This standard has been prepared so that design engineers may determine the correct pressure classification of asbestos-cement transmission pipe to use under various combinations of internal pressure (static, operating, and surge) and external load (earth and superimposed live loads). Combined loading curves depicting the relationship between hydrostatic loading and external loading capabilities are included to expedite the selection of the correct pipe strength classification. This standard also presents criteria for determining the type of pipe to be used under various soil and water conditions.