U.S. computer manufacturer Apple has reportedly secured exclusive rights to use the metal by the U.S. specialists Liquidmetal Technologies developed materials. According to a mandatory reporting of Liquid Metal to the U.S. Securities and Exchange Commission, Apple has acquired for an undisclosed sum for the exclusive Lizenrechte field of consumer electronics, among others reported the U.S. newspaper Baltimore Sun. Existing agreements with manufacturers of the metal specialist sports equipment and medical equipment and defense companies are not affected by the license agreement.
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Thursday, August 12, 2010
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Heater Tube Failures relating to metal alloys
25.2 Heater Tube Failures
Heater tubes are designed to operate at a particular pressure an temperature. The design pressure of the tube is not the inlet operating pressure of the heater. The design tube pressure is the heater charge pump dead-head, or shut-in, pressure, as discussed in Chap. 29. The design temperature of the tube is not the heater outlet process operating temperature. The design tube temperature is the anticipated or calculated maximum tube skin temperature (at end-of-run conditions), which is simply the temperature of the exterior metal surface of the tube. Many plants call this temperature the tube metal indication (TMI).
The calculated tube skin temperature is mainly a function of the fouling resistance assumed inside the tube. The greater the assumed fouling resistance, the higher the design tube skin temperature, and the thicker the tube wall. In a sense, then, we partially assume the design tube thickness, on the basis of experience, for a particular plant service.
A typical process heater tube diameter is 4 to 10 in. Tube thickness is usually between 0.25 and 0.50 in. Heater tubes are often constructed
out of chrome steel. A high chrome content is 13 percent. The chrome content increases the heat resistance of the tube. A tube with a 11 to 13 percent chrome content can normally withstand a skin temperature of up to 1300 to 1350°F. A low-chrome-content tube of perhaps 3 percent may be limited to 1200°F tube metal temperature. Naturally, the pressure, thickness, and diameter of the tube, all affect its maximum
Heater tubes are designed to operate at a particular pressure an temperature. The design pressure of the tube is not the inlet operating pressure of the heater. The design tube pressure is the heater charge pump dead-head, or shut-in, pressure, as discussed in Chap. 29. The design temperature of the tube is not the heater outlet process operating temperature. The design tube temperature is the anticipated or calculated maximum tube skin temperature (at end-of-run conditions), which is simply the temperature of the exterior metal surface of the tube. Many plants call this temperature the tube metal indication (TMI).
The calculated tube skin temperature is mainly a function of the fouling resistance assumed inside the tube. The greater the assumed fouling resistance, the higher the design tube skin temperature, and the thicker the tube wall. In a sense, then, we partially assume the design tube thickness, on the basis of experience, for a particular plant service.
A typical process heater tube diameter is 4 to 10 in. Tube thickness is usually between 0.25 and 0.50 in. Heater tubes are often constructed
out of chrome steel. A high chrome content is 13 percent. The chrome content increases the heat resistance of the tube. A tube with a 11 to 13 percent chrome content can normally withstand a skin temperature of up to 1300 to 1350°F. A low-chrome-content tube of perhaps 3 percent may be limited to 1200°F tube metal temperature. Naturally, the pressure, thickness, and diameter of the tube, all affect its maximum
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