# Difference Between Tube and Pipe

In the manufacturing industry, pipes and tubes are often categorized as the same terms, since both of them are hollow from the inside and have basically the same geometrical shape. This however is not true and there are a couple of major differences which completely distinguish the two structures from each other.

The first difference is that pipe is a vessel, whereas tube is a structural entity. Secondly, the dimensions of the pipe are measured using the internal diameter, whereas the dimensions of the tube are measured using the external diameter. The third dimension which can be used to measure hollow structures like a pipe and tube is the wall thickness. This parameter is used in calculation of both these structures.

For any hollow structure, the outer diameter of the structure is the sum of the inner diameter and two times the wall thickness. Tubes are normally seam welded, whereas pipes are generally seamless. There are some tubes which are also used for the transportation of fluids, especially in the agricultural sector, where water at high pressure is passed through them. To use these tubes however, the structural integrity has to be verified using the pressure vessel test. This is because of the seam present in the tubes. Under high pressure, this seam can becomes a source of pressure release, and can affect the overall functioning.

### Instructions

• 1

Tubes

Tubes are used in structural terms. The strength of any tube structure depends on its wall thickness. Greater is the wall thickness, greater will be the strength of the tube. Hence a tube can be defined in terms of its outside diameters and the wall thickness. There are many shapes in which tubes can be made, and are not limited to being circular only. There can be square and rectangular tubes as well. These oddly shaped tubes are however built from a mother tube which is always round in shape.

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• 2

Pipes

Pipes are normally used for the transportation of gases and fluids, and it is for this very reason that the internal diameter becomes the dimension of significance. Pipes are identified through Nominal Pipe Size and Diameter nominal in the inches and the metric system respectively.

Pipes can be made by a variety of mechanical processes, such as forming, drawing and extrusion. They are mainly made of steel, but other materials can also be used depending on the requirement.

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