DIN 6923 Hex Flange Nut for Marine Piping and Flange Connections
DIN 6923 Hex Flange Nut for Marine Piping and Flange Connections
sinofastener supplies DIN 6923 hex flange nuts (superseded by DIN EN 1661 / ISO 4161) in A2-70, A4-70, and Class 8/10 steel for marine piping flanges, engine room skids, and deck equipment bolting. The integrated flange eliminates the need for a separate washer, distributes clamping load over a larger bearing surface, and resists loosening under vibration — critical in shipboard environments. Sizes M5 through M20, with serrated or smooth flange options. Products conform to DIN 6923 dimensional requirements and can be supplied with material certificates and dimensional inspection reports per ISO 4042.
What Is a DIN 6923 Hex Flange Nut?
ADIN 6923 hex flange nut is a hexagonal nut with an integrated circular flange at the bearing face. The flange acts as a built-in washer, spreading the clamp load across a wider area than a standard hex nut (ISO 4032). This design reduces damage to soft gasket surfaces, improves load distribution on slotted or oversized holes, and provides vibration resistance — especially in the serrated-flange variant, where teeth bite into the mating surface to prevent rotation.
DIN 6923 was published in 1983 and has been replaced by DIN EN 1661:1998, which is identical to ISO 4161. Both standards share the same dimensional table, so nuts marked to either standard are dimensionally interchangeable. Thread tolerance is 6G per ISO 965-2.
Marine Applications
| Application | Typical Size | Material | Source |
|---|---|---|---|
| Marine piping flange connections | M10–M20 | A4-70 (316 SS) | DIN 6923 Table 1; ISO 4161 |
| Engine room skid mounting | M12–M16 | A4-70 / Class 10 | DIN 6923 scope: M5–M20 |
| Deck equipment base plates | M10–M16 | A2-70 (304 SS) | DIN 6923 Table 1 |
| HVAC duct flange joints | M6–M10 | A2-70 | DIN 6923 flange bears on thin sheet |
| Ballast tank pipe supports | M12–M20 | A4-70 / HDG Class 10 | DIN 6923; ISO 4161 |
Specifications and Materials
Standard References:
- DIN 6923 / DIN EN 1661 / ISO 4161 — Dimensions
- ISO 965-2 — Thread tolerance 6G
- ISO 3506-1 / ISO 3506-2 — Stainless steel mechanical properties (A2-70, A4-70)
- ISO 898-2 — Carbon steel nut proof load (Class 8, 10)
DIN 6923 Dimensional Table (all dimensions in mm; per DIN EN 1661 / ISO 4161 Table 1):
| Thread d | Pitch p | c min | d_a min | d_a max | d_c max | d_w min | e min | m max | m min | s nom | s min | r max |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| M5 | 0.8 | 1.0 | 5 | 5.75 | 11.8 | 9.8 | 8.79 | 5 | 4.7 | 8 | 7.78 | 0.3 |
| M6 | 1.0 | 1.1 | 6 | 6.75 | 14.2 | 12.2 | 11.05 | 6 | 5.7 | 10 | 9.78 | 0.36 |
| M8 | 1.25 | 1.2 | 8 | 8.75 | 17.9 | 15.8 | 14.38 | 8 | 7.6 | 13 | 12.73 | 0.48 |
| M10 | 1.5 | 1.5 | 10 | 10.8 | 21.8 | 19.6 | 16.64 | 10 | 9.6 | 15 | 14.73 | 0.6 |
| M12 | 1.75 | 1.8 | 12 | 13 | 26 | 23.8 | 20.03 | 12 | 11.6 | 18 | 17.73 | 0.72 |
| M14 | 2.0 | 2.1 | 14 | 15.1 | 29.9 | 27.6 | 23.36 | 14 | 13.3 | 21 | 20.67 | 0.88 |
| M16 | 2.0 | 2.4 | 16 | 17.3 | 34.5 | 31.9 | 26.75 | 16 | 15.3 | 24 | 23.67 | 0.96 |
| M20 | 2.5 | 3.0 | 20 | 21.6 | 42.8 | 39.9 | 32.95 | 20 | 18.9 | 30 | 29.67 | 1.2 |
Material and Mechanical Properties:
| Grade | Material | Tensile Strength | Proof Load | Standard |
|---|---|---|---|---|
| A2-70 | Austenitic SS (304) | ≥ 700 MPa | Per ISO 3506-2 Table 3 | ISO 3506-2 |
| A4-70 | Austenitic SS (316/316L) | ≥ 700 MPa | Per ISO 3506-2 Table 3 | ISO 3506-2 |
| Class 8 | Carbon steel (C ≤ 0.58%, Mn ≥ 0.25%) | Proof load per ISO 898-2 | Per ISO 898-2 Table 1 | ISO 898-2 |
| Class 10 | Carbon steel, heat treated | Proof load per ISO 898-2 | Per ISO 898-2 Table 1 | ISO 898-2 |
Why Choose sinofastener for DIN 6923 Hex Flange Nuts?
| Full size range: M5–M20 in stock, serrated and smooth flange variants |
| Material flexibility: A2-70 (304), A4-70 (316L), Class 8, Class 10 to suit environment |
| Dimensional compliance: All dimensions per DIN EN 1661 / ISO 4161, thread tolerance 6G per ISO 965-2 |
| Surface treatment: Passivated (stainless steel per ASTM A967); Hot-dip galvanized (carbon steel per ISO 10684) |
| Quality documentation: EN 10204 3.1 material certificates, dimensional inspection reports |
| Annual capacity: 50,000 tons — supports bulk project supply and just-in-time delivery |
Standards Reference
| Standard | Scope |
|---|---|
| DIN 6923 / DIN EN 1661 / ISO 4161 | Hexagon nuts with flange — dimensions and specifications |
| ISO 965-2 | ISO general purpose metric screw threads — tolerances for screws and nuts — Grade 6G |
| ISO 3506-1 | Mechanical properties of corrosion-resistant stainless steel fasteners — Bolts, screws and studs |
| ISO 3506-2 | Mechanical properties of corrosion-resistant stainless steel fasteners — Nuts |
| ISO 898-2 | Mechanical properties of fasteners made of carbon steel and alloy steel — Part 2: Nuts |
| ISO 4042 | Electroplated coating systems for fasteners |
| ASTM A967 | Standard specification for chemical passivation treatments for stainless steel parts |
| ISO 10684 | Hot dip zinc coatings on fasteners |
FAQ
Q1: Is DIN 6923 still valid, or should I specify ISO 4161 instead?
DIN 6923 has been superseded by DIN EN 1661, which is identical to ISO 4161. The dimensional tables are the same, so existing drawings referencing DIN 6923 remain valid. For new designs, we recommend specifying ISO 4161 to align with international procurement.
Q2: What is the difference between serrated and smooth flange?
Serrated flanges have teeth on the bearing face that grip the mating surface, preventing rotation under vibration — ideal for engine room and piping applications. Smooth flanges are used when the mating surface must not be damaged, such as gasket faces or painted panels.
Q3: Can DIN 6923 flange nuts replace a hex nut plus flat washer combination?
Yes. The flange provides a bearing surface equivalent to a standard flat washer (ISO 7089), eliminating one component from the assembly. This reduces installation time and inventory, while ensuring consistent load distribution.
Q4: Which material should I use for sea water piping?
For sea water piping and ballast systems, A4-70 (316/316L stainless steel per ISO 3506-2) is the standard choice due to superior pitting and crevice corrosion resistance in chloride environments. For less aggressive conditions, A2-70 (304) is acceptable.
Contact sinofastener for DIN 6923 Hex Flange Nuts:
Email: sales@sinofastener.com | bobo@sinofastener.com
Tel: 0574-86592068
Website: www.zlfastener.com | www.sinofastener.com (Main)
