An Unexpected Reducer: Engineering a Pipe Connection Solution in the Field

During a large diameter pipeline shutdown, that permitted no more than 72-hours total shutdown to replace approximately 24-meters (78-feet) of 1,067-millimeter diameter (42-inch) pipe, a significant hurdle was identified in the field. The installing contractor supplied new steel pipe to connect to the existing prestressed concrete cylinder pipe (PCCP) but did not successfully match the steel pipe diameter with that of the PCCP bell and spigot. This paper reviews the solution developed in the field, within 4-hours of notification to the design engineer, and successfully installed by the contractor less than 36-hours later. The design included a built up concentric reducer to connect the new steel pipeline with the existing PCCP installation. In order to ensure timely completion, the design was prepared with careful consideration of the contractor's available materials, equipment, and staff. To date, the affectionately nicknamed Frankenstein reducers have proven to be effective solutions and are a dependable asset in the owner’s water transmission system.