Single-Phase Pipe Hydraulics and Pipe Sizing

This particular course entitled “Single-Phase Pipe Hydraulics & Pipe Sizing” under the specialization entitled “Design of Industrial Piping Systems” is mainly aimed at predicting the optimum pipe diameter of the piping system to meet the given process requirement when it is subjected to a single-phase fluid flow. Here, the piping system is either a single-path piping system or a multiple-path piping system. To achieve the single-point objective, i.e., the Sizing of the Ping System, essential concepts of single-phase fluid flow through pipes are covered, essential mathematical expressions are derived to understand the intricacy of the single-phase phenomena, and the importance of each term in governing equations is explained.

To begin with, the key role of the pipe in transporting the fluid from the source to the destination is explained by citing numerous applications. The pipes may be subjected to single-phase fluid flow or multi-phase flow. This course is dedicated to single-phase hydraulics. In most practical situations, process flow conditions such as fluid flow rate and operating conditions are the input to determine the pipe diameter. However, the pressure drop is a constraint. To meet the pressure drop constraint for the given process flow conditions, the designer must be thorough with the dynamics of single-phase fluid flow in straight pipes, pipe fittings, valves, etc. Sigle-phase fluid flow phenomena are well established and hence the pressure drop in a piping system can be predicted accurately.

In single-phase fluid flow, irrespective of the type of the fluid, i.e., gas or liquid, the flow resistance factor, known as friction factor depends on the Reynolds Number along with other important parameters. Indeed, the Reynolds Number decides the type of flow regime, i.e., laminar or turbulent. The pressure drop is directly proportional to the length of the pipe and the square of the fluid velocity or mass flux, and interestingly, the pressure drop is inversely proportional to the pipe diameter. This means that as the diameter increases, the pressure drop decreases. The constant of proportionality is the friction factor. This concept behind pipe hydraulics is brought up very well in this course. The friction factor for turbulent flow is different from laminar flow. The former is a function of the Reynolds number and relative roughness of the pipe whereas the latter is the function of only Reynolds number. Various friction factor correlations for turbulent flow along with their applicability are available and presented in this course. The pressure drop in pipes is considered as the skin frictional pressure drop. However, the pressure drop in pipe fittings is mostly due to the eddies formation in the zones where the fluid separates from the pipe wall and fluid mixing at locations downstream of the pipe. These head losses are considered minor losses, however, in some cases, they are significant when compared with the major head losses offered by the straight pipes. Minor losses can be determined by considering either the loss coefficients or equivalent lengths of various pipe fittings. The detailed discussion and demonstration of pressure drop predictions are well covered in this course.

This course is not limited to single-path single-phase pipe hydraulics. Multiple-path piping systems popularly known as piping networks are also considered and the prediction of pressure drop in these networks is demonstrated by using well-accepted methodologies. Pressure drop calculation in the header and branching pipelines, when they are connected to various fluid sources, is discussed in this course. Though piping systems are operated at a steady state most of the time, they are also subjected to transients during startup and shutdown operations. Piping systems are also subjected to transients due to oscillatory fluid flow, water hammer, and steam hammer. These transients and the pressure rise due to the water hammer are well covered in this course. Finally, the hydraulics of liquid flow in inclined pipes under gravity is also covered in this particular course.