Chapter 14 Oxyfuel Gas Cutting 431 Test Your Knowledge Write your answers on a separate sheet of paper. Do not write in this book. 1. What is the ignition temperature of a metal? 2. Is an oxyfuel gas cut smooth or rough when complete? 3. Are the preheat fl ames used after the cutting has begun? Why? 4. What is the purpose of the preheating jets or orifi ces in a cutting torch tip? When is the cutting oxygen valve opened? 5. What are the two types of fl ame-cutting torches called? 6. When adjusting pressures before lighting a cutting torch, why is it necessary to check the pressures with the torch cutting lever in the fully open position? 7. What oxygen and acetylene pressures are used when cutting 1/2″ (12.7mm) plate steel with a positive-pressure torch? 8. List two conditions that may cause the slag stream to lag behind the torch tip (drag). 9. What is meant by the terms “kerf” and “drag”? 10. When are two-piece cutting tips used? 11. Why is it necessary to provide a higher oxygen pressure with a cutting torch than with a welding torch? 12. If too much oxygen is used when cutting, the cut widens out and leaves a(n) _____ kerf. 13. Should the cutting torch be moved toward, from side to side, or away from the welder? 14. How should the cutting torch be held, in relation to the work, when cutting thin sheet steel? 15. Is it possible to cut a piece to shape and to place a bevel on the metal at the same time? 16. What determines the size tip to be used when cutting pipe? 17. When piercing a hole in a plate, how is the torch held in relation to the base metal? What are the requirements for preheat when piercing, compared to starting a cut on the edge of a plate? 18. How is it possible to cut off rivet heads without damaging metal plates that are riveted together? 19. Although automatic cutting machines are self- operating, what initial adjustments must be made by the operator to properly set up the machine? 20. List at least four safety precautions that must be accomplished before starting a fl ame-cutting operation.