What is Gas Welding? • Gas Welding relies on the combustion of fuel gases, usually Oxygen and Acetylene to heat metals at the welding point • Widely used in welding tubes and pipes • Commonly referred to as oxyacetylene welding
Main Components of Gas Welding • Oxygen and Fuel Cylinders • Two-stage Regulators (one per tank) • Two Hoses • Green (Oxygen) • Red (Fuel) • Check Valve • Non-return Valve • Welding Torch
Dangers of Gas Welding • Burns • Eye Damage • Retinal burning and cataracts • Heat Exposure • Torch burns at around 6000° F
Dangers of Gas Welding • Asphyxiation • Leaks of poisonous gases • Confined space welding without proper ventilation • Explosions/Fire • Due to ignition of leaking gases • Acetylene very unstable when stored above 15 psi
OSHA RegulationsHighlights- Subpart J • Transportation • 1926.350(a)(1) Valve protection caps shall be in place and secured. • (2) When cylinders are hoisted, they shall be secured on a cradle, slingboard, or pallet. They shall not be hoisted or transported by means of magnets or choker slings. • (3) Cylinders shall be moved by tilting and rolling them on their bottom edges. They shall not be intentionally dropped, struck, or permitted to strike each other violently. • (9) Compressed gas cylinders shall be secured in an upright position at all times except, if necessary, for short periods of time while cylinders are actually being hoisted or carried.
OSHA RegulationsHighlights- Subpart J • Storage and Placement • (10) Oxygen cylinders in storage shall be separated from fuel-gas cylinders or combustible materials (especially oil or grease), a minimum distance of 20 feet (6.1 m) or by a noncombustible barrier at least 5 feet (1.5 m) high having a fire-resistance rating of at least one-half hour. • 1926.350(b)(3) Fuel gas cylinders shall be placed with valve end up whenever they are in use. They shall not be placed in a location where they would be subject to open flame, hot metal, or other sources of artificial heat. • (4) Cylinders containing oxygen or acetylene or other fuel gas shall not be taken into confined spaces.
OSHA RegulationsHighlights- Subpart J • Welding Process • 1926.352(a) When practical, objects to be welded, cut, or heated shall be moved to a designated safe location or, if the objects to be welded, cut, or heated cannot be readily moved, all movable fire hazards in the vicinity shall be taken to a safe place, or otherwise protected. • (g) For the elimination of possible fire in enclosed spaces as a result of gas escaping through leaking or improperly closed torch valves, the gas supply to the torch shall be positively shut off at some point outside the enclosed space whenever the torch is not to be used or whenever the torch is left unattended for a substantial period of time, such as during the lunch period. Overnight and at the change of shifts, the torch and hose shall be removed from the confined space. Open end fuel gas and oxygen hoses shall be immediately removed from enclosed spaces when they are disconnected from the torch or other gas-consuming device. • (i) Drums containers, or hollow structures which have contained toxic or flammable substances shall, before welding, cutting, or heating is undertaken on them, either be filled with water or thoroughly cleaned of such substances and ventilated and tested.
Injury Statistics • Nearly 365,000 welding-related eye injuries occur annually • An estimated cost to employers of $467 million annually • More than half of injured workers returning to work in less than two days and 95 percent in less than seven days • Deaths occur annually due to explosions, falls while welding and burns http://www.ohsonline.com/articles/46296/
Specific ExamplesExcel Data 1991-2004 • Employee #1 connected a high-pressure oxygen bottle to welding equipment without installing a regulator to control the oxygen pressures to the system and oxygen manifold. Pressure built up and the manifold ruptured, killing employee #1. • At approximately 3:30 p.m. on June 28, 1993, employee #1 was in a front end loader bucket using an oxygen/acetylene welding torch to cut off nuts from a panel on the side of an asphalt storage tank. An explosion occurred. Employee #1 died from his injuries on July 2, 1993, at approximately 10:00 a.m.
Specific ExamplesExcel Data 1991-2004 • Employee #1, a self-employed welder, was welding rebar onto a steel structure of a building in order to hang brooms. There was a flash and then a fireball, and a series of explosions. Employee #1 was burned on 91 percent of his body. He died approximately two days later. • Employee #1 was installing a catwalk on a fuel tank when a spark from the welding torch set off an explosion in the tank. No part of the catwalk was supposed to be welded directly to the tank. The explosion may have been caused by a welding spark or by hot slag that came in contact with fuel vapors escaping through the opening of the tank at the cover plate.
Proper Gas Welding Procedures • Inspect equipment for wear and leaks • Replace bad hoses • Use flint lighter to ignite flame • Open cylinder valves very slowly to keep sudden high pressures from exploding the regulators http://www.cdc.gov/nasd/docs/d001601-d001700/d001691/d001691.html
Proper Gas Welding Procedures • Open and light acetylene first, then open and adjust oxygen to a neutral flame • When finished, close valves, bleed the lines, neatly coil hoses and replace equipment. • Have a fire extinguisher accessible http://www.cdc.gov/nasd/docs/d001601-d001700/d001691/d001691.html
PPE Requirements • Safety goggles or welding helmet with filter shade 5 required for gas welding • Flame resistant hand coverage or gloves • Maximum clothing coverage and protection • Flame resistant • Woolen Material • Proper fall protection when necessary
Be Smart, Weld Safe! For more information, please visit “Fundamentals of Professional Welding” http://184.108.40.206/sweethaven/BldgConst/Welding/lessonmain.asp?lesNum=4&modNum=1