Coupling nuts

An extension nut in accordance with DIN 6334 is a hexagonal coupling nut used especially for extending threaded parts such as threaded rods.

General description
DIN 6334 Extension Nut – General Description
Shape: Hexagonal
Length: Approximately 3 × nominal diameter (e.g. M10 → length approx. 30 mm)
Thread: Usually metric ISO threads (M)
Material: Steel, acid-resistant steel (A2, A4), brass, etc.
Strength classes: 6, 8, 10 (standard strength classes)
Finish: Coated or uncoated

Strength classes and suitability
Strength class 10: High strength, suitable for structures requiring high durability.
Strength class 6 or softer: Easier to machine, suitable for welding (harder steel is not easily suitable for welding without preheating).
Uncoated: Better suited for welding.
Coated: Zinc-plated, hot-dip galvanized, electro-galvanized – protects against corrosion, but is not directly suitable for welding unless the coating is removed.

Non-standard extension nuts
Special lengths: For example, longer nuts for special applications
Other wrench sizes: Non-standard wrench size, e.g. for confined spaces – requires machining
Special materials: Acid-resistant steels, plastics, aluminum
Internal threads with different thread types: E.g. UNC, UNF, Whitworth – these thread types are available by special order and require machining