A tube, or tubing, is a long hollow cylinder used for moving

fluid In physics, a fluid is a liquid, gas, or other material that may continuously motion, move and Deformation (physics), deform (''flow'') under an applied shear stress, or external force. They have zero shear modulus, or, in simpler terms, are M ...

s (

liquid Liquid is a state of matter with a definite volume but no fixed shape. Liquids adapt to the shape of their container and are nearly incompressible, maintaining their volume even under pressure. The density of a liquid is usually close to th ...

s 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 A hose is a flexible hollow tube or pipe designed to carry fluids from one location to another, often from a faucet or hydrant. Early hoses were made of leather, although modern hoses are typically made of rubber, canvas, and helically wound w ...

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.

Manufacture

There are three classes of manufactured tubing: seamless, as-welded or electric resistant welded (ERW), and drawn-over-mandrel (DOM). * Seamless tubing is produced via

extrusion Extrusion is a process used to create objects of a fixed cross section (geometry), cross-sectional profile by pushing material through a Die (manufacturing), die of the desired cross-section. Its two main advantages over other manufacturing pro ...

or rotary piercing. * Drawn-over-mandrel tubing is made from cold-drawn electrical-resistance-welded tube that is drawn through a die and over a mandrel to create such characteristics as dependable weld integrity, dimensional accuracy, and an excellent surface finish.

Standards

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 ASTM International, formerly known as American Society for Testing and Materials, is a standards organization that develops and publishes voluntary consensus technical international standards for a wide range of materials, products, systems and s ...

A213 Standard Specification for Seamless Ferritic and Austenitic Alloy-Steel Boiler, Superheater, Heat-Exchanger Tubes. *ASTM A269 Standard Specification for Seamless and Welded Austenitic Stainless Steel Tubing for General Service *ASTM A270 Standard Specification for Seamless and Welded Austenitic Stainless Steel Sanitary Tubing *ASTM A511 Standard Specification for Seamless Stainless Steel Mechanical Tubing *ASTM A513 Standard Specification for Electric-Resistance-Welded Carbon and Alloy Steel Mechanical Tubing *ASTM A554 Standard Specification for Welded Stainless Steel Mechanical Tubing *

British Standard British Standards (BS) are the standards produced by the BSI Group which is incorporated under a royal charter and which is formally designated as the national standards body (NSB) for the UK. The BSI Group produces British Standards under th ...

1387:1985 Specification for screwed and socketed steel tubes and tubulars and for plain end steel tubes suitable for welding or for screwing to BS 21 pipe threads ASTM material specifications generally cover a variety of grades or types that indicate a specific material composition. Some of the most commonly used are: *TP 304 *TP 316 *MT 304 *MT 403 *MT 506 In installations using

hydrogen Hydrogen is a chemical element; it has chemical symbol, symbol H and atomic number 1. It is the lightest and abundance of the chemical elements, most abundant chemical element in the universe, constituting about 75% of all baryon, normal matter ...

, 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 Oxygen is a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), group in the periodic table, a highly reactivity (chemistry), reactive nonmetal (chemistry), non ...

, 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 100607 ami.ac.uk with a tensile strength of 10 MPa and an 8 mm outside diameter and 2 mm thick walls. The maximum pressure may be calculated as follows: : Outside diameter = : Wall thickness = :

Tensile strength Ultimate tensile strength (also called UTS, tensile strength, TS, ultimate strength or F_\text in notation) is the maximum stress that a material can withstand while being stretched or pulled before breaking. In brittle materials, the ultimate ...

= 10 * 1000000 [ Pa] : Bursting pressure = (Tensile strength * Wall thickness * 2 / (10 * Outside diameter) ) * 10 [Pa] Gives bursting pressure of 5 MPa. Using a

safety factor In engineering, a factor of safety (FoS) or safety factor (SF) expresses how much stronger a system is than it needs to be for its specified maximum load. Safety factors are often calculated using detailed analysis because comprehensive testing i ...

: :Pressure max = (Tensile strength * Wall thickness * 2 / (10 * Outer diameter) ) * 10 / Safety_factor [Pa] 33

Applications

Tubes are essential components in heat exchange systems to assist with cooling down motors and other instruments. Industrial applications use pressure-resistant tubes to safely contain gases and liquids under pressure without leading to air leakage or malfunction. Moreover, devices powered by ultrasound often employ special types of thin-walled tubes that can generate vibration when exposed to an electric field. Finally, tube components provide efficient energy conservation in housing insulation materials such as silicon rubber foam insulation and polyethylene foam insulation.

References

External links