ISO 8788:2020

INTERNATIONAL ISO
STANDARD 8788
Third edition
2020-05
Aerospace — Nuts, metric —
Tolerances of form and position
Aéronautique et espace — Écrous métriques — Tolérances de forme
et de position
Reference number
ISO 8788:2020(E)
©
ISO 2020

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ISO 8788:2020(E)

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ISO 8788:2020(E)

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Types of nuts, illustration of tolerances of form and position, values.1
Annex A (informative) Plain nuts .10
Annex B (informative) Slotted nuts .11
Annex C (informative) Self-locking nuts with wrenching feature, with plastic locking ring .12
Annex D (informative) Self-locking hexagonal nuts, with wrenching feature, formed out-of-
round .13
Annex E (informative) Self-locking bihexagonal nuts, with wrenching feature, formed out-
of-round .14
Annex F (informative) Self-locking clinch/shank nuts .15
Annex G (informative) Self-locking anchor nuts, two lug .16
Annex H (informative) Self-locking anchor nuts, single lug .17
Annex I (informative) Self-locking anchor nuts, corner .18
Bibliography .19
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ISO 8788:2020(E)

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
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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 documents 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).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
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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 third edition cancels and replaces the second edition (ISO 8788:2000), of which it constitutes a
minor revision.
The changes compared to the previous edition are as follows:
— informative references changed from dated to undated and moved to the Bibliography;
— the document editorially revised.
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.
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INTERNATIONAL STANDARD ISO 8788:2020(E)
Aerospace — Nuts, metric — Tolerances of form and
position
1 Scope
This document defines the tolerances of form and position of metric nuts meant for aerospace
construction. These tolerances comply with ISO 1101, ISO 2692 and ISO 5459.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
4 Types of nuts, illustration of tolerances of form and position, values
See Table 1 for the tolerances of form and position to be applied in relation to the type of nut, Table 2 to
Table 11 for the illustration of tolerances of form and position for different types of nut. See Tables 12
and Table 13 for the values of the tolerances. In the “illustration” column, only one type of nut has been
shown as an example, but the corresponding tolerance applies to all types of nut specified in the third
column.
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ISO 8788:2020(E)

2 © ISO 2020 – All rights reserved
Table 1 — Tolerances of form and position to be applied in relation to the type of nut
Sequence number
Plain nuts Slotted Self-locking nuts
nuts
Table Tolerance of former position with wrenching feature clinch/shank anchor
formed out-of-round two-lug single-lug corner
w
...