Semiautomatic welding is becoming the most popular welding method. The electrode is usually a long length of small-diameter bare wire, usually in coil form, which the welding operator manually positions and advances along the weld joint. The consumable electrode is normally motor-driven at a pre selected speed through the nozzle of a hand-held welding gun or torch.
Automatic welding is very similar to semiautomatic welding, except that the electrode is automatically positioned and advanced along the prescribed weld joint. Either the work may advance below the welding head or the mechanized head may move along the weld joint.
There are, in addition to the three basic welding methods, many welding processes which may be common to one or more of these methods.
]]>This is a hazardous procedure. The hazard to the worker is due to the toxic gases generated by the thermal breakdown of the polurethane foam. The gases that eveolve from the buring foam depend on the amount of oxygen available. Combustion products of poplyurethane foam in a clean, hot fire with monoxide and traces of hydrogen cyanide.
Remember - all residue must be cleaned from the metal prior to welding.
]]>The main reference used for welding symbols is the joint. The joint is used to designate the type of weld to be made, its location, contour, extent, dimensiuons and other additional information. Any joint that is welded is indicated by a symbol and will have an arrow side and an other side.
The tail of the symbol is used for designating the welding and cutting processes as well as the welding specifications, procedures or the supplementary information to be used in making the weld. If a welder knows the size and type of weld, he only has part of the information necessary for making the weld. The process, identification or filler metal that is to be used, whether or not peening or root chipping is required and other pertinent data must be related to the welder.
]]>Oxygen and Acetylene are stored under pressure in steel cylinders . They are sized by the cuft. of either Oxygen or Acetylene that they hold.Cylinders should be tested regularly with the date of the last test stamped on the top of the cylinder. Cylinders should always be secured and used in the upright position. When a cylinder is not being used, remember that the valve cap should always be in place.