Valves shatter

Fig. 291. Preparation of titanium metal by the process of van Arkel and de Boer. g) pyrex bulb a, b, c) tri-ai lar arrangement of tungsten bus bars d, (h) tungsten wires h) iodine storage flask 0 shatter valve n) steel ball.

Detonation failures in pipe networks are always downstream from the ignition source. They usually occur at pipe elbows or other pipe constrictions, such as valves. Blast pressures can shatter an elbow into many small fragments. A detonation in light-gauge ductwork can tear the duct along seams and can also produce a large amount of structural distortion in the torn ducts. 

A supposedly empty tankwagon, which may have still held 12 tonnes of oxirane, was filled with water as the first stage of a cleaning process and the valves then closed. Several hours later, an explosion shattered the tank, sending parts up to 600 metres distance. It appears that filling will not have given complete mixing but left an oxirane... 

Carbon monoxide is admitted slowly and the pressure boosted to ca. 1600 p.s.i. The vessel is allowed to stand connected to the gas line for 10 minutes, and the valve is then closed. The shaking mechanism is adjusted for widest possible oscillation to allow the steel ball to roll back and forth to shatter the ampoule and mix the reactants. The vessel is heated to 100° and maintained at this temperature for 4 to 6 hours, f The vessel is allowed to cool, and then with the valve at the top the contained gas is bled off through the vent line. The pressure vessel is opened in a hood, and its contents are transferred into a 1-1. distilling flask containing ca. 500 ml. of water. The ether is distilled off at low temperature. When the ether has been removed, the receiver is changed and the water in the flask boiled. The tungsten hexacarbonyl is carried over into the receiver with the steam, j Water is removed on a Buchner funnel, and the product is purified by redistillation from 3 to 5% sodium hydroxide solution, by vacuum sublimation at 60 to 70°, or by crystallization from ethyl ether. The yield varies from 6 to 8 g. (68 to 90%), depending upon conditions. ... 

Fig. 34. Briscoe break-seal valve. The capillary point S is still open during sealing to side 1, but several scratches have been made at a. Then h is fused by means of a very small flame introduced through o, with air entering at d. Next the valve is sealed to the other side, the Hg-filled hammer bar is carefully introduced and d is sealed. A sharp movement applied from the outside will shatter the valve.

An organic sulphate was prepared by adding an amine into a 0.9 m reactor containing sulphuric acid. On the day of the incident the reactor had been charged with sulphuric acid by one shift and the next shift started the amine addition. The operator noted that the temperature had not risen and found the stirrer switched off. He switched on the stirrer, the two immiscible liquids mixed with rapid liberation of heat. The relief valve was blown off and glassware shattered. 

The gases are insoluble in water so can be collected over water. The non-return valve stops water getting into the equipment. If cold water hits the hot tube it will shatter. 

Laboratory fume hoods and the associated exhaust ducts should be constructed of nonflammable materials. They should be equipped with either vertical or horizontal sashes that can be closed The glass within the sash should be either laminated safety glass that is at least 7/32 inch thick or other equally safe matraial that will not shatter if there is an explosion within the hood. The utility control valves, electrical receptacles, and other fixtures should he located outside the hood to minimize the need to reach within the hood proper. Other specifications regarding the construction materials, plumbing requirements, and interior design will vary, depending on the intended use of the hood. (See Chapter 6, sections 6.C.1.1 and 6.C.I.2.)... 

Barriers/Controls 3) All gauges have been equipped with shatter-proof glass to prevent hazardous release of energy due to gauge failure. All valves have been rated and proof tested, in accordance with American Society of Mechanical Engineers (ASME) requirements, for use in this system. 

Controlled Risk Assessment 3) Design per applicable ASME codes have reduced the likelihood of such a risk to improbable and, if component failure were to occur, the shatter-proof gauges and rated valves would decrease the hazard category to marginal. A Controlled RAC of 3E is therefore assigned. 

---