This manual provides appropriate analytical concepts to address the principles of buried steel pipe design and attempts to correct misusage of the 1958 Modified Iowa Formula. The most current work of Dr. Reynold K. Watkins and others is presented in this book to develop the external loading design concepts provided. The goal of ""Buried Flexible Steel Flexible Steel Pipe"" is to offer sound information on the structural design and analysis of buried steel pipe - for water and wastewater - consistent with the latest pipe/soil design concepts of the industry. In conjunction with the external design of the pipe/soil interaction, the manual addresses internal pressure design, vacuum and external fluid pressure analysis, and many other non-standard conditions pipe designers will likely encounter. This manual will be valuable to students and professionals involved in pipe design.