EN 26157-1:1991
(Main)Fasteners - Surface discontinuities - Part 1: Bolts, screws and studs for general requirements (ISO 6157-1:1988)
General Information
- Abstract
Establishes limits for various types of products and applies also to these products with: nominal thread diameters of 5 mm and larger, product grades A und B, property classes up to and including 10.9; the annex contains a sampling plan.
- Status
- Published
- Publication Date
- 15-Oct-1991
- Technical Committee
- CEN/TC 185 - Threaded and nonthreaded mechanical fasteners and accessories
- Current Stage
- 9093 - Decision to confirm - Review Enquiry
- Start Date
- 28-Jul-2006
- Completion Date
- 28-Jul-2006
- Directive
- Not Harmonized97/23/EC - Pressure equipment
Overview
EN 26157-1:1991 - Fasteners - Surface discontinuities - Part 1: Bolts, screws and studs for general requirements (ISO 6157-1:1988) is a CEN standard that establishes limits and acceptance criteria for surface discontinuities on common threaded fasteners. The standard applies to bolts, screws and studs with nominal thread diameters of 5 mm and larger, for product grades A and B, and for property classes up to and including 10.9. An annex provides a sampling plan for inspection.
This standard is identical to ISO 6157-1:1988 and has been adopted in national implementations (for example SIST EN 26157-1).
Key topics and technical requirements
- Scope and applicability: Defines which fasteners are covered (diameter ≥ 5 mm, grades A/B, property classes ≤ 10.9).
- Types of surface discontinuities: Describes categories of surface defects that can affect performance and appearance (e.g., laps, cracks, seams, tears) - the standard sets limits for such discontinuities.
- Acceptance criteria: Establishes limits and criteria for when a fastener is acceptable, conditionally acceptable, or rejected due to surface discontinuities.
- Sampling plan: Annex includes a sampling procedure to determine lot conformity without inspecting every item, enabling statistically based quality control.
- Reference to ISO series: Aligned with ISO 6157-1:1988, enabling harmonized inspection and procurement across international markets.
(Note: EN 26157-1 sets the framework and acceptance limits rather than prescriptive manufacturing steps. For detailed inspection techniques or measurement procedures, refer to complementary documents or inspection standards.)
Applications
- Quality control and acceptance testing in fastener manufacturing lines.
- Incoming inspection criteria for suppliers and procurement teams in automotive, construction, machinery and general engineering.
- Defining contractual acceptance criteria in purchase orders and specifications to ensure consistent product quality.
- Guiding inspection plans for third-party auditors and certification bodies.
- Useful for design engineers and maintenance teams who need assurance that fasteners meet surface integrity requirements to avoid fatigue or corrosion initiation.
Who uses this standard
- Fastener manufacturers and production engineers
- Quality assurance and inspection teams
- Procurement and sourcing professionals
- Mechanical designers and reliability engineers
- Third‑party testing and certification bodies
Related standards
- ISO 6157-1:1988 (identical content)
- Other parts of the ISO 6157 series and national adoptions (for full series context and related defect classification)
Keywords: EN 26157-1:1991, fasteners, surface discontinuities, bolts screws studs, ISO 6157-1, sampling plan, nominal thread diameter 5 mm, product grades A B, property class 10.9, CEN.
Relations
- Effective Date
- 28-Jan-2026
- Effective Date
- 28-Jan-2026
- Effective Date
- 28-Jan-2026
- Effective Date
- 28-Jan-2026
- Effective Date
- 28-Jan-2026
- Effective Date
- 28-Jan-2026
- Effective Date
- 28-Jan-2026
- Effective Date
- 28-Jan-2026
- Effective Date
- 28-Jan-2026
- Effective Date
- 28-Jan-2026
Frequently Asked Questions
EN 26157-1:1991 is a standard published by the European Committee for Standardization (CEN). Its full title is "Fasteners - Surface discontinuities - Part 1: Bolts, screws and studs for general requirements (ISO 6157-1:1988)". This standard covers: Establishes limits for various types of products and applies also to these products with: nominal thread diameters of 5 mm and larger, product grades A und B, property classes up to and including 10.9; the annex contains a sampling plan.
Establishes limits for various types of products and applies also to these products with: nominal thread diameters of 5 mm and larger, product grades A und B, property classes up to and including 10.9; the annex contains a sampling plan.
EN 26157-1:1991 is classified under the following ICS (International Classification for Standards) categories: 21.060.10 - Bolts, screws, studs. The ICS classification helps identify the subject area and facilitates finding related standards.
EN 26157-1:1991 has the following relationships with other standards: It is inter standard links to EN 14399-7:2007, EN 14399-10:2018, EN 14399-7:2018, EN 14399-3:2005, EN 14399-8:2007, EN 14399-10:2009, EN 14399-4:2015, EN 14399-4:2005, EN 14399-8:2018, EN 14399-3:2015. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.
EN 26157-1:1991 is associated with the following European legislation: EU Directives/Regulations: 97/23/EC; Standardization Mandates: M/071. When a standard is cited in the Official Journal of the European Union, products manufactured in conformity with it benefit from a presumption of conformity with the essential requirements of the corresponding EU directive or regulation.
EN 26157-1:1991 is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.
Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Vezni elementi - Površinske napake - 1. del: Vijaki za splošne zahteveVerbindungselemente - Oberflächenfehler - Teil 1: Schrauben für allgemeine Anforderungen (ISO 6157-1:1988)Eléments de fixation - Défauts de surface - Partie 1: Boulons, vis et goujons d'usage général (ISO 6157-1:1988)Fasteners - Surface discontinuities - Part 1: Bolts, screws and studs for general requirements (ISO 6157-1:1988)21.060.10
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