ISO 7044:2012

Prevailing torque type all-metal hexagon nuts with flange, style 2 - Product grades A and B

ISO 7044:2012 specifies the characteristics of prevailing torque type all-metal hexagon nuts with flange (style 2) and threads M5 to M20 inclusive, in product grade A for threads up to and including M16 and product grade B for threads above M16, and with property classes 8, 9, 10 and 12.

Écrous hexagonaux à embase, autofreinés, tout métal, style 2 — Grades A et B

General Information

• Status: Published
• Publication Date: 16-Aug-2012
• ICS: 21.060.20 - Nuts
• Technical Committee: ISO/TC 2/SC 12 - Fasteners with metric internal thread
• Drafting Committee: ISO/TC 2/SC 12 - Fasteners with metric internal thread
• Current Stage: 9093 - International Standard confirmed
• Start Date: 01-Jul-2022
• Completion Date: 13-Dec-2025

Relations

• Revises: ISO 7044:1997 - Prevailing torque type all-metal hexagon nuts with flange - Product grades A and B
• Effective Date: 16-Feb-2012

Overview

ISO 7044:2012 specifies the characteristics of prevailing-torque all‑metal hexagon nuts with flange (style 2) for metric threads M5 to M20. It covers product grades A and B (grade A for threads up to and including M16; grade B for threads above M16) and applies to nuts with property classes 8, 9, 10 and 12. This third edition (2012) is a minor revision and references dimensional and performance requirements from existing ISO fastener standards.

Key topics and technical requirements

• Scope and sizing
  • Threads covered: M5–M20 inclusive.
  • Product grades: A (≤ M16) and B (> M16).
  • Property classes: 8, 9, 10, 12.
  • Dimensions correspond to ISO 4161 with the added prevailing‑torque feature.
• Materials and tolerances
  • Material: steel (general requirements per ISO 8992).
  • Thread tolerance class: 6H.
• Mechanical and performance requirements
  • Mechanical properties referenced to ISO 898‑2 and prevailing torque performance to ISO 2320.
• Finish and surface integrity
  • Electroplating per ISO 4042; non‑electrolytically applied zinc flake coatings per ISO 10683.
  • Surface discontinuity limits per ISO 6157‑2 and acceptance per ISO 3269.
• Gauging and inspection
  • Annex A describes a recommended gauging method using two plain ring gauges (A and B) and an additional feeler/ring gauge (C) to verify hexagon height, flange thickness and corner fill.
• Designation
  • Example format: Prevailing torque type hexagon nut with flange ISO 7044 - M12 - 8

Applications and who uses this standard

• Typical applications
  • Assemblies requiring a self‑locking nut where sustained prevailing torque is needed (machines, automotive subassemblies, industrial equipment).
  • Situations calling for flange nuts to distribute load and prevent loosening without separate washers.
• Primary users
  • Fastener manufacturers specifying production and inspection criteria.
  • Design engineers selecting locking nuts (mechanical, automotive, heavy machinery).
  • Procurement/specification writers who need a clear product designation for purchasing.
  • Quality/inspection teams using the gauging and acceptance procedures during incoming inspection.

Related standards

• ISO 4161 - Hexagon nuts with flange, style 2 (dimensional basis)
• ISO 261 / ISO 724 / ISO 965‑2 - Metric thread general plan, basic dimensions and tolerances
• ISO 898‑2, ISO 2320 - Mechanical and performance properties for nuts
• ISO 4759‑1 - Tolerances for fasteners (product grades)
• ISO 4042, ISO 10683 - Coating requirements
• ISO 6157‑2, ISO 3269, ISO 8992 - Surface integrity, acceptance, and general fastener requirements

Keywords: ISO 7044, prevailing torque nut, all‑metal hexagon nut with flange, flange nut, product grade A, product grade B, M5–M20, property class 8 9 10 12, fastener standards, gauging.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 7044
Third edition
2012-09-01
Prevailing torque type all-metal hexagon
nuts with flange, style 2 — Product
grades A and B
Écrous hexagonaux à embase, autofreinés, tout métal, style 2 —
Grades A et B
Reference number
©
ISO 2012
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISO’s
member body in the country of the requester.
ISO copyright office
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Tel. + 41 22 749 01 11
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Published in Switzerland
ii © ISO 2012 – All rights reserved

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Dimensions . 1
4 Requirements and reference International Standards . 4
5 Designation . 4
Annex A (informative) Gauging of hexagon nuts with flange . 5
Bibliography . 7
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International
Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 7044 was prepared by Technical Committee ISO/TC 2, Fasteners, Subcommittee SC 12, Fasteners with
metric internal thread.
This third edition cancels and replaces the second edition (ISO 7044:1997), of which it constitutes a minor revision.
iv © ISO 2012 – All rights reserved

INTERNATIONAL STANDARD ISO 7044:2012(E)
Prevailing torque type all-metal hexagon nuts with flange, style
2 — Product grades A and B
1 Scope
This International Standard specifies the characteristics of prevailing torque type all-metal hexagon nuts with
flange (style 2) and threads M5 to M20 inclusive, in product grade A for threads up to and including M16 and
product grade B for threads above M16, and with property classes 8, 9, 10 and 12.
NOTE The dimensions of the nuts correspond to those given in ISO 4161 plus prevailing torque feature.
If other specifications are required, they can be selected from existing International Standards, for example
ISO 261, ISO 724, ISO 898-2, ISO 965-2, ISO 2320 and ISO 4759-1.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced document
(including any amendments) applies.
ISO 225, Fasteners — Bolts, screws, studs and nuts — Symbols and descriptions of dimensions
ISO 261, ISO general purpose metric screw threads — General plan
ISO 724, ISO general-purpose metric screw threads — Basic dimensions
ISO 898-2, Mechanical properties of fasteners made of carbon steel and alloy steel — Part 2: Nuts with
specified property classes — Coarse thread and fine pitch thread
ISO 965-2, ISO general purpose metric screw threads — Tolerances — Part 2: Limits of sizes for general
purpose external and internal screw threads — Medium quality
ISO 2320, Prev
...