Piping design in production facilities involves the selection of a pipe diameter and a wall thickness that is capable of transporting fluid from one piece of process equipment to another, within the allowable pressure drop and pressure rating restraints imposed by the process. The first step in being able to make these changes is to understand how pressure drops in these lines are calculated. This is discussed in this chapter, while the next chapter discusses the concepts involved in choosing a line size and a pressure rating.
While this chapter emphasizes piping that exists within a facility, the concepts included on pressure drop are equally valid for determining the pressure drop in flowlines, pipelines, gas transmission lines, etc.
These Articles first introduces the basic principles for determining pressure drops in piping and then discusses the flow equations for liquid flow, compressible flow, and two-phase flow. Finally, it shows how to calculate pressure drop in valves and fittings when using the various flow equations. The last part of this chapter includes some example calculations for determining the pressure drop in various types of pipe.