tightening torque, same basis as the coarse chart; the fine-thread stress area As follows ISO 898-1:2013 Table 6 (this page takes M14 As = 125 mm²).
| Class | Rp0.2 (MPa) | Target preload (kN) | K 0.12 N·m | K 0.15 N·m | K 0.20 N·m |
|---|---|---|---|---|---|
| 4.8 | 340 | 29.7 | 50 | 62 | 83 |
| 8.8 | 640 | 56 | 94 | 118 | 157 |
| 10.9 | 940 | 82.3 | 138 | 173 | 230 |
| 12.9 | 1100 | 96.3 | 162 | 202 | 270 |
| A2-70 | 450 | 39.4 | 66 | 83 | 110 |
| A4-80 | 600 | 52.5 | 88 | 110 | 147 |
Each K column shows the tightening torque at that nut factor (N·m). K combines thread and bearing-surface friction: 0.12 ≈ well lubricated (MoS₂ / assembly paste), 0.15 ≈ normal assembly oil (typical default), 0.20 ≈ unlubricated or plated surfaces. Select by your actual lubrication condition; verify on site for critical joints.
Basis of Calculation & Sources
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 (M14 As = 115 mm²). Yield strengths are published values from ISO 898-1 (carbon/alloy steel) and ISO 3506-1 (stainless A2/A4). The three K columns follow the standard stud-bolt torque table format (K = 0.12 / 0.15 / 0.20), the same three-column output as the online torque calculator's stud bolt mode.
Stainless note: A2/A4 austenitic studs gall easily under frictional heating. Always apply anti-seize on both the thread and the nut-bearing surface, and verify the installed torque on site.
Boundary: this chart is a simplified K-factor estimate, not a full VDI 2230 analysis (which also accounts for joint resilience, embedment and assembly method). Friction and lubrication are the dominant variables — the spread between K 0.12 and K 0.20 can reach ~65% of the torque value. Always follow the design specification or the manufacturer's torque table.
Corresponding standard page
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FAQ
What is the tightening torque for an M14 stud bolt?
It depends on the nut factor K (thread + bearing friction / lubrication): K 0.12 ≈ 127 N·m, K 0.15 ≈ 159 N·m, K 0.20 ≈ 212 N·m (class 10.9, typical for stud bolts in flange service, at 70% of Rp0.2 target preload). Select the K matching your actual lubrication — no single torque exists without its friction condition.
What is the target preload for an M14 stud bolt?
At 70% of Rp0.2: class 4.8 ≈ 27.4 kN, 8.8 ≈ 51.5 kN, 10.9 ≈ 75.7 kN; stainless A2-70 ≈ 36.2 kN and A4-80 ≈ 48.3 kN. Preload is independent of the K value — K only converts preload into torque.
When should I use K 0.12, 0.15 or 0.20?
K is the nut factor combining thread and bearing-surface friction. Use 0.12 for well-lubricated assembly (MoS₂ paste or assembly oil on both threads and nut face), 0.15 as the typical default for normal lubrication, and 0.20 for unlubricated or plated (zinc/cadmium) surfaces. Field torque-tension verification is recommended for critical flange joints.
Can I use carbon-steel stud torque values for stainless M14 (A2-70/A4-80)?
No. The classes have different yield strengths (A2-70 = 450 MPa, A4-80 = 600 MPa), so target preloads differ; and austenitic stainless thread pairs gall easily — always apply anti-seize and verify the installed torque on site.
Related References
Stud Bolt Torque Calculator
Interactive version: this size pre-filled in stud bolt mode with K 0.12/0.15/0.20 columns, fine threads and torque check.
M14 Hex Bolt Torque Chart
Same size, regular hex bolt tightening torques by friction state — compare with the stud bolt values above.
M14 Threaded Rod & Stud Bolt Weight Chart
kg/m and per-piece weights for the same size across the full length series, for quotation and logistics.
Metric Bolt Torque Chart (Reference)
Full M6–M36 tables with disclosed formula and GB/ISO clause citations; every value reproducible.
Disclaimer: This chart is an engineering estimation for selection and budgeting only. It does not constitute assembly instructions or acceptance criteria.