EN 26157-3:1991
(Main)Fasteners - Surface discontinuities - Part 3: Bolts, screws and studs for special requirements (ISO 6157-3:1988)
Fasteners - Surface discontinuities - Part 3: Bolts, screws and studs for special requirements (ISO 6157-3:1988)
Establishes limits for various types of products and applies to these products with: nominal thread diameters of 5 mm and larger, product grades A and B, nominal lengths 1 10 d (or longer if specified), property class 12.9, and property classes 8.8, 9.8, and 10.9 (when specified or agreed); the annex contains a sampling plan.
Verbindungselemente - Oberflächenfehler - Teil 3: Schrauben für besondere Anforderungen (ISO 6157-3:1988)
Eléments de fixation - Défauts de surface - Partie 3: Boulons, vis et goujons pour applications particulières (ISO 6157-3:1988)
1.1 La présente partie de l'ISO 6157 fixe les limites des divers types de défauts de surface des vis et goujons pour des applications particulières. Elle s'applique aux vis et goujons
de diamètre nominal de filetage 5 mm et supérieur ;
de grades A et B ;
de longueur nominale l < 10d (ou plus sur spécification) ;
de classe de qualité 12.9 ;
de classes de qualité 8.8, 9.8 et 10.9 si la norme de produit le spécifie ou par accord entre le fournisseur et le client.
1.2 La présence de défauts de surface dans les limites admises dans le chapitre 3 ne doit cependant pas affecter le respect des valeurs minimales de caractéristiques mécaniques et fonctionnelles spécifiées dans l'ISO 898-1. Lorsque des conditions de tenue en fatigue sont exigées, la tenue en fatigue des vis présentant des défauts ne doit pas être inférieure à celle des vis sans défaut du même lot.
NOTES Les figures données en illustration dans
Vezni elementi - Površinske napake - 3. del: Vijaki za posebne zahteve
General Information
- 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
- 97/23/EC - Pressure equipment
Relations
- Effective Date
- 28-Jan-2026
- Effective Date
- 28-Jan-2026
Overview
EN 26157-3:1991 (identical with ISO 6157-3:1988) is a CEN standard that defines limits for surface discontinuities (surface defects) on high-strength fasteners. It specifically covers bolts, screws and studs for special requirements, establishing acceptance criteria and inspection guidance to ensure integrity and reliability of threaded fasteners used in critical applications. The standard also includes an annex with a sampling plan for inspection procedures.
Key Topics and Requirements
- Scope of application
- Applies to fasteners with nominal thread diameters of 5 mm and larger.
- Covers product grades A and B.
- Intended for nominal lengths 1–10 d (or longer when specified or agreed).
- Property classes
- Directly applicable to property class 12.9.
- Also applicable to property classes 8.8, 9.8 and 10.9 when specified or agreed between parties.
- Surface discontinuities
- Sets limits for types and sizes of surface defects (cracks, laps, seams, folds, cold shuts, etc.) that may affect fastener performance.
- Defines accept/reject criteria based on severity and location of discontinuities.
- Inspection and sampling
- Includes an annex with a sampling plan to guide batch inspection and quality control.
- Reference harmony
- Harmonized with ISO 6157-3:1988, ensuring international alignment on defect classification and acceptance.
Applications
- Manufacturers use EN 26157-3:1991 to set production quality controls, define acceptable surface conditions, and reduce risk of in-service failure for high-strength fasteners.
- Quality and inspection engineers implement the sampling plan and acceptance criteria during incoming inspection and final inspection.
- Purchasing and procurement teams reference the standard in technical specifications and purchase orders to ensure supplied bolts, screws and studs meet agreed surface quality.
- Design and maintenance professionals rely on these limits when specifying fasteners for safety- or performance-critical assemblies (e.g., heavy machinery, transportation, energy infrastructure) that require high-strength property classes.
Related Standards
- ISO 6157-3:1988 - the international standard identical in content.
- Other parts of the EN 26157 series (surface discontinuities for different product groups) - consult for washers, nuts, rivets, or general fastener requirements.
This standard is essential for anyone specifying, producing, inspecting or procuring high-strength bolts, screws and studs where surface integrity directly affects safety and performance. Keywords: EN 26157-3:1991, fasteners, surface discontinuities, bolts screws studs, property class 12.9, thread diameter ≥5 mm, sampling plan.
Frequently Asked Questions
EN 26157-3:1991 is a standard published by the European Committee for Standardization (CEN). Its full title is "Fasteners - Surface discontinuities - Part 3: Bolts, screws and studs for special requirements (ISO 6157-3:1988)". This standard covers: Establishes limits for various types of products and applies to these products with: nominal thread diameters of 5 mm and larger, product grades A and B, nominal lengths 1 10 d (or longer if specified), property class 12.9, and property classes 8.8, 9.8, and 10.9 (when specified or agreed); the annex contains a sampling plan.
Establishes limits for various types of products and applies to these products with: nominal thread diameters of 5 mm and larger, product grades A and B, nominal lengths 1 10 d (or longer if specified), property class 12.9, and property classes 8.8, 9.8, and 10.9 (when specified or agreed); the annex contains a sampling plan.
EN 26157-3:1991 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 26157-3:1991 has the following relationships with other standards: It is inter standard links to EN 14219:2003, EN 1662:1997. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.
EN 26157-3:1991 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 26157-3:1991 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 - 3. del: Vijaki za posebne zahteveVerbindungselemente - Oberflächenfehler - Teil 3: Schrauben für besondere Anforderungen (ISO 6157-3:1988)Eléments de fixation - Défauts de surface - Partie 3: Boulons, vis et goujons pour applications particulieres (ISO 6157-3:1988)Fasteners - Surface discontinuities - Part 3: Bolts, screws and studs for special requirements (ISO 6157-3:1988)21.060.10Sorniki, vijaki, stebelni vijakiBolts, sc
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