ISO 8179-1:2017

Ductile iron pipes, fittings, accessories and their joints - External zinc-based coating - Part 1: Metallic zinc with finishing layer

ISO 8179-1:2017 specifies an external protective coating system which is factory applied to ductile iron pipeline components as specified in ISO 2531, ISO 7186 and ISO 16631. This coating system comprises an electro-deposited metallic zinc-based coating of - pure metallic zinc with a purity of 99,99 %, - zinc and aluminium alloy with or without other metals, or - other zinc alloys followed by a finishing layer that can be bituminous paint or synthetic resin compatible with zinc-based coating. NOTE ISO 8179-2 deals with zinc-rich paint coating.

Tuyaux, raccords et accessoires en fonte ductile et leurs assemblages — Revêtement extérieur à base de zinc — Partie 1: Zinc métallique avec couche de finition

General Information

• Status: Published
• Publication Date: 24-Jul-2017
• ICS: 23.040.10 - Iron and steel pipes
• Technical Committee: ISO/TC 5/SC 2 - Cast iron pipes, fittings and their joints
• Drafting Committee: ISO/TC 5/SC 2 - Cast iron pipes, fittings and their joints
• Current Stage: 9093 - International Standard confirmed
• Start Date: 22-Jun-2023
• Completion Date: 13-Dec-2025

Relations

• Revises: ISO 8179-1:2004 - Ductile iron pipes - External zinc-based coating - Part 1: Metallic zinc with finishing layer
• Effective Date: 17-Aug-2013

Overview

ISO 8179-1:2017 specifies an external zinc‑based protective coating system factory‑applied to ductile iron pipeline components (pipes, fittings and accessories) covered by ISO 2531, ISO 7186 and ISO 16631. The standard requires a metallic zinc‑based layer - either pure metallic zinc (99.99% purity), zinc‑aluminium alloys or other zinc alloys - followed by a finishing layer (bituminous paint or compatible synthetic resin). It sets performance, inspection and test requirements to ensure consistent corrosion protection of ductile iron pipeline components.

Key topics and technical requirements

• Coating materials: Pure metallic zinc (99.99 %), zinc‑aluminium or other zinc alloys, plus a compatible finishing layer (bituminous or synthetic resin).
• Surface condition: Substrate must be dry and free of rust, oil, grease and loose particles before coating.
• Method of application: Metallic zinc or zinc alloy is applied by thermal spray (molten metal projected as droplets). Manufacturer defines acceptable surface appearance and minor irregularities.
• Zinc‑based coating mass:
  • Typical requirement: ≥ 200 g/m2 mean, local minimum 180 g/m2.
  • Low‑corrosivity agreement: 130 g/m2 mean, local minimum 110 g/m2.
  • Higher masses may be agreed for very corrosive soils.
• Finishing layer thickness: Mean dry film thickness ≥ 70 µm, local minimum 50 µm; upper limit ≤ 250 µm to avoid blistering.
• Damage limits and repairs:
  • Minor handling damage acceptable if < 5 cm2 per m2 and max 5 mm in minor dimension.
  • Repairs by metallic zinc spray or zinc‑rich paint (>85% zinc in dry film); paint repair mass must be at least 20% above nominal metallic coating mass.
• Test and inspection methods:
  • Factory quality control using coated tokens (250×100 mm or 500×50 mm) to measure zinc mass by mass difference with a correction factor.
  • Dry film thickness measured by micrometer, weighing method or suitable gauges (magnetic, wet‑film correlation) per ISO 2808.
  • Annex A describes field verification techniques (e.g., gas evolution method) and precautions for finished products.
• Soil corrosivity guidance: Annex B provides field‑of‑use considerations for selection of coating mass vs. soil characteristics.

Applications and users

ISO 8179-1:2017 is used by:

• Manufacturers of ductile iron pipes, fittings and accessories for factory coating specification and quality control
• Pipeline design engineers and specifiers who set corrosion‑protection requirements
• Procurement teams and asset owners (water, wastewater, buried pipelines) selecting coated ductile iron components
• Inspectors and testing laboratories performing acceptance checks and field verification

Related standards

• ISO 8179-2 (zinc‑rich paint coatings)
• ISO 2531, ISO 7186, ISO 16631 (ductile iron pipeline components)
• ISO 2808 (paint film thickness test methods)

Keywords: ISO 8179-1:2017, ductile iron pipes, zinc-based coating, metallic zinc, finishing layer, coating mass, dry film thickness, thermal spray, zinc-rich paint, corrosion protection.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 8179-1
Third edition
2017-07
Ductile iron pipes, fittings, accessories
and their joints — External zinc-based
coating —
Part 1:
Metallic zinc with finishing layer
Tuyaux, raccords et accessoires en fonte ductile et leurs
assemblages — Revêtement extérieur à base de zinc —
Partie 1: Zinc métallique avec couche de finition
Reference number
©
ISO 2017
© ISO 2017, 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. [phone]
Fax [phone]
[e-mail]
www.iso.org
ii © ISO 2017 – All rights reserved

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Materials . 1
5 Zinc-based coating . 2
5.1 Pipeline component surface condition . 2
5.2 Method of application . 2
5.3 Coating characteristics . 2
5.4 Zinc-based coating mass . 2
5.5 Repairs to the zinc-based coating . 3
6 Finishing layer . 3
7 Test methods . 3
7.1 Determination of zinc-based coating mass . 3
7.2 Determination of the dry film thickness of the finishing layer . . 4
Annex A (informative) Field verification of the metallic zinc-based coating mass on a
finished product . 5
Annex B (informative) Field of use in relation to the characteristics of soils .8
Bibliography .10
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: w w w . i s o .org/ iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 5, Ferrous metal pipes and metallic fittings,
Subcommittee SC 2, Cast iron pipes, fittings and their joints.
This third edition cancels and replaces the second edition (ISO 8179-1:2004), which has been technically
revised. The following changes have been made:
2 2
— the minimum quantity of Zn has been increased from 130 g/m to 200 g/m ;
— the revision recognizes the technological advancements in the field regarding zinc-based coatings
to increase the lifetime and reliability of ductile iron pipelines, improving protection to different
types of corrosion (including general and localized) and the use of new alloy enrichments.
A list of all parts in the ISO 8179 series can be found on the ISO website.
iv © ISO 2017 – All rights reserved

INTERNATIONAL STANDARD ISO 8179-1:2017(E)
Ductile iron pipes, fittings, accessories and their joints —
External zinc-based coating —
Part 1:
Metallic zinc with finishing layer
1 Scope
This document specifies an external protective coating system which is factory applied to ductile iron
pipeline components as specified in ISO 2531, ISO 7186 and ISO 16631. This coating system comprises
an electro-deposited metallic zinc-based coating of
— pure metallic zinc with a purity of 99,99 %,
— zinc and aluminium alloy with or without other metals, or
— other zinc alloys
followed by a finishing layer that can be bituminous paint or synthetic resin compatible with zinc-based
coating.
NOTE ISO 8179-2 deals with zinc-rich paint coating.
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 2808, Paints and varnishes — Determination of film thickness
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:
— IEC Electropedia: available at http:// www .electropedia .org/
— ISO Online browsing platform: available at http:// www .iso .org/ obp
4 Materials
The coating materials shall be
— pure metallic zinc with a purity of 99,99 %,
— zinc and aluminium alloy with or without other metals, or
— other zinc alloys
followed by a finishing layer that can be bituminous paint or synthetic resin compatible with zinc-
based layer.
5 Zinc-based coating
5.1 Pipeline component surface condition
The pipeline component surface shall be dry and free from rust and any non-adhering particles or
foreign matter such as oil or grease.
The metallic zinc-based coating shall be applied to the as-cast annealed external surface of the pipeline
component, or to a blast-cleaned or ground surface at the manufacturer’s discretion.
5.2 Method of application
The metallic zinc-based coating shall be applied by a spraying process in which metallic zinc or zinc
alloy is heated to a molten state and projected in small droplets by spray guns on to the pipeline
component surface.
The design and construction of the spray equipment are not within the scope of this document.
5.3 Coating characteristics
The metallic zinc-based coating shall cover the outside surface of the pipeline component and shall be
free from such defects as bare patches or lack of adhesion.
A spiralled appearance is permissible provided that the zinc-based coating masses comply with the
requirements of 5.4.
The manufacturer shall define those coating irregularities which are considered not detrimental to the
performance of the coating system.
Damaged areas of zinc-based coating caused by handling are acceptable, provided that the area of
damage is less than 5 cm per square metre and that the minor dimension of the damaged area does not
exceed 5 mm.
Greater areas of damage shall be repaired in accordance with 5.5.
5.4 Zinc-based coating mass
The mean mass of zinc-based coating measured in accordance with 7.1 shall be as follows:
2 2
— not less than 200 g/m with a local minimum of 180 g/m ;
— in low corrosive areas, by agreement between the purchaser and the supplier, 130 g/m of zinc with
a local minimum of 110 g/m ;
— in case of very corrosive soils, the manufacturer and the purchaser may decide to use additional
coating mass.
The manufacturer shall visually inspect each pipeline component for quality and uniformity of coating
and shall carry out regular measurements of zinc-based coating masses in accordance with the method
described in 7.1.
The factory quality control tests ensure conformity to the standard. Factory quality control tests
shall be the sole determinant of coating thickness acceptance. Where informative field verification is
required, one of the methods described in Annex A shall be agreed upon between the manufacturer and
the purchaser.
For the selection of coatings in relation to the characteristics of soils, Annex B can be consulted.
2 © ISO 2017 – All rights reserved

5.5 Repairs to the zinc-based coating
Areas left uncoated, e.g. under the test token, and coating damage in excess of that permitted in 5.3
shall be repaired by either
a) metallic zinc spray complying with 5.4, or
b) application of a zinc-rich paint containing more than 85 % zinc, by mass, in the dried film. The
mean mass of the applied paint shall not be less than 20 % above the nominal coating mass of the
metallic zinc-based coating.
6 Finishing layer
After the zinc-based coating has been applied, the pipeline component shall be given a finishing layer of
bituminous paint or synthetic resin compatible with the zinc-based coating.
Application of this finishing layer may be done by any proven process such as spraying or brush coating
at the manufacturer’s discretion. It shall uniformly cover the zinc-based coating and be free from bare
patches or lack of adhesion.
The mean dry film thickness of the finishing layer measured in accordance with 7.2 shall be not less
than 70 μm with a local minimum thickness of 50 μm. The method of coating thickness measurement is
at the manufacturer’s discretion.
In order to avoid blistering, the mean dry film thickness of the finishing layer shall not exceed 250 μm.
7 Test methods
7.1 Determination of zinc-based coating mass
A rectangular token is attached along the pipeline component axis before passing it through the zinc-
based coating equipment. The minimum token sizes shall be either
a) 250 mm × 100 mm,
...