Pressurized containers

Anhydrous HCl is stored in Hquid form under pressure at —25° C and these pressure containers are rated for 2—24 MPa (300—350 psig). The material of constmction for this purpose is carbon steel which should be ductile at very low (—87°C) temperatures. 

Aerosols. Pressurized containers to deHver aerosolized dmg products through appropriate systems of valves and actuators have been available since the 1950s (see Aerosols). Such dosage forms are used as external appHcations of lotions and creams, for oral inhalation, or for treatment of the vaginal cavity, eg, contraceptive foams. Aerosols contain two- or three-phase systems, wherein a volatile Hquid or admixture of Hquids is sealed in a... 

The methylamiaes and ethylamiae have vapor pressures above atmospheric at ambient temperatures and are available ia the pure form only ia pressurized containers. These amines are also sold as aqueous solutions with vapor pressures below atmospheric for ease of handling. Diethylamiae, triethylamiae, and all of the higher mol wt amines are sold as the pure compounds. 

Tanks are used in innumerable ways in the chemical process iadustry, not only to store every conceivable Hquid, vapor, or soHd, but also ia a number of processiag appHcations. For example, as weU as reactors, tanks have served as the vessels for various unit operations such as settling, mixing, crystallisation (qv), phase separation, and heat exchange. Hereia the main focus is on the use of tanks as Hquid storage vessels. The principles outlined, however, can generally be appHed to tanks ia other appHcations as weU as to other pressure-containing equipment. 

Pure zirconium tetrachloride is obtained by the fractional distillation of the anhydrous tetrachlorides in a high pressure system (58). Commercial operation of the fractional distillation process in a batch mode was proposed by Ishizuka Research Institute (59). The mixed tetrachlorides are heated above 437°C, the triple point of zirconium tetrachloride. AH of the hafnium tetrachloride and some of the zirconium tetrachloride are distiUed, leaving pure zirconium tetrachloride. The innovative aspect of this operation is the use of a double-sheU reactor. The autogenous pressure of 3—4.5 MPa (30—45 atm) inside the heated reactor is balanced by the nitrogen pressure contained in the cold outer reactor (60). However, previous evaluation in the former USSR of the binary distiUation process (61) has cast doubt on the feasibHity of also producing zirconium-free hafnium tetrachloride by this method because of the limited range of operating temperature imposed by the smaH difference in temperature between the triple point, 433°C, and critical temperature, 453°C, a hafnium tetrachloride. 

Butadiene is primarily shipped in pressurized containers via railroads or tankers. U.S. shipments of butadiene, which is classified as a flammable compressed gas, are regulated by the Department of Transportation (254). Most other countries have adopted their own regulations (30). Other information on the handling of butadiene is also available (255). As a result of the extensive emphasis on proper and timely responses to chemical spills, a comprehensive handbook from the National Fire Protection Association is available (256). 

Ethyl chloride is handled and transported in pressure containers under conditions similar to those appHed to methyl chloride. In the presence of moisture, ethyl chloride can be moderately corrosive. Carbon steel is used predominantly for storage vessels and prolonged contact with copper should be avoided. 

The piping system shall have no pressure-containing components of cast iron or other nonductile metal. 

Decanter centrifuges with mechanical shaft-to-casing seals are available for pressure containment up to 1,1 VIPa (150 p.sig), similar to the nozzle-disk centrifuge. They can be built to operate at temperatures from -87 to -t-2fi0°(i (-125 to -t-500°F),... 

Design for pressure containment Provide adequately designed relief device Use less severe operating conditions... 

Design system for deflagration pressure containment where practical... 

All circumferential and longitudinal butt welds of pressure containing casings shall be 100% radiographed, if possible. All other welds shall be magnetic-particle or liquid-penetrant examined. 

The turbine undergoes three basic tests, these are hydrostatic, mechanical, and performance. Hydrostatic tests are to be conducted on pressure-containing parts with water at least one-and-a-half times the maximum operating pressure. The mechanical run tests are to be conducted for at least a period of four hours at maximum continuous speed. This test is usually done at no-load conditions. It checks out the bearing performance and vibration levels as well as overall mechanical operability. It is suggested that the user have a representative at this test to tape record as much of the data as possible. The data are helpful in further evaluation of the unit or can be used as base-line data. Performance tests should be conducted at maximum power with normal fuel composition. The tests should be conducted in accordance with ASME PTC-22, which is described in more detail in Chapter 20. 

The ASME code provides the basic requirements for over-pressure protection. Section I, Power Boilers, covers fired and unfired steam boilers. All other vessels including exchanger shells and similar pressure containing equipment fall under Section VIII, Pressure Vessels. API RP 520 and lesser API documents supplement the ASME code. These codes specify allowable accumulation, which is the difference between relieving pressure at which the valve reaches full rated flow and set pressure at which the valve starts to open. Accumulation is expressed as percentage of set pressure in Table 1. The articles by Rearick and Isqacs are used throughout this section. 

In process engineering, moles are used extensively in performing (lie calculations. A mole is defined as that mass of a substance that is numen cally equal to its molecular weight. Avogadro s Law states that identical volumes of gas at the same temperature and pressure contain equal numbers of molecules for each gas. It can be reasoned that these identical volumes will have a weight proportional to the molecular weight of the gas. If the mass is expressed as... 

Cover the classification, packaging and labelling of dangerous goods. The requirements for design, manufacture, modification, repair, approval, certification and marking of transportable pressure containers are included. The role of approved persons to comply with the regulations is explained. 

Fire Hazards - Flash Point Not flammable Flammable Limits in Air (%) Not flammable Fire Extinguishing Agents Not pertinent Fire Extinguishing Agents Not To Be Used Not pertinent Special Hazards of Combustion Products Not pertinent Behavior in Fire Pressurized containers may explode and release toxic and irritating vapors Ignition Tenperature Not pertinent Electrical Hazard Not pertinent Bunting Rate Not pertinent. 

A rupture disc device is a non-reclosing pressure relief device actuated by inlet static pressure and designed to function by the bursting of a pressure containing disc. 

A rupture disc is the pressure containing and pressure sensitive element of a rupture disc device. 

Deflagration pressure containment is an approach for selecting the design pressure of a vessel so that it is capable of withstanding the maximum pressure resulting from an internal deflagration. Vessels or process equipment can be designed to either... 

NFPA 69 (1997) provides equations for calculating the required design pressures for both types of containment design. It also discusses the limitations of deflagration pressure containment design. 

Pressure containment can also be provided by using piping systems with a pressure rating above the anticipated maximum pressure generated during a deflagration. 

More information about pressure containment design is available in NFPA 69 and the books by Bartknecht (1981, 1989) and Eckhoff (1997). 

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