ISO 8168:2025
(Main)Aerospace — Bolts, with MJ threads, made of heat and corrosion resisting steel, strength class 1 100 MPa — Procurement specification
Aerospace — Bolts, with MJ threads, made of heat and corrosion resisting steel, strength class 1 100 MPa — Procurement specification
This document specifies the characteristics and quality assurance requirements for MJ thread bolts made of heat and corrosion resisting steel, of strength class 1 100 MPa, for aerospace construction. It is applicable whenever it is referenced in a definition document.
Aéronautique et espace — Vis à filetages MJ, en acier résistant à la chaleur et à la corrosion, de classe de résistance 1 100 MPa — Spécification d'approvisionnement
General Information
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Buy Standard
Standards Content (Sample)
International
Standard
ISO 8168
Fourth edition
Aerospace — Bolts, with MJ threads,
2025-07
made of heat and corrosion
resisting steel, strength class 1 100
MPa — Procurement specification
Aéronautique et espace — Vis à filetages MJ, en acier résistant à
la chaleur et à la corrosion, de classe de résistance 1 100 MPa —
Spécification d'approvisionnement
Reference number
© ISO 2025
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Quality assurance . 2
4.1 General .2
4.2 Qualification inspection conditions . . .3
4.3 Acceptance inspection conditions . .3
4.4 Use of “statistical process control” (SPC) .3
5 Requirements . 4
Annex A (informative) Cross-sectional areas and formulae for tensile loads .16
Annex B (informative) Cross-sectional areas and formulae for double shear loads .18
Bibliography . 19
iii
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.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 20, Aircraft and space vehicles, Subcommittee
SC 4, Aerospace fastener systems.
This fourth edition cancels and replaces the third edition (ISO 8168:2016), which has been technically
revised.
The main changes are as follows:
— editorial revision of the document;
— new tables for sampling;
— additional requirements in Table 1, item no 2 "Dimensions";
— additional requirements in Table 1 item no 4-1 "Tensile strength";
— additional requirements in Table 1 item no 4-3 "Hardness";
— additional requirements in Table 1 item no 4 "Recess removal torque".
Any feedback or questions on this document should be directed to the user’s national standards body.
A complete listing of these bodies can be found at www.iso.org/members.html.
iv
International Standard ISO 8168:2025(en)
Aerospace — Bolts, with MJ threads, made of heat and
corrosion resisting steel, strength class 1 100 MPa —
Procurement specification
1 Scope
This document specifies the characteristics and quality assurance requirements for MJ thread bolts made of
heat and corrosion resisting steel, of strength class 1 100 MPa, for aerospace construction.
It is applicable whenever it is referenced in a definition document.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements 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 3452-1, Non-destructive testing — Penetrant testing — Part 1: General principles
ISO 5855-2, Aerospace — MJ threads — Part 2: Limit dimensions for bolts and nuts
ISO 7961, Aerospace — Bolts — Test methods
AS/EN 9138, Aerospace Series - Quality Management Systems Statistical Product Acceptance Requirements
1)
ASTM E112:2004, Standard Test Methods for Determining Average Grain Size
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
batch
quantity of finished parts, manufactured using the same process, from a single material cast (single heat
of alloy), having the same definition document (3.3) number, diameter, heat-treated together to the same
specified condition and produced as one continuous run
3.2
inspection lot
quantity of bolts from a single production batch (3.1) having the same definition document (3.3) number
3.3
definition document
document specifying directly or indirectly all the requirements for products
Note 1 to entry: The definition document may be an International Standard, an in-house standard or a drawing.
1) Published by: ASTM International (US) https:// www .astm .org/ .
3.4
crack
rupture in the material which may extend in any direction and which may be intercrystalline or
transcrystalline in character
3.5
seam
longitudinal open surface defect
3.6
lap
surface defect caused by folding over metal fins or sharp corners and then forming them into the surface
3.7
crevice
hollow area at thread crest
3.8
inclusions
non-metallic particles originating from the material manufacturing process
Note 1 to entry: These particles may be isolated or arranged in strings.
3.9
sampling plan
plan according to which one or more samples are taken in order to obtain information and possibly reach a
decision
Note 1 to entry: In this document, each sampling plan specifies the number of bolts to be inspected as a function of the
size of the batch (3.1) and the acceptance number [number of defective items acceptable (Ac); see ISO 2859-1].
3.10
simple random sampling
sampling of n items from a population of N items in such a way that all possible combinations of n items have
the same probability of being chosen
3.11
grip length
shank length
dimension from top of head (flush head bolt) or underhead bearing surface (protruding head bolt) to the end
of full cylindrical portion of shank, excluding the thread radius at shank/slope transition
3.12
IRR
initial reliability requirement
inspection reliability requirement
minimum acceptable outgoing yield or probability of conformance
4 Quality assurance
4.1 General
The manufacturer shall be capable of providing a continuous production of bolts complying with the
quality requirements specified in this document. The manufacturer should implement a recognized quality
management system.
2)
The purpose of qualification inspections of bolts is to check that the design and manufacturing conditions
of a bolt allow it to satisfy the requirements of this document.
2) In order to simplify the text, the term “inspections” used in this document also refers to “inspections and tests”.
Quality documentation for parts produced in accordance with this document shall be maintained for a
minimum period of 10 years.
The purpose of a production acceptance inspection of a bolt is to check, as simply as possible, using a method
which is inexpensive but representative of the actual conditions of use, with the uncertainty inherent in
statistical sampling, that the bolt satisfies the requirements of this document.
Production acceptance inspections shall be carried out by, or under the responsibility of, the manufacturer.
4.2 Qualification inspection conditions
Unless otherwise specified, the inspection shall be carried out on:
— each type and diameter of bolt;
— 25 bolts selected from a single inspection lot by simple random sampling.
The test programme can be reduced, or the qualification granted, without inspection: any such decision
shall be based on the results obtained on similar types and diameters of bolts provided that the design and
manufacturing conditions are identical.
The inspections shall be repeated on any bolt if the manufacturing conditions have been modified.
Table 2 indicates the allocation of bolt samples for the inspections.
4.3 Acceptance inspection conditions
Inspections shall be carried out on each production batch or inspection lot. Bolts from the batch or lot to be
inspected shall be selected by simple random sampling.
Each bolt may be submitted to several inspections, provided that none of the characteristics to be verified
has been previously altered during any of these inspections.
Acceptance inspections and tests are specified in Table 1. They shall be carried out on each production batch
or inspection lot. Table 1 specifies the test methods and sampling tables to be used for each test. Fasteners
from the batch to be tested shall be selected by sampling in accordance with AS/EN 9138.
The bolts to be subjected to destructive inspections may be those on which non-destructive inspections
have been carried out.
If a more stringent inspection is deemed necessary, all or part of the qualification inspections may be
performed during the acceptance inspections. In this case, the number of bolts submitted is the same as that
submitted for the qualification inspection.
Production batches or inspection lots declared unacceptable after the production acceptance inspections
shall be submitted for re-inspection only after all the defective units have been removed and/or defects
have been corrected. In this case, the attribute(s) that caused the rejection shall be verified using a sample
of twice the normal size but the maximum number of allowed defective items shall be the same as in the
original inspection.
4.4 Use of “statistical process control” (SPC)
When a characteristic is obtained by a controlled statistical process, the manufacturer has the option, in
order to declare conformity of the characteristic, to forgo the final systematic sampling provided in this
document, if she or he can formally justify this choice by the standards quoted in it as a basis.
This justification includes the following phases:
— analysis of the key characteristics of the product;
— analysis of the risks for each implemented process;
— determination of the parameters and/or characteristics to be respected under SPC;
— determination of the capabilities of each process;
— drawing up of an inspection plan and integration in the manufact
...
FINAL DRAFT
International
Standard
ISO/FDIS 8168
ISO/TC 20/SC 4
Aerospace — Bolts, with MJ threads,
Secretariat: DIN
made of heat and corrosion
Voting begins on:
resisting steel, strength class 1 100
2025-05-08
MPa — Procurement specification
Voting terminates on:
2025-07-03
Aéronautique et espace — Vis à filetages MJ, en acier résistant à
la chaleur et à la corrosion, de classe de résistance 1 100 MPa —
Spécification d'approvisionnement
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
WITH THEIR COMMENTS, NOTIFICATION OF ANY
RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE
AND TO PROVIDE SUPPOR TING DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
Reference number
ISO/FDIS 8168:2025(en) © ISO 2025
FINAL DRAFT
ISO/FDIS 8168:2025(en)
International
Standard
ISO/FDIS 8168
ISO/TC 20/SC 4
Aerospace — Bolts, with MJ threads,
Secretariat: DIN
made of heat and corrosion
Voting begins on:
resisting steel, strength class 1 100
MPa — Procurement specification
Voting terminates on:
Aéronautique et espace — Vis à filetages MJ, en acier résistant à
la chaleur et à la corrosion, de classe de résistance 1 100 MPa —
Spécification d'approvisionnement
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
WITH THEIR COMMENTS, NOTIFICATION OF ANY
RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE
AND TO PROVIDE SUPPOR TING DOCUMENTATION.
© ISO 2025
IN ADDITION TO THEIR EVALUATION AS
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
or ISO’s member body in the country of the requester.
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland Reference number
ISO/FDIS 8168:2025(en) © ISO 2025
ii
ISO/FDIS 8168:2025(en)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Quality assurance . 2
4.1 General .2
4.2 Qualification inspection conditions . . .3
4.3 Acceptance inspection conditions . .3
4.4 Use of “statistical process control” (SPC) .3
5 Requirements . 4
Annex A (informative) Cross-sectional areas and formulae for tensile loads .16
Annex B (informative) Cross-sectional areas and formulae for double shear loads .18
Bibliography . 19
iii
ISO/FDIS 8168:2025(en)
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.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 20, Aircraft and space vehicles, Subcommittee
SC 4, Aerospace fastener systems.
This fourth edition cancels and replaces the third edition (ISO 8168:2016), which has been technically
revised.
The main changes are as follows:
— editorial revision of the document;
— new tables for sampling;
— additional requirements in Table 1, item no 2 "Dimensions";
— additional requirements in Table 1 item no 4-1 "Tensile strength";
— additional requirements in Table 1 item no 4-3 "Hardness";
— additional requirements in Table 1 item no 4 "Recess removal torque".
Any feedback or questions on this document should be directed to the user’s national standards body.
A complete listing of these bodies can be found at www.iso.org/members.html.
iv
FINAL DRAFT International Standard ISO/FDIS 8168:2025(en)
Aerospace — Bolts, with MJ threads, made of heat and
corrosion resisting steel, strength class 1 100 MPa —
Procurement specification
1 Scope
This document specifies the characteristics and quality assurance requirements for MJ thread bolts made of
heat and corrosion resisting steel, of strength class 1 100 MPa, for aerospace construction.
It is applicable whenever it is referenced in a definition document.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements 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 3452-1, Non-destructive testing — Penetrant testing — Part 1: General principles
ISO 5855-2, Aerospace — MJ threads — Part 2: Limit dimensions for bolts and nuts
ISO 7961, Aerospace — Bolts — Test methods
AS/EN 9138, Aerospace Series - Quality Management Systems Statistical Product Acceptance Requirements
1)
ASTM E112:2004, Standard Test Methods for Determining Average Grain Size
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
batch
quantity of finished parts, manufactured using the same process, from a single material cast (single heat
of alloy), having the same definition document (3.3) number, diameter, heat-treated together to the same
specified condition and produced as one continuous run
3.2
inspection lot
quantity of bolts from a single production batch (3.1) having the same definition document (3.3) number
3.3
definition document
document specifying directly or indirectly all the requirements for products
Note 1 to entry: The definition document may be an International Standard, an in-house standard or a drawing.
1) Published by: ASTM International (US) https:// www .astm .org/ .
ISO/FDIS 8168:2025(en)
3.4
crack
rupture in the material which may extend in any direction and which may be intercrystalline or
transcrystalline in character
3.5
seam
longitudinal open surface defect
3.6
lap
surface defect caused by folding over metal fins or sharp corners and then forming them into the surface
3.7
crevice
hollow area at thread crest
3.8
inclusions
non-metallic particles originating from the material manufacturing process
Note 1 to entry: These particles may be isolated or arranged in strings.
3.9
sampling plan
plan according to which one or more samples are taken in order to obtain information and possibly reach a
decision
Note 1 to entry: In this document, each sampling plan specifies the number of bolts to be inspected as a function of the
size of the batch (3.1) and the acceptance number [number of defective items acceptable (Ac); see ISO 2859-1].
3.10
simple random sampling
sampling of n items from a population of N items in such a way that all possible combinations of n items have
the same probability of being chosen
3.11
grip length
shank length
dimension from top of head (flush head bolt) or underhead bearing surface (protruding head bolt) to the end
of full cylindrical portion of shank, excluding the thread radius at shank/slope transition
3.12
IRR
initial reliability requirement
inspection reliability requirement
minimum acceptable outgoing yield or probability of conformance
4 Quality assurance
4.1 General
The manufacturer shall be capable of providing a continuous production of bolts complying with the
quality requirements specified in this document. The manufacturer should implement a recognized quality
management system.
2)
The purpose of qualification inspections of bolts is to check that the design and manufacturing conditions
of a bolt allow it to satisfy the requirements of this document.
2) In order to simplify the text, the term “inspections” used in this document also refers to “inspections and tests”.
ISO/FDIS 8168:2025(en)
Quality documentation for parts produced in accordance with this document shall be maintained for a
minimum period of 10 years.
The purpose of a production acceptance inspection of a bolt is to check, as simply as possible, using a method
which is inexpensive but representative of the actual conditions of use, with the uncertainty inherent in
statistical sampling, that the bolt satisfies the requirements of this document.
Production acceptance inspections shall be carried out by, or under the responsibility of, the manufacturer.
4.2 Qualification inspection conditions
Unless otherwise specified, the inspection shall be carried out on:
— each type and diameter of bolt;
— 25 bolts selected from a single inspection lot by simple random sampling.
The test programme can be reduced, or the qualification granted, without inspection: any such decision
shall be based on the results obtained on similar types and diameters of bolts provided that the design and
manufacturing conditions are identical.
The inspections shall be repeated on any bolt if the manufacturing conditions have been modified.
Table 2 indicates the allocation of bolt samples for the inspections.
4.3 Acceptance inspection conditions
Inspections shall be carried out on each production batch or inspection lot. Bolts from the batch or lot to be
inspected shall be selected by simple random sampling.
Each bolt may be submitted to several inspections, provided that none of the characteristics to be verified
has been previously altered during any of these inspections.
Acceptance inspections and tests are specified in Table 1. They shall be carried out on each production batch
or inspection lot. Table 1 specifies the test methods and sampling tables to be used for each test. Fasteners
from the batch to be tested shall be selected by sampling in accordance with AS/EN 9138.
The bolts to be subjected to destructive inspections may be those on which non-destructive
...
ISO/FDIS 8168:2025(en)
ISO/TC 20/SC 4
Secretariat: DIN
Date: 2025-01-2204-24
Aerospace — Bolts, with MJ threads, made of heat and corrosion
resisting steel, strength class 1 100 MPa — Procurement
specification
Aéronautique et espace — Vis à filetages MJ, en acier résistant à la chaleur et à la corrosion, de classe de
résistance 1 100 MPa — Spécification d'approvisionnement
FDIS stage
ISO/FDIS 8168:2025(en)
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication
may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying,
or posting on the internet or an intranet, without prior written permission. Permission can be requested from either ISO
at the address below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: + 41 22 749 01 11
EmailE-mail: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
ISO/FDIS 8168:2025(en)
Contents
Foreword . iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Quality assurance . 3
4.1 General . 3
4.2 Qualification inspection conditions. 3
4.3 Acceptance inspection conditions . 3
4.4 Use of “statistical process control” (SPC) . 4
5 Requirements . 4
Annex A (informative) Cross-sectional areas and formulae for tensile loads . 20
Annex B (informative) Cross-sectional areas and formulae for double shear loads . 22
Bibliography . 24
iii
ISO/FDIS 8168:2025(en)
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.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types of
ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent rights
in respect thereof. As of the date of publication of this document, ISO had not received notice of (a) patent(s)
which may be required to implement this document. However, implementers are cautioned that this may not
represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 20, Aircraft and space vehicles, Subcommittee
SC 4, Aerospace fastener systems.
This fourth edition cancels and replaces the third edition (ISO 76898168:2016), which has been technically
revised.
The main changes are as follows:
— — editorial revision of the document;
— — new tables for sampling;
— — additional requirements in Table 1Table 1,, item no 2 "Dimensions";
— — additional requirements in Table 1Table 1 item no 4-1 "Tensile strength"";
— — additional requirements in Table 1Table 1 item no 4-3 "Hardness"";
— — additional requirements in Table 1Table 1 item no 4 "Recess removal torque".
Any feedback or questions on this document should be directed to the user’s national standards body.
A complete listing of these bodies can be found at www.iso.org/members.html.
iv
DRAFT International Standard ISO/FDIS 8168:2025(en)
Aerospace — Bolts, with MJ threads, made of heat and corrosion
resisting steel, strength class 1 100 MPa — Procurement specification
1 Scope
This document specifies the characteristics and quality assurance requirements for MJ thread bolts made of
heat and corrosion resisting steel, of strength class 1 100 MPa, for aerospace construction.
It is applicable whenever it is referenced in a definition document.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements 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 3452--1, Non-destructive testing — Penetrant testing — Part 1: General principles
ISO 5855--2, Aerospace — MJ threads — Part 2: Limit dimensions for bolts and nuts
ISO 7961, Aerospace — Bolts — Test methods
AS/EN 9138, Aerospace Series - Quality Management Systems Statistical Product Acceptance Requirements
11)
ASTM E112:2004, Standard Test Methods for Determining Average Grain Size
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— — ISO Online browsing platform: available at https://www.iso.org/obp
— — IEC Electropedia: available at https://www.electropedia.org/
3.1 3.1
batch
quantity of finished parts, manufactured using the same process, from a single material cast (single heat of
alloy), having the same definition document (3.3(3.3)) number, diameter, heat-treated together to the same
specified condition and produced as one continuous run
3.2 3.2
inspection lot
quantity of bolts from a single production batch (3.1(3.1)) having the same definition document (3.3(3.3))
number
Published by: ASTM International (US) https://www.astm.org/.
1)
Published by: ASTM International (US) https://www.astm.org/.
ISO/FDIS 8168:2025(en)
3.3 3.3
definition document
document specifying directly or indirectly all the requirements for products
Note 1 to entry: The definition document may be an International Standard, an in-house standard or a drawing.
3.4 3.4
crack
rupture in the material which may extend in any direction and which may be intercrystalline or
transcrystalline in character
3.5 3.5
seam
longitudinal open surface defect
3.6 3.6
lap
surface defect caused by folding over metal fins or sharp corners and then forming them into the surface
3.7 3.7
crevice
hollow area at thread crest
3.8 3.8
inclusions
non-metallic particles originating from the material manufacturing process
Note 1 to entry: These particles may be isolated or arranged in strings.
3.9 3.9
sampling plan
plan according to which one or more samples are taken in order to obtain information and possibly reach a
decision
Note 1 to entry: In this document, each sampling plan specifies the number of bolts to be inspected as a function of the
size of the batch (3.1(3.1)) and the acceptance number [number of defective items acceptable (Ac); see ISO 2859-1].
3.10 3.10
simple random sampling
sampling of n items from a population of N items in such a way that all possible combinations of n items have
the same probability of being chosen
3.11
acceptable quality level
AQL
maximum percent defective (or the maximum number of defects per hundred units) that, for purposes of
sampling inspection, can be considered satisfactory as a process average
Note 1 to entry: Variant: quality level, which in a sampling plan (3.9), corresponds to a specified but relatively high
probability of acceptance.
3.163.11 3.12
grip length
shank length
dimension from top of head (flush head bolt) or underhead bearing surface (protruding head bolt) to the end
of full cylindrical portion of shank, excluding the thread radius at shank/slope transition
ISO/FDIS 8168:2025(en)
3.173.12 3.13
IRR
initial reliability requirement
inspection reliability requirement
a minimum acceptable outgoing yield or probability of conformance
4 Quality assurance
4.1 General
The manufacturer shall be capable of providing a continuous production of bolts complying with the quality
requirements specified in this document. The manufacturer should implement a recognized quality
management system.
22)
The purpose of qualification inspections of bolts is to check that the design and manufacturing conditions
of a bolt allow it to satisfy the requirements of this document.
Quality documentation for parts produced in accordance with this document shall be maintained for a
minimum period of 10 years.
The purpose of a production acceptance inspection of a bolt is to check, as simply as possible, using a method
which is inexpensive but representative of the actual conditions of use, with the uncertainty inherent in
statistical sampling, that the bolt satisfies the requirements of this document.
Production acceptance inspections shall be carried out by, or under the responsibility of, the manufacturer.
4.2 Qualification inspection conditions
Unless otherwise specified, the inspection shall be carried out on:
— — each type and diameter of bolt;
— — 25 bolts selected from a single inspection lot by simple random sampling.
The test programme can possibly be reduced, or the qualification granted, without inspection: any such
decision shall be based on the results obtained on similar types and diameters of bolts provided that the design
and manufacturing conditions are identical.
The inspections shall be repeated on any bolt if the manufacturing conditions have been modified.
Table 2Table 2 indicates the allocation of bolt samples for the inspections.
4.3 Acceptance inspection conditions
Inspections shall be carried out on each production batch or inspection lot. Bolts from the batch or lot to be
inspected shall be selected by simple random sampling.
Each bolt may be submitted to several inspections, provided that none of the characteristics to be verified has
been previously altered during any of these inspections.
In order to simplify the text, the term “inspections” used in this document also refers to “inspections and tests”.
2)
In order to simplify the text, the term “inspections” used in this document also refers to “inspections and tests”.
ISO/FDIS 8168:2025(en)
Acceptance inspections and tests are specified in Table 1Table 1. They shall be carried out on each production
batch or inspection lot. Table 1Table 1 specifies the test methods and sampling tables to be used for each test.
Fasteners from the batch to be tested shall be selected by sampling in accordance with AS/EN 9138.
The bolts to be subjected to destructive inspections may be those on which non--destructive inspections have
been carried out.
If a more stringent inspection is deemed necessary, all or part of the qualification inspections may be
performed during the acceptance inspections. In this case, the number of bolts submitted is the same as that
submitted for the qualification inspection.
Production batches or inspection lots declared unacceptable after the production acceptance inspections shall
be submitted for re-inspection only after all the defective units have been removed and/or defects have been
corrected. In this case, the attribute(s) that caused the rejection shall be verified using a sample of twice the
normal size but the maximum number of allowed defective items shall be the same as in the original
inspection.
4.4 Use of “statistical process control” (SPC)
When a characteristic is obtained by a controlled statistical process, the manufacturer has the option, in order
to declare conformity of the characteristic, to forgo the final systematic sampling provided in this document,
if she or he can formally justify this choice by the standards quoted in it as a basis.
This justification includes the following phases:
— — analysis of the key characteristics of the p
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