Safe Practices

Safety Lesson Objectives When you finish this lesson you will understand: Safe practices and cautions when working around welding Learning Activities 1.View Slides; 2.Read Notes, 3.Listen to lecture 4.Do on-line workbook 5.Do homework Keywords Gas Cylinder, Protective Clothing, Eye Filter Plate Number, Fumes, Gases, Ventilation, Toxic Materials, Fires, Fire Extinguishers, Radiography

Safe Practices Training Read & understand Manufacturer’s Data Sheets Read & understand Material safety data sheets (MSDS) Read & understand AWS precautionary labels

AWS Welding Handbook

General Housekeeping Protect Vision Of others (protective screens) Of welder (considered below) Wall Reflectivity (TiO 2 & ZnO pigment) Remove tripping objects on floor Provide safe walkways and designated work areas For above ground work provide railings provide safety line and harness Prepare for unexpected events (escape routs) Fire Explosion Proper storage of goods and equipment Proper hook up of equipment

Welding Arcs Emit powerful visible and ultra-violet (UV) light Can cause burns on the skin similar to sunburn and severe irritation of the eyes –Shield bare hands, arms, and neck from the arc –Use an appropriate level of shielding glass GTAW, current A (minimum 8, suggested 12) Oxygen cutting, plate thickness < 1inch (suggested 3 or 4) Should not be operated near degreasing baths – UV light can decompose the vapor to form poisonous gas Health and Safety T

AWS Welding Handbook

General Housekeeping Protect Vision Of others (protective screens) Of welder (considered below) Wall Reflectivity (TiO 2 & ZnO pigment) Remove tripping objects on floor Provide safe walkways and designated work areas For above ground work provide railings provide safety line and harness Prepare for unexpected events (escape routs) Fire Explosion Proper storage of goods and equipment Proper hook up of equipment

General Housekeeping Protect Vision Of others (protective screens) Of welder (considered below) Wall Reflectivity (TiO 2 & ZnO pigment) Remove tripping objects on floor Provide safe walkways and designated work areas For above ground work provide railings provide safety line and harness Prepare for unexpected events (escape routes) Fire Explosion Proper storage of goods and equipment Proper hook up of equipment

Fires Sparks & spatter can ignite (remove flammable materials) Oxygen Enrichment (Normal air contains 21% oxygen) Some dust and metal chips are highly explosive (Al, Mg, etc) Detect it Rescue all persons at risk Prevent it spreading Extinguish it Combustible Material Source of Ignition Oxygen

Class A Fires involving solid materials, usually of an organic nature, in which combustion takes place with the formation of glowing embers Class B Fires involving flammable liquids, liquefiable solvents and flammable gases Class c Fires involving energized electrical equipment Class D Fires involving combustible metals

Balchin & Castner, “Health & Safety…”, McGraw Hill, 1993

General Housekeeping Protect Vision Of others (protective screens) Of welder (considered below) Wall Reflectivity (TiO 2 & ZnO pigment) Remove tripping objects on floor Provide safe walkways and designated work areas For above ground work provide railings provide safety line and harness Prepare for unexpected events (escape routs) Fire Explosion Proper storage of goods and equipment Proper hook up of equipment

Balchin & Castner, “Health & Safety…”, McGraw Hill, 1993

AWS Welding Handbook

Gas Cylinder Safety No oil or grease in connections Left handed threads = flammable Asphyxiation –Confined spaces –Heavy gases (argon, carbon dioxide)collect in pits, tanks Acetylene –Never use copper fittings –Special fire precautions Health and Safety T

Balchin & Castner, “Health & Safety…”, McGraw Hill, 1993

Balchin & Castner, “Health & Safety…”, McGraw Hill, 1993

Balchin & Castner, “Health & Safety…”, McGraw Hill, 1993

Balchin & Castner, “Health & Safety…”, McGraw Hill, 1993

Balchin & Castner, “Health & Safety…”, McGraw Hill, 1993 Protective Cap On Tank Secured

Personal Protection Clothing Ear and Eye Protection Protection from Fumes and Gases Electrical Shock Protection Protection from X-ray on Inspection

Protective Clothing Sturdy Shoes/Boots Woolen or Treated Cotton Clothing (no synthetic or plastic) Cuffless pants (pockets covered) Cap for hair protection Leather gloves Aprons, leggings, sleeves,caps Ear protection from noise Eye Protection Goggles Helmet with UV lens

AWS Welding Handbook

Balchin & Castner, “Health & Safety…”, McGraw Hill, 1993

Balchin & Castner, “Health & Safety…”, McGraw Hill, 1993

Balchin & Castner, “Health & Safety…”, McGraw Hill, 1993 Noise Control

Balchin & Castner, “Health & Safety…”, McGraw Hill, 1993 UV Shield

AWS Welding Handbook

Balchin & Castner, “Health & Safety…”, McGraw Hill, 1993

Balchin & Castner, “Health & Safety…”, McGraw Hill, 1993

Fumes and Gases Fumes are the solid particles –Large particles settle out –Small particles may be filtered out –Measured in milligrams per cubic meter Gases act as the carrier of the fumes and are generally invisible –Measured in parts per million Threshold limit values (TLV) Health and Safety T

Fumes (Products of volatilization, reaction, oxidation of consumables, base metals, coatings and atmospheric contaminants.) Composition and Quality depend on: Base metal composition Process used Consumable used Coating on work (paint, galvanized, plating) Contaminates in atmosphere (hydrocarbon cleaning)

Balchin & Castner, “Health & Safety…”, McGraw Hill, 1993

Potentially Hazardous Gases Carbon monoxide Fluorides Nitrogen oxides Ozone Phosgene (decomposition products of hydrocarbons) Simple Asphyxiates Helium Argon Carbon dioxide Nitrogen

Factors Affecting Gas & Fume Generation Rates Welding Current E6010 E7018 Arc Voltage (arc length) Type of metal transfer or process Shielding Gas higher with CO 2 more with He than Ar Welding Process Consumables See p 528 for more info

Highly Toxic Materials Materials with exposure limits of 1.0 mg/m 3 or less Antimony Arsenic Barium Beryllium Cadmium Chromium Cobalt Copper Lead Manganese Mercury Nickel Selenium Silver Vanadium The next table lists some possible sources of these

AWS Welding Handbook

Ventilation Open air and shop ventilation Local fume extraction Dust respirator Air-fed welding helmet Health and Safety T

Balchin & Castner, “Health & Safety…”, McGraw Hill, 1993

AWS Welding Handbook

Balchin & Castner, “Health & Safety…”, McGraw Hill, 1993

Balchin & Castner, “Health & Safety…”, McGraw Hill, 1993

Balchin & Castner, “Health & Safety…”, McGraw Hill, 1993

Water Table for Fume Control when Cutting

Work on Vessels Contaminated by Hazardous Materials Step 1: Remove hazardous material Step 2: Cleaning Water Cleaning Chemical Cleaning Steam Cleaning Mechanical Cleaning Combined methods Balchin & Castner, “Health & Safety…”, McGraw Hill, 1993

Step 3: Making vessel non-explosive and non-flammable Replace air in vessel with inert gas or water

Electrical Safety Sources Welding power supplies Instrumentation Water reduces resistance Proper Grounding The work lead is not the grounding lead Other Concerns Cables, Connections and Fuse Capacity Multiple welders on same structure

Balchin & Castner, “Health & Safety…”, McGraw Hill, 1993

Balchin & Castner, “Health & Safety…”, McGraw Hill, 1993

It is now time to evaluate the course and your instructor. Please click here to enter the COURSE FINAL EVALUATION

Oxyfuel Gas Welding & Cutting Processes Torches Used only with fuel for which it is designed Use recommended fuel and oxygen pressure Use striker to start (never matches or cigarette lighter) Hoses Red - Fuel Gas - Left-hand thread Green - Oxygen - Right hand thread Backfires & Flashback Can ignite hose (especially oxygen) Overheated tips, insufficient flow Purge line before igniting Reverse Flow Check Valves Flashback Arresters

Arc Welding & Cutting Potential Hazards Fumes Gases Electric Shock Infrared and Ultraviolet Radiation Burns Fire Explosions Noise (sometimes)

Resistance Welding Potential Hazards Electric Shock from contact with high voltage terminals Ejection of small particles of molten metal from weld Crushing of some part of body between electrodes or other moving components of the machine Protective Devices - Mech. Guarding Static Safety Devices to prevent head movement during maintenance Emergency Stop Buttons Protective Devices - Elect. Interlocks on Enclosure Doors Grounding of secondary

Brazing & Soldering Potential Hazards Burns Gases Furnace Atmosphere Fuel Gas Hydrogen Dissociated Ammonia Fumes Electrical Shock Radiation Chemicals Equipment Ventilation Wash Stands Equipment to purge furnace before introduction of atmosphere Drying of Dip Braze Parts before dipping

High Frequency Welding Potential Hazards & Prevention Lethal Voltages (400-20,000 V) Safety Interlock on Doors Output Leads in Metal ducting Induction Coils Grounded Noise

Electron Beam Welding Potential Hazards Electric Shock (20kV) X-rays Visible Radiation Fumes & Gases in Out of Vacuum Installations

Laser Beam Welding & Cutting Potential Hazards Eye damage from beam (cornea & retina) Safety Glass Filters matched for Wavelength Skin Burns from Beam Fumes Electrical Shock Contact with Cryogenic Coolants

Thermal Spraying Potential Hazards Electric Shock Fire (explosion) Fumes and gases Dust Arc Radiation Noise

Adhesive Bonding Potential Hazard Flammable Materials Toxic Materials

Parent Metal and Surface Coatings Low carbon steel - usually little problem High manganese (12-14%) steel - manganese fumes Stainless steel and aluminum - reflecting surfaces increase risk of ozone formation, especially in GMAW of aluminum Copper zinc alloy - excess copper and zinc fumes cause “metal fume fever” Lead - only welded with low-heat-input process Cadmium and beryllium - extremely poisonous Magnesium - Class D fire danger if spark is present Health and Safety T

Hazards Mechanical –Do not weld completely closed vessels without allowing for expansion of trapped air Electrical –Most welding equipment works at a relatively low voltage –Ground the work by a separate cable –Keep SMAW open circuit voltage to minimum required in damp or sweaty conditions Health and Safety T