Tube (fluid conveyance)

For structural tubing, see Hollow structural section.
A series of tubes

A tube, or tubing, is a long hollow cylinder used for moving fluids (liquids or gases) or to protect electrical or optical cables and wires.

The terms "pipe" and "tube" are almost interchangeable, although minor distinctions exist  generally, a tube has tighter engineering requirements than a pipe. Both pipe and tube imply a level of rigidity and permanence, whereas a hose is usually portable and flexible. A tube and pipe may be specified by standard pipe size designations, e.g., nominal pipe size, or by nominal outside or inside diameter and/or wall thickness. The actual dimensions of pipe are usually not the nominal dimensions: A 1-inch pipe will not actually measure 1 inch in either outside or inside diameter, whereas many types of tubing are specified by actual inside diameter, outside diameter, or wall thickness.


Main article: Tube drawing

There are three classes of manufactured tubing: seamless,[1] as-welded or electric resistant welded (ERW), and drawn-over-mandrel (DOM).


There are many industry and government standards for pipe and tubing. Many standards exist for tube manufacture; some of the most common are as follows:

ASTM material specifications generally cover a variety of grades or types that indicate a specific material composition. Some of the most commonly used are:

In installations using hydrogen, copper and stainless steel tubing must be factory pre-cleaned (ASTM B 280) and/or certified as instrument grade. This is due to hydrogen's particular propensities: to explode in the presence of oxygen, oxygenation sources, or contaminants; to leak due to its atomic size; and to cause embrittlement of metals, particularly under pressure.

Calculation of strength

For a tube of silicone rubber[2] with a tensile strength of 10 MPa and an 8 mm outer diameter and 2 mm thick walls. The maximum pressure may be calculated as follows:

Outer diameter = 0.008 [meter]
Wall thickness = 0.002 [meter]
Tensile strength = 10 * 1000000 [Pa]
Pressure burst = (Tensile strength * Wall thickness * 2 / (10 * Outer diameter) ) * 10 [Pa]

Gives burst pressure of 5 MPa.

Using a safety factor:

Pressure max = (Tensile strength * Wall thickness * 2 / (10 * Outer diameter) ) * 10 / Safety_factor [Pa]

See also

Wikisource has the text of the 1911 Encyclopædia Britannica article Tube.


  1. "API 5L Grade B seamless tube PSL1 & PSL2". HYSP Steel Pipe.
  2. "Mechanical properties of metals". 100607

External links

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