Preparing to Weld The fi rst requirement prior to welding is to check over the welding area and review the welding equipment for safety. Once all safety regulations have been reviewed and you are wearing the proper clothing and personal protective equipment, welding can begin. Set up the welding machine and review for safety as covered in Chapter 10. Determine the material to be welded. Select the appropriate type and size of electrode for your job. Chapter 11 covers information about electrodes, including suggested amperage and polarity. Guides published by electrode manufacturers also provide polarity and amperage information. Wear comfortable, fi re-resistant clothing for SMAW. Protect all areas of your skin from burns caused by arc rays or molten metal. Button shirts and jackets at the collar. Wear a cap to protect your head and hair. Wear gloves to protect your hands and forearms. Also, wear hard-toed, high- top shoes or boots. Avoid wearing pants with cuffs because hot metal or sparks can be caught in them. Do not wear clothing with ragged edges or loose threads. The edges and threads may catch fi re easily. Make a visual safety inspection of your welding outfi t or station. Refer to Chapter 10 for information about inspecting a welding outfi t. SMAW Safety Precautions Arc welding presents dangers of electrical shock, fumes and gases, hot metal, arc rays, and fi re. The importance of safety precautions cannot be stressed enough. The application of proper safety precautions prevents injury to personnel and damage to equipment. Safety precautions that may be applied to all forms of arc welding include: • Always have qualifi ed people perform all installation, maintenance, and repair work on equipment and electrical circuits. • Do not touch the electrode and the workpiece or worktable at the same time with bare skin, wet gloves, or wet clothing. The electrode and work circuits are hot (voltage is present) when the welding machine is on. • Do not weld on damp or metal fl oors. If welding must be done on a damp or metal fl oor, be certain you are insulated from it. • Keep the welding machine, welding cables, electrode holder, lugs, and clamps in safe working order. • Connect the worktable or workpiece to a good electrical ground. • Never make polarity or current range changes on the welding machine while the machine is under load. Under load means current is fl owing for welding or the electrode holder is touching the table or workpiece. • Avoid breathing hazardous fumes or gases while welding. Fumes should be removed from the weld area before they pass the welder’s face. • Use extra ventilation or wear a supplied air breathing apparatus (positive-pressure respirator) when welding on lead, cadmium, or galvanized (zinc-coated) metals. These metals produce toxic or poisonous fumes. • Do not weld near degreasing or cleaning chemicals that contain chlorinated hydrocarbons. Arc welding rays and the heat of the arc can react with these solvents to produce phosgene gas. Phosgene gas is a highly toxic and poisonous gas. Parts cleaned with chlorinated hydrocarbons must be thoroughly rinsed to remove these cleaning agents. • Always wear clothing that is fl ame-resistant for protection from fi re, molten metal, and harmful arc rays. Arc rays can cause skin burns on exposed skin. Clothing must cover all parts of the body. Wear clean, oil-free clothing, such as leathers. Wear a cap, gloves, high-top shoes, and pants without cuffs. • Never look at an arc without the proper eye protection. Arc rays can cause permanent eye damage. • Always use an arc welding helmet with the proper fi lter lens in place. • Set up nonfl ammable screens around weld areas. The screens protect others in the area from arc rays and metal spatter. • Remove all fl ammable or explosive materials from welding areas. Fire extinguishers should be available. 168 Section 2 Shielded Metal Arc Welding Copyright Goodheart-Willcox Co., Inc.