ISO 5855-3:1999
(Main)Aerospace — MJ threads — Part 3: Limit dimensions for fittings for fluid systems
Aerospace — MJ threads — Part 3: Limit dimensions for fittings for fluid systems
This part of ISO 5855 specifies limit dimensions of MJ threads for fluid systems fittings for aerospace construction.
Aéronautique et espace — Filetage MJ — Partie 3: Dimensions limites pour raccordements de systèmes de fluides
La présente partie de l'ISO 5855 prescrit les dimensions limites du filetage MJ pour raccordements de systèmes de fluides pour les constructions aérospatiales.
General Information
- Status
- Published
- Publication Date
- 20-Oct-1999
- Technical Committee
- ISO/TC 20/SC 4 - Aerospace fastener systems
- Drafting Committee
- ISO/TC 20/SC 4 - Aerospace fastener systems
- Current Stage
- 9093 - International Standard confirmed
- Start Date
- 19-Oct-2021
- Completion Date
- 14-Feb-2026
Relations
- Revises
ISO 5855-3:1988 - Aerospace — MJ threads — Part 3: Limit dimensions for fittings for fluid systems - Effective Date
- 15-Apr-2008
Overview
ISO 5855-3:1999 is an international standard developed by the International Organization for Standardization (ISO) under the title Aerospace - MJ threads - Part 3: Limit dimensions for fittings for fluid systems. The standard defines the limit dimensions for MJ (metric screw thread, aerospace series) threads used in fittings designed for aerospace fluid systems. This ensures compatibility, reliability, and interchangeability of threaded fittings found in critical aviation and spaceflight fluid systems, such as hydraulics and fuel systems.
MJ threads are specifically engineered to meet the demanding requirements of aerospace construction, where thread form, strength, and integrity directly impact safety and system performance.
Key Topics
- MJ Thread Specification: Defines the limit dimensions for external and internal MJ threads used in aerospace fluid system fittings, covering a range of nominal diameters and pitches.
- Tolerance Classes: Specifies required tolerance classes for thread assembly, external threads, and internal threads-ensuring consistent fit and function.
- Coated Threads: Provides guidelines for the permissible dimensions of threads before and after the application of coatings, accounting for changes in dimensions due to surface treatments.
- Root Radius and Profiles: Outlines requirements for root radii and the form of thread profiles to achieve optimal stress distribution and fatigue resistance.
- Dimension Tables: Includes precise tabular data for major, pitch, and minor diameters for both types of threads (external and internal), ensuring accurate manufacturing and inspection.
- Deviation Limits: Specifies maximum permissible deviations on pitch (lead) and half flank angle to maintain effective sealing and mechanical strength.
Applications
ISO 5855-3:1999 is indispensable for aerospace manufacturers, engineers, and quality assurance professionals involved in the design, production, and maintenance of fluid system components, with key applications including:
- Hydraulic and Fuel Fittings: Used in aircraft systems, ground support equipment, and spacecraft to ensure leak-tight, durable connections for fluid transfer.
- Quality Control: Essential reference for inspection and verification of thread dimensions on production lines or during maintenance checks.
- Component Interchangeability: Enables international and cross-industry compatibility of fluid fittings, promoting supply chain flexibility and maintenance efficiency.
- Safety Assurance: Supports the achievement of the highest levels of reliability in mission-critical systems by standardizing thread dimensions and tolerances.
- Procurement Specifications: Used to specify required thread types and dimensions when sourcing components and raw materials for aerospace projects.
Related Standards
To comprehensively address the requirements for MJ threads in aerospace applications, ISO 5855-3:1999 should be used in conjunction with the following related standards:
- ISO 5855-1:1999 - Aerospace - MJ threads - Part 1: General requirements: Establishes the overall requirements for MJ threads.
- ISO 5855-2:1999 - Aerospace - MJ threads - Part 2: Limit dimensions for bolts and nuts: Provides limit dimensions for bolts and nuts using MJ threads.
- ISO 965-1:1998 - General-purpose metric screw threads - Tolerances - Part 1: Principles and basic data: Supplies foundational data and thread tolerance principles.
Other relevant international and industry-specific standards may apply for testing, material selection, and additional product qualifications within the aerospace sector.
Adhering to ISO 5855-3:1999 supports the safe, reliable, and effective deployment of MJ thread fittings throughout aerospace fluid systems. This enhances product quality, promotes interoperability, and aligns with best practices in international aerospace engineering.
Buy Documents
ISO 5855-3:1999 - Aerospace — MJ threads — Part 3: Limit dimensions for fittings for fluid systems Released:10/21/1999
ISO 5855-3:1999 - Aéronautique et espace — Filetage MJ — Partie 3: Dimensions limites pour raccordements de systemes de fluides Released:10/21/1999
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Frequently Asked Questions
ISO 5855-3:1999 is a standard published by the International Organization for Standardization (ISO). Its full title is "Aerospace — MJ threads — Part 3: Limit dimensions for fittings for fluid systems". This standard covers: This part of ISO 5855 specifies limit dimensions of MJ threads for fluid systems fittings for aerospace construction.
This part of ISO 5855 specifies limit dimensions of MJ threads for fluid systems fittings for aerospace construction.
ISO 5855-3:1999 is classified under the following ICS (International Classification for Standards) categories: 49.030.10 - Screw threads. The ICS classification helps identify the subject area and facilitates finding related standards.
ISO 5855-3:1999 has the following relationships with other standards: It is inter standard links to ISO 5855-3:1988. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.
ISO 5855-3:1999 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)
INTERNATIONAL ISO
STANDARD 5855-3
Second edition
1999-10-15
Aerospace — MJ threads —
Part 3:
Limit dimensions for fittings for fluid systems
Aéronautique et espace — Filetage MJ —
Partie 3: Dimensions limites pour raccordements de systèmes de fluides
A
Reference number
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 3.
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.
International Standard ISO 5855-3 was prepared by Technical Committee ISO/TC 20, Aircraft and space vehicles,
Subcommittee SC 4, Aerospace fastener systems.
This second edition cancels and replaces the first edition (ISO 5855-3:1988), of which it constitutes a technical
revision.
ISO 5855 consists of the following parts, under the general title Aerospace — MJ threads:
Part 1: General requirements
Part 2: Limit dimensions for bolts and nuts
Part 3: Limit dimensions for fittings for fluid systems
© ISO 1999
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 the publisher.
International Organization for Standardization
Case postale 56 • CH-1211 Genève 20 • Switzerland
Internet iso@iso.ch
Printed in Switzerland
ii
INTERNATIONAL STANDARD © ISO ISO 5855-3:1999(E)
Aerospace — MJ threads —
Part 3:
Limit dimensions for fittings for fluid systems
1 Scope
This part of ISO 5855 specifies limit dimensions of MJ threads for fluid systems fittings for aerospace construction.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of this
part of ISO 5855. For dated references, subsequent amendments to, or revisions of, any of these publications do not
apply. However, parties to agreements based on this part of ISO 5855 are encouraged to investigate the possibility of
applying the most recent edition of the normative documents indicated below. For undated references, the latest edition
of the normative document referred to applies. Members of ISO and IEC maintain registers of currently valid
International Standards.
ISO 965-1:1998, ISO general-purpose metric screw threads — Tolerances — Part 1: Principles and basic data.
ISO 5855-1:1999, Aerospace — MJ threads — Part 1: General requirements.
3 Nominal diameters and pitches
See Table 1.
Table 1 — Nominal diameters and pitches
Dimensions in millimetres
Nominal diameter Pitch Nominal diameter Pitch
d or D P d or D P
81 27
10 30
12 1,25 33 1,5
14 36
16 39
18 1,5 42
20 48 2
22 50
© ISO
4 Tolerance classes
See Table 2.
Table 2 — Tolerance classes
Assembly External threads Internal threads
d 6h D 5H
General case (clearance 1
may be nil)
d 4h D 4H
2 2
6g 5H
d D
Requiring systematic 1
clearance
d 4g D 4H
2 2
5 Provisions for coated threads
Before coating, the dimensions of the threads shall be compatible with the thickness of the coating selected and
with the limit dimensions for finished parts specified in clause 6.
6 Limit dimensions for finished parts (coated or uncoated)
6.1 External threads
6.1.1 4h6h external threads
Figure 1 illustrates the position and the form of the limit profiles (maximum and minimum) in relation to the basic
profile (see ISO 5855-1).
Tables 3 and 4 specify the limit dimensions.
a
Pitch – DP
b
Basic and maximum profiles
c
Basic profile
d
Minimum profile
Figure 1 — Limit profiles for external threads (clearance may be nil)
© ISO
Table 3 — Limit dimensions for 4h6h external threads
Dimensions in millimetres
Thread designation Major diameter Pitch diameter Minor diameter
d d d
2 3
T T T
d d2 d3
a a
max. min. (6h) max. min. (4h) max. min.
8,00 7,82 0,18 7,350 7,279 0,071 6,845 6,713 0,132
MJ8 ´ 1-4h6h
10,00 9,82 0,18 9,350 9,279 0,071 8,845 8,713 0,132
MJ10 ´ 1-4h6h
12,000 11,788 0,212 11,188 11,103 0,085 10,557 10,396 0,161
MJ12 ´ 1,25-4h6h
14,000 13,764 0,236 13,026 12,936 0,09 12,268 12,087 0,181
MJ14 ´ 1,5-4h6h
16,000 15,764 0,236 15,026 14,936 0,09 14,268 14,087 0,181
MJ16 ´ 1,5-4h6h
18,000 17,764 0,236 17,026 16,936 0,09 16,268 16,087 0,181
MJ18 ´ 1,5-4h6h
20,000 19,764 0,236 19,026 18,936 0,09 18,268 18,087 0,181
MJ20 ´ 1,5-4h6h
22,000 21,764 0,236 21,026 20,936 0,09 20,268 20
...
NORME ISO
INTERNATIONALE 5855-3
Deuxième édition
1999-10-15
Aéronautique et espace — Filetage MJ —
Partie 3:
Dimensions limites pour raccordements de
systèmes de fluides
Aerospace — MJ threads —
Part 3: Limit dimensions for fittings for fluid systems
A
Numéro de référence
Avant-propos
L'ISO (Organisation internationale de normalisation) est une fédération mondiale d'organismes nationaux de
normalisation (comités membres de l'ISO). L'élaboration des Normes internationales est en général confiée aux
comités techniques de l'ISO. Chaque comité membre intéressé par une étude a le droit de faire partie du comité
technique créé à cet effet. Les organisations internationales, gouvernementales et non gouvernementales, en
liaison avec l'ISO, participent également aux travaux. L'ISO collabore étroitement avec la Commission
électrotechnique internationale (CEI) en ce qui concerne la normalisation électrotechnique.
Les Normes internationales sont rédigées conformément aux règles données dans les Directives ISO/CEI, Partie 3.
Les projets de Normes internationales adoptés par les comités techniques sont soumis aux comités membres pour
vote. Leur publication comme Normes internationales requiert l'approbation de 75 % au moins des comités
membres votants.
La Norme internationale ISO 5855-3 a été élaborée par le comité technique ISO/TC 20, Aéronautique et espace,
sous-comité SC 4, Éléments de fixation pour constructions aérospatiales.
Cette deuxième édition annule et remplace la première édition (ISO 5855-3:1988), dont elle constitue une révision
technique.
L’ISO 5855 comprend les parties suivantes, présentées sous le titre général Aéronautique et espace — Filetage
MJ:
Partie 1: Exigences générales
Partie 2: Dimensions limites pour vis et écrous
Partie 3: Dimensions limites pour raccordements de systèmes de fluides
© ISO 1999
Droits de reproduction réservés. Sauf prescription différente, aucune partie de cette publication ne peut être reproduite ni utilisée sous quelque
forme que ce soit et par aucun procédé, électronique ou mécanique, y compris la photocopie et les microfilms, sans l'accord écrit de l'éditeur.
Organisation internationale de normalisation
Case postale 56 • CH-1211 Genève 20 • Suisse
Internet iso@iso.ch
Imprimé en Suisse
ii
NORME INTERNATIONALE © ISO ISO 5855-3:1999(F)
Aéronautique et espace — Filetage MJ —
Partie 3:
Dimensions limites pour raccordements de systèmes de fluides
1 Domaine d’application
La présente partie de l'ISO 5855 prescrit les dimensions limites du filetage MJ pour raccordements de systèmes de
fluides pour les constructions aérospatiales.
2 Références normatives
Les documents normatifs suivants contiennent des dispositions qui, par suite de la référence qui en est faite,
constituent des dispositions valables pour la présente partie de l'ISO 5855. Pour les références datées, les
amendements ultérieurs ou les révisions de ces publications ne s'appliquent pas. Toutefois, les parties prenantes
aux accords fondés sur la présente partie de l'ISO 5855 sont invitées à rechercher la possibilité d'appliquer les
éditions les plus récentes des documents normatifs indiqués ci-après. Pour les références non datées, la dernière
édition du document normatif en référence s'applique. Les membres de l'ISO et de la CEI possèdent le registre des
Normes internationales en vigueur.
ISO 965-1:1998, Filetages métriques ISO pour usages généraux — Tolérances — Partie 1: Principes et données
fondamentales.
ISO 5855-1:1999, Aéronautique et espace — Filetage MJ — Partie 1: Exigences générales.
3 Diamètres nominaux et pas
Voir Tableau 1.
Tableau 1 — Diamètres nominaux et pas
Dimensions en millimètres
Diamètre nominal Pas Diamètre nominal Pas
d ou D P d ou D P
81 27
10 30
12 1,25 33 1,5
14 36
16 39
18 1,5 42
20 48 2
22 50
© ISO
4 Classes de tolérances
Voir Tableau 2.
Tableau 2 — Classes de tolérances
Assemblage Filetage extérieur Filetage intérieur
Courant (jeu d 6h D 5H
pouvant être nul) d 4h D 4H
2 2
Nécessitant un d 6g D 5H
jeu systématique d 4g D 4H
2 2
5 Dispositions pour filetages revêtus
Avant revêtement, les dimensions doivent être compatibles avec l'épaisseur du revêtement retenu et avec les
dimensions limites des pièces prêtes à l'emploi données dans l'article 6.
6 Dimensions limites pour pièces prêtes à l'emploi (revêtues ou non revêtues)
6.1 Filetage extérieur
6.1.1 Filetage extérieur 4h6h
La Figure 1 illustre la position ainsi que la forme des profils limites (maximum et minimum) par rapport au profil de
base (voir ISO 5855-1).
Les Tableaux 3 et 4 donnent les dimensions limites.
a
Pas ± DP
b
Profils de base et maximal
c
Profil de base
d
Profil minimal
Figure 1 — Profils limites du filetage extérieur (jeu pouvant être nul)
© ISO
Tableau 3 — Dimensions limites des filetages extérieurs 4h6h
Dimensions en millimètres
Désignation du filetage Diamètre extérieur Diamètre sur flancs Diamètre intérieur
d d d
2 3
T T T
d d2 d3
max. min. a max. min. a max. min.
(6h) (4h)
8,00 7,82 0,18 7,350 7,279 0,071 6,845 6,713 0,132
MJ8 ´ 1-4h6h
10,00 9,82 0,18 9,350 9,279 0,071 8,845 8,713 0,132
MJ10 ´ 1-4h6h
12,000 11,788 0,212 11,188 11,103 0,085 10,557 10,396 0,161
MJ12 ´ 1,25-4h6h
14,000 13,764 0,236 13,026 12,936 0,09 12,268 12,087 0,181
MJ14 ´ 1,5-4h6h
16,000 15,764 0,236 15,026 14,936 0,09 14,268 14,087 0,181
MJ16 ´ 1,5-4h6h
18,000 17,764 0,236 17,026 16,936 0,09 16,268 16,087
...
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