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FULLERKREG DIN 6334 hexagonal long coupling nuts in Q195 low carbon steel with electroplated zinc finish combine the cost-effectiveness of low carbon steel with reliable atmospheric corrosion protection. Conforming to the DIN 6334 standard, the nut length is exactly 3 times the nominal thread diameter (3×d), providing the extended thread engagement required to reliably join two threaded rods, studs, or anchor bolts end-to-end. The electroplated zinc (electro-galvanised) coating delivers a bright, uniform silver appearance and provides effective corrosion protection for indoor, sheltered outdoor, and general industrial environments. Q195 low carbon steel ensures excellent weldability and ductility, while the zinc coating meets standard corrosion resistance requirements at the most competitive price point in the DIN 6334 range. Available in thread sizes M3 through M56.
All dimensions in mm. Nut length m = 3×d (DIN 6334). Tolerances per DIN 6334. Unit weight (g) is theoretical reference value for Q195 steel (density 7.85 g/cm³), excluding zinc coating weight.
| Thread d |
Pitch (mm) |
Nut Length m = 3×d (mm) |
Across Flats s (mm) |
Across Corners e min (mm) |
Unit Weight (g/pc) |
|---|---|---|---|---|---|
| M3 | 0.5 | 9.0 | 5.50 | 6.01 | ~0.7 |
| M4 | 0.7 | 12.0 | 7.00 | 7.66 | ~1.5 |
| M5 | 0.8 | 15.0 | 8.00 | 8.79 | ~2.7 |
| M6 | 1.0 | 18.0 | 10.00 | 11.05 | ~4.9 |
| M8 | 1.25 | 24.0 | 13.00 | 14.38 | ~10.3 |
| M10 | 1.5 | 30.0 | 16.00 | 17.77 | ~19.2 |
| M12 | 1.75 | 36.0 | 18.00 | 20.03 | ~31.5 |
| M14 | 2.0 | 42.0 | 22.00 | 24.49 | ~54.2 |
| M16 | 2.0 | 48.0 | 24.00 | 26.75 | ~76.9 |
| M18 | 2.5 | 54.0 | 27.00 | 29.56 | ~106 |
| M20 | 2.5 | 60.0 | 30.00 | 32.95 | ~146 |
| M22 | 2.5 | 66.0 | 32.00 | 35.03 | ~182 |
| M24 | 3.0 | 72.0 | 36.00 | 39.55 | ~251 |
| M27 | 3.0 | 81.0 | 41.00 | 45.20 | ~374 |
| M30 | 3.5 | 90.0 | 46.00 | 50.85 | ~512 |
| M33 | 3.5 | 99.0 | 50.00 | 55.37 | ~670 |
| M36 | 4.0 | 108.0 | 55.00 | 60.79 | ~877 |
| M39 | 4.0 | 117.0 | 60.00 | 66.44 | ~1133 |
| M42 | 4.5 | 126.0 | 65.00 | 71.30 | ~1409 |
| M45 | 4.5 | 135.0 | 70.00 | 76.95 | ~1735 |
| M48 | 5.0 | 144.0 | 75.00 | 82.60 | ~2100 |
| M52 | 5.0 | 156.0 | 80.00 | 88.25 | ~2612 |
| M56 | 5.5 | 168.0 | 85.00 | 93.56 | ~3185 |
* Nut length m = 3×d per DIN 6334. Across Corners (e) calculated from s × 1.155. Unit weights are theoretical reference values for Q195 steel (density 7.85 g/cm³), excluding zinc coating; actual weights may vary ±5%. Sizes M39 and above may have longer lead times — please enquire.
| Parameter | Specification |
|---|---|
| Standard | DIN 6334 |
| Also Known As | Long Hex Nut, Coupling Nut, Extension Nut, Stud Connector Nut, Barrel Nut |
| Material | Q195 Low Carbon Structural Steel (GB/T 700) |
| Surface Treatment | Electroplated Zinc (Electro-Galvanised) |
| Zinc Coating Thickness | 5–12 μm (standard electro-zinc per ISO 4042) |
| Zinc Coating Appearance | Bright silver / clear passivated |
| Salt Spray Resistance | ≥ 72 hours (white rust, per ISO 9227) |
| Nut Length | 3×d (three times nominal thread diameter) |
| Thread Type | Metric coarse thread (ISO 68-1) |
| Thread Tolerance | 6H (after plating) |
| Property Class | Class 4 (per ISO 898-2) |
| Thread Size Range | M3 – M56 |
| Tensile Strength | ≥ 400 MPa |
| Hardness | ≤ 188 HV |
| RoHS Compliant | Yes (trivalent chromium passivation — Cr⁶⁺-free) |
| Packaging | Bulk bag / box; custom packaging available |
DIN 6334 specifies hexagonal long nuts with a length equal to 3 times the nominal thread diameter (m = 3×d). This extended length provides significantly greater thread engagement than a standard hex nut, making DIN 6334 coupling nuts the correct choice for joining two externally threaded components — such as threaded rods, studs, or anchor bolts — end-to-end. The electroplated zinc finish is applied after threading and provides cathodic protection to the steel substrate. Trivalent chromium (Cr³⁺) passivation is applied over the zinc layer for enhanced corrosion resistance and RoHS compliance — no hexavalent chromium (Cr⁶⁺) is used.
| Surface | Material | Corrosion Resistance | Appearance | Typical Environment |
|---|---|---|---|---|
| Zinc Plated ✓ | Q195 steel | Good (≥72h salt spray) | Bright silver | Indoor, sheltered outdoor, general industrial |
| Bare (uncoated) | Q195 steel | Low | Mill finish | Pre-coat assemblies; post-weld painting |
| Passivated | A2 (SUS304) | Very Good | Bright stainless | General industrial, outdoor, light corrosion |
| Passivated | A4 (SUS316) | Excellent | Bright stainless | Marine, chemical, food-grade, offshore |
| Nut Type | Standard | Nut Length | Thread Engagement | Typical Use |
|---|---|---|---|---|
| Standard Hex Nut | DIN 934 / ISO 4032 | ~0.8×d | Short | Single bolt/stud fastening |
| High Hex Nut | ISO 4033 | ~0.9×d | Medium | Higher load single fastening |
| Long Coupling Nut | DIN 6334 | 3×d | Full engagement both ends | Rod-to-rod / stud-to-stud joining ✓ |
DIN 6334 Hex Coupling Nuts — Q195 Low Carbon Steel, Zinc Plated actual product photos:
| [ Photo 1 ] | [ Photo 2 ] | [ Photo 3 ] | [ Photo 4 ] |
| Grade | C (%) | Mn (%) | P (%) | S (%) | Si (%) |
|---|---|---|---|---|---|
| Q195 | ≤ 0.12 | ≤ 0.50 | ≤ 0.035 | ≤ 0.040 | ≤ 0.30 |
* Q195 ultra-low carbon content (≤ 0.12%) ensures excellent weldability and ductility. Approximate international equivalents: S185 (EN 10025-2), A36 (ASTM A36), SS330 (JIS G3101). Hardness ≤ 188 HV eliminates hydrogen embrittlement risk during zinc electroplating acid pickling process.
| Property Class | Proof Load Stress (MPa) | Tensile Strength (MPa) | Hardness (HV max) | Min. Elongation |
|---|---|---|---|---|
| Class 4 | ≥ 510 | ≥ 400 | ≤ 188 | ≥ 22% |
* Hardness ≤ 188 HV (Class 4) is below the hydrogen embrittlement risk threshold, making Q195 the safest material choice for electroplated zinc fasteners. No baking / de-embrittlement treatment required.
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