SMAW FACILITATOR’S GUIDE OPENING NOTES FOR THE TEACHER: The Facilitator’s Manual is to be used as a reference tool for teachers to plan lessons related to the SMAW Units of Study. The following lesson plans are based around the lesson slides in the SMAW PowerPoint presentations and should be used in conjunction with the units of study. Print-outs can be made of each lesson if teachers want to hand hard copies to the students in the class. Arc Welding Safety Safe welding practices shall always be used.  Teachers and students should read and understand the following before welding: – Warning Labels on welding equipment, with consumable packaging and in instruction manuals – Material Safety Data Sheets (MSDS) available with consumable packaging and online at http://www.lincolnelectric.com/en-us/support/msds/Pages/sds-search.aspx • Teachers and students should also be familiar with the following information – ‘Safety in Welding, Cutting, and Allied Processes’ (ANSI Z49.1) free download available at www.aws.org/technical/facts/Z49.1-2005-all.pdf – Lincoln Electric’s Arc Welding Safety (E205) and additional arc welding safety information available at http://www.lincolnelectric.com/en-us/education-center/welding- safety/Pages/welding-safety.aspx W ELDING connects your world ELECTRIC SHOCK Contact with metal parts which are “electrically hot” can cause injury or death because of the effect of the shock upon your body or a fall which may result from your reaction to the shock. The electric shock hazard associated with arc welding may be divided into two categories which are quite different: – Primary Voltage Shock (i.e. 230, 460 volts); and – Secondary Voltage Shock (i.e. 20-100 volts). The primary voltage shock is very hazardous because it is much greater voltage than the welder secondary voltage. You can receive a shock from the primary (input) voltage if you touch a lead inside the welder with the power to the welder “on” while you have your body, or hand, on the welder case or other grounded metal. Remember that turning the welder power switch “off” does not turn the power off inside the welder. Your welder should be installed by a qualified electrician so it will be correctly wired for the primary voltage which supplies it power and so the case will be connected to an earth ground. The case must be grounded so that if a problem develops inside the welder a fuse will blow, disconnecting the power and letting you know that repair is required. Never ignore a blown fuse because it is a warning that something is wrong. A secondary voltage shock occurs when you touch a part of the electrode circuit — perhaps a bare spot on the electrode cable — at the same time another part of your body is touching the metal upon which you’re welding (work). To receive a shock your body must touch both sides of the welding circuit — electrode and work (or welding ground) — at the same time. To prevent secondary voltage shock, you must develop and use safe work habits. Remember the voltage at the electrode is highest when you are not welding (open circuit voltage). • Wear dry gloves in good condition when welding. • Do not touch the electrode or metal parts of the electrode holder with skin or wet clothing. • Keep dry insulation between your body (including arms and legs) and the metal being welded or ground (i.e. metal floor, wet ground). • Keep your welding cable and electrode holder in good condition. Repair or replace any damaged insulation. Keep your gloves dry even if you have to keep an extra pair. Use plywood, rubber mats, or some other dry insulation to stand or lie upon. Insulate your body from the metal you are welding. Don’t rest your body, arms, or legs on the workpiece, especially if your clothing is wet or bare skin is exposed (and it should not be if you are dressed properly). In addition to the normal safety precautions, if welding must be performed under electrically hazardous conditions (in damp locations or while wearing wet clothing; on metal structures such as floors, gratings or scaffolds; when in cramped positions such as sitting, kneeling or lying, if there is a high risk of unavoidable or accidental contact with the work piece or ground) use the following equipment: • Semiautomatic DC Constant Voltage Welder • DC Manual (Stick) Welder • AC Welder with Reduced Voltage Control Always inspect your electrode holder before turning the welder on. Replace the holder if it is damaged. Remember, a stick electrode is always “electrically hot” when the welder is on — treat it with respect. If you do experience a shock, think of it as a warning — check your equipment, work habits and work area to see what is wrong before continuing to weld. 2 W ELDING connects your world FUMES AND GASES The fume plume contains solid particles from the consumables, base metal, and base metal coating. For common mild steel arc welding, depending on the amount and length of exposure to these fumes, most immediate or short term effects are temporary, and include symptoms of burning eyes and skin, dizziness, nausea, and fever. For example, zinc fumes can cause metal fume fever, a temporary illness that is similar to the flu. Long-term exposure to welding fumes can lead to siderosis (iron deposits in the lungs) and may affect pulmonary function. Bronchitis and some lung fibrosis have been reported. Some consumables contain certain compounds in amounts which may require special ventilation and/or exhaust. These Special Ventilation products can be identified by reading the labels on the package. If Special Ventilation products are used indoors, use local exhaust. If Special Ventilation products are used outdoors, a respirator may be required. Various compounds are sometimes found in welding fume, for example: Chromium: Chromium is on the IARC (International Agency for Research on Cancer) and NTP (National Toxicology Program) lists chromium as posing a carcinogenic risk to humans. Fumes from the use of stainless steel, hardfacing and other types of consumables contain chromium and/or nickel. Some forms of these metals are known or suspected to cause lung cancer in processes other than welding, asthma has also been reported. Therefore, it is recommended that precautions be taken to keep exposures as low as possible. OSHA recently adopted a lower PEL (Permissible Exposure Limit) for chromium. Manganese: Manganese overexposure may affect the central nervous system, resulting in poor coordination, difficulty in speaking, and tremor of arms or legs. This condition is considered irreversible. There is one easy way to reduce the risk of exposure to hazardous fumes and gases: keep your head out of the fume plume! As obvious as this sounds, the failure to follow this advice is a common cause of fume and gas overexposure because the concentration of fume and gases is greatest in the plume. Keep fumes and gases from your breathing zone and general area using natural ventilation, mechanical ventilation, fixed or moveable exhaust hoods or local exhaust at the arc. Finally, it may be necessary to wear an approved respirator if adequate ventilation cannot be provided. There are also steps that you can take to identify hazardous substances in your welding environment. First, read the product label and material safety data sheet for the electrode posted in the work place or in the electrode or flux container to see what fumes can be reasonably expected from use of the product and to determine if special ventilation is needed. Secondly, know what the base metal is, and determine if there is any paint, plating, or coating that could expose you to toxic fumes and/or gases. Remove it from the metal being welded, if possible. If you start to feel uncomfortable, dizzy or nauseous, there is a possibility that you are being overexposed to fumes and gases, or suffering from oxygen deficiency. Stop welding and get some fresh air immediately. Notify your supervisor and co-workers so the situation can be corrected and other workers can avoid the hazard. Be sure you are following these safe practices, the consumable labeling and MSDS and improve the ventilation in your area. Do not continue welding until the situation has been corrected. You should understand a few basic terms that will be used in this section: Natural Ventilation is the movement of air through the workplace caused by natural forces. Outside, this is usually the wind. Inside, this may be the flow of air through open windows and doors. 3 W ELDING connects your world Mechanical Ventilation is the movement of air through the workplace caused by an electrical device such as a portable fan or permanently mounted fan in the ceiling or wall. Source Extraction (Local Exhaust) is a mechanical device used to capture welding fume at or near the arc and filter contaminants out of the air. The ventilation or exhaust needed for your application depends upon many factors such as: • workspace volume • workspace configuration • number of welders • welding process and current • consumables used (mild steel, hardfacing, stainless, etc.) • allowable levels (TLV, PEL, etc.) • material welded (including paint or plating) • natural airflow Your work area has adequate ventilation when there is enough ventilation and/or exhaust to control worker exposure to hazardous materials in the welding fumes and gases so the applicable limits for those materials is not exceeded. See Supplement 1 for the legal limits, the OSHA PEL (Permissible Exposure Limit), and the recommended guideline, the ACGIH TLV (Threshold Limit Value), for many compounds found in welding fume. Important Safety Note: When welding with electrodes which require special ventilation such as stainless or hardfacing (see instructions on container or MSDS) or on lead or cadmium plated steel and other metals or coatings which produce hazardous fumes, keep exposure as low as possible and below exposure limit values (PEL and TLV) for materials in the fume using local exhaust or mechanical ventilation. In confined spaces or in some circumstances, for example outdoors, a respirator may be required if exposure cannot be controlled to the PEL or TLV. Additional precautions are also required when welding on galvanized steel. Source Extraction Equipment Mechanical ventilation is an effective method of fume control for many welding processes. Because it captures fume near the arc or source of the fume, which is more efficient in most cases, local exhaust, also called "source extraction", is a very effective means to control welding fume. Source extraction of welding fumes can be provided by mobile or stationary, single or multi-station, exhaust and/or filtration equipment designed with adjustable fume extraction arms nozzles or guns, by fixed enclosures, booths or tables with extraction canopies also known as down-draft, or by back-draft or cross-draft tables/booths. Source extraction of weld fume falls into two categories: low vacuum/high volume, or high vacuum/low volume. Fume extraction is only one component in reducing welding fume. Users should also consider the selection of the welding process, welding procedure, or consumable. Many times a combination of fume extraction, training, process change, and/or consumable change is needed to reduce the amount of fume to acceptable levels. Solutions to a particular application may involve one or all of these factors and the user must determine which solution best fits their application. OSHA regulations include specific requirements for exhaust systems which should be reviewed when selecting fume extraction systems. 4 W ELDING connects your world Working in Confined Spaces When arc welding in a confined area, such as a boiler, tank, or the hold of a ship, bear in mind that all the hazards associated with normal arc welding are amplified, so the precautions mentioned here are even more important. This subject is very complicated and only these precautions related to arc welding will be discussed in this brochure. Per OSHA document 29 CFR 1910.146, a particular area is considered a confined space if it: 1) Is large enough and so configured that an employee can bodily enter and perform assigned work; and 2) Has limited or restricted means for entry or exit (for example, tanks, vessels, silos, storage bins, hoppers, vaults, and pits are spaces that may have limited means of entry.); and 3) Is not designed for continuous employee occupancy. There is a greater danger that enough flammable gases may be present in the confined space to cause an explosion. The metal of the enclosure can become part of the welding circuit, so any metal you touch (the walls, floor, ceiling) is electrically "hot". Welding fumes can accumulate more rapidly, with a higher concentration; gases can force out the breathable air, suffocating you in the process. Per OSHA document 29 CFR 1910.146(d)(5)(iii); after an area has been deemed a confined space, the existence of the following atmospheric hazards are to be determined: 1) Test for oxygen 2) Test for combustible gases and vapors 3) Test for toxic gases and vapors The workplace and OSHA rules regarding confined spaces must be followed. Make sure that your body is insulated from the work-piece using dry insulation. Wear dry gloves and only use a well-insulated electrode holder. Semiautomatic constant voltage welders with cold electrode or stick welders equipped with a device to lower the no-load voltage are recommended, especially when the work area is wet. Make sure that there is adequate ventilation and exhaust (a respirator or an air-supplied respirator may be necessary depending on the application), and that there are no flammable coatings, liquids or gases nearby. Lastly, you must have someone outside the enclosure trained to handle emergencies, with rescue procedures and a means to disconnect power to your equipment and pull you out if danger arises. For more information on environmental products and solutions: 1. Lincoln Environmental Systems (E13.40) 2. Environmental System Selection Guide (MC05-183) 3. www.lincolnelectric.com Quick Link: "Safety" 5 W ELDING connects your world Supplement 1 6 W ELDING connects your world Supplement 2 BIBLIOGRAPHY AND SUGGESTED READING ANSI Z87.1, Practice for Occupational and ANSI, Standard Z49.1, Safety in Welding, Cutting Educational Eye and Face Protection, American and Allied Processes. Z49.1 is now available for National Standards Institute, 11 West 42nd Street, download at no charge at New York, NY 10036. http://www.lincolnelectric.com/community/safety/ or at the AWS website http://www.aws.org. Arc Welding and Your Health: A Handbook of Health Information for Welding. Published by The AWS F1.1, Method for Sampling Airborne American Industrial Hygiene Association, 2700 Particulates Generated by Welding and Allied Prosperity Avenue, Suite 250, Fairfax, VA 22031- Processes. 4319. AWS F1.2, Laboratory Method for Measuring Fume NFPA Standard 51B, Cutting and Welding Generation Rates and Total Fume Emission of Processes, National Fire Protection Association, 1 Welding and Allied Processes. Batterymarch Park, P.O. Box 9146, Quincy, MA 02269-9959. AWS F1.3, Evaluating Contaminants in the Welding Environment: A Strategic Sampling Guide. OSHA General Industry Standard 29 CFR 1910 Subpart Q. OSHA Hazard Communication AWS F1.5, Methods for Sampling and Analyzing Standard 29 CFR 1910.1200. Available from the Gases from Welding and Allied Processes. Occupational Safety and Health Administration at http://www.osha.org or contact your local OSHA AWS F3.2, Ventilation Guide for Welding Fume office. Control The following publications are published by The AWS F4.1, Recommended Safe Practices for the American Welding Society, P.O. Box 351040, Preparation for Welding and Cutting of Containers Miami, Florida 33135. AWS publications may be and Piping That Have Held Hazardous Substances. purchased from the American Welding society at http://www.aws.org or by contacting the AWS at AWS SHF, Safety and Health Facts Sheets. 800-854-7149. Available free of charge from the AWS website at http://www.aws.org. 7 W ELDING connects your world UNIT: SMAW PROBLEM AREA  How do I strike and establish an arc? NATIONAL STANDARDS:  NM-MEA.9-12.1: Understand measurable attributes of objects and the units, systems, and processes of measurement  NM-PROB.CONN.PK-12.3: Recognize and apply mathematics in contexts outside of mathematics.  NS-PHYSICAL SCIENCE: Interactions of energy and matter STUDENT LEARNING OBJECTIVES: AS A RESULT OF THIS LESSON, THE STUDENT WILL …  Learn to strike and establish an arc SMAW Lesson #1 TIME: INSTRUCTION TIME FOR THIS LESSON: 1 HR. • Objective: Strike and establish an arc • Equipment: RESOURCES: – Single Process – Constant Curren t PAowWeSr S‘Soauferctey in Welding, Cutting, and Allied Processes’ (ANSI Z49.1)  Idealarc 250  a nd Laicncceoslsno rEielesctric’s ‘Safety in Arc Welding’ (E205)  Precision TIG 225 and accessories  Stick Electrode Welding Guide (C2.410) – Multi-Process  Stick Electrode Product Catalog (C2.10)  Power MIG 350 MP  New Lessons in Arc Welding • Material: – Mild Steel Plate 1/8” or thicker – 1/8” Fleetweld 5P+ (E6010) for DC or Fleetwe ld 180 (E6011) for AC 8 38 W ELDING connects your world TOOLS, EQUIPMENT, AND SUPPLIES:  Tools and Equipment: - Single Proce-s Cso nstant Current Power S ource  Idealarc 250 and accessories  Precision TIG 225 and accessories - Mult-iProces s  Power MIG 350 MP  Supplies: - Mild Steel Plate 1/8” or thicker - 1/8” Fleetweld 5P+ (E6010) for DC or Fleetweld 180 (E6011) for AC KEY TERMS: THE FOLLOWING TERMS ARE PRESENTED IN THIS LESSON AND APPEAR IN BOLD:  Strike  Arc  Constant Current  Multi-Process  Mild Steel TEACHER NOTES: Suggested discussions include information regarding the following: An arc is maintained when the welding current is forced across a gap between the electrode tip and the base metal. Two general methods of striking an arc are scratching and tapping. The scratch start method is easier for beginners and when using an AC machine. In the tap start method, the electrode is moved downward to the base metal in a vertical direction. The principal difficulty encountered in striking the arc is “freezing” when the electrode sticks or fuses to the work. Remind students to never remove the shield from the face if the electrode is frozen. Free the electrode with the shield in front of the eyes, as it will “flash” when it comes loose. Constant Current (CC) power sources are used in the SMAW process. A CC power source is one in which current or amperage remains constant even for changes in welding voltage. The welding voltage changes as changes in arc length occur. Constant current SMAW machines are either AC, DC or AC/DC. Welding polarity is determined by the preferred polarity of the electrode used or the capability of the welding power source. Some examples of constant current welding machines include the Idealarc 250 and the AC-225. Multi-process welding machines have the ability to perform many different welding processes (i.e. Stick and MIG welding). These machines are very popular in welding schools due to their ability to change over from one welding process to the next. Some examples of multi-process welding machines include the Power MIG 350MP and the Invertec V-350. Mild steel is a common term for low carbon steels which have good weldability. Tips for easier arc starts: Recommend DC- polarity and amperage settings in the higher end of the recommended amperage range (90-100 Amps). This makes striking an arc easier and allows students to gain confidence. 9 W ELDING connects your world Fleetweld 5P+ (E6010) is classified as a fast freeze, mild steel electrode. It is ideal for welding on dirty, rusty, greasy, or painted steel. It’s a first choice for pipe welding as well as for vertical-up and overhead plate welding. Fleetweld 5P+ is a long-time favorite among operators who handle cross-country and in-plant pipe welding. A whipping technique is commonly used with this electrode. Preferred polarity: DC+ Fleetweld 180 (E6011) Classified as a Fast Freeze, Out-of-Position, Mild Steel Stick Electrode, this electrode offers excellent arc stability for performance with AC power sources. A great stick electrode with the ability to start easily on low open circuit voltage (OCV) welders. A whipping technique is commonly used with this electrode. Preferred polarity: AC INTEREST APPROACH:  Assemble the students into the shop area. Demonstrate both methods of striking an arc making sure to follow proper safety guidelines. Have the students make observations about how each method begins and how to establish the correct arc length. Lead a discussion on the correct process for each method. To gain practical knowledge of classroom content, allow 1 hr. for the students to practice the following exercises: LESSON INSTRUCTIONS Exercise A: Strike an arc using the scratch start method. 1. Clean the base material by brushing the metal free of dirt and scale. 2. Position your work piece flat on metal table top or plate. 3. Attach work clamp securely to work or table. 4. Set the polarity and amperage on the machine: DC+ at 85-125A for 1/8” E6010 electrode. 5. Place bare end of electrode in holder so that it is gripped securely at a 90-degree angle to the jaws. 6. Turn welder “ON”. 7. Assume a natural position and grasp holder firmly but comfortably by using either one or both hands. Using both hands helps to steady electrode and reduce fatigue. To use both hands, rest left elbow on work table and, with the left hand, steady the right hand by holding the right wrist. (Directions given for a right handed welder.) 8. Hold electrode above plate and move it down until it is about an inch above plate. Hold it upright to the plate, inclined at an angle of 65 to 70 degrees in the direction of travel. 9. Place the shield in front of your eyes. 10. Strike the arc like a large match by gently and quickly scratching the electrode on the metal with a wrist motion. A sudden burst of light will be produced on contact with the plate. 11. Withdraw electrode to form an excessively long arc, about 3/16”. This long arc is held only a second or two after which a normal arc length of 1/16” to 1/8” is assumed. The long arc prevents the large drops of metal that pass across the arc from shorting out the arc causing it to “freeze” and stick to the plate. It also establishes the weld puddle, eliminates excessive 10