ISO/DIS 7788

Steel -- Surface finish of hot-rolled plates and wide flats -- Delivery requirements

Acier -- État de surface des tôles et larges-plats laminés à chaud -- Conditions de livraison

Standards Content (sample)

DRAFT INTERNATIONAL STANDARD
ISO/DIS 7788
ISO/TC 17/SC 3 Secretariat: AFNOR
Voting begins on: Voting terminates on:
2020-07-27  2020-10-19
Steel — Surface finish of hot-rolled plates and wide flats —
Delivery requirements

Acier — État de surface des tôles et larges-plats laminés à chaud — Conditions de livraison

ICS: 77.140.50
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,
This document is circulated as received from the committee secretariat.
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
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WHICH REFERENCE MAY BE MADE IN
Reference number
NATIONAL REGULATIONS.
ISO/DIS 7788:2020(E)
RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
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PROVIDE SUPPORTING DOCUMENTATION. ISO 2020
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ISO/DIS 7788:2020(E)
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ISO/DIS 7788:2020(E)
Contents  Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1  Scope ................................................................................................................................................................................................................................. 1

2  Normative references ...................................................................................................................................................................................... 1

3  Terms and definitions ..................................................................................................................................................................................... 1

4  General ............................................................................................................................................................................................................................ 3

5  Classification ............................................................................................................................................................................................................ 3

6  Requirements .......................................................................................................................................................................................................... 3

6.1 Depth and affected area of discontinuities ..................................................................................................................... 3

6.1.1 Depth .......................................................................................................................................................................................... 3

6.1.2 Affected area ........................................................................................................................................................................ 4

6.2 Repair requirements .......................................................................................................................................................................... 6

6.2.1 Class A ....................................................................................................................................................................................... 6

6.2.2 Class B ....................................................................................................................................................................................... 7

6.3 Repair procedures ................................................................................................................................................................................ 7

6.3.1 Grinding ................................................................................................................................................................................... 7

6.3.2 Welding .................................................................................................................................................................................... 8

Annex A (Informative) Action to undertake in function of the depth of discontinuities and

nominal thickness of the products .................................................................................................................................................10

Bibliography .............................................................................................................................................................................................................................13

© ISO 2020 – All rights reserved iii
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ISO/DIS 7788:2020(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

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 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

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www .iso .org/ patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation on 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 the following

URL: www .iso .org/ iso/ foreword .html.

This document was prepared by Technical Committee ISO/TC 17, Steel, Subcommittee SC 3 ,Steels for

structural purposes.

This second edition cancels and replaces the first edition (ISO 7788:1985), which has been technically

revised.
The main changes compared to the previous edition are as follows:
— updated normative reference
— new definitions added

— deletion of distinction concerning boilers and pressure vessel applications (Clause 4)

— new definition of two classes and three subclasses added (Clause 5)

— new Clause 6: concerning “depth and determination of affected areas”, “repair requirements” and

“repair procedures”
— deletion of Annex A

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 © ISO 2020 – All rights reserved
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ISO/DIS 7788:2020(E)
Introduction

Responsibility for the required surface finish rests with the material producer, who has to take the

necessary precautions.

However, rolling or heat-treatment scale may conceal surface discontinuities. In these conditions, the

producer can only take account of discontinuities which are visible to the naked eye.

© ISO 2020 – All rights reserved v
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DRAFT INTERNATIONAL STANDARD ISO/DIS 7788:2020(E)
Steel — Surface finish of hot-rolled plates and wide flats —
Delivery requirements
1  Scope

This document specifies delivery requirements which apply to the surface finish of hot-rolled plates

and wide flats rolled on reversing mills, with nominal thickness ≥ 3 mm and ≤ 400 mm.

For plates with a nominal thickness greater than 400 mm and for special applications for which a different

surface condition is required, special agreements shall be made at the time of enquiry and order.

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 6929, Steel products — Vocabulary
ISO 7452, Hot-rolled steel plates — Tolerances on dimensions and shape

ISO 9034, Hot-rolled structural steel wide flats — Tolerances on dimensions and shape

ISO 9606-1, Qualification testing of welders — Fusion welding — Part 1: Steels

ISO 15607, Specification and qualification of welding procedures for metallic materials — General rules

3  Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 6929 and the following apply.

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/
3.1
imperfections

surface discontinuities other than cracks, shells and seams with a depth and/or an area equal to or less

than a specified value
Note 1 to entry: Discontinuities that shall be repaired are regarded as defects.
3.2
defects

surface discontinuities with a depth and/or area greater than a specified limiting value and all cracks,

shell and seams irrespective of their depth or/and area
3.3
rolled-in scale, pitting (to be regarded as discontinuities)

marks on the rolled surface varying in shape, thickness and frequency, resulting from the unsatisfactory

subsequent removal of scale from the stock before or during hot-rolling and processing.

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ISO/DIS 7788:2020(E)
3.4
indentations and roll marks (to be regarded as discontinuities)

roll marks appearing at periodic intervals caused by damaged rolls or pinch rolls

Note 1 to entry: Indentations (depressions) or roll marks (protuberances) can be distributed at definite distances

apart or irregularly throughout the length and width of the stock.. Indentations can be caused, inter alia, by

protuberances on rolls or rollers.
3.5
scratches and grooves (to be regarded as discontinuities)

mechanical damages varying in width, depth and length at the surface, mostly parallel or at right angles

to the rolling direction.

Note 1 to entry: They may be slightly rolled over and seldom contain scale. These damages are caused by friction

between the stock and parts of the equipment due to relative movements.
3.6
spills, slivers (to be regarded as discontinuities)
minute surface discontinuities of an irregular and flake-like nature

Note 1 to entry: Spills / slivers are elongated in the direction of rolling, their extent depending on the degree of

reductions. They are still connected – as minute particles of shell – to the base metal at certain points.

3.7
blisters (to be regarded as discontinuities)

blow holes of varying size and shape located closely beneath the surface and appearing during hot rolling

3.8
hot tears (to be regarded as discontinuities)

variably orientated material discontinuities in the surface region varying in length, width and depth

and occurring in preferred directions and/or distributed over a limited area

Note 1 to entry: Hot tears arise in the processing of slab ingots, roughed slabs and continuously cast slabs and are

associated with the steel, with stresses in the initial material or with adverse forming conditions.

3.9
sand patches (to be regarded as discontinuities)

non-metallic inclusions in the surface that vary in size and shape. They are elongated in the direction of

rolling, randomly localized and they are distinctly coloured, standing out from their background

3.10
cracks (to be always considered as defects, see 6.2.1.2.3)

localized discontinuities of varying length and varying orientation related to the rolling direction in the

region of the surface and which may less frequently occur as crazing

Note 1 to entry: Cracks are due mainly to material stresses which arise during the cooling process.

3.11
shell and seams (to be always considered as defects, see 6.2.1.2.3)

overlapping material being irregularly distributed over areas of the rolled product and being only

partially connected with the base material

Note 1 to entry: The overlapping portions of the surface varying in shape and extent. There is a preponderance of

non-metallic inclusions and/or scale among the shell.Shell can originate during casting or because of the shifting

or sliding of layers of the material during hot rolling. Seams are caused mainly when defects in the semi-product

parallel to the rolling direction, for instance, flame-cutting burrs, are overlapped during rolling.

Note 2 to entry: To get information about other surface of defects on the flat products, refer to valid references,

including reference [3] in the bibliography.
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ISO/DIS 7788:2020(E)
4  General

Responsibility for the required surface condition, whether the product is delivered descaled or not,

rests with the material producer, who has to take the necessary precautions. The producer can only

take account of discontinuities which are visible to the naked eye. Rolling or heat-treatment scale may

conceal surface discontinuities.

If the purchaser needs to be sure that all discontinuities visible to the naked eye have been identified,

assesses and where necessary repaired before delivery, products should be ordered descaled.

If, during the subsequent descaling or working operations by the user, t
...