Chapter 15 Oxyfuel Gas Cutting 421 Copyright Goodheart-Willcox Co., Inc. Pro Tip The very tip of the light blue inner cone is the hottest area of a neutral flame. This is why maintaining the proper distance between the inner cone and the base metal is important in oxyfuel welding and cutting. 15.5.2 Cutting Thick Steel Steel over 1/2″ (13 mm) thick should be cut by holding the torch so the tip is perpendicular to the surface of the base metal being cut. See Figure 15-19. A cut is normally started at the edge of the stock. See Figure 15-20. The torch can be moved from left to right, or from right to left. Either direction is good if it permits the welder to look into the kerf and check cutting progress. If a line of travel is chalked on the metal, torch movement from right to left enables a right-handed welder to most easily follow the guide- lines on the metal. When cutting thick steel, remember that the thicker the steel, the greater the time that is required to raise the temperature of the steel high enough to make clean cuts. The heat must be applied in a broad area around the cut, Figure 15-21A. After the steel has been heated to a dull cherry red, cutting begins when the oxygen jet is opened by pressing on the cut- ting lever. See Figure 15-21B. As soon as the cutting action starts, the torch tip is moved at a steady rate. See Figure 15-22. Direction torch movement 70°–75° Goodheart-Willcox Publisher Figure 15-18. Recommended procedure for cutting thin steel. The two preheat flames are aligned with the cut. Section A-A Front View Travel 90° A A Side View 90° Goodheart-Willcox Publisher Figure 15-19. A recommended technique for cutting thick steel. Note the position of the torch tip preheat orifices in relation to the line of the cut. Two preheat flames are in the line of the torch progress. This position enables one preheat flame to be ahead of the cut, two flames to heat the sides of the cut, and one flame to heat down in the kerf.