Oxyacetylene

Fig. 2. (a) The shielded-metal arc-welding system, (b) The oxyacetylene welding process. 

Other uses of oxyacetylene flames in mill operations are in building up or hardfacing metal, lancing (piercing a hole in a metal mass), and a variety of metal cleaning procedures. A minor but interesting fuel use of acetylene is in flame spectrophotometry where oxygen and nitrous oxide are used as oxidants in procedures for a wide variety of the elements. 

Originally used as an illuminant, acetjiene [74-86-2] fiom carbide quickly found use ia oxyacetylene welding (qv) and cutting, ia the... 

In the United States calcium carbide-based acetylene is mainly used in the oxyacetylene welding market although some continues to be used for production of such chemicals as vinyl ethers and acetylenic alcohols. Calcium carbide is used extensively as a desulfurizing reagent in steel and ductile iron production allowing steel mills to use high sulfur coke without the penalty of excessive sulfur in the resultant steel (see Sulfurremoval and recovery). Calcium cyanamide production continues in Canada and Europe (see Cyanamides). 

The largest use for calcium carbide is in the production of acetylene for oxyacetylene welding and cutting. Companies producing compressed acetylene gas are located neat user plants to minimize freight costs on the gas cylinders. Some acetylene from carbide continues to compete with acetylene from petrochemical sources on a small scale. In Canada and other countries the production of calcium cyanamide from calcium carbide continues. More recentiy calcium carbide has found increased use as a desulfurizing reagent of blast-furnace metal for the production of steel and low sulfur nodular cast iron. 

Selected physical properties of oxygen are included in Table 9.24. It is a colourless, odourless and tasteless gas which is essential for life and considered to be non-toxic at atmospheric pressure. It is somewhat soluble in water and is slightly heavier than air. Important uses are in the steel and glass industries, oxyacetylene welding, as a chemical intermediate, waste-water treatment, fuel cells, underwater operations and medical applications. 

Cast Iron (e.g. BS1453) Oxyacetylene Gray irons but not malleable Matching color Not machinable... 

Brass (60 Cu/40 Zn) Oxyacetylene Gray and malleable irons Often called bronze welding... 

The main rises of a sintered metal flame arrester are in the sensing heads of flammable gas detectors and in flame arresters for gas welding (oxyacetylene) equipment. 

OH and Rexarc of West Alexandria, OH. These are small diameter nnits nsed mostly for oxyacetylene welding eqnipment. 

A contact on a safe will recognize attack by drilling, sawing, filing, explosions and oxyacetylene or thermic lance. 

Brazed Silver-brazed connectors are commonly used for joining non-ferrous piping in the pressure and temperature range where their use is practical. Use of this type of connector is limited to installations in which the piping temperature will not exceed 425°F and the pressure in cold lines will not exceed 3000 psi. Heating the joint with an oxyacetylene torch melts the alloy. This causes the alloy insert to melt and fill the few thousandths of an inch annular space between the pipe and fitting. 

Brazing Satisfactory brazed joints in molybdenum have been made using oxyacetylene torch and furnace brazing techniques. 

Oxyacetylene, manual metal are, tungsten inert gas, metal inert gas, carbon dioxide, pulsed are, fused are, submerged arc, electro slag and electron beam... 

Oxyacetylene Welding gas welding in which the fuel gas is acetylene and which is burnt in an oxygen atmosphere. 

Flame Cleaning Now little used as a preparatory method, flame cleaning is a process whereby an intensely hot oxyacetylene flame is played on the surface of the steel. In theory, differential expansion causes millscale to detach. In practice, there is evidence that the treatment may not remove thin, tightly adhering millscale. Also, steel less them 5 mm thick can buckle. Finally, the process can burn in chemicals deposited on the surface, causing premature paint failure. 

In this method an oxyacetylene or oxypropane flame is passed across the steel. The sudden heating causes millscale and other rust scales to flake off as a result of the differential expansion between the scale and the metal. In addition, any rust present is dehydrated. Immediately after the passage of the flame, any loose millscale and rust that remains is removed by wire brushing. This generally leaves a powdery layer which must also be removed by dusting down. 

Oxyacetylene torches used for welding reach temperatures near 2000°C. The reaction involved in die combustion of acetylene is... 

Calculate AH and AE at 25°C for the reaction that takes place when an oxyacetylene torch is used. 

Self-Test 6.16A Calculate the standard enthalpy of formation of ethyne, the fuel used in oxyacetylene welding torches, from the information in Tables 6.4 and 6.5. 

Detonation gun (D-gun) which uses the energy of continuous, controlled explosions of oxyacetylene mixtures to obtain the necessary kinetic energy. 

Because of its high chemical reactivity, acetylene has found wide use in synthesis of vinyl chloride, vinyl acetate, acrylonitrile, vinyl ethers, vinyl acetylene, trichloro- and tetrachloro-ethylene etc., in oxyacetylene cutting and welding, and as a fuel for atomic absorption instruments. 

A number of other deposition methods have been used for growing diamond, with varying degrees of success. These include oxyacetylene welding torches, arc jets and plasma torches, laser ablation and hquid phase crystallisation, but none of these yet reahstically compete with the hot filament or microwave systems for reliability and reproducibility. 

Cardiovascular effects have been noted in occupationally exposed workers after exposure to high levels of lead following exposure durations of as short as 4 weeks. Construction workers (race not specified) using oxyacetylene torches to cut a metal bridge that had been painted with lead-based paint were reported to exhibit increases in heart rate and blood pressure after 4 weeks of exposure (Marino et al. 

Oxo processes, 13 768 17 725 for amyl alcohols, 2 770-771 described, 2 36-41 major producers using, 2 29-3 It for producing odd-numbered higher alcohols, 2 1, 10 5 215-217 Oxo reaction, in higher olefins, 17 712 Oxosuccinic acid, 23 419 Oxprenolol, molecular formula and structure, 5 156t Ox-Tran instruments, 3 402 Oxyacanthine, 2 88 Oxyacetylene flame, 1 221 Oxy acids... 

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