Buried pressure pipelines: designing for thrust restraint

This design guide presents information for restraining thrust forces generated by changes in direction or cross-sectional area of fluid flow in buried pressure pipeline networks. The thrust restraint methods covered include thrust block design for pipes installed using unrestrained joints, restrained joint design for pipes installed using a proportion of restrained joints, and anchor block design to restrain a free end of a welded thermoplastic pipe. Thrust restraint methods for under pressure connections and line stop installations, the connecting of a restrained joint pipeline to an unrestrained pipeline, and bracing against abandoned pipelines left in situ, are also covered. A step-by-step design approach for each method is detailed, and worked examples are included. The guidance is principally for the routine design of thrust forces up to 1000 kN, limiting both the pressure range, pipe diameter and size of restraining structures. However, the methods described are also applicable to thrust forces above 1000 kN when supervision is given by engineers with appropriate experience in the design of complex thrust restraint.