AWWA D104-2017 Automatically Controlled Impressed-Current Cathodic Protection for the Interior Submerged Surfaces of Steel Water Storage Tanks.pdf

1、AWWA Standard SM Automatically Controlled, Impressed-Current Cathodic Protection for the Interior Submerged Surfaces of Steel Water Storage Tanks Effective date: Dec. 1, 2017. First edition approved by AWWA Board of Directors Jan. 27, 1991. This edition approved June 11, 2017. Approved by American N

2、ational Standards Institute Aug. 3, 2017. ANSI/AWWA D104-17 (Revision of ANSI/AWWA D104-11) Copyright 2017 American Water Works Association. All Rights Reserved. ii AWWA Standard This document is an American Water Works Association (AWWA) standard. It is not a specification. AWWA standards describe

3、minimum requirements and do not contain all of the engineering and administrative information normally contained in specifications. The AWWA standards usually contain options that must be evaluated by the user of the standard. Until each optional feature is specified by the user, the product or serv

4、ice is not fully defined. AWWA pub- lication of a standard does not constitute endorsement of any product or product type, nor does AWWA test, certify, or approve any product. The use of AWWA standards is entirely voluntary. This standard does not supersede or take precedence over or displace any ap

5、plicable law, regulation, or code of any governmental authority. AWWA standards are intended to represent a consensus of the water industry that the product described will provide satisfactory ser- vice. When AWWA revises or withdraws this standard, an official notice of action will be placed on the

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7、ard implies a consensus of those substantially concerned with its scope and provisions. An American National Standard is intended as a guide to aid the manufacturer, the consumer, and the general public. The existence of an American National Standard does not in any respect preclude anyone, whether

8、that person has approved the standard or not, from manufacturing, marketing, purchasing, or using products, processes, or proce - dures not conforming to the standard. American National Standards are subject to periodic review, and users are cau- tioned to obtain the latest editions. Producers of go

9、ods made in conformity with an American National Standard are encouraged to state on their own responsibility in advertising and promotional materials or on tags or labels that the goods are produced in conformity with particular American National Standards. Caution n oti Ce : The American National

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12、ours of work by your fellow water professionals. Revenue from the sales of this AWWA material supports ongoing product development. Unauthorized distribution, either electronic or photocopied, is illegal and hinders AWWAs mission to support the water community. This AWWA content is the product of th

13、ousands of ISBN-13, print: 978-1-62576-274-0 eISBN-13, electronic: 978-1-61300-458-6 DOI:http:/dx.doi.org/10.12999/AWWA.D104.17 All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopy, recording, or

14、any information or retrieval system, except in the form of brief excerpts or quotations for review purposes, without the written permission of the publisher. Copyright 2017 by American Water Works Association Printed in USAiii Committee Personnel The AWWA Cathodic Protection Task Force, which develo

15、ped this standard, had the following personnel at the time: David H. Kroon, Chair C.W. Dessens, City of Houston, Houston, Texas (AWWA) R.A. Gummow, Correng Consulting Services, Downsview, Ont., Canada (AWWA) T.D. Hopper, Tank Connection Affiliate Group, Lindale, Texas (AWWA) C.C. Johnson, Corrpro Co

16、mpanies Inc., San Diego, Calif. (AWWA) R.J. Kochilla, City of Cleveland, Parma, Ohio (AWWA) D.H. Kroon, Aegion Corporation, Houston, Texas (AWWA) L.D. Scott, Paso Robles TankBrown-Minneapolis Tank Inc., Paso Robles, Calif. (AWWA) G.R. Stein, Tank Industry Consultants, Indianapolis, Ind. (AWWA) J.J.

17、Sweeney, CST Storage, Dekalb, Ill. (AWWA) The Standards Committee on Steel and Composite Water Storage Tanks, which reviewed and approved this standard, had the following personnel at the time of approval: Stephen W. Meier, Chair Gregory R. Stein, Vice-Chair User Members J. Camarena, East Bay Munici

18、pal Utility District, Oakland, Calif. (AWWA) T.M. Dawson Jr., Emerald Coast Utilities Authority, Pensacola, Fla. (AWWA) M.F. Gaffey, Naval Facilities Expeditionary Warfare Center, Washington Navy Yard, D.C. (AWWA) R.E. McCuller, City of Grand Prairie, Grand Prairie, Texas (AWWA) N.J. Meder, Connecti

19、cut Water Company, Clinton, Conn. (AWWA) J.L. Ortiz, San Francisco Public Utilities Commission, San Francisco, Calif. (AWWA) R.B. Potts, Louisville Water Company, Louisville, Ky. (AWWA) G. Terrell, Birmingham Water Works Board, Birmingham, Ala. (AWWA) General Interest Members D.M. Algranti, Albert A

20、. Webb Associates, Riverside, Calif. (AWWA) J.W. Birkhoff, Birkhoff, Hendricks June 17, 2001; June 13, 2004; and Jan. 23, 2011. This edition of the standard was approved on June 11, 2017. I.C. Acceptance. In May 1985, the US Environmental Protection Agency (USEPA) entered into a cooperative agreemen

21、t with a consortium led by NSF International (NSF) to develop voluntary third-party consensus standards and a certification program for direct and indirect drinking water additives. Other members of the original consortium included the Water Research Foundation (formerly AwwaRF) and the Conference o

22、f State Health and Environmental Managers (COSHEM). The American Water Works Association (AWWA) and the Association of State Drinking Water Administrators (ASDWA) joined later. In the United States, authority to regulate products for use in, or in contact with, drinking water rests with individual s

23、tates. Local agencies may choose to impose requirements more stringent than those required by the state. To evaluate the health effects of products and drinking water additives from such products, state and local agencies may use various references, including * American National Standards Institute,

24、 25 West 43rd Street, Fourth Floor, New York, NY 10036. Persons outside the United States should contact the appropriate authority having jurisdiction. Copyright 2017 American Water Works Association. All Rights Reserved. viii 1. Specific policies of the state or local agency. 2. Two standards devel

25、oped under the direction of NSF*: NSF/ANSI 60 Drinking Water Treatment ChemicalsHealth Effects, and NSF/ANSI 61 Drinking Water System ComponentsHealth Effects. 3. Other references, including AWWA standards, Food Chemicals Codex, Water Chemicals Codex, and other standards considered appropriate by th

26、e state or local agency. Various certification organizations may be involved in certifying products in accor- dance with NSF/ANSI 61. Individual states or local agencies have authority to accept or accredit certification organizations within their jurisdictions. Accreditation of certi- fication orga

27、nizations may vary from jurisdiction to jurisdiction. Annex A, “Toxicology Review and Evaluation Procedures,” to NSF/ANSI 61 does not stipulate a maximum allowable level (MAL) of a contaminant for substances not regulated by a USEPA final maximum contaminant level (MCL). The MALs of an unspecified l

28、ist of “unregulated contaminants” are based on toxicity testing guidelines (noncarcinogens) and risk characterization methodology (carcinogens). Use of Annex A procedures may not always be identical, depending on the certifier. ANSI/AWWA D104 does not address additives requirements. Thus, users of t

29、his standard should consult the appropriate state or local agency having jurisdiction in order to 1. Determine additives requirements, including applicable standards. 2. Determine the status of certifications by parties offering to certify products for contact with, or treatment of, drinking water.

30、3. Determine current information on product certification. II. Special Issues. II.A. Protective Coatings. Protective coatings are commonly used in steel water storage tanks. They are an effective method of corrosion control except where holidays exist in the coating caused by poor surface preparatio

31、n, improper application, defective materials, unanticipated conditions, deterioration over time, or damage. When properly designed and maintained, cathodic protection systems will mitigate corrosion at the submerged locations where there are coating holidays or other coating defects. A properly appl

32、ied coating reduces the surface area of bare steel in contact with the drinking water that requires cathodic protection, and reduces the amount of * NSF International, 789 North Dixboro Road, Ann Arbor, MI 48105. Both publications available from the National Academy of Sciences, 500 Fifth Street, NW

33、, Washington, DC 20001. Copyright 2017 American Water Works Association. All Rights Reserved. ix current required to cathodically protect the tank interior submerged surface. Use and maintenance of protective coatings extend the life of the cathodic protection system and reduce operating costs. For

34、submerged areas of a tank, cathodic protection can also reduce the frequency of coating maintenance. Cathodic protection or coatings can independently reduce corrosion on the interior submerged surfaces; however, the combination of coatings and cathodic protection may be more economical and effectiv

35、e than using coatings or cathodic protection alone. II.B. Cathodic Protection. The two major components of an automatically controlled, impressed-current cathodic protection system are the direct current (DC) power supply controller (rectifier) and the anode system. The range of output current capac

36、ity required for an automatically controlled rectifier in a specific application is determined by assuming the area of submerged bare steel to be protected when the interior tank coating is new and when the interior coating has deteriorated to the point at which recoating is necessary. In potable wa

37、ter, current density requirements can range from 0.5 to 5.0 mA/ft 2(5.4 to 53.8 mA/m 2 ) of bare steel surface. Applications involving turbulence, high temperature, or a combination of these may require higher current densities. For newly coated tanks, the total current requirement may be as little

38、as 1 percent of the current required to protect an uncoated surface. As a rule, rectifiers for newly coated tanks should have sufficient current capacity to protect the anticipated bare submerged surface area before coating repair or replacement. The required operating voltage of a rectifier for a s

39、pecific tank depends on the current required to provide adequate protection and the total circuit resistance of the system. Automatically controlled rectifier systems should be used for cathodic protection of water storage tanks when AC power is available to the tank site. Automatically controlled s

40、ystems use one or more long-life reference electrodes to monitor the protection levels maintained on the submerged surfaces. The rectifier controller continuously monitors the potential difference between the reference electrode and the tanks submerged surface, referred to as the tank-to-water poten

41、tial, which will be free of IR (current resistance, or voltage) drop error. IR drop must be eliminated or minimized to accurately determine if the voltage difference between the submerged surface of the tank and the reference elec- trode meets the criteria for cathodic protection. The controller ins

42、tantaneously interrupts the flow of cathodic protection current, providing an IR drop-free measurement, which closely approximates the polarized potential. The controller compares the measured tank- to-water potential to a preset value and automatically adjusts the voltage output of the rectifier, to either increase or decrease current accordingly. Automatic units include a tank-to-water potential monitoring meter, which can be easily checked by the purchaser. Copyright 2017 American Water Works Association. All Rights Reserved.