Design of Industrial Piping Systems

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.

This particular course entitled “Pipe Material Specification” under the specialization entitled “Design of Industrial Piping Systems” is mainly aimed at piping system design aspects. The major differences between tube and pipe should be known to the designer first. The right selection of the straight pipe for a given process requirement is entirely based on the sound knowledge of the designer on pipe manufacturing techniques, pipe ends, pipe materials, and ASME B31 pressure piping series. Designers should be capable of determining the pipe wall thickness for the internal pressure as well as external pressure based on the ASME B31.3 code and selecting of proper schedule number from the ASME B36.10M and B36.19M standards. Piping is composed of pipe fittings, valves, flanges, gaskets, nuts and bolts, etc. Therefore, designers should be acquainted with various types of fittings, importance, ends, pressure-temperature ratings, and material. Similarly, designers should be acquainted with various types of flanges, ends, face finishing, pressure-temperature ratings, materials, and similar knowledge on gaskets and nuts and bolting. Valves are used for isolation, regulation, and one-way operations. Therefore, types, end connections, material, pressure-temperature ratings, internal construction, internal parts, and functioning of valves should be known to the designer for their right selection. PFDs, P&IDs, General Arrangement Drawings (GADs), and Piping Isometrics are important drawings for any process plant; and development, reading, and interpreting these drawings is one of the desired requirements that the designer should possess. To fulfill this requirement the designer should be thorough with certain symbols used to present a three-plane piping system on a 2D sheet such as GADs, etc. The designers must familiarize themselves with general abbreviations, service codes, line number identification, ‘insulation and heat tracing codes’, representations of pipelines, boundaries, off-page connectors, pipe fittings, piping valves, piping components, and ‘fire, and safety’. In a nutshell, the designer should be thorough with the legend sheet of a particular industry. The flexibility of a piping system is a major issue and it is dicey if the piping system doesn’t have inherent flexibility. Therefore, designers should be masters in all aspects of pipe stress analysis and perform flexibility analysis using industry-accepted pipe stress analysis software. They should be in a position to suggest the optimum pipe routing with appropriate supports, hangers, and expansion joints. To become an expert in flexibility analysis the designer should be well familiar with various types of primary supports, secondary supports, various types of hangers, good practices followed in piping and equipment layout known as layout rules, and expansion joints. Further, it is a requirement expected from the designer, i.e., the design of jacketed piping. Vibration-induced loads are to be included in the pipe flexibility analysis. Unless the designer knows the sources for pipe vibration and types; the effect of vibration cannot be captured in the stress analysis process. The piping system needs insulation and a thorough knowledge of the types, shapes, and materials is essential. Pipes may be routed through underground. Therefore, designers should be capable of making the decision when the underground piping is preferred. If preferred, the designer should know what sort of challenges going to be faced that arise from corrosion and land sliding, and what are remedial solutions. Hence, designers should know about proper cathodic protection as it is one of the remedial solutions to prevent the UG pipe. The course is aimed to address all these aspects and these essential topics are included in the course. These are explained and demonstrated in a lucid form therefore, the learners can easily grasp the concepts and acquire the required skillset as mentioned above.

This particular course entitled “Two-Phase Pipe Hydraulics & Pipe Sizing” under the specialization entitled “Design of Industrial Piping Systems” is mainly aimed at predicting the two-phase total static pressure drop in a given piping system when both gas and liquid flow through it concurrently. Pressure drops including heat transfer coefficients depend on two-phase flow regimes since two-phase patterns and local internal structure are different for different flow regimes. Therefore, the formation of various two-phase flow regimes in horizontal and vertical pipes is to be known to the designer, and at the same time, the influence of bend on the formation of two-phase flow regimes in upstream and downstream pipes should also be known. The presence of a bend is inevitable in the piping systems of a plant and its presence restricts the formation of certain two-phase flow regimes commonly found in individual horizontal and vertical pipes for the given flow rates of gas and liquid and pipe diameter. Surprisingly, bend allows the formation of slug flow regimes in both horizontal and vertical pipe runs of a piping system. This is a nerve-wracking issue for the designer since the slug flow regime harms the piping system and in some situations, the slug flow regime becomes the main cause of the failure of the piping system. Therefore, the designer should be cautious during the design of two-phase piping systems and avoid the slug flow regime formation at any cost while designing the two-phase piping system. Looking into the severity of two-phase flow on the piping system integrity, the present course focuses on the formation of two-phase flow regimes in horizontal and vertical pipes and their identification based on gas and liquid flow rates using two-phase flow pattern maps. Next, the course focuses on the effect of bends on two-phase flow regime formation in both upstream and downstream pipelines as piping systems are made of connecting straight pipe runs using bends. From this discussion, the learner gets a fair idea about the formation of a certain type of two-phase flow regime, when it happens, and why it happens. Next, the two-phase terminologies are covered as these are frequently used in two-phase piping system design. The relationship among them is equally important in the design and hence, covered in the present course. These terminologies and their relations assist the learner in understanding, analyzing, and applying the various two-phase models to design the two-phase piping system. Certain idealizations are to be made while dealing with the gas and liquid two-phase flow through the pipe. Single-phase is well-established, not two-phase. To take advantage of suggested single-phase correlations by the investigators, the two-phase models are developed by assuming liquid alone flows through the pipe with the two-phase mixture flow rate. This assumption introduces the error as it does not appeal the reality. Therefore, while developing the models a term called two-phase multiplier is introduced and made as a multiplication factor to the single-phase pressure drop, to predict the two-phase frictional pressure drop within the acceptable range. The developed models are popularly known as the Homogeneous Equilibrium Model, Separated Flow Model, and Drift Flux Model, and the present course is focused on these models. Various two-phase multipliers, methods, techniques, and void fraction correlations are covered in detail in this course. Finally, in this course, practical two-phase problems are considered to demonstrate the prediction of total static pressure drop which is a sum of two-phase frictional, accelerational, and gravitational pressure drops using the two-phase well-known models, methods, techniques, two-phase multipliers, and void fraction correlations and how closely they predict so that learner cannot face any hiccup while he/she designing the two-phase piping systems including single path and multi-path piping systems known as piping networks.