Bridge Crossing Piping System Design Using Welded Steel Pipe or Ductile Iron Pipe

Pipeline bridge crossings are the nexus of two prevalent forms of infrastructure and must be evaluated and designed with both in mind. Bridge crossings present a unique set of design challenges compared to a traditional underground piping system. These include thermal gradients, external bracing, weathering resistance, bridge movement, and other factors that all influence the design process. While extensive design guidance exists from ASCE and other organizations with regard to stress analysis of the piping itself, the same depth of information is absent with regard to overall pipeline system design. This paper will present an overview of methodologies for pipeline system design of bridge crossings using either ductile iron pipe or welded steel pipe (the two most commonly used piping materials for both large and small diameter bridge crossings). Advantages and disadvantages of each material and the various joints available for both will be highlighted and reviewed.