A man walking on a street of London was asked, "Where are you coming from?" He replied, "I am coming fork the tube". He was coming from the under-ground rail, also known as Tube Rail. A common man understands a pipe as a large tube. A tube is understood as a small pipe. There are no universally accepted definition for pipe and tube. In the power plant terminology, a pipe is considered to convey fluids. A tube is considered to take part in heat transfer, while conveying fluids. A tube can be hollow circular or hollow rectangular. Hollow circular tubes are used for conveying fluids. Hollow rectangular tubes are used for structural purposes. A pipe can convey the following: gas or liquid or gas-solid mixture or gas-liquid mixture or liquid-solid mixture or gas-liquid-solid mixture. The piping is designed normally as a mechanical static device. The following assumptions are made in the design of piping: linear behavior, elastic material, homogenous material, isotropic material behavior, steady-state loading and static piping. Even-though none of these six assumptions are true, these assumptions are used to simplify the design procedure. These assumptions introduce inaccuracies in the design. Hence, factors of safety are used to take care-of these assumptions. Factors of safety are also known as factors of ignorance or factors of uncertainty. The factor of safety normally used for piping is about 1.5. The piping is used in home, industry and power plants. In any human activity the structures and piping are indispensable.

   "Who invented the pipe", asked a person. There was no answer. The answer is, "There is no answer". Pipes are used from time immemorial. The first use of piping for human activity is use of bamboo sticks for conveying fluids. The man who first used the pipe might not have had a name. He is believed to be a pre-historic man. Piping consists of pipes and appurtenance. The pipes can be classified as thin pipes and thick pipes. There are no universally acceptable definition for thin pipe and thick pipe. The type of pipe is decided by the following ratio:

Nominal thickness

   Iron and steel are popularly used for piping, due to economical considerations. Copper, brass and bronze were used in the eighteenth and nineteenth century. The use of piping has increased with industrialization. Piping is used in agriculture for pumping water and drip-irrigation. The human body has arteries and veins. These are pipes. In the Yoga practice, several postures (asanas) are practiced. The blood circulation can be altered by different postures. But, the human body is very complex. No acceptable flow analysis of blood circulation in human body is available.

   Piping handles gas, liquid and solid. Solid has a shape and volume. Liquid has volume, but no shape. Liquid changes its shape according to the shape of the container. Gas changes its shapes and volume according to its container. Pipe carries gas, liquid and solid.

   "Can we have common specification for materials?" The answer is, "No". To accept the ISO sizes for Metric threads for bolts, studs, screws and nuts, the humanity has spent about a century. Hence, the present conclusion is: The materials specifications can't be universalized within our life span. Hence, we will not spend time on improbable objectives.

   The presentation in this book is simple, to make this book useful for self-learning. This book will be useful for the students, the practicing engineers and the researchers. The theory and practice are two hands to swim through the evolution of design. An "arm-chair engineer" will not be useful to the industry or the academy. "Seeing is believing". This book attempts to present the universally proven concepts and practices. Both empirical and analytical methods are presented.