safe practices safety lesson objectives when you finish this lesson you will understand: safe...

Safe Practices

Safety

Lesson ObjectivesWhen 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

lecture4. Do on-line

workbook5. Do homework

KeywordsGas Cylinder, Protective Clothing, Eye Filter Plate Number, Fumes, Gases, Ventilation, Toxic Materials, Fires, Fire Extinguishers, Radiography

http://we019.eng.ohio-state.edu/wenc/wenc.cfm

http://we019.eng.ohio-state.edu/we300/w300t/we300.htm

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 (TiO2 & 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 50-150A (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

0.1.1.6.1.T5.95.12





• Prepare for unexpected events (escape routes)• Fire• Explosion


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

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

0.1.1.6.1.T7.95.12


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


Noise Control


UV Shield

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

0.1.1.6.1.T8.95.12

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)

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 CO2

• more with He than Ar• Welding Process• Consumables

24.2I54.1I

See p 528 for more info

Highly Toxic Materials

Materials with exposure limits of 1.0 mg/m3 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

Ventilation

• Open air and shop ventilation

• Local fume extraction

• Dust respirator

• Air-fed welding helmet

Health and Safety

0.1.1.6.1.T11.95.12

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


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

Electrical Safety

Shock Currents Category Effect> 6 milliamperes Primary Causes Direct Physical Harm0.5 to 6 mA Secondary Causes involuntary muscle reaction

without usually causing directphysical harm

0.5 PerceptionThreshold

Begin to feel tingle

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

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

COURSE FINAL EVALUATION

safe practices safety lesson objectives when you finish this lesson you will understand: safe...

Documents