UW-Eau Claire Facilities Planning & Management 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 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 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 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 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 Oxygen-fuel gas welding and cutting
UW-Eau Claire Facilities Planning & Management 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 Oxygen-fuel gas welding and cutting
UW-Eau Claire Facilities Planning & Management 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. Oxygen-fuel gas welding and cutting
UW-Eau Claire Facilities Planning & Management Service Pipe Systems –There are special requirements for service pipe systems when using oxygen or acetylene. Oxygen Acetylene or Acetylene Compounds Oxygen-fuel gas welding and cutting
UW-Eau Claire Facilities Planning & Management 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. Oxygen-fuel gas welding and cutting
UW-Eau Claire Facilities Planning & Management 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. Oxygen-fuel gas welding and cutting
UW-Eau Claire Facilities Planning & Management 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. Oxygen-fuel gas welding and cutting
UW-Eau Claire Facilities Planning & Management 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 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. Arc Welding & Cutting
UW-Eau Claire Facilities Planning & Management 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 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. Arc Welding & Cutting
UW-Eau Claire Facilities Planning & Management 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 Resistance Welding Note: FP&M only does spot welding.
UW-Eau Claire Facilities Planning & Management 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 Resistance Welding
UW-Eau Claire Facilities Planning & Management 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 Welding/Cutting Hazards Potential Hazards Cont.: –Metal fumes from vaporizing of the work with the extremely hot arcs may be inhaled into the workers 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 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 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 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 Tungsten Inert Gas Welding (TIG)
UW-Eau Claire Facilities Planning & Management 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 Shielding Gases: Inert –Argon, Helium »Used for aluminum alloys and stainless steels. Active –1 to 5% Oxygen, 3 to 25% CO 2 »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. Gas Metal Arc Welding (MIG) Cont.
UW-Eau Claire Facilities Planning & Management 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 Benefits Simple, portable,& inexpensive Self flux provided by electrode Provides all position flexibility Shielding Gases No shield gases added Lower sensitivity to Wind Shielded Metal Arc Welding (SMAW)/Stick Welding
UW-Eau Claire Facilities Planning & Management 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). Shielded Metal Arc Welding (SMAW)/Stick Welding Cont.:
UW-Eau Claire Facilities Planning & Management 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: Cutting
UW-Eau Claire Facilities Planning & Management 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 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 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 Manufactures specifications. Avoid electrical shock DONT wrap cables around any body part. Ensure fittings are tight.
UW-Eau Claire Facilities Planning & Management 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 employees – DONT block your exit. Ensure that adequate ventilation and lighting are in place.
UW-Eau Claire Facilities Planning & Management 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 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 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 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 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
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
UW-Eau Claire Facilities Planning & Management Any Questions ??