This standard has been prepared so that the user may quickly determine the correct pressure classification of asbestos-cement pressure pipe to use under various combinations of internal pressure (working and surge) and external load (earth and superimposed live loads) in water distribution systems. Combined loading curves depicting the relationship between internal pressure and external load capabilities are included to expedite the selection of pipe class, which is defined in ANSI/AWWA C400. NOTE: Appendix A contains a friction loss of head chart based on the Hazen-Williams formula. Appendix B is a discussion of entrapped air. 1.1.1 Pressure classes. Pipe pressure class designations of 100, 150, and 200 refer to the similarly numbered classes listed in ANSI/AWWA C400, Standard for Asbestos-Cement Pressure Pipe, 4 In. Through 16 In. (100 mm Through 400 mm), for Water Distribution Systems. 1.1.2 Installation. Detailed coverage of the installation of asbestos-cement pipe can be found in ANSI/AWWA C603. Major revisions to AWWA C401-83 (R86) included in this edition of the standard are as follows: Sec. I.C, Acceptance, was added to the foreword; Sec. II.C, Special Issues, was added to the foreword. This section now includes a discussion on criteria for selecting the type of asbestos-cement pipe. This section formerly appeared in the foreword to ANSI/AWWA C400-80 (R86); Sec. III, Modification to Standard, was added to the foreword; Sec. 1.4, Permeation, was added; The discussion on water hammer and surge analysis (Sec. B.1 through Sec. B.6) was deleted from appendix B and the title of the appendix revised to "Entrapped Air"; Appendix C, Functional Power Requirements, was deleted in its entirety.