Capped steels

These steels account for over 90% of all steel production, There are numerous varieties, depending upon carbon content and method of production. In one classification, there are killed steels, semikilled steels, rimmed steels, and capped steels, These are described in considerable detail under Iron Metals, Alloys, and Steels. 

When Ihe top end of the mgol is scaled alter pouring, ihe term cupped steel is applied Big-cnil-dmvn bottle-lop molds are used and. after a small addition of aluminum, are seated by using a heavy metal cap. Steels of this type arc used for sheet, strip, skclp. tin plate, wire, and hais. 

Note 5 API Modification to ASTM A 36 requires the manganese content to have a range of 0.80 to 1.20. The material supplied shall be other than rinined or capped steel. 

Reference Markers. Plant layout on the site requires a starting or reference point after the exact location of the property has been determined by permanent property markers already established or by independent survey of a local surveying firm. Markers are usually large-diameter capped steel pipe set in concrete, located outside the construction area, so that directional and elevation data can be taken relative to these permanent posts. One marker is called the zero corner point and all measurements start from there. Plant north and its relation to true north are next set up so that master plot plans can be oriented to the plant site and surveying stakes located in the working area. 

A loss in ductility accompanied hy an increase in hardness and strength that occurs when low-carbon steel (especially rimmed or capped steel) is aged following plastic deformation. The degree of embrittlement is a function of aging time and temperature, occurring in a matter of minutes at about 200 °C (400 °F), but requiring a few hours to a year at room temperature. 

Tellurium improves the machinability of copper and stainless steel, and its addition to lead decreases the corrosive action of sulfuric acid on lead and improves its strength and hardness. Tellurium is used as a basic ingredient in blasting caps, and is added to cast iron for chill control. Tellurium is used in ceramics. Bismuth telluride has been used in thermoelectric devices. 

The rectifying section contains three or four bubble cap (wine) plates in the top section of the stiU to produce distillates up to 160° proof. Whiskey stills are usually made of copper, especially in the rectifying section, which often yields a superior product. Additional copper surface in the upper section of the column may be provided by a demister, a flat disk of copper mesh. Stainless steel is also used in some stills. 

FIG. 14-79 Cost of trays in plate towers. Price includes tray deck, bubble caps, risers, downcomers, and structural-steel parts. The stainless steel designated is type 410 Peters and Timmerhaus, Plant Design and Economics for Cbemical Engineers, 4th ed., McGraw-Hill, New York, 1.9.91). 

Tubercles are mounds of corrosion product and deposit that cap localized regions of metal loss. Tubercles can choke pipes, leading to diminished flow and increased pumping costs (Fig. 3.1). Tubercles form on steel and cast iron when surfaces are exposed to oxygenated waters. Soft waters with high bicarbonate alkalinity stimulate tubercle formation, as do high concentrations of sulfate, chloride, and other aggressive anions. 

Figure 3.23 Perforation at a dish-shaped depression on the internal surface of a large-diameter steel pipe. A large tubercle capped the depression but was dislodged during tube sectioning. (Courtesy of National Association of Corrosion Engineers, Corrosion 89 Paper No. 197 by H. M. Herro.)...

Stainless steels attacked by sulfate reducers show well-defined pits containing relatively little deposit and corrosion product. On freshly corroded surfaces, however, black metal sulfides are present within pits. Rust stains may surround pits or form streaks running in the direction of gravity or flow from attack sites. Carbon steel pits are usually capped with voluminous, brown friable rust mounds, sometimes containing black iron sulfide plugs fFig. 6.10). 

Figure 16.1 shows part of a steel tank which came from a road tank vehicle. The tank consisted of a cylindrical shell about 6 m long. A hemispherical cap was welded to each end of the shell with a circumferential weld. The tank was used to transport liquid ammonia. In order to contain the liquid ammonia the pressure had to be equal to the saturation pressure (the pressure at which a mixture of liquid and vapour is in equilibrium). The saturation pressure increases rapidly with temperature at 20°C the absolute pressure is 8.57 bar at 50°C it is 20.33 bar. The gauge pressure at 50°C is 19.33 bar, or 1.9MN m . Because of this the tank had to function as a pressure vessel. The maximum operating pressure was 2.07 MN m" gauge. This allowed the tank to be used safely to 50°C, above the maximum temperature expected in even a hot climate. 

Electrochemical cells are assembled in the glove-box. The cell is a 2320-type coin cell (23 mm OD and 2.0 mm thickness) as schematically shown in Fig. 5. The cell includes the electrolyte, the cell cap and can which are stainless steel, a polypropylene gasket used to seal the cell, the two electrodes, the separator between the electrodes, as well as a stainless spacer and a mild steel disc spring which are used to increase the pressure on the electrodes. Once the cell is assembled in the right order, the cell is sealed by a pressure crimper inside the glove-box. 

Many researchers choose to buy expensive GPC/SEC columns from one of the major producers because that producer s columns had been used in the past or because of a successful marketing campaign by one particular producer. It should be noted that repacked columns can be obtained for a fraction of the cost of new columns. American Polymer Standards repacked columns are guaranteed to perform just as well as new columns from any company. When a column is repacked the only parts reused are the stainless-steel tube and end caps. This hardware is then repacked using new frits and new ST-DVB gel. Each column is individually tested in a quality control laboratory and shipped in the customer s choice of solvent. American Polymer Standards offers a column repacking service because it is a practical, inexpensive way for customers to acquire state of the art GPC/SEC columns. 

Figure 13.3 Schematic diagram of the parallel cryogenic trap MDGC-IR-MS system A, splitless injection port B, RC-5 non-polar first-stage separation column C, HP 5970B MSD D, HP 5965B IRD E, four-poit two-way valve (300 °C maximum temperature) F, external auxiliary earner gas G, six-poit selection valve (300 °C maximum temperature) H, stainless-steel cryogenic caps I, tliree-poit two- way valve (300 °C maximum temperature) ...

The column is designed as an ammonia rectifier-stripper using fundamental design techniques. A 48-in. diameter column will handle at least 500 tons of refrigeration system load for the above temperature range, using 10 bubble cap trays with 32, 4-in. pressed steel caps per tray (slot area = 7.81 in. /cap riser area 4.83 in. /cap 3 ft 0 in. weir length). Tray... 

Straight steel pipes up to 600 mm in diameter and six or more metres in length are usually lined by centrifugal casting. In this technique, the prepared preheated pipe is fitted with end caps and placed into the heated casting oven. Freshly mixed liquid polyurethane is then injected into the pipe which is then spun round its longitudinal axis until the polyurethane has cured to form a solid lining. 

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