INTERNATIONAL ISO

STANDARD 23278

Second edition
2015-03-01

Non-destructive testing of welds —

Magnetic particle testing —
Acceptance levels
Contrôle non destructif des assemblages soudés — Contrôle par
magnétoscopie — Niveaux d’acceptation

Reference number
ISO 23278:2015(E)

© ISO 2015
ISO 23278:2015(E)


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Contents Page

Foreword......................................................................................................................................................................................................................................... iv
1 Scope.................................................................................................................................................................................................................................. 1
2 Normative references....................................................................................................................................................................................... 1
3 Terms and definitions...................................................................................................................................................................................... 1
4 Testing parameters............................................................................................................................................................................................. 1
5 Acceptance levels.................................................................................................................................................................................................. 2
5.1 General............................................................................................................................................................................................................ 2
5.2 Removal of imperfections............................................................................................................................................................... 2
Annex A (informative) Recommended testing parameters........................................................................................................... 3
Bibliography................................................................................................................................................................................................................................. 4

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ISO 23278:2015(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
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electrotechnical standardization.
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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).
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to Trade (TBT), see the following URL: Foreword — Supplementary information.
The committee responsible for this document is ISO/TC 44, Welding and allied processes, Subcommittee
SC 5, Testing and inspection of welds.
This second edition cancels and replaces the first edition (ISO 23278:2006), which has been
technically revised.

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INTERNATIONAL STANDARD ISO 23278:2015(E)

Non-destructive testing of welds — Magnetic particle

testing — Acceptance levels

1 Scope
This International Standard specifies acceptance levels for indications from imperfections in
ferromagnetic steel welds detected by magnetic particle testing.
The acceptance levels are primarily intended for use during manufacture examination.
NOTE They can also be used for in-service inspection.

The acceptance levels in this International Standard are based on detection capabilities that can be
expected when using techniques specified in ISO 17638 and parameters recommended in Annex A. The
acceptance levels can be related to welding standards, application standards, specifications or codes.
Such a relationship is shown in ISO 17635 for ISO 5817.
Acceptance levels for grouped indications are not covered by this International Standard.

2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO/TS 18173, Non-destructive testing — General terms and definitions

3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO/TS 18173 and the following apply.
3.1
linear indication
l
indication having a length greater than three times its width
3.2
non-linear indication
d
indication having a length less than or equal to three times its width

4 Testing parameters
Many parameters, either individually or in combination, will affect the ability of a technique to detect
imperfections of a given size and orientation with respect to the condition of the test surface.
Detection of small imperfections is highly dependent on the surface condition of the weld and the
detection media used. Examples of the application of these parameters to give a high probability of
detection are given in Annex A.

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ISO 23278:2015(E)


5 Acceptance levels

5.1 General
The width of the test surface shall include the weld metal and the adjacent parent metal up to a distance
of 10 mm on each side.
Acceptance levels prescribed for linear indications are those corresponding to the evaluation level.
Indications lower than this shall not be taken into account. Acceptable indications do not have to be recorded.
Any adjacent indications separated by less than the major dimension of the smaller shall be assessed as
a single, continuous indication.
Local grinding may be used to improve the classification of all or just part of a test surface, when it is
required to work to a higher detection limit than that expected by the existing weld surface condition.
Acceptance levels are given in Table 1.

Table 1 — Acceptance levels for indications from imperfections

Dimensions in millimetres
Acceptance levela
Type of indication
1 2 3
Linear indication
l ⩽ 1,5 l ⩽ 3 l ⩽ 6
l = length of indication
Non-linear indication
d ⩽ 2 d ⩽ 3 d ⩽ 4
d = major axis dimension
a Acceptance levels 2 and 3 may be specified with a suffix “X”, which denotes that all linear indications detected shall be
assessed to level 1. However, the probability of detection of indications smaller than those denoted by the original acceptance
level can be low.

5.2 Removal of imperfections

Where the product specification permits, local grinding may be used to reduce or remove imperfections
which are the cause of unacceptable indications. All such areas shall be re-tested and evaluated with the
same magnetic system and technique.

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 ISO 23278:2015(E)


Annex A
(informative)

Recommended testing parameters

Recommended testing parameters for reliable detection of small imperfections are given in Table A.1.
The surfaces are in the as-welded condition. It may be necessary to improve the surface condition, e.g. by
abrasive paper or local grinding, to permit accurate interpretation of indications. The detection media
are given in order of preference.

Table A.1 — Recommended testing parameters

Acceptance level Surface condition Detection media
Fluorescent or colour contrast with
1 Fine surface a
contrast aid
Fluorescent or colour contrast with
2 Smooth surface b
contrast aid
Colour contrast with contrast aid or fluo-
3 General surface c
rescent with low sensitivity
a The weld cap and parent material offer smooth clean surfaces with negligible undercut, rippling and spatter. The surface
finish is typical of welds, made by automatic TIG-welding; submerged arc welding (fully mechanized) and manual metal arc
welding with iron powder electrodes.
b The weld cap and parent material offer reasonably smooth surfaces with minimal undercut, rippling and spatter. The
surface finish is typical of welds made by manual metal arc welding vertical downwards and MAG-welding using argon rich
gas for the capping runs.
c The weld cap and parent material are in the as-welded condition. The surface finish is typical of welds made by manual
metal arc welding or MAG-welding in any position.

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ISO 23278:2015(E)


Bibliography

[1] ISO 5817, Welding — Fusion-welded joints in steel, nickel, titanium and their alloys (beam welding
excluded) — Quality levels for imperfections
[2] ISO 17635, Non-destructive testing of welds — General rules for metallic materials
[3] ISO 17638, Non-destructive testing of welds — Magnetic particle testing

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