External Zinc-Coating of
Ductile Iron Pipe (ISSN 0317-5669)
National Standard of Canada
CAN/CSA-B131.1-M88 (ISO 8179-1985)
Technical Committee on Ductile Iron Pipe
J.H. Miller Canron Pipe,
Oakville, Ontario
G. Aldworth MacLaren's Engineering Inc.,
Toronto, Ontario
G. Bratton Langley, British Columbia
W. Gates Halifax Water Commission,
Halifax, Nova Scotia
A. Gosselin Ville de Lachine,
Lachine, Quebec
J.R. Leach Regional Municipality of Hamilton-Wentworth,
Hamilton, Ontario
B.J. Parson Insurers' Advisory Organization of Canada,
Toronto, Ontario
C.F. Safrance Consumers' Gas Co.,
Toronto, Ontario
R.J. Wright Underwriters' Laboratories of Canada,
Scarborough, Ontario
J. Carnegie Canadian Standards Association,
Rexdale, Ontario
Preface
This is the first edition of CSA Standard CAN/CSA-B131.1, External Zinc-Coating of Ductile Iron Pipe. This Standard, in CSA format and with a CSA designation, is ISO Standard 8179-1985, Ductile Iron Pipe-External Zinc Coating, modified editorially to suit Canadian users.
This Standard has been prepared by the Technical Committee on Ductile Iron Pipe under the jurisdiction of the Standards Steering Committee on Ferrous Metals and has been formally approved by these Committees. It has been approved as a National Standard of Canada by the Standards Council of Canada.
August 1988
Notes:
- Use of the masculine gender in this Standard is not meant to exclude the feminine gender when applied to persons. Similarly, use of the singular does not exclude the plural (and vice versa) when the sense allows.
- Although the intended primary application of this Standard is stated in its Scope, it is important to note that it remains the responsibility of the user of the Standard to judge its suitability for his particular purpose.
- CSA Standards are subject to periodic review, and suggestions for their improvement will be referred to the appropriate committee.
- All inquiries regarding this Standard, including requests for interpretation, should be addressed to Canadian Standards Association, Standards Division, 178 Rexdale Boulevard, Rexdale, Ontario M9W 1R3.
Requests for interpretation should
a. define the problem, making reference to the specific clause, and, where appropriate, include an illustrative sketch;
b. provide an explanation of circumstances surrounding the actual field condition; and
c. be phrased where possible to permit a specific "yes" or "no" answer.
Interpretations are published in CSA Information Update. For subscription details and a free sample copy, write to CSA Marketing or telephone (416) 747-4019.
1. Scope and Field of Application
1.1 This Standard deals with the external coating of ductile iron pipe at the factory by zinc-coating.
1.2 This Standard includes specifications for the zinc-coating, application requirements, and coating inspection. Also included are requirements for the finishing layer applied to the zinc-coated surface.
1.3 Pipe to be coated shall comply with one of the following:
ANSI/AWWA
C151/A21.51, 1986
Ductile-iron pipe, centrifugally cast in metal molds or sand-lined molds for water or other liquids.
ISO 2531, 1986
Ductile iron pipes, fittings and accessories for pressure pipelines.
2. Coating Materials - Coating materials shall be either metallic zinc with a content of at least 99%, or zinc-rich paint which contains at least 85% zinc in dry film.
3. Application
3.1 Pipe Surface Condition
3.1.1 The zinc-coating shall normally be applied to oxide-surfaced pipe. It may be applied to blast-cleaned pipe.
3.1.2 The pipe surface shall be dry, and free from rust or nonadhering particles or foreign matter such as oil or grease.
3.2 Method of Application
3.2.1 Metallic Zinc-Coating - The zinc-coating shall be applied at the factory by projecting small droplets of zinc heated to the molten state by means of spray-guns. NOTE: The design and construction of the spray equipment are not within the Scope of this Standard.
3.2.2 Zinc-Rich Paint Coating - The zinc-coating shall be applied at the factory by spraying or brushing zinc-rich paint onto the pipe surface. NOTE: The design and construction of the coating equipment are not within the Scope of this Standard.
4. Characteristics of the Coating
4.1 Appearance
4.1.1 The zinc-coating shall cover the external surface of the pipe, apart from the socket face. The coating shall be free from defects such as bare patches or lack of adhesion. A spiraled appearance is permissible provided the zinc- coating mass complies with the requirements of Clause 4.2.
4.1.2 Pipes with damaged areas of coating caused by handling are acceptable, provided the area of damage is less than 5 cm2 per square meter coated.
4.1.3 The manufacturer is permitted to carry out repairs by any procedure of his choice, for example zinc-rich painting, provided the requirements of Clauses 4.2 and 5 are met.
4.2 Zinc-Coating Mass
4.2.1 Metallic Zinc-Coating - The mass of sprayed metal as measured under the conditions defined in Cause
5.4 shall be not less than 130 g/m2.
4.2.2 Zinc-Rich Paint Coating - The mass of zinc-coating as measured under the conditions defined in Clause 5.4 shall be not less than 150 g/m2.
5. Inspection
5.1 Inspection tests shall be the responsibility of the manufacturer. If requested by the customer, the manufacturer shall provide a certificate of test.
5.2 The manufacturer shall ensure uniformity of the coating by periodic local measurement. Continuous inspection shall be carried out by visual examination during local measurement.
5.3 Inspections shall occur at least twice a month at each factory preferable on pipes of different diameters.
5.4 Coating Mass Measurement Procedure
5.4.1 A rectangular sample holder film of 500 m length and 50 mm width is applied to the pipe before passing it through the zinc-coating equipment. The sample holder shall be placed longitudinally in line with the outside surface of the pipe wall.
5.4.2 The mass of zinc-coating Zm expressed in grams per square meter, is calculated from the mass difference of the sample holder before and after pipe coating.
Zm = 40 (M2 - M1) K
where
M1 and M2 = the mass of the sample holder before and after zinc-coating, expressed to an accuracy of 0.1 g
K = a correction factor depending on the nature of the sample holder which takes account of the difference in surface roughness between the sample holder and the pipe
For sand blasted steel sheet: 1.0 </= K </= 1..2
For polyester sheet: 1.15 </= K </= 1.20
In case of zinc-rich painting, M2 should be measured after the sample has been dried for 5 hours at 100 degrees C.
6. Finishing Layer
6.1 After zinc-coating, the pipe shall be given a finishing coat based on bituminous products or synthetic resins compatible with zinc, applied by any proven procedure such as gun-spraying or brush-coating.
6.2 The finishing layer shall have good adherence and shall be free from defects such as bare patches or trickles. After drying it shall not be sticky.
6.3 The mean thickness of the finishing layer shall be not less than 70 microns, and nowhere less than 50 microns.
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