1、ANSI/AWWA C105/A21.5-10 (Revision of ANSI/AWWA C105/A21.5-05) AWWA Standard Effective date: Oct. 1, 2010. First edition approved by AWWA Board of Directors in 1972. This edition approved June 20, 2010. Approved by American National Standards Institute July 15, 2010. 6666 West Quincy Avenue Advocacy
2、Denver, CO 80235-3098 Communications T 800.926.7337 Conferences www.awwa.org Education and TrainingScience and TechnologySections The Authoritative Resource on Safe Water Polyethylene Encasement for Ductile-Iron Pipe Systems ii AWWA Standard This document is an American Water Works Association (AWWA
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12、ling infoansi.org. 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 any information or retrieval system, except in the form of brief excerpts or quotations for review purposes,
13、without the written permission of the publisher. Copyright 2010 by American Water Works Association Printed in USAiii Committee Personnel Subcommittee 4, Coatings and Linings, which reviewed and developed this revision, had the fol- lowing personnel at the time: Richard W. Bonds, Chair General Inter
14、est Members D.R. Kroon, Corrpro Companies Inc., Houston, Texas (AWWA) P.I. McGrath Jr., Consultant, Birmingham, Ala. (AWWA) J.R. Plattsmier, HDR Engineering Inc., Denver, Colo. (AWWA) E.S. Ralph,* Standards Engineer Liaison, AWWA, Denver, Colo. (AWWA) D.W. Russom, Russom Technical Services LLC, Vilo
15、nia, Ark. (AWWA) C.R. Schwenker, Malcolm Pirnie Inc., Arlington, Va. (AWWA) P.A. Selig, Consultant, Birmingham, Ala. (AWWA) W.H. Smith, W.H. Smith provided new figures showing installation methods; and extended the length of connecting piping to be wrapped from 2 ft (0.6 m) to 3 ft (0.9 m). Addition
16、ally, a requirement for wrapping service lines of dissimilar metals for a distance of 3 ft (0.9 m) from the ductile-iron pipe was also incorporated. In the 1993 revision of the standard, Sec. 4.1, Materials, was expanded to include 4-mil high-density cross-laminated (HDCL) polyethylene, and Class B
17、(colors) mate- rial was added to allow the purchase of colored polyethylene. Additionally, Table 1 was modified to reflect reduced tube widths comparable with push-on joint pipe and fittings, * International Organization for Standardization (ISO), ISO Central Secretariat, 1 ch. de la Voie- Creuse, C
18、ase postale 56, CH-1211, Geneva 20, Switzerland. CIPRA became the Ductile Iron Pipe Research Association (DIPRA) in 1979.xi and the size range was expanded to include 60- and 64-in. (1,500- and 1,600-mm) pipe. A recommendation that circumferential wraps of tape be placed at 2-ft (0.6-m) intervals al
19、ong the barrel of the pipe for installation below the water table or in areas subject to tidal actions was added to Sec. 4.3.1, and Sec. 4.3.6 was revised to indicate the preferred method of making direct service taps on polyethylene-encased pipe. An illustration of this procedure was added. In 1999
20、, the format was changed to AWWA standard style; Sec. II.D, Copper Service Connections, was added to the foreword of the standard; and, definitions of parties and types of polyethylene film were added to Section 3, Definitions, of the standard. Additionally, changes to Sec. 4.1, Materials, included:
21、 (1) deletion of low- density polyethylene film; (2) the addition of linear low-density polyethylene film and appropriate material requirements and physical properties; (3) increasing the tensile strength requirements for the high-density cross-laminated polyethylene film; (4) the addition of impact
22、- and tear-resistance requirements for both polyethylene materials; (5) deletion of the minus tolerance on film thickness for both materials; and, (6) the addition of an ultraviolet inhibitor to any natural or colored film except black film con- taining 2 percent or more of carbon black. Other chang
23、es to the standard included the addition of Sec. 4.3, Marking, to facilitate traceability and to help ensure compliance with the standard; the addition of an alternate method of using a 3-ft (0.9-m) sheet of polyethylene rather than a 3-ft (0.9-m) length of polyethylene tube for joint makeup to Sec.
24、 4.4.2.2, Method; and, the addition of Sec. 5.1, Inspection and Certification by Manufacturer, to help ensure compliance with the standard. Also, in appendix A, a new paragraph on stray current corrosion and a new section on uniquely severe environ- ments were added. Additionally, the resistivity ra
25、nges in Table A.1, Soil-Test Evalua- tion, were increased to make the procedure more conservative. The next edition of ANSI/AWWA C105/A21.5 was approved by the AWWA Board of Directors on June 12, 2005. This edition of ANSI/AWWA C105/A21.5 was approved on June 20, 2010. II. Special Issues. II.A. Usef
26、ul Life of Polyethylene. Tests of polyethylene used to protect ductile- iron and gray-iron pipe have shown that after 40 years of exposure to severely corrosive soils, strength loss and elongation reduction are insignificant. US Bureau of Reclamation (BUREC) studies* of polyethylene film used underground illustrate * Laboratory and Field Investigations of Plastic Films. US Department of the Interior, Bureau of Reclamation, Rept. No. ChE-82 (September 1968).
