9314 Tubes

Tube is a product that is hollow and long in relation to its cross section, which may be round, a regular hexagon, a regular octagon, an ellipse, or a rectangle, and has uniform wall thickness. Seamless tubes, common in pressure applications, are made without a metallurgical weld resulting from the method of manufacture; such tubes can be produced from a hollow ingot or by piercing a solid ingot. Pipe is tube that is made in standardized diameter and wall thickness combinations. Tube is produced by several different methods.

Drawn tube is made by pulling material through a die (ASTM B210, Drawn Seamless Tubes and B483, Drawn Tubes for General Purpose Applications). Drawn tube is available in straight lengths or coils, but coils are generally available only as round tubes with a wall thickness of 0.083 in. (2 mm) or less and only in non-heat-treatable alloys. Drawn seamless tubes are used in surface condensers, evaporators, and heat exchangers, in wall thicknesses up to 0.200 in. and diameters up to 2.00 in., and in alloys 1060, 3003, 5052, 5454, and 6061 (ASTM B234, Drawn Seamless Tubes for Condensers and Heat Exchangers and B404, Seamless Condenser and Heat-Exchanger Tubes with Integral Fins). Heat exchanger tube is very workable and is tested for leak tightness and marked "HE."

Welded tube is produced from sheet or plate that is rolled into a circular shape and then longitudinally welded by gas tungsten or gas metal arc welding. Tube from ASTM B547, Formed and Arc-Welded Round Tube, is available in diameters from 9 to 60 in. (230 to 1520 mm) in wall thicknesses from 0.125 to 0.500 in. (3.15 to 12.5 mm). Tube from ASTM B313, Round Welded Tubes, are made in wall thicknesses from 0.032 in. (0.80 mm) to 0.125 in. (3.20 mm).

Extruded tube (ASTM B241, Seamless Pipe and Seamless Extruded Tube, B345, Seamless Pipe and Seamless Extruded Tube for Gas and Oil Transmission and Distribution Piping Systems, B429, Extruded Structural Pipe and Tube, and B491, Extruded Round Tubes for General Purpose Applications) is made by the extrusion process, discussed above. Tube may be extruded and then drawn to minimize ovality, a process sometimes called sizing. Forgings

Forgings are one of the oldest wrought products, since they can be produced by simply hammering a hot lump of metal into the desired shape. A hammer, hydraulic press, mechanical press, upsetter, or ring roller is used to form the metal. Both castings and forgings can be used to produce parts with complex shapes; forgings are more expensive than castings but have more uniform properties and better ductility [3].

There are two types of forgings: open die forgings and closed die forgings (Table 9.25). Open die forgings (also called hand forgings) are produced without lateral confinement of the material during the forging operation. Minimum mechanical properties are not guaranteed for open die forgings unless specified by the customer, so they don't tend to be used for applications where structural integrity is critical.

Closed die forgings (also called die forgings) are more common and are produced by pressing the forging stock (made of ingot, plate, or extrusion) between a counterpart set of dies. Popular uses of closed die forgings are automotive and aerospace applications; they have been made up to 23 ft (7 m) long and 3100 lb (1400 kg) in weight. Die forgings are divided into four categories described below, from the least intricate, lowest quantity forgings, and lowest cost to the w

TABLE 9.25 Mechanical Property Limitsā€”Die ForgingsĀ©
0 0

Post a comment