BS ISO 8179-2-2017 pdf free download.Ductile iron pipes, fittings, accessories and their joints – External zinc-based coating Part 2: Zinc-rich paint
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 a zinc-rich paint followed by a finishing layer that can be bituminous paint or synthetic resin compatible with zinc rich paint coating.
NOTE ISO 8179-1 addresses metallic zinc-based coatings.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
No terms and definitions are listed in this document.
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4 Materials
The coating materials shall be zinc-rich paint with organic or/and inorganic binder and zinc content of at least a mass fraction of 85 % in the dry film followed by a finishing layer that can be bituminous paint or synthetic resin compatible with zinc-rich paint coating.
5 Zinc-rich paint coating
5.1 Pipeline component surface condition
The pipeline component surface shall be dry and free from rust or any non-adhering particles or foreign matter such as oil or grease.
The zinc-rich paint 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 zinc-rich paint coating shall be applied by a spraying or brushing process onto 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 zinc-rich paint coating shall cover the outside cylindrical 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-rich paint 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-rich paint coating caused by handling are acceptable, provided that the area of damage is less than 5 cm 2 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-rich paint coating mass
The mean mass of zinc-rich paint coating measured in accordance with 7.1 shall be as follows:
— not less than 235 g/m 2 with a local minimum of 210 g/m 2 ;
— in low corrosive areas, by agreement between the purchaser and the supplier, 150 g/m 2 with a local minimum of 130 g/m 2 .
NOTE The masses of zinc-rich paint coating are equivalent to 200 g/m 2 with a local minimum of 180 g/m 2 of metallic zinc coating (first case) and 130 g/m 2 with a local minimum of 110 g/m 2 of that (second case).
Where there are very corrosive soils the manufacturer and the purchaser may decide to use an additional coating mass of zinc-rich paint. For the selection of coatings in relation to the characteristics of soils Annex B can be consulted.
The manufacturer shall visually inspect each pipeline component for quality and uniformity of coating and shall carry out regular measurements of zinc-rich paint coating masses in accordance with the method described in 7.1.
The factory quality control tests ensure conformity to the standard. Where informative field verification is required, one of the methods described in Annex A shall be agreed upon between the manufacturer and the purchaser.
5.5 Repairs to the zinc-rich paint coating
The manufacturer is permitted to carry out repairs by zinc-rich paint containing more than 85 % zinc in the dry film provided that the requirements of Clause 4, 5.3 and 5.4 are met.
6 Finishing layer
After the zinc-rich paint coating has been applied, the pipeline component shall be given a finishing layer of bituminous paint or synthetic resin compatible with the zinc-rich paint 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-rich paint 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 is at the manufacturer’s discretion.BS ISO 8179-2 pdf download.