430 Modern Welding and correct handling of oxygen and fuel gas equip- ment. Since many potential hazards exist when cutting, every welder must follow approved proce- dures to eliminate these dangers. Review applicable safety guidelines in Chapter 12. Cutting operations result in a considerable number of fl ying sparks, which are globules (ball-shaped parti- cles) of molten metal. The following guidelines help prevent accidents during cutting operations: ● Floors on which cutting is done should be concrete or other fi reproof material. ● Workbenches and other necessary shop furniture should be made of metal or other fi re-resistant material. ● Oil, paper, wood shavings, gasoline, lint, or other fl ammable materials should not be in the room where cutting is performed. ● Leather or slow-burning fabrics such as denim should be worn. Trousers should have no cuffs. Pockets and clothing should be inspected for possible fl ammable materials such as buttons, combs, plastic rules, matches, pencils, and other items. ● Objects being fl ame-cut may present additional hazards. Tanks and containers should be welded or cut only by an experienced welder. It is generally required to pass an inert gas or steam through the tank as it is being cut. The fl ow of steam or inert gas is intended to displace any combustible gases in the tank. This process is often required for hours prior to any attempted cutting operation. The tank may also be fi lled with water, except in the area of the work. In all cases, the tank must be vented to prevent the entrapment (holding) of potentially explosive gases. This work should never be done except under the supervision of a qualifi ed safety engineer. A small amount of fl ammable material in such a container or tank can cause a powerful explosion. ● Certain metals, such as magnesium, can burn with an explosive force if fl ame-cut. Be certain of what material is being cut. ● Face and hands must be protected from metal spatter. ● A fi re extinguisher for use in emergencies, should always be at hand while fl ame cutting. It is recommended that a fi re watch be posted during cutting operations. ● In Chapter 12, the correct procedures for setting up and handling cylinders, regulators, hoses, and torches were explained. Be sure to know these procedures. It is a good idea to review Chapter 12. ● Review metal fume hazards described in Chapter 12. Be sure to know what metal is being worked on before performing any oxyfuel gas cutting operation. Check that ventilation systems are working. Review safety information in Chapter 1. ● The normal atmosphere contains about 21% oxygen by volume. As the oxygen content in an enclosed space is increased above this percentage, there is an increasing danger of a spark or fl ame causing a fi re or explosion. ● Never use acetylene at a pressure greater than 15 psig (103kPa). Acetylene becomes unstable above that pressure and may explode.