SIST EN ISO 6157-2:2004

Overview

EN ISO 6157-2:2004 (ISO 6157-2:1995) specifies permissible surface discontinuities for nuts. It covers nuts with nominal thread diameters from 5 mm to 39 mm, product grades A and B, and all mechanical property classes referenced in ISO 898-2 and ISO 898-6 unless otherwise agreed. The standard defines types of surface defects, dimensional limits, inspection and evaluation procedures to ensure nuts meet functional and mechanical requirements.

Key topics and technical requirements

• Scope and applicability

  • Applies to nuts (5–39 mm) across property classes in ISO 898-2 and ISO 898-6.
  • Mechanical and dimensional requirements of the applicable product standards remain mandatory even when discontinuities are within limits.

• Types of surface discontinuities

  • Cracks (quench, forging, inclusion): limits include a maximum of two forging cracks across a bearing face (neither deeper than 0.05·d), no crack into tapped hole beyond first full thread, and first thread crack depth ≤ 0.5·H1 (H1 = 0.541·P).
  • Seams: permitted up to a depth of 0.05·d.
  • Voids: depth h