Welding, Cutting and Brazing

1. Welding, Cutting and Brazing 29 CFR 1910.251 & 1926.350 Subpart Q & J By: Chou Lor, Safety Coordinator UW-Eau Claire Facilities Planning & Management

2. Welding, Cutting and Brazing • Training Objectives • Three Specific Types of Welding Modules • Methods of Arc Welding • Welding Hazards • Safe Work Practices • Fire Protection & Prevention • Proper Ventilation for Welding • Welding Operators Protection UW-Eau Claire Facilities Planning & Management

3. Three Specific Types of Welding Modules • In this Welding, Cutting, and Brazing module, three specific types of welding are covered. These are listed below: • Oxygen-fuel gas welding and cutting • Arc welding and cutting • Resistance welding UW-Eau Claire Facilities Planning & Management

4. Oxygen-fuel gas welding & Cutting • The elements of Oxygen-fuel gas welding and cutting: • General Requirements • Cylinders • Service Pipe Systems • Pipe System Protection UW-Eau Claire Facilities Planning & Management

5. Oxygen-fuel gas welding and cutting • General Requirements • Focuses on using Acetylene Safely • Flammable • Unstable • Cannot be adjusted above 15 psi • Safe Work Practices • Blow out cylinder valve • Turn on cylinder valve first and then adjust the regulator pressure screw. • Never stand in front or behind a regulator when opening the cylinder valve • Open cylinder valve slowly • The pressure adjusting screw: • Turning clockwise allows the gas allows to flow. • Turning counterclockwise reduces or stop the gas flow. UW-Eau Claire Facilities Planning & Management

6. Oxygen-fuel gas welding and cutting • General Requirements Cont.: • Safe Work Practices • Purge oxygen and acetylene passages • Light the acetylene • Never use oil or grease • Do not use oxygen as a substitute for air • Keep your work area clean UW-Eau Claire Facilities Planning & Management

7. Oxygen-fuel gas welding and cutting • Cylinders • Cylinder approval and marking • marked for the purpose of identifying the gas content, with either the chemical or trade name of the gas • Storage of cylinders • Storage area must be well ventilated • Cylinders must be at least 20 feet from combustibles • Valves must be closed • Valve protection must be in place • Inside storage must be limited to 2,000 cubic feet. • Cylinders must be stored in upright position • Oxygen must be at least 20 feet from fuel gas or 5 feet with a 1/2 hour fire barrier • Separate oxygen from fuel gas UW-Eau Claire Facilities Planning & Management

8. Oxygen-fuel gas welding and cutting • Cylinders Cont.: • Operating Procedures • Operation must emphasize the absence of oily or greasy substances. Follow these rules of operation: • Cylinders, cylinder valves, couplings, regulators, hose, and apparatus shall be kept free from oily or greasy substances. • Oxygen cylinders or apparatus shall not be handled with oily hands or gloves. • A jet of oxygen must never be permitted to strike an oily surface, greasy clothes, or enter a fuel oil or other storage tank. UW-Eau Claire Facilities Planning & Management

9. Oxygen-fuel gas welding and cutting • Service Pipe Systems • There are special requirements for service pipe systems when using oxygen or acetylene. • Oxygen • Acetylene or Acetylene Compounds UW-Eau Claire Facilities Planning & Management

10. Oxygen-fuel gas welding and cutting • Pipe System Protection • The entire service pipe system must be protected against build-up of excessive pressure and leaks. This protection is accomplished with: • Protective equipment • Regulators • Proper hose and hose connections. UW-Eau Claire Facilities Planning & Management

11. Oxygen-fuel gas welding and cutting • Pipe System Protection Cont.: • Protective equipment is divided into the two categories listed here: • Pressure Relief Devices • The pressure relief device should discharge upwards to a safe location. • Pressure relief valves are required in fuel-gas piping systems to prevent excessive pressure build up within the system. UW-Eau Claire Facilities Planning & Management

12. Oxygen-fuel gas welding and cutting • Pipe System Protection Cont.: • Approved protective equipment shall be installed in fuel-gas piping to prevent: • Backflow of oxygen into the fuel-gas supply system • Passage of a flash back into the fuel-gas supply system • Excessive back pressure of oxygen in the fuel-gas supply system. UW-Eau Claire Facilities Planning & Management

13. Arc Welding and Cutting • Definition: • A fusion process wherein the coalescence of the metals is achieved from the heat of an electric arc formed between an electrode and the work. • Application • Installation • Operation & Maintenance UW-Eau Claire Facilities Planning & Management

14. Arc Welding & Cutting • Application • Applies to a large and varied group of processes that use an electric arc as the source of heat to melt and join metals. • Installation • Arc welding requires proper installation of equipment. • A critical part of installation is ensuring that proper grounding is completed. UW-Eau Claire Facilities Planning & Management

15. Arc Welding & Cutting • Operation & Maintenance • All connections to the machine shall be checked to make certain that they are properly made. • The work lead shall be firmly attached to the work. • Magnetic work clamps shall be free from adherent metal particles of spatter on contact surfaces. • Coiled welding cable shall be spread out before use to avoid serious overheating and damage to insulation. UW-Eau Claire Facilities Planning & Management

16. Arc Welding & Cutting • Operation and Maintenance Cont.: • During welding operations, cables with splices within 10 feet (3m) of the holder shall not be used. • Welders should not coil or loop welding electrode cable around parts of their body. • Cables with damaged insulation or exposed bare conductors shall be replaced. • Joining lengths of work and electrode cables shall be done by the use of connecting means specifically intended for that purpose. • The connecting means shall have insulation adequate for the service conditions. UW-Eau Claire Facilities Planning & Management

17. Resistance Welding • Definition: • This is a group of fusion welding processes that use heat and pressure to make the coalescence. • The heat comes from electrical resistance to current flow at the site of the weld. • The processes include: • Spot Welding • Projection Welding • Seam Welding Note: FP&M only does spot welding. UW-Eau Claire Facilities Planning & Management

18. Resistance Welding • Spot Welding • A process typically used in high-volume, rapid welding applications. • The pieces to be joined are clamped between two electrodes under force, and an electrical current is sent through them. • The advantages of spot welding are many and include the fact that it is: • An economical process • Adaptable to a wide variety of materials including low carbon steel, coated steels, stainless steel, aluminum, nickel, titanium, and copper alloys • Applicable to a variety of thicknesses • A process with short cycle times • A robust process • Tolerant to fit-up variations UW-Eau Claire Facilities Planning & Management

19. Welding/Cutting Hazards • Potential Hazards • Fires may start by hot materials igniting nearby combustibles. • Burns to the operator may occur if unprotected skin comes into contact with the extremely hot work. • Magnetic fields could easily destroy/disrupt electronic components, stored data if not careful. UW-Eau Claire Facilities Planning & Management

20. Welding/Cutting Hazards • Potential Hazards Cont.: • Metal fumes from vaporizing of the work with the extremely hot arcs may be inhaled into the worker’s lungs. • Certain metals and metal oxide fumes, including zinc, cadmium and beryllium, produce serious illnesses when inhaled. • Fluxes used with welding to create inert atmospheres at the point of the weld also present inhalation hazards. • All welding and cutting must have adequate ventilation to protect the person doing the welding and those working around the welding area. UW-Eau Claire Facilities Planning & Management

21. Methods of Arc Welding • Three Types of Welding Methods: • Tungsten Inert Gas Welding (TIG) • Gas Metal Arc Welding (MIG) • Shielded Metal Arc Welding (SMAW)/ Stick Welding UW-Eau Claire Facilities Planning & Management

22. Tungsten Inert Gas Welding (TIG) • Definition: • TIG welding is an arc that is formed between a non-consumable tungsten electrode and the metal being welded. • Gas is fed through the torch to shield the electrode and molten weld pool. • Benefits: • Welds with or without filler metal • Precise control of welding variables (heat) • Low distortion • Shielding Gases: • Argon • 2 to 5% Hydrogen • w/Helium UW-Eau Claire Facilities Planning & Management

23. Tungsten Inert Gas Welding (TIG) • Applications • Most commonly used for aluminum and stainless steel • For steel • Slower and more costly than consumable welding • Except for thin sections or where very high quality is needed UW-Eau Claire Facilities Planning & Management

24. Gas Metal Arc Welding (MIG) • Definition: • The heat source is formed by creating an electric arc between the work piece and a wire, which is fed continuously into the weld pool. • Benefits: • Long welds can be made without starts and stops • Minimal skill required • Minimal cleaning of surface before weld • Allows welding in all positions UW-Eau Claire Facilities Planning & Management

25. Gas Metal Arc Welding (MIG) Cont. • Shielding Gases: • Inert • Argon, Helium • Used for aluminum alloys and stainless steels. • Active • 1 to 5% Oxygen, 3 to 25% CO2 • Used for low and medium carbon steels • Applications • Gas Metal Arc Welding (MIG) is used to weld all commercially important metals, including steel, aluminum, copper, and stainless steel. UW-Eau Claire Facilities Planning & Management

26. Shielded Metal Arc Welding (SMAW)/Stick Welding • Definition: • Consumable electrode coated with chemicals that provide flux and shielding • The filler metal (here the consumable electrode) is usually very close in composition to the metal being welded. UW-Eau Claire Facilities Planning & Management

27. Shielded Metal Arc Welding (SMAW)/Stick Welding • Benefits • Simple, portable,& inexpensive • Self flux provided by electrode • Provides all position flexibility • Shielding Gases • No shield gases added • Lower sensitivity to Wind UW-Eau Claire Facilities Planning & Management

28. Shielded Metal Arc Welding (SMAW)/Stick Welding Cont.: • Applications • Construction, pipelines, shipbuilding, fabrication job shops. • Used for: Steels, stainless steels, cast irons. • Not used for aluminum and its alloys, or copper and its alloys (energy density is too high). UW-Eau Claire Facilities Planning & Management

29. Cutting • Definition: • A stream of oxygen is directed against a piece of heated metal, causing the metal to oxidize or burn away. • Making a Cut • Mark a line as a guide. • Turn on acetylene as for welding and light. • Turn on oxygen adjusting flame to neutral. • Make sure the oxygen lever flame remains neutral. • Place metal on the cutting table so metal will fall clear. • Flame Types: Oxidizing Carborizing Neutral UW-Eau Claire Facilities Planning & Management

30. Brazing • Definition: • A process which a filler metal is placed at or between the faying surfaces, the temperature is raised high enough to melt the filler metal but not the base metal. • The molten metal fills the spaces by capillary attraction. • Torch Brazing • Oxy-fuel torch with a carburizing flame • First heat the joint then add the filler metal UW-Eau Claire Facilities Planning & Management

31. Safe Work Practices • Electric & Gas Welding • Safety Check: • Ensure electrical cord, electrode holder and cables are free from defects • No cable splices within 10 feet of electrode holder. • Ensure welding unit is properly grounded. This helps to avoid over heating. • All defective equipment shall be repaired or replaced before using. UW-Eau Claire Facilities Planning & Management

32. Safe Work Practices • Electric & Gas Welding Cont.: • Safety Check: • Remove all jewelry – rings, watches, bracelets, etc… • Ensure PPE e.g.. welding hood, gloves, rubber boots or safety shoes, apron are available and in good condition. • Ensure fire extinguisher is charged and available. • Ensure adequate ventilation and lighting is in place. • Set Voltage Regulator to Manufacture’s specifications. • Avoid electrical shock DON’Twrap cables around any body part. • Ensure fittings are tight. UW-Eau Claire Facilities Planning & Management

33. Safe Work Practices • Electric & Gas Welding Cont.: • Safety Check: • Inspect hoses for cuts and frayed areas. • Set gauges to desired PSI. • Ensure that sufficient PPE is made available. • Locate welding screens to protect employee’s – DON’Tblock your exit. • Ensure that adequate ventilation and lighting are in place. UW-Eau Claire Facilities Planning & Management

34. Fire Protection & Prevention • Fire hazards must be removed, or • Guards installed, or • Welding/cutting must NOT take place • Hot work permit should be used outside designated areas to ensure that all fire hazards are controlled • Use of fire watch • 1/2 hour after operation ceases UW-Eau Claire Facilities Planning & Management

35. Fire Protection & Prevention Cont.: • Welding areas should meet the following requirements: • Floors swept & cleared of combustibles 35 ft. radius of work area. • Flammable and combustible liquids kept 35 ft. radius of work area. • At least one fire extinguisher – on site • Protective dividers to contain sparks and slag • Welding curtains • Non-combustible walls • Fire resistant tarps & blankets UW-Eau Claire Facilities Planning & Management

36. Proper Ventilation for Welding • Ventilation • Proper ventilation can be obtained either naturally or mechanically. • Natural Ventilation is considered sufficient for welding and brazing operations if the present work area meets these requirements: • Space of more than 10,000 square feet is provided per welder • A ceiling height of more than 16 feet. • Mechanical ventilation options generally fall into two basic categories. • Low vacuum system which takes large volumes of air at low velocities. • High vacuum system that are captured and extracted fumes as near to the work as possible. UW-Eau Claire Facilities Planning & Management

37. Proper Ventilation for Welding • Ensure protection from fumes and gases by one or a combination of the following: • Good general ventilation. • Use of a booth. • Local exhaust ventilation on the hand piece. • Air supply to the helmet. UW-Eau Claire Facilities Planning & Management

38. Welding Operators Protection • Welding involves specialized personal protection that must be worn every time you perform welding operations. The following is a list of basic PPE: • Fire-resistant gloves • Aprons • Safety shoes • Helmet • Ultraviolet radiation filter plate (arc welding) • Goggles with filter lenses UW-Eau Claire Facilities Planning & Management

39. Welding, Cutting and Brazing • Summary • Major hazards include: • Fire • Burns • Shock • Toxic Exposure • Follow proper procedures to prevent fires • Use appropriate engineering controls • Wear appropriate PPE UW-Eau Claire Facilities Planning & Management

40. Any Questions ?? Please visit FP&M Website (www.uwec.edu/facmgt./index.htm) for additional information. UW-Eau Claire Facilities Planning & Management