In piping systems, unbalanced hydrostatic and hydrodynamic forces (called thrust forces) occur where there are changes in the direction or diameter of a pipe, such as at bends (elbows), reducers, tees, dead ends, valves, etc. Unbalanced thrust forces can lead to leakage, joint separation, and soil erosion, often with catastrophic results. In most civil engineering applications, the hydrodynamic thrust forces are insignificant and can be ignored. In underground piping systems, thrust forces are usually balanced with concrete bearing and gravity thrust blocks, restrained joints, or a combination.
This .ZIP file contains two Mathcad Prime 3.0 worksheets that perform design calculations for pipeline thrust restraint:
Lusk_Pipeline Thrust Block Design.mcdx sizes concrete bearing and gravity thrust blocks for hydrostatic conditions for a range of pipe sizes and bend deflection angles and for fittings such as tees, reducers, dead ends, and closed valves. Thrust blocks are most commonly used on smaller water distribution piping at modest pressures.
Lusk_Pipeline Restrained Joint Design.mcdx determines the required length of pipe that must be restrained on one or both sides of a fitting for a single pipe size with varying depths of cover. Restrained joints are most commonly used on larger water transmission mains and/or for higher pressure applications.
In addition, this .ZIP file contains Adobe Acrobat .PDF printouts of the two Mathcad Prime 3.0 worksheets for users who are working with other versions of Mathcad and a copy of the primary reference for these two worksheets, Thrust Restraint Design for Ductile Iron Pipe, Sixth Edition, by the Ductile Iron Pipe Research Association (DIPRA).
None of the math in these worksheets is very complicated, but it can be tedious to calculate numerous thrust restraint designs on a large project, which is why we automate such things.
