Discard thickness

On older process units, you may still encounter piping with sentry holes. Let s say I have a Vfc-in thick pipe. The corrosion allowance for the pipe is Vi in. A number of small holes are drilled into the pipe, to a depth of in. When we start leaking at these small holes, this means that the pipe has corroded to its discard thickness in the area of the sentry hole. Incidentally, you can stop the resulting leak, at least in carbon steel water lines, with a brass wood screw and a screwdriver. I have also done this on hydrocarbon lines under an 80 psig pressure, but perhaps that is not too smart. 

For example, a steel pipe is V2 in thick, or 250 mils. Its discard thickness is % in thick, or 125 mils. If the corrosion rate is measured at 25 mils per year, then the expected life of the pipe is 5 years. Corrosion rates in excess of 10 mils per year are normally considered excessive and unacceptable, at least in petroleum refineries. 

Fit securely to the lower end of the condenser (as a receiver) a Buchner flask, the side-tube carrying a piece of rubber tubing which falls well below the level of the bench. Steam-distil the ethereal mixture for about 30 minutes discard the distillate, which contains the ether, possibly a trace of unchanged ethyl benzoate, and also any biphenyl, CeHs CgHs, which has been formed. The residue in the flask contains the triphenyl carbinol, which solidifies when the liquid is cooled. Filter this residual product at the pump, wash the triphenyl-carbinol thoroughly with water, drain, and then dry by pressing between several layers of thick drying-paper. Yield of crude dry product, 8 g. The triphenyl-carbinol can be recrystallised from methylated spirit (yield, 6 g.), or, if quite dry, from benzene, and so obtained as colourless crystals, m.p. 162. ... 

The spht is of variable thickness, and some of the spUt is too thin for leather production. The thin parts are trimmed off and discarded for coUagen recovery. The trimmed spUt is tanned separately. 

The solution was heated on a steam bath for 6 hours. After cooling, the whole was poured into water and the oil extracted well with ether, the ether solution was discarded and the aqueous solution neutralized with 1 N sulfuric acid. A heavy oil separated which was taken into ether, washed with water, bicarbonate solution and again with water. After drying, the ether was removed to give a thick oil which solidified on standing (34.6 grams). After recrystallization from an ether-petroleum ether mixture it formed needles, MP 108°-112°C. 

The spectrum recorded at 230 K was discarded in the fit procedure because above 200 K the effective thickness decreases drastically because of a significant softening of protein-specific modes [16]. From the simultaneous fit of the spectra in the temperature range 3.2-200 K, the Debye temperature was determined as do = 215 K. AEq proved to be a temperature-dependent quantity, which is discussed later (see Sect. 9.4.2). 

Recovery of IC-0. Combine 20 g of the air-dried soil with 100 niL of a mixed solvent of methanol and 0.1 M ammonium chloride (4 1, v/v) in a 250-mL stainless-steel centrifuge tube, shake the mixture with a mechanical shaker for 30 min and centrifuge at 8000 r.p.m. for 2 min. Filter the supernatant through a Celite layer (1-cm thick) under reduced pressure into a 500-mL flask. Add 100 mL of mixed solvent of methanol and 0.5 M sodium hydroxide solution (4 1, v/v) to the residue and then extract and filter in the same manner. Combine the flltrates and concentrate to approximately 40 mL on a water-bath at ca 40 °C by rotary evaporation. Add 10 mL of distilled water and adjust the pH of the aqueous layer to 7 with hydrochloric acid. Transfer the aqueous solution into a 200-mL separatory funnel and shake the solution with 50 mL of mixed solvent of dichloromethane and acetone (1 1, v/v) for 5 min. Discard the mixed solvent and adjust the pH of the aqueous layer to 1.5 with hydrochloric acid. Extract the solution with three portions of 50 mL of diethyl ether. Combine the diethyl ether extracts and dry over anhydrous sodium sulfate. Concentrate to dryness on a water-bath at ca 40 °C by rotary evaporation. 

Usually in evaporation the thick liquor is the valuable product and the vapour is condensed and discarded. There are, however, specific situations where the opposite is true. In this context, mention may be made of the fact that mineral-containing water is often evaporated to yield a solid-free product for boiler feed, for special process requirements, or for human consumption. This technique is often called water distillation, but technically it is evaporation. 

The No. 300 M.S.T. cellophane is sufficiently thick to resist reasonable tearing and is waterproof each cellophane liner is used only once, then discarded. The authors have found it convenient to purchase this cellophane in precut 6 X 12 inch sheets in lots of 10,000 (available from the Zellerbach Paper Company, Los Angeles, Calif.). 

The supernatant is discarded and mixed well with the Vortex. A few drop of pellet are placed in a PreservCyt Solution Vial and allowed to sit for no less than 15 min. If the pellet/specimen is too thick or bloody, few more drops of CytoLyt are added, and the specimen is centrifuged for the third time. 

Ester interchange between the additive and polymer would be expected if the mixture were held for an excessive time in the melt. In order to avoid the potential for interchange, the blendings were conducted in solution and heated only for a time necessary to melt press films for flammability testing. An alternative method of film preparation by solvent casting of films was discarded due to difficulties in preparing uniform, sufficiently thick, solvent free films for evaluation. 

Figure 26.1 shows an 8-in-thick demister below the top head. A demister pad resembles a giant Brillo pad without the soap. Many process plants have discarded demister pads lying around their scrap heaps, so you may have already seen what they look like. 

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