Cleaning entering vessels

Rail cars, tank trucks, and some reactors and storage tanks were cleaned manually by personnel who entered the vessel fatalities occurred from unexpected or undetected low oxygen content or toxicity. An inherently safer system is a rotating pressurized water spray head that does the cleaning without vessel entry. 

Many people have been killed or overcome because they entered vessels or other confined spaces that had not been thoroughly cleaned or tested. About 63 people are killed this way every year in the United States about 40 of those are would-be rescuers (see Section 11.6) [25]. A number of incidents are described here. Another is described in Section 9.1.5 (c), and others involving nitrogen are described in Section 12.3. Sometimes it seems that vessels are more dangerous empty than full. 

CO temperature in cleaning vessel was not consistent and was hotter at the top than at the bottom Insufficient heating of CO entering vessel. Poor positioning of extractor control thermocouple Designed, fabricated and installed temperature controlled water bath with heat exchanger and repositioned thermocouples... 

As a general rule, vacuum relief devices are permitted on offsite storage vessels handling clean finished products, since there is essentially no possibility of an internal ignition source. However, vacuum relief devices which permit breaking of a vacuum with inerts or flammable vapors are not permitted on process equipment, since they are not judged to be sufficiently rehable to provide adequate protection under all circumstances. Vacuum devices which permit air to enter may be considered, however, in cases where the equipment does not or cannot contain flammables e.g., some steam systems. 

Materials, processes, and control parameters for drug production are stated in written documents. Production personnel follow procedures and record materials used, amounts weighed, and date of operation. Equipment, reaction vessels, and the production area are cleaned and their status recorded in logbooks. Throughout the production stages, equipment conditions (e.g., pH, pressure, stirring speed, and temperature) are also recorded. Adjustments to in-process control parameters, if permitted, are entered onto batch records. 

According to Cameron et al. [11], mercury is redistributed into all of the hydrocarbon cuts after stream cracking. They found that the most highly contaminated fractions were butyl or propyl cuts, accounting for approximately 90 to 95% of the total mercury in the distillation column. About 75% of the mercury that entered a steam cracked unit was not found in the hydrocarbon products, but, rather, contaminated the internals of the unit. Of course, this mercury, when contacted with a clean, mercury-free feedstock wiU render the product mercury-rich. On the other hand, should the raw mercury-containing feedstock or one of its contaminated cuts be transported to another site, then the transport vessel will be polluted. 

In another tank collapse incident, a tank containing a solution of ammonia and water was being emptied and cleaned. After employees emptied the tank of liquid ammonia, they added water to rinse the vessel. While the water was being added the sides of the tank were sucked in. The ammonia vapor remaining in the tank dissolved in the water so rapidly that air could not enter through the vent to prevent the collapse. [8]... 

The emulsion enters the desalter vessel where a high-voltage electrostatic field is applied. The electrostatic field causes the dispersed water droplets to coalesce, agglomerate, and settle to the lower portion of the vessel. The various contaminants from the crude oil concentrate in the water phase. The salts, minerals, and other water-soluble impurities are discharged from the settler to the effluent system. Clean, desalted hydrocarbon product flows from the top of the settler and is ready for the next processing step. 

Every pressure vessel must be inspected officially each year, at a time when it is cooled and thoroughly cleaned out. The apparatus is entered only after it is shown that a candle burns normally inside. Usually, only the manhole is opened and the apparatus is blown out with compressed air. Two people should always work together, and the results of the inspection should be certified officially. Frequently, a gauge can be used to measure accurately any change in the walls of the vessel. The liner must be removed for inspection. The autoclave is... 

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