Metallic and other inorganic coatings — Cleaning and preparation of metal surfaces — Part 1: Ferrous metals and alloys

ISO 27831-1:2008 specifies processes for the cleaning of the surfaces of ferrous metals and their alloys to remove any irrelevant or unwanted deposits or other material at any stage of manufacture, storage or service and for the preparation of these surfaces for further treatment. It does not cover cleaning operations associated with the preliminary removal of heavy deposits of oil, grease or dirt accumulated during operational service, preparations for welding or the cleaning of electrical contacts. However, many of the processes included in this part of ISO 27831 may be used for these operations at the discretion of the users of this part of ISO 27831. It covers processes which are needed for the preparation of metal surfaces prior to the application of the following surface coatings: electrodeposited metal coatings; autocatalytic metal coatings (autocatalytic and displacement types); conversion coatings; hot-dipped coatings; sprayed metal coatings; diffusion coatings; coatings produced by vitreous enamelling; coatings produced by physical vapour deposition of aluminium and cadmium; powder coatings. It describes processes for carrying out the following treatments: degreasing; descaling; pickling; de-rusting; chemical smoothing; electropolishing. It relates the processes described above to the following metals: non-corrosion-resisting steels, cast irons and pure irons; corrosion-resisting and heat-resisting steels.

Revêtements métalliques et autres revêtements inorganiques — Nettoyage et préparation des surfaces métalliques — Partie 1: Métaux ferreux et alliages

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Status
Published
Publication Date
01-Oct-2008
Current Stage
9093 - International Standard confirmed
Start Date
20-Mar-2013
Completion Date
18-Dec-2018
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ISO 27831-1:2008 - Metallic and other inorganic coatings -- Cleaning and preparation of metal surfaces
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INTERNATIONAL ISO
STANDARD 27831-1
First edition
2008-10-15
Metallic and other inorganic coatings —
Cleaning and preparation of metal
surfaces —
Part 1:
Ferrous metals and alloys
Revêtements métalliques et autres revêtements inorganiques —
Nettoyage et préparation des surfaces métalliques —
Partie 1: Métaux ferreux et alliages
Reference number
ISO 27831-1:2008(E)
ISO 2008
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ISO 27831-1:2008(E)
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ii © ISO 2008 – All rights reserved
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ISO 27831-1:2008(E)
Contents Page

Foreword............................................................................................................................................................ vi

Introduction ...................................................................................................................................................... vii

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

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

3 Terms and definitions........................................................................................................................... 2

4 Essential information to be supplied by the purchaser to the processor ...................................... 3

5 Requirements ........................................................................................................................................ 3

6 Standard cleaning methods................................................................................................................. 4

7 Non-corrosion-resisting steels, cast irons and pure irons .............................................................. 5

7.1 Non-corrosion-resisting steels............................................................................................................ 5

7.1.1 Selection of method of cleaning ......................................................................................................... 5

7.1.2 Stress relief heat treatment ................................................................................................................. 5

7.1.3 General degreasing and cleaning ....................................................................................................... 5

7.1.3.1 Steels of tensile strength up to 1 000 MPa ................................................................................. 5

7.1.3.2 Steels of tensile strength in the range 1 000 MPa to 1 400 MPa .............................................. 5

7.1.3.3 Steels of tensile strength in the range 1 400 MPa to 1 800 MPa .............................................. 5

7.1.3.4 Steels of tensile strength over 1 800 MPa .................................................................................. 6

7.1.4 Preparation prior to electroplating...................................................................................................... 6

7.1.5 Preparation prior to autocatalytic nickel plating ...............................................................................7

7.1.6 Preparation prior to phosphate treatment.......................................................................................... 7

7.1.7 Preparation prior to sherardizing........................................................................................................ 7

7.1.8 Preparation prior to hot-dip galvanizing ............................................................................................ 8

7.1.8.1 Steel items other than castings ................................................................................................... 8

7.1.8.2 Steel castings ................................................................................................................................ 8

7.1.9 Preparation prior to metal spraying.................................................................................................... 8

7.1.9.1 Spraying for protection against corrosion and high-temperature oxidation.......................... 8

7.1.9.2 Spraying for reclamation (recycling) purposes ......................................................................... 8

7.1.10 Preparation prior to the application of diffusion coatings ............................................................... 8

7.1.11 Preparation prior to vitreous enamelling ........................................................................................... 9

7.1.11.1 Conventional enamelling method................................................................................................ 9

7.1.11.2 Alternative enamelling method.................................................................................................... 9

7.1.12 Preparation prior to hot tinning......................................................................................................... 10

7.1.12.1 Preparation for ordinary mild-steel surfaces ........................................................................... 10

7.1.12.2 Preparation of non-reactive mild-steel surfaces (TRI process) ............................................. 10

7.1.13 Preparation prior to physical vapour deposition of cadmium and aluminium............................. 10

7.2 Cast irons ............................................................................................................................................ 10

7.2.1 General degreasing and cleaning ..................................................................................................... 10

7.2.2 Preparation prior to electroplating.................................................................................................... 10

7.2.3 Preparation prior to autocatalytic nickel plating ............................................................................. 10

7.2.4 Preparation prior to phosphating and the application of other conversion coatings................. 10

7.2.5 Preparation prior to hot tinning......................................................................................................... 11

7.2.5.1 “Direct chloride” method (TRI process) ................................................................................... 11

7.2.5.2 Preparation prior to electroplating with a readily tin-platable metal ..................................... 11

7.2.6 Preparation prior to hot-dip galvanizing .......................................................................................... 11

7.2.7 Preparation prior to metal spraying.................................................................................................. 11

7.2.8 Preparation prior to diffusion coating .............................................................................................. 12

7.2.9 Preparation prior to vitreous enamelling ......................................................................................... 12

8 Corrosion-resisting and heat-resisting steels ................................................................................. 12

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ISO 27831-1:2008(E)

8.1 Corrosion-resisting steels.................................................................................................................. 12

8.1.1 Stress-relieving heat treatment ......................................................................................................... 12

8.1.2 General degreasing and cleaning ..................................................................................................... 12

8.1.3 Preparation prior to electroplating.................................................................................................... 12

8.1.4 Preparation prior to autocatalytic nickel plating ............................................................................. 12

8.1.5 Preparation prior to metal spraying .................................................................................................. 12

8.1.5.1 Preparation for metal spraying ..................................................................................................12

8.1.5.2 Spraying for reclamation (recycling) purposes........................................................................ 13

8.1.6 Preparation prior to vitreous enamelling — Austenitic steels ....................................................... 13

8.2 Heat-resisting steels ........................................................................................................................... 13

9 Pretreatment of metals prior to powder coating.............................................................................. 14

9.1 General degreasing and cleaning ..................................................................................................... 14

9.2 Preparation of non-corrosion-resisting steels................................................................................. 14

9.3 Preparation of corrosion-resisting steels......................................................................................... 14

10 Cleaning and preparation processes................................................................................................ 14

10.1 Process A — Organic-solvent degreasing and cleaning ................................................................ 14

10.1.1 General ................................................................................................................................................. 14

10.1.2 Method A1 — Hot solvent, not water-rinsable ................................................................................. 15

10.1.3 Method A2 — Cold solvent, not water-rinsable ............................................................................... 15

10.1.4 Method A3 — Hot solvent, water-rinsable ........................................................................................ 15

10.1.5 Method A4 — Cold solvent, water-rinsable ...................................................................................... 15

10.1.6 Method A5 — Petroleum fuel based mixtures containing emulsifying agents ............................ 15

10.1.7 Method A6 — Ultrasonic cleaning..................................................................................................... 16

10.2 Process B — Alkaline degreasing..................................................................................................... 16

10.2.1 General ................................................................................................................................................. 16

10.2.2 Method B1 — General-purpose alkaline degreasing....................................................................... 16

10.2.3 Method B2 — Mild alkaline degreasing ............................................................................................16

10.2.4 Method B3 — Cathodic alkaline degreasing .................................................................................... 16

10.3 Process C — Acid emulsion cleaning............................................................................................... 16

10.4 Process D — Abrasive cleaning ........................................................................................................ 17

10.4.1 General ................................................................................................................................................. 17

10.4.2 Method D1 — Coarse-abrasive blasting ........................................................................................... 17

10.4.3 Method D2 — Fine-abrasive blasting ................................................................................................ 17

10.4.4 Method D3 — Scouring....................................................................................................................... 17

10.4.5 Method D4 — Tumbling...................................................................................................................... 17

10.4.6 Method D5 — Wire brushing.............................................................................................................. 17

10.5 Process E — Caustic-alkali descaling .............................................................................................. 18

10.5.1 Method E1 — Sodium hydride descaling ......................................................................................... 18

10.5.2 Method E2 — Alkali permanganate descaling ................................................................................. 18

10.6 Process F — Acid pickling without electrolysis .............................................................................. 18

10.6.1 General ................................................................................................................................................. 18

10.6.2 Method F1 ............................................................................................................................................ 18

10.6.3 Method F2 ............................................................................................................................................ 18

10.6.4 Method F3 ............................................................................................................................................ 18

10.6.5 Method F4 ............................................................................................................................................ 19

10.6.6 Method F5 ............................................................................................................................................ 19

10.7 Process G — Acid dipping................................................................................................................. 19

10.7.1 General ................................................................................................................................................. 19

10.7.2 Method G1............................................................................................................................................ 19

10.7.3 Method G2............................................................................................................................................ 19

10.8 Process H — Anodic pickling ............................................................................................................ 20

10.8.1 General ................................................................................................................................................. 20

10.8.2 Method H1............................................................................................................................................ 20

10.8.3 Method H2............................................................................................................................................ 20

10.8.4 Method H3............................................................................................................................................ 20

10.9 Process J — Acid de-rusting ............................................................................................................. 20

10.10 Process K — Alkaline de-rusting....................................................................................................... 21

10.10.1 General ................................................................................................................................................. 21

10.10.2 Method K1 (for light rust) ................................................................................................................... 21

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ISO 27831-1:2008(E)

10.10.3 Method K2 (for heavy rust) ................................................................................................................ 21

10.10.4 Method K3 (for heavy rust) ................................................................................................................ 22

10.11 Process L — Chemical smoothing and electropolishing of steels ............................................... 22

10.11.1 Method L1 — Chemical smoothing process (for non-corrosion-resisting steels) ...................... 22

10.11.2 Method L2 — Electropolishing of corrosion-resisting steels ........................................................ 22

10.12 Process M — Passivation and removal of surface contamination from corrosion-resisting

steels and surface preparation prior to electroplating ................................................................... 23

10.12.1 Method M1 — Passivation ................................................................................................................. 23

10.12.2 Method M2 — Test for surface contamination................................................................................. 23

10.12.3 Method M3 — Alternative test for surface contamination.............................................................. 23

10.12.4 Method M4 — Preparation of corrosion-resisting steels prior to electroplating ......................... 24

Annex A (informative) Maintenance of organic and vapour degreasing baths ......................................... 25

Annex B (informative) The control of acidity in vapour cleaning baths ..................................................... 26

Annex C (normative) Method for the determination of oxidizable material in sulfuric acid..................... 27

Bibliography ..................................................................................................................................................... 28

© ISO 2008 – All rights reserved v
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ISO 27831-1:2008(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.

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 27831-1 was prepared by Technical Committee ISO/TC 107, Metallic and other inorganic coatings,

Subcommittee SC 3, Electrodeposited coatings and related finishes.

ISO 27831 consists of the following parts, under the general title Metallic and other inorganic coatings —

Cleaning and preparation of metal surfaces:
⎯ Part 1: Ferrous metals and alloys
⎯ Part 2: Non-ferrous metals and alloys
vi © ISO 2008 – All rights reserved
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ISO 27831-1:2008(E)
Introduction

The adhesion of deposited coatings depends upon the efficiency of degreasing and cleaning processes used

on the substrate surface. The removal of grease, oil and dirt and all other forms of contamination left from

fabrication processes or due to corrosion/erosion of surfaces in storage or in service is essential for successful

production of a pristine, chemically clean active surface for deposition of coatings.

The surface contaminants can be

⎯ corrosion products, mould sand or mould release agents on ferrous and non-ferrous castings;

⎯ corrosion products and mill scales on hot-rolled steel sheet, girders, etc. (broken mill scale is cathodic to

the underlying substrate);
⎯ oil and rolling lubricant on cold-rolled steel sheet;
⎯ rolling lubricant on e.g. cold-rolled aluminium sheet;

⎯ corrosion products on delivery or during storage on hot-dip-galvanized steel sheet or angle bars/brackets;

⎯ other undesirable materials from storage and handling.
The difficulty of coating these surfaces is well known.

Cleaning processes for removing surface contaminants are varied, depending, among other things, on the

identification and classification of the soil as well as the size and shape of the substrate, the degree of

cleanliness required, the availability of the facilities needed, the cost of the processes used and their impact

on the environment, and the nature of subsequent processes to which the substrate is going to be subjected.

ISO 27831 includes cleaning processes ranging from mechanical methods (which give the least degree of

cleanliness) to chemical and ultrasonic methods (which give a higher degree of surface preparation) and

substrate conditioning by glow discharge plasma (sputter cleaning) for vapour deposition.

ISO 27831 describes practices for cleaning a variety of metals and metal alloys prior to the application of a

range of coatings or without any coating requirements.

The cleaning processes described in ISO 27831-1 and ISO 27831-2 are indicative only of those most

commonly used in practice. However, there are numerous formulations of solutions and numerous proprietary

processes available which are not included in ISO 27831-1 or ISO 27831-2. Wherever possible, references to

particular processes have been made. For references concerning all other processes included in either part of

ISO 27831, the publications given in the Bibliography in the respective part should be consulted.

ISO 27831-1 covers ferrous metals and their alloys, whilst ISO 27831-2 covers non-ferrous metals and their

alloys. For ISO 27831-2 to be usable, as far as possible, as a “stand-alone” document, Clauses 1 to 6 of

ISO 27831-1 have been included in it as Clauses 1 to 6 and the numbering of the other clauses follows the

same sequence as in ISO 27831-1. Additionally, since some of the cleaning and preparation processes

specified for ferrous materials in ISO 27831-1 can also be used for non-ferrous metals, the cleaning and

preparation processes follow the same sequence, using the same designations, as in ISO 27831-1.

© ISO 2008 – All rights reserved vii
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INTERNATIONAL STANDARD ISO 27831-1:2008(E)
Metallic and other inorganic coatings — Cleaning and
preparation of metal surfaces —
Part 1:
Ferrous metals and alloys

WARNING — This part of ISO 27831 may not be compliant with some countries’ health, safety and

environmental legislation. It calls for the use of substances and/or procedures that may be injurious to

health if adequate safety measures are not taken. This part of ISO 27831 does not address any health

hazards, safety or environmental matters, or legislation associated with its use. It is the responsibility

of the user of this part of ISO 27831 to establish appropriate health, safety and environmentally

acceptable practices and take appropriate action to comply with any national, regional and/or

international regulations. Compliance with this part of ISO 27831 does not, of itself, confer immunity

from legal obligations.
1 Scope

This part of ISO 27831 specifies processes for the cleaning of the surfaces of ferrous metals and their alloys

to remove any irrelevant or unwanted deposits or other material at any stage of manufacture, storage or

service and for the preparation of these surfaces for further treatment. It does not cover cleaning operations

associated with the preliminary removal of heavy deposits of oil, grease or dirt accumulated during operational

service, preparations for welding or the cleaning of electrical contacts. However, many of the processes

included in this part of ISO 27831 may be used for these operations at the discretion of the users of this part

of ISO 27831.

This part of ISO 27831 covers processes which are needed for the preparation of metal surfaces prior to the

application of the following surface coatings:
⎯ electrodeposited metal coatings;
⎯ autocatalytic metal coatings (autocatalytic and displacement types);
⎯ conversion coatings;
⎯ hot-dipped coatings;
⎯ sprayed metal coatings;
⎯ diffusion coatings;
⎯ coatings produced by vitreous enamelling;
⎯ coatings produced by physical vapour deposition of aluminium and cadmium;
⎯ powder coatings.
© ISO 2008 – All rights reserved 1
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ISO 27831-1:2008(E)

This part of ISO 27831 describes processes for carrying out the following treatments:

⎯ degreasing;
⎯ descaling;
⎯ pickling;
⎯ de-rusting;
⎯ chemical smoothing;
⎯ electropolishing.

This part of ISO 27831 relates the processes described above to the following metals:

⎯ non-corrosion-resisting steels, cast irons and pure irons;
⎯ corrosion-resisting and heat-resisting steels.
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 2064, Metallic and other inorganic coatings — Definitions and conventions concerning the measurement

of thickness

ISO 2080, Metallic and other inorganic coatings — Surface treatment, metallic and other inorganic coatings —

Vocabulary

ISO 4527, Metallic coatings — Autocatalytic (electroless) nickel-phosphorus alloy coatings — Specification

and test methods

ISO 9587, Metallic and other inorganic coatings — Pretreatment of iron or steel to reduce the risk of hydrogen

embrittlement

ISO 9588, Metallic and other inorganic coatings — Post-coating treatments of iron or steel to reduce the risk

of hydrogen embrittlement

ISO 22778, Metallic coatings — Physical vapour-deposited coatings of cadmium on iron and steel —

Specification and test methods

ISO 22779, Metallic coatings — Physical vapour-deposited coatings of aluminium — Specification and test

methods
3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 2064, ISO 2080, ISO 9587,

ISO 9588, ISO 22778 and ISO 22779 apply.
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ISO 27831-1:2008(E)
4 Essential information to be supplied by the purchaser to the processor

When ordering articles to be processed in accordance with this part of ISO 27831, the purchaser shall provide

the following information in writing, e.g. in the contract, in the purchase order or on the engineering drawing:

a) the number of this part of ISO 27831 (ISO 27831-1);

b) the specification and metallurgical condition of the material of which the item is made;

c) the tensile strength of the steel components and the requirements for stress relief and post-cleaning

embrittlement relief heat treatments of the steel to reduce the risk of hydrogen embrittlement (see 7.1);

d) the cleaning method or methods given in this part of ISO 27831 which are to be used, and any deviation

from these methods (e.g. the use of a proprietary method for health or safety reasons);

e) details of any particular requirements for special surfaces;
f) details of any special procedures (e.g. process H, method H1);

g) details of any particularly difficult surface condition and any special information regarding coatings to be

removed or coatings or inserts to be protected;

h) where appropriate, details of the surface coating which is to be subsequently applied.

5 Requirements
...

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