Design Of Piping Systems

The more complex industry becomes, the more vital becomes the role played by fluids in the industrial machine. One hundred years ago water was the only important fluid which was conveyed from one point to another in pipe. Today, almost every conceivable fluid is handled in pipe during its production, processing, transportation, or utilization. The age of atomic energy and rocket power has added fluids such as liquid metals, i.e., sodium. potassium, bismuth, as well as liquid oxygen, nitrogen etc. to the list of more common fluids such as oil, water, gases, acids, and liquors that are being transported in pipe today. Nor is the transportation of fluids the only phase of hydraulics which warrants attention now. Hydraulic and pneumatic mechanisms are used extensively for the controls of modern aircraft, sea-going vessels, automotive equipment, machine tools, earth-moving and road-building machines, and even in scientific laboratory equipment where precise flow of fluid is required.

Although the literature on pipe sizing is massive, reflecting its importance, sizing remains a somewhat intractable technology. Piping flow phenomena are frequently complex and often not well understood. Nevertheless, engineers and technicians too often size piping by rules of thumb, ignoring sound sizing principles. When economical sizing is mentioned, some engineers immediately think of balancing energy and investment costs to minimize an annualized cost.

It is better to think of economical sizing in a broader context, because there is usually one best and most economical size and that size may have nothing to do with energy consumption. For example, pipe sizes to and from fixed pressure utility headers do not affect plant energy consumption. Yet in a given application there is a minimum size that will give satisfactory operation, and is therefore the most economical size. The term "economical size" is too ingrained in the literature to change, but the designer should constantly strive for economical sizes in the broader sense.

One rational approach to pipe sizing involves first determining if pipe size affects plant energy consumption. If so, optimum sizing should be given further consideration. If not, it should be totally ignored, and another rational basis selected. In  other case, the following sizing limitations should be considered:

• Pressure-drop availability

• Two-phase flow patterns

• Drain-piping design

• Erosion corrosion

• Noise and cavitation

• Flow distribution

• Transient and vibration phenomena

• Piping expansion and support   

MEConsult has its credit the complete layout and engineering design of plant piping for a number of industrial applications, the prominent of the lot being that for Lever Chemicals Limited and Lever Brothers Limited. The final product have included piping layout maps developed on an in-house MECAD System as support materials to the elaborate design documents.