Safe Practices.

Safe Practices

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

Read & understand Manufacturer’s Data Sheets
Safe Practices Training Read & understand Manufacturer’s Data Sheets Read & understand Material safety data sheets (MSDS) Read & understand AWS precautionary labels Safe practices relates to a lot of different things. These including Training, the understanding of the use of manufacturer’s safe practice data sheet, and the understanding of the safe use of materials. All manufacturers are required to provide you with the operational information for their product and Material Safety Data Sheet outlining any safety issue with the use of the product or material. You should make it a point to obtain and read all of the manufacturers instruction material before starting the process or using the material. The American Welding Society has also developed a series of precautionary labels for hazardous operations and materials and these need to be fully understood.

This is an example of a safety label
This is an example of a safety label. Notice it includes all sorts of warnings of hazards from a lot of different sources. AWS Welding Handbook

Of others (protective screens) Of welder (considered below)
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 Let us get into some actual safety issues. Here are listed some general housekeeping issues. The first listed is protection of visions. To keep others from being injured by arc flashes, it is good practice to have protective screen judiciously places to keep the weld isolated from general traffic or personnel. The welder will also need protection from the arc, but this will be covered below. Note that arcs can also be reflected from the surrounding wall. With long exposure this can be almost as bad as direct observation of the arc. Paints containing titanium oxide and zinc oxide pigments tend to absorb light and this helps protect from arc flash.

Welding Arcs Emit powerful visible and ultra-violet (UV) light
Health and Safety 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 Why is it important to have the screens to protect yourself and others? T

Here is an example of a safety shielding for general public protection
Here is an example of a safety shielding for general public protection. Note that it also protects each welder for the arc flash of the other welder. Often a second set of shielding to protect the walkways around the work area would also be provided. There are a number of shields that can be obtained from fully opaque canvas shields as illustrated here to some which are partially transparent so people can watch the operation. These need to be purchased with some knowledge of the intensity of the arc being shielded. 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 Good housekeeping also dictates that items not be left around on the floor or around other work areas where they might cause a tripping hazard. The general public while walking through a work area tend not to look down or be careful where they walk so tripping becomes a hazard. The welder, who is under the hood and has other protective gear on, often does not see tripping items. In fact it is much better to provide safe clearly marked walkways for people where the tripping hazards and material moving hazards are minimized. In mills where material is moved overhead, the crane operators are particularly careful about not moving material over designated walkways. These precautions are particularly appropriate when working above ground. Safety railing and safety lines to protect from falling should be provided.

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 routes) Fire Explosion Proper storage of goods and equipment Proper hook up of equipment One should also be prepared for unexpected event such as fire or explosion. Every personnel should have in their mind the closest escape route and a secondary escape route in case the closest way out is blocked. A knowledge of the proper fire equipment and fire extinguishers should also be a part of your tool kit.

Fires Detect it Combustible Rescue all persons at risk Material
Prevent it spreading Extinguish it Combustible Material Source of Ignition Oxygen 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)

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 (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 Finally, proper storage and transport of goods and equipment is important. And proper hook up is important. One of the most critical are the gas cylinders.

Cylinder gases can in some cases be recognized by the type of cylinder the gas is in. For example propane and to some extent acetylene is in a cylinder like that illustrated in (a). It has a protective guard which is a part of the cylinder itself. The other gases can be in cylinders which look quite alike and care must be exercised when selecting these as the hazards vary with the type of gas as noted here. The type and size of thread on the value has been standardized so that ordinarily mistakes can not be made when hooking up a regulator. Never force a regulator onto a tank connection. It may not be the gas you really want. Balchin & Castner, “Health & Safety…”, McGraw Hill, 1993

This is a list of the thread connection numbers as specified by the Compressed Gas Association Standard AWS Welding Handbook

Gas Cylinder Safety No oil or grease in connections
Health and Safety 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 T

Here are a few safety things about the oxy-acetylene tanks, particularly when moving them about. First of all note the chain which locks the tanks to the cart. This eliminates the chance of falling and breaking off the valves. Some of these tanks can be compressed to very high pressures making the tanks a projectile when the valve brakes. There are also flash back arrestors and both the acetylene and the oxygen tanks. If a flame were to go up the hoses, this arrestor would stop it from entering into the tanks and causing an explosion. This equipment also has a check valve located at the torch. This keeps the gas from flowing backwards in the event that someone makes a mistake in the opening or purging of the hose lines. Balchin & Castner, “Health & Safety…”, McGraw Hill, 1993

The tanks are provided with protective covers which help protect the valves from unwanted bumps. The propane tanks have the permanently attached guard, the other cylinders have caps which screw onto to top of the cylinder protecting the valve. Whenever the tanks are not in use the cap needs to be in place. Balchin & Castner, “Health & Safety…”, McGraw Hill, 1993

Here is a cut away of the acetylene tank
Here is a cut away of the acetylene tank. You can see where the screw cap goes on the top. It also has a safety device. The acetylene is absorbed in a porous material of acetone and if the pressure in the take were to get too great, the safety device would allow some of the gas to escape. Balchin & Castner, “Health & Safety…”, McGraw Hill, 1993

Here is a good situation where the tanks are tied down in a cage
Here is a good situation where the tanks are tied down in a cage. In this case, a distribution system to the welder is provided so that the takes do not even need to be near the work stations. Balchin & Castner, “Health & Safety…”, McGraw Hill, 1993

Protective Cap On Tank Secured
When moving individual cylinders, always use a cart with a securing device. Never move a tank by rolling it on end in case it falls, and always during moving have the valve cap in place. Balchin & Castner, “Health & Safety…”, McGraw Hill, 1993

Personal Protection Clothing Ear and Eye Protection
Protection from Fumes and Gases Electrical Shock Protection Protection from X-ray on Inspection Let us move now from the general housekeeping and overall safety issues to the specific issues related to keeping you and the welder, the welding operator or the welding supervisor safe during your regular performance of your duties.

Woolen or Treated Cotton Clothing (no synthetic or plastic)
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 Listed here are the personal protective clothing that the well dressed welder should wear.. These include sturdy boots with steel toe protection, woolen or flame resistant treated clothing without cuffs or pockets where sparks might collect, a cap for hair protection, leather gloves, aprons leggings ear and eye protection.

Here is an example of a safe welder.
AWS Welding Handbook

Here is an example of goggles with flip-up filters for use with oxy-acetylene. These are not to be used for welding. Balchin & Castner, “Health & Safety…”, McGraw Hill, 1993

This a table recommending eye protection for various jobs a welder might do.
Balchin & Castner, “Health & Safety…”, McGraw Hill, 1993

Noise Control Here is a helmet with noise control ear protectors.

UV Shield There are many helmets with UV shield protection. Here is one of the most expensive and elaborate, but many less exotic helmets work just fine as well. Balchin & Castner, “Health & Safety…”, McGraw Hill, 1993

This is a table of recommend eye shield number for various processes an current level.

This is an additional table for eye filter number for various processes.

Since light energy drops off as the square of the distance, the safe distance from the arc for various lengths of exposure can be calculated. This table lists these values. For long time exposure (8 hours) note how far one has to be removed to avoid being overexposed. Balchin & Castner, “Health & Safety…”, McGraw Hill, 1993

Fumes and Gases Fumes are the solid particles
Health and Safety 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) Let us now talk a bit about fumes. Fumes are solid particulate. The larger particles settle out, the smaller particles need to be filtered out and very small particles are problems. Gasses are the carrier of the fumes and are generally invisible. Fumes are generally measured in milligrams per cubic meter and gasses in parts per million. There are threshold limits of safety values for each. 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) Fumes are a product of the volatilization, reaction of chemical elements, oxidation of consumable, base metals or coatings and atmospheric contaminants. The composition and Quality depends on the items listed.

This chart shows a schematic of the size of particle and gases and in particular those sizes which are detrimental in that they get caught in the lungs, we see that very fine particles we define as gases and these tend not to be trapped in the lung tissue. Those that are not toxic pose little problem. Particles which are very course we call grits and these are generally settled out or filtered out in the mucus linings and also do not cause problems. The intermediate size particulate are the dangerous ones. 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 Listed here are some of the potentially hazardous gases associated with welding. These are toxic when breathed. Other gases are listed as simple asphyxiates. These are not necessarily toxic but they will remove oxygen from the normal breathing atmosphere and thus suffocate the welder when conditions are right.

Factors Affecting Gas & Fume Generation Rates Welding Current E6010
Arc Voltage (arc length) Type of metal transfer or process Shielding Gas higher with CO2 more with He than Ar Welding Process Consumables There are factors which effect the generation of fumes and gases as listed here. The higher the welding current the higher the rate of fumes. (Actually current to a power, dependent on electrode - a few are listed here). Arc voltage also has an effect. The higher voltage means longer arc length. The more the arc length, the greater the region from which fumes can be generated and thus the more fumes occur. The type of metal transfer has an effect. Short arc generates fewer fumes than the rotating jet transfer. There are more fumes with Carbon dioxide and helium shielding gas than with argon. Submerged arc has fewer fumes than open arc processes. 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 There are many metals which are toxic in themselves. Some of these are listed here and welding on materials containing these elements should be done with care. The next table lists some possible sources of these

This table lists where some of these toxic metals may come from.

Ventilation Open air and shop ventilation Local fume extraction
Health and Safety Ventilation Open air and shop ventilation Local fume extraction Dust respirator Air-fed welding helmet The answer to fume and gases is adequate ventilation. This may take the form of open air shop ventilation, or local fume extraction equipment. There are also personal safety equipment such as dust respirators and air-fed welding helmets. T

Here are illustrated various ventilation conditions
Here are illustrated various ventilation conditions. In (a) the welder has taken a position where fumes and gases come directly up under the hood. This situation can be improved by local air flow by simply opening windows to get cross ventilation or by forced air circulation. An adjustment to the welder position © is also somewhat effective. But the best is (d) local extraction. Balchin & Castner, “Health & Safety…”, McGraw Hill, 1993

Here is an actual photo of local extraction ventilation.

In extreme conditions, the use of a dust respirator as illustrated here may be in order.

In addition, an under the hood forced air ventilation systems as shown here might be employed.

When welding in enclosed contained locations, special precautions must be taken. This is especially true when using shielding gases like argon which are heavier than air. During welding as the shielding gas fills the container, it forces the air out causing the welder to suffocate. 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 Explosive fumes can cause an additional hazard. When welding on vessel that previously contained hazardous materials the steps listed here must be followed. First the hazardous materials are removed, and the tank is cleaned using one or more of the methods listed here. 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 Then the tank is back filled with inert gas or water to remove any remaining fumes before the weld is made.

Electrical Safety Sources Proper Grounding Welding power supplies
Instrumentation Water reduces resistance Proper Grounding The work lead is not the grounding lead Electrical safety is also important. It only takes small amounts of current to do permanent damage. Currents as low as 1/2 milliamp are perceptible, but current levels as low as 6 milliamps can cause permanent physical damage. Sources of current are power supplies and instrumentation. Be certain that proper grounding is provided for all electrical equipment. Other Concerns Cables, Connections and Fuse Capacity Multiple welders on same structure

Finally, the use of X-rays for non-destructive testing often occurs in areas near where welders are working. When available, a lead lined room with safety interlocks should be used. Balchin & Castner, “Health & Safety…”, McGraw Hill, 1993

When an X-ray room is not available, the test area should be roped off for a suitable distance.

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 Equipment 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
Health and Safety 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 T

Hazards Mechanical Electrical
Health and Safety 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 T

Safe Practices.

Similar presentations

Presentation on theme: "Safe Practices."— Presentation transcript:

Similar presentations

About project

Feedback

Log in

Auth with social network:

Safe Practices.

Similar presentations

Presentation on theme: "Safe Practices."— Presentation transcript:

Similar presentations

About project

Feedback