High-pressure safety

Safety High pressure gas tanks, particularly those with regulators, should be strapped down so that they don t fall, break off the valve, and turn into jet-powered projectiles. 

Reppe s work also resulted in the high pressure route which was estabUshed by BASF at Ludwigshafen in 1956. In this process, acetylene, carbon monoxide, water, and a nickel catalyst react at about 200°C and 13.9 MPa (2016 psi) to give acryUc acid. Safety problems caused by handling of acetylene are alleviated by the use of tetrahydrofuran as an inert solvent. In this process, the catalyst is a mixture of nickel bromide with a cupric bromide promotor. The hquid reactor effluent is degassed and extracted. The acryUc acid is obtained by distillation of the extract and subsequendy esterified to the desked acryhc ester. The BASF process gives acryhc acid, whereas the Rohm and Haas process provides the esters dkecdy. 

Sta.rting from Phenol. Phenol can be selectively oxidized into -benzoquinone with oxygen. The reaction is catalyzed by cuprous chloride. At low catalyst concentration, the principal drawback of this method is the high pressure of oxygen that is required, leading to difficult safety procedures. It appears that a high concentration of the catalyst (50% of Cu(I)—phenol) allows the reaction to proceed at atmospheric pressure (58). 

Health and safety factors in in situ operations are associated with high temperature, high pressure steam, or high pressure air. Environmental considerations relate to air and water quaUty and surface reclamation. In some environmentally sensitive areas such as the oil sands deposits in Utah, environmental considerations may make development unfeasible. 

If an ethyl ether fire occurs, carbon dioxide, carbon tetrachloride, and dry chemical fire extinguishers meeting National Eire Prevention Association Code 1 and 2 requirements may be used successhiUy (23). Water may also be effectively appHed (see Plant safety). Hose streams played into open tanks of burning ethyl ether serve only to scatter the Hquid and spread the fire. However, ether fires may be extinguished by a high pressure water spray that cools the burning surface and smothers the fire. Automatic sprinklers and deluge systems are also effective. 

Safety Devices Pressure relief devices, flame arresters, and methods for handhng effluent from controlled releases provide control of accidental undesirable events. Special equipment should be considered for highly toxic chemical service. The following matters are considered ... 

Since discharges of vapors from highly hazardous toxic materials cannot simply be released to the atmosphere, the use of a weak seam roof is not normally acceptable. It is best that tanks be designed and stamped for 15 psig to provide maximum safety, and pressure relief systems must be provided to vent to equipment that can collect, contain, and treat the effluent. 

Critical Equipment Equipment, instrumentation, controls, or systems whose malfunction or failure would likely result in a catastrophic release of highly hazardous chemicals, or whose proper operation is required to mitigate the consequences of such release. (Examples are most safety systems, such as area LEL monitors, fire protection systems such as deluge or underground systems, and key operational equipment usually handling high pressures or large volumes.)... 

Annunciation control (for low pressure alarm, high pressure alarm and operation ot the safety valve etc.)... 

High pressure autoclaves may be used fitted with remote control behind safety barricades, which are necessary beeause of the danger of explosions. In a typical process the autoclave is half-filled with alcohol containing 15%... 

High Pressure Technology Association (1975) High Pressure Safety Code, Leeds. 

A pressure sensor giving a continuous indication which is displayed on the control panel and can be observed by the operator. The sensor has a high pressure safety interlock set at a predetermined pressure that activates an emergency shutdown system. 

Although many engineers provide only the minimum adequate vessel design to minimize costs, it is inherently safer to minimize the use of safety interlocks and administrative controls by designing robust equipment. Passive hardware devices can be substituted for active control systems. For example, if the design pressure of the vessel system is higher than the maximum expected pressure, an interlock to trip the system on high pressure or temperatures may be unnecessary. 

For example, increasing a valve size or installing a larger pump could result in high pressure in a vessel, thus increasing the risk of a release. Sanders (1993) presents a number of examples of changes affecting the safety of a plant. 

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