Hand-held blow pipes

84.68 Machinery and apparatus for soldering, brazing or welding, whether or not capable of cutting, other than those of heading 85.15; gas-operated surface tempering machines and appliances. 8468.10 - Hand-held blow pipes - Other gas-operated machinery and apparatus 8468.80 - Other machinery and apparatus 8468.90 - Parts 8468.20 The heading covers : and apparabs, whether or not ca able of cutting, those refared to in the text o heading 85.15. classified in their own appropriate headings. ? (B) Gas-operated surface tempering machines and appliances. (I) GAS-OPERATED APPLIANCES FOR WO-G METAL, ETC. The appliances of this group are operated by means of a very hot flame produced by the combustion of an inflammable gas in a jet of oxygen or air. In general, these appliances can be used not on1 for the operations referred to in the heading, but also for other operations requiring a similar i igh temperature (e.g., preliminary heating for certain operations, or refilling worn parts or cavities with metal); in ractice certaln appliances are specialised for these other operations, but they remain in this hea ng provided they operate in the same manner and on the same principle as the other appliances of the headmg. All the appliances of this group have an arrangement for bringing two gases to the nozzle which has two outlets, either concentric or side by side; one of the gases is inflammable (acetylene, butane, propane, coal gas, hydrogen, etc.) and the other compressed air or oxygen. The heading covers hand-operated appliances and also machines. (A) HAND-OPERATED GAS WELDING, ETC., APPLIANCES (BLOWPIPES) Blowpipes are said to be of high- ressure or low-pressure type de ending on whether they are designed to be connected to a \igh or low-pressure source o inflammable as. In the high- ressure type, the compression gives the gas the velocity required to produce t e flame jet; wlth e low-pressure type a compressor is necessary. P % Both types of blowpi es are otherwise of more or less similar construction. In design, they consist of a handle or ody fitted with the supply pipes, at the exit of which (the nozzle) the gas is ignited; they general1 also include regulating valves, etc. The apparatus is connected to an external gas supply by ?f exible tubing. E To enable the appliances to be adapted to the e of work concerned (e.g., to blast-furnace tapping, rivet removin , grooving or simple eating) the tubes and nozzles are usually interchangeable (variab e aperture nozzles, multiple nozzle orifices, flame-separatin nozzles, etc.). Some blowpipes are specially designed for particular operations, e.g., welding lowpipes equipped with a water-cooling system, for heavy work. T P % (B) MACHINES FOR WELDING, ETC. These are based on the same principles as the hand-operated appliances in Part (A) above, and consist essentially of fixed or adjustable blowpipes. Other parts of the machine (e.g., feed-tables, jaws, slide-rests and 'ointed arms) either enable the part being worked to be fixed, guided or moved forward, or a low the nozzles to be moved or adjusted according to the progress of the work. / (C) SURFACE TEMPERING MACHINES These consist of a number of nozzles arranged according to the shape of the object to be treated; the flames from these nozzles project on to the surface to be tempered a heat of such intensity that it is rapidly brought to the temperature required, but this heat does not penetrate far below the surface. Once the surface has been brought to the re uired tempering temperature, sprays of cooling liquid are directed on the article or it is immerse in a bath of the liqu~d. (11) GAS-OPERATED APPLIANCES FOR WELDING THERMOPLASTICS This heading also includes certain a pliances for welding or sealin thermoplastic materials or articles thereof. The a pliances of &s headin operate by means o a flame or a jet of hot air, nitrogen or inert gas %om a welding torch. &e air or other gases may be heated by passage through a gas-heated tube. ? (111) MACHINERY AND APPARATUS FOR WELDING, OTHER THAN GAS-OPERATED APPLIANCE This group includes : (1) Machinery and mechanical appliances for welding by means of grooved wheels or heated irons, other than hand soldenng irons (heading 82.05) and other than electrical apparatus of heading 85.15. (2) Friction welding machines. PARTS Sub'ect to the general provisions regarding the classification of parts (see the General Exp anato Note to Section XVI), the heading also covers parts of the machines and apparatus of this hcaTmg. The heading also includes accessory attachments such as supports (ball, roller, etc.). The heading also excludes : (a) Blow lamps and brazing lamps of heading 82.05. (b) Machinery and apparatus for spraying molten metal (heading 84.24). (c) Apparatus for cutting or piercing rock or concrete, using the high temperature produced by burning iron or steel in a jet of oxygen (heading 84.79). (d) Welding, brazing or soldering machines and apparatus, using both gas and electricity (heading 85.15).