Stud link anchor chain cables, grade K4 - End links; Text in German and English
1Key Takeaways
This standard applies to the end links of K4 grade stud link anchor chain cables with three-section connector components conforming to DIN 81854.
2Expert Interpretation
This article provides an in-depth interpretation of the DIN 81850:2007-12 standard for K4 grade stud anchor chain end rings. It details the calculation formulas for the end ring dimensions w²=3.3d² and p²=3.65d², compares them to ISO 1704, and provides material requirements, inspection standards, and practical application guidelines. It also covers technical parameter tables for end rings in sizes from 19 to 58 mm.
DIN 81850 Standard Overview and Technical Background
DIN 81850:2007-12, "Anchor Chain End Links — Grade K4," is a key product standard for marine and offshore technology, jointly developed by the German Standards Institute's Standards Committee for Marine and Marine Technology (NSMT) and the Round Chain Standards Committee (NRK). This standard specifically specifies the design, manufacturing, and inspection requirements for K4-grade studded anchor chain end links, a key component of the DIN 81854 triple-link connector.
Standard technical parameters and size system
The biggest technical change of this standard is the shift from the d reference system of ISO 1704:1991 to the d2 reference system:
| Parameters | ISO 1704:1991 | DIN 81850:2007 | Variation range |
|---|---|---|---|
| Width w2 | 4d | 3.3d2 | -17.5% |
| Pitch p2 | 4.35d | 3.65d2 | -16.1% |
| Base diameter | d | d2=1.2d | +20% |
This base conversion is intended to make the end links have similar size ratios to ordinary and oversized link links, improving overall coordination and consistency of mechanical properties.
Detailed Technical Parameters of End Rings
| Nominal Thickness d(mm) | d2(mm) | p2(mm) | w2(mm) | Weight(kg) | Tolerance Grade |
|---|---|---|---|---|---|
| 19 | 22 | 80 | 73 | 0.78 | ႇ |
| 20.5 | 24 | 88 | 79 | 1.0 | ႇ |
| 22 | 26 | 95 | 86 | 1.3 | ႇ |
| 24 | 28 | 102 | 92 | 1.6 | ႇ |
| 26 | 32 | 117 | 106 | 2.4 | ႇ |
| 28 | 34 | 124 | 112 | 2.9 | ႇ |
| 30 | 36 | 131 | 119 | 3.4 | ႇ |
| 32 | 38 | 139 | 125 | 4.0 | ႇ |
Note: Weight calculation formula G = 73.46 × d2³ × 10⁻⁶, where d2 is in mm and weight is in kg.
Material and manufacturing requirements
The end ring material must comply with the requirements of DIN 17115 standard 1.6758 (23MnNiMoCr5-4) steel grade. This low-alloy, high-strength steel has excellent mechanical properties and weldability.
Manufacturing process requirements:
- The cross-sectional area of the end ring arc shall not be less than the cross-sectional area determined by d2
- Use butt welding process and deburr the weld longitudinally
- Dimensional tolerances shall be implemented in accordance with the limit deviations specified in the standard
- Surface quality shall comply with the requirements of DIN 81841
Inspection and test standards
The inspection of end rings shall be carried out in accordance with the following standards:
| Inspection items | Based on standards | Technical requirements |
|---|---|---|
| Material inspection | DIN 17115 | Chemical composition, mechanical properties |
| Assembly inspection | DIN 81846-1/2 | Assembly method, preload requirements |
| Test force requirements | DIN 81841 | Breaking force, test force value |
| Dimensional inspection | DIN 81850 | Tolerance range, geometric shape |
Standard implementation recommendations and application cases
In actual applications, the end ring marking example: DIN 81850 — K4 — 32, indicates a K4 grade end ring that complies with the DIN 81850 standard, with a nominal thickness of 32mm.
Application Notes:
- End rings must be used with ordinary chain links of corresponding specifications
- Weld quality and dimensional tolerances must be checked before installation
- Regularly check end rings for wear and deformation
- Inspections should be conducted more frequently in severe sea conditions
This standard is used in conjunction with relevant standards: DIN 81833 (Anchoring Equipment Components), DIN 81834 (Terminology), DIN 81835-100 (Nominal Dimensions), and DIN 81854 (Triple-Link Connectors), which together constitute a complete anchor chain standard system.
Technological Evolution and Future Development
The technological evolution from DIN V 81850:1999-03 to DIN 81850:2007-12 is mainly reflected in the optimization of the dimensional system and the modernization of the standard structure. Future development trends include:
- Advances in material technology may lead to higher-strength end ring products
- Improvements in manufacturing processes will improve production efficiency and product quality
- Further coordination and unification with international standards
- Application of digital and intelligent inspection technologies
It should be noted that some technical content of this standard may involve patent issues, and users should confirm the relevant intellectual property status on their own.