EN 1667:1997

Overview

EN 1667:1997 is a European Standard established by CEN that specifies the technical requirements for prevailing torque type all-metal hexagon nuts with flange and metric fine pitch threads. This standard applies to nuts with nominal thread diameters ranging from 8 mm up to and including 20 mm. It covers product grade A for sizes up to 16 mm and product grade B for sizes greater than 16 mm. Additionally, the standard defines property classes 6, 8, and 10, ensuring mechanical strength and performance consistency in industrial applications.

This standard is based on the ISO 12126:1997 specification but includes modifications to fit the European market and manufacturing practices. EN 1667:1997 serves as an essential guideline for designers, suppliers, and manufacturers dealing with all-metal hexagon nuts with flanges, supporting quality assurance and interchangeability.

Key Topics

• Prevailing Torque Type Nuts
  The standard describes nuts that provide a prevailing torque feature, which means they resist loosening under vibration without additional locking devices. This is achieved through the all-metal design and the flange.

• All-Metal Construction
  These nuts are manufactured entirely from metal, offering durability, high strength, and resistance to environmental stress compared to polymer-insert nuts.

• Hexagon Shape with Flange
  The hexagonal shape with an integrated flange distributes load over a larger surface area, reducing damage to the clamped parts and eliminating the need for washers.

• Metric Fine Pitch Threads
  EN 1667 covers fine pitch metric threads for thread diameters from 8 to 20 mm. Fine pitch threads are preferred for precision applications requiring higher tensile strength and better fatigue resistance.

• Product Grades and Property Classes

  • Grade A applies to thread sizes up to and including 16 mm.
  • Grade B applies to thread sizes larger than 16 mm.
  • Property classes 6, 8, and 10 define varying levels of mechanical performance and strength.

• Compatibility and Modification
  Although based on ISO 12126:1997, this standard includes specific modifications relevant to the European market for improved application and manufacturing consistency.

Applications

EN 1667:1997 prevailing torque all-metal hexagon nuts with flanges and metric fine pitch threads are widely used in various industrial and mechanical assemblies where strong, reliable fastening is critical. Typical applications include:

• Automotive Industry
  For engine assembly, transmission units, and chassis components requiring resistant fasteners under vibration and thermal cycling.

• Heavy Machinery and Equipment
  These nuts ensure safety and integrity in construction, agricultural machinery, and industrial machines operating in demanding environments.

• Aerospace and Defense
  Fine pitch, all-metal nuts with prevailing torque prevent loosening under dynamic loads and vibration, essential for aerospace components.

• Precision Engineering
  Used where tight tolerances and secure clamping with minimal thread play are necessary, such as instrumentation and electronic casings.

• General Manufacturing
  Provides robust fastening solutions for metal structures, frames, and assemblies across various manufacturing sectors.

Related Standards

• ISO 12126:1997
  The international base standard for prevailing torque type all-metal hexagon nuts with metric fine pitch threads, which EN 1667:1997 modifies to suit European requirements.

• EN ISO 4032
  Standard for hexagon nuts with coarse and fine pitch threads, commonly referenced alongside EN 1667 for various nut types.

• EN 14399 Series
  Covers high-strength structural fasteners, which may be used in conjunction with EN 1667 nuts in high-load assemblies.

• ISO 4033
  International standard for hexagon nuts with flange, related to the flange nut designs specified in EN 1667.

Keywords: EN 1667:1997, prevailing torque nut, all-metal hexagon nut, flange nuts, metric fine pitch thread, ISO 12126 modification, product grade A, product grade B, property classes, mechanical fasteners, heavy machinery nuts, automotive hex nuts, industrial fastening solutions.