ISO 8179-2:1995 pdf download – Ductile iron pipes — External zinc coating – Part 2: Zinc rich paint with finishing layer.
This part of 1SO 8179 deals with a factory-appliedprotectiveexternal coating system for centrifugallycast ductile iron pipes as specified in ISO 2531 andISO 7186.This coating system comprises a metalliczine layer followed by a finishing layer.
2Normative references
The following standards contain provisions which,through reference in this text,constitute provisions ofthis part of ISO 8179.At the time of publication, theeditions indicated were valid.All standards are subjectto revision, and parties to agreements based on thispart of ISO 8179 are encouraged to investigate thepossibility of applying the most recent editions of thestandards indicated below. Members of IEC and ISOmaintain registere of currentlyvalid lnternationalStandards.
ISO 2531:1991.Ductile iron pipes, fittings and access-ories for pressure pipe-lines.
ISO 7186: 1983，Ductile iron pipes and accessories fornon-pressure pipe-lines.
Materials
The coating materials are zinc rich paint with inorganicbinder and a zinc content of at least 85 %(/m ) in thedry film,and bituminous paint or synthetic resincompatible with zinc rich paint.
4Zinc rich paint coating4.1 Pipe surface condition
The pipe surface shall be dry and free from rust or anynon-adhering particles or foreign matter such as oil orgrease.
The zinc shall be applied to the oxidized externallsurface of the pipe,or to a blast-cleaned or groundsurface, at the manufacturer’s discretion.
4.2Method of application
The zinc rich paint coating shall be applied by a spray-ing or a brushing process on to the pipe surface.
The design and construction of the coating equipmentis not within the scope of this part of ISO 8179.
4.3Coating characteristics
The zinc rich paint coating shall cover the outaidediameter of the pipe.and shall be free from suchdefects as bare patches or lack of adhesion.
spiralled appearance is permissible provided that thezinc rich paint coating masses comply with the re-quirements of 4.4.
Damaged areas of zinc rich paint coating caused byhandling are acceptable.provided that the area ofdamage is less than 5 cm2 per square metre and thatthe minor dimension of the damaged area does notexceed 5 mm.
Greater areas of damage shall be repaired in accord-ance with 4.6
The LaldwrTwty of the aric rich paint cuatiny is checked by visual inspection of the token. in the event of lack of uniformity, pieces 50 mm x 50 mm shall be cut from the token in the lightar zones and the local minimia’n mass of zinc rich paint coating determined according to the above method
4.6 R.paira to th, zinc rich paint coating
The manufacturer is permitted to carry out repairs by zinc rich paint coating, provided that the requirements of dause 3, and subclauses 4.3 and 44 are met
5 Finishing layer
After zinc rich paint coating, the pipsi Shall be j)rven d finishing layer of bituminous paint or syrthelic resin compatibte wtth the zinc rich paint coating.
Application of this 1lriiheng layer may ha ctnria by any proven process such as spraying o brush coating at the manufacturer’s discretri. It shall uniformly cover the zinc rich paint coating arid be free from bare patches or lack of adhesion.
The mean dry film thickness of the finishing layer shalt be not less than 70 p.m with a local minimum thickness of 50 pm.
Venficetion of the dry film thickness of the finishing layer shall be carried out by measurement
al d.rect’ on the pipes by means of suitable gauges, e.g. magnetic, or by using a “wet film” thickness gauge where a correlation between wet film thickness and dry film thickness can be demonstrated or
b) inthectly on a sample token Wtiach is attached to the pipe before coating and is used after coating to measure the dry film thickness by appropriate means. eg. micrometer. magnetic thickness gauge or bye weight method Similar to 4.5.