A tube, or tubing, is a long hollow cylinder used to convey fluids (liquids or gases).
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.
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There are three classes of manufactured tubing: seamless, 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.
For a tube of silicone rubber[1] with a tensile strength of 10 MPa and a 8 mm outer diameter and 2 mm thick walls. The maximum pressure may be calculated as follows:
Gives burst pressure of 5 MPa.
Using a safety factor: