ISO 8168:2016

DRAFT INTERNATIONAL STANDARD
ISO/DIS 8168
ISO/TC 20/SC 4 Secretariat: DIN
Voting begins on: Voting terminates on:
2015-10-12 2016-01-12
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
ICS: 49.030.20
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENT AND APPROVAL. IT IS
THEREFORE SUBJECT TO CHANGE AND MAY
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
Reference number
NATIONAL REGULATIONS.
ISO/DIS 8168:2015(E)
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 SUPPORTING DOCUMENTATION. ISO 2015

---------------------- Page: 1 ----------------------
ISO/DIS 8168:2015(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2015, Published in Switzerland
All rights reserved. Unless otherwise specified, 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
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2015 – All rights reserved

---------------------- Page: 2 ----------------------
ISO/DIS 8168
Contents Page
Foreword .v
1 Scope .1
2 Normative references .1
3 Terms and definitions .2
4 Quality assurance .3
4.1 General .3
4.2 Qualification inspection conditions .4
4.3 Acceptance inspection conditions .4
4.4 Use of “statistical process control (SPC)” .4
5 Requirements .5
Annex A (informative) Cross-sectional areas and formulae for tensile and tension fatigue loads . 18
Annex B (informative) Cross-sectional areas and formulae for double shear loads . 20

iv © ISO 2015 – All rights reserved

---------------------- Page: 3 ----------------------
ISO/DIS 8168
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 8168 was prepared by Technical Committee ISO/TC 20, Aircraft and space vehicles, Subcommittee SC 4,
Aerospace fastener systems.
This third edition cancels and replaces the second edition (ISO 8168:1988) which has been technically revised.

© ISO 2015 – All rights reserved v

---------------------- Page: 4 ----------------------
DRAFT INTERNATIONAL STANDARD ISO/DIS 8168

Aerospace — Bolts, with MJ threads, made of heat and
corrosion resisting steel, strength class 1 100 MPa —
Procurement specification
1 Scope
This International Standard 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 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 2859-1:1999, Sampling procedures for inspection by attributes — Part 1: Sampling schemes indexed by
acceptance quality limit (AQL) for lot-by-lot inspection
ISO 3452-1, Non-destructive testing — Penetrant testing — Part 1: General principles
ISO 4288, Geometrical Product Specifications (GPS) — Surface texture: Profile method — Rules and
procedures for the assessment of surface texture
ISO 5855-2, Aerospace — MJ threads — Part 2: Limit dimensions for bolts and nuts
ISO 6892-1, Metallic materials — Tensile testing — Part 1: Method of test at room temperature
ISO 7870-1, Control charts — Part 1: General guidelines
ISO 7961, Aerospace — Bolts — Test methods
ISO 7870-3, Control charts — Part 3: Acceptance control charts
ISO 7870-2, Control charts - Part 2: Shewhart control charts
ISO/TR 13425, Guidelines for the selection of statistical methods in standardization and specification
ASTM E112:2004, Standard Test Methods for Determining Average Grain Size
© ISO 2015 – All rights reserved 1

---------------------- Page: 5 ----------------------
ISO/DIS 8168
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
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 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 having the same definition document number.
3.3
definition document
document specifying directly or indirectly all the requirements for products.
NOTE The definition document may be an International Standard, an in-house standard or a drawing.
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 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 In this International Standard, each sampling plan specifies the number of bolts to be inspected as a function
1)
of the size of the batch and the acceptance number [number of defective items acceptable (Ac) ].
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.

1) Ac = acceptance number (supplementary information taken from ISO 2859-1).
2 © ISO 2015 – All rights reserved

---------------------- Page: 6 ----------------------
ISO/DIS 8168
3.11
critical defect
defect that, according to judgement and experience, is likely to result in hazardous or unsafe conditions for
individuals using, maintaining or depending upon the considered product, or that is likely to prevent
performance of the function of a major end item.
3.12
major defect
defect other than critical, that is likely to result in failure or to reduce materially the usability of the considered
product for its intended purpose.
3.13
minor defect
defect that is not likely to reduce materially the usability of the considered product for its intended purpose, or
that is a departure from the established specifications having little bearing on the effective use or operation of
this product.
3.14
limiting quality
LQ
〈sampling plan〉 quality limit which corresponds to a specified and relatively low probability of acceptance.
NOTE 1 It is the limiting lot quality characteristic that the consumer is willing to accept with a low probability that a lot of
this quality would occur.
NOTE 2 For the purposes of this International Standard, the limiting quality quoted in Table 4 corresponds to a
probability of acceptance of 10 %.
3.15
acceptable quality limit
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 Variant: quality level, which in a sampling plan, corresponds to a specified but relatively high
probability of aссeptance
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 International Standard. It is recommended that the manufacturer be certified to a
recognized quality management system. The certification authority may be the prime contractor.
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 International Standard.
Quality documentation for parts produced in accordance with this International Standard shall be maintained
for a minimum period of 10 years.
Qualification of the bolts shall be granted by the Certification Authorities in the purchaser's country, or their
appointed representative, who may be the prime contractor.

2) In order to simplify the text, the term “inspections” used in this International Standard also refers to “inspections and
tests”.
© ISO 2015 – All rights reserved 3

---------------------- Page: 7 ----------------------
ISO/DIS 8168
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 International Standard.
Production acceptance inspections shall be carried out by the manufacturer or under his responsibility.
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 may 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 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 characteristics to be verified has
been previously altered during any of these inspections.
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 with the same number of defective items acceptable.
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 International
Standard, if he is capable of formally justifying this choice by using ISO/TR 13425 and the standards quoted
in it as a basis.
This justification will include 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;
4 © ISO 2015 – All rights reserved

---------------------- Page: 8 ----------------------
ISO/DIS 8168
 drawing up of an inspection plan and integration in the manufacturing process;
 drawing up of routes and control charts (ISO 7870-3, ISO 7870-1, ISO 7870-2);
 use of control charts for data consolidation;
 determination of the audits to be run and the control to be carried out to ensure reliability of the device.
To be usable in production, this process shall be validated beforehand by the qualifying body, either during the
qualification phase, or a posteriori according to the case, by analysing the justificatory file and the results of
the qualification inspections such as provided for in Clause 5. Such an SPC process is not applicable to
destructive tests apart from the stress durability test.
5 Requirements
The requirements of this International Standard are given in Table 1 and, unless otherwise specified, they
apply to bolts that are ready for use. The test temperature, unless otherwise specified, shall be the ambient
temperature. These requirements complement the requirements of all other standards or specifications
referenced in the definition document.
Table 1 — Requirements and test methods
Inspection and Desig- Sample
Clause Characteristic Requirement
a
test method nation size
5.1 Material In accordance with the definition See material standard. As required
document by semi-
finished
product
5.2 Dimensions In accordance with the definition Standard gauging Q 20
document
A Tables 3
and 4
5.3 Manufacturing
5.3.1 Forging The heads of the bolts shall be According to the Q
formed by a hot or cold forging manufacturing route

process before heat treatment.
In the case of hot forging, the The equipment used
equipment shall ensure that a shall be approved.
constant temperature of less than
1 090 °C is guaranteed throughout
the production batch.
5.3.2 Heat treatment The forged blanks shall be heat- According to the Q
treated to produce the properties process route

required by the definition
The equipment used
document. Blanks shall not be
shall be approved.
heat-treated more than twice.
5.3.3 Removal of If machining is required, it is
...