Welding Inspector Safety Practices PDF

CHAPTER 2 Safe Practices for Welding Inspectors Contents Introduction ..................................................................................................................................................................2-20 Eye and Face Protection ........................................

CHAPTER 2 Safe Practices for Welding Inspectors Contents Introduction ..................................................................................................................................................................2-20 Eye and Face Protection ..............................................................................................................................................2-50 Protective Clothing.......................................................................................................................................................2-80 Noise...............................................................................................................................................................................2-80 Machinery Guards........................................................................................................................................................2-80 Fumes and Gases ..........................................................................................................................................................2-90 Exposure Factors ..........................................................................................................................................................2-90 Ventilation .....................................................................................................................................................................2-10 Handling of Compressed Gases...................................................................................................................................2-12 Manifolds.......................................................................................................................................................................2-14 Gases ..............................................................................................................................................................................2-15 Electric Shock ...............................................................................................................................................................2-15 Key Terms and Definitions ..........................................................................................................................................2-19 2-1 CHAPTER 2—SAFE PRACTICES FOR WELDING INSPECTORS WELDING INSPECTION TECHNOLOGY Chapter 2—Safe Practices for Welding Inspectors Introduction Welding inspectors often work in the same environment as the welder, so they can be exposed to many potential safety hazards. These include electric shock, falling, radiation, eye hazards such as ultraviolet light and particulate matter in the air, smoke and fumes, and falling objects. Safety is not to be taken lightly; even though the welding inspector may only be exposed to these conditions momentarily. The welding inspector should observe all safety precautions such as use of safety glasses, hard hats, protective clothing or any other appropriate apparatus for a given situation. For a more detailed look at recommended safety precautions refer to ANSI Z49.1, Safety in Welding, Cutting, and Allied Processes. Safety is an important consideration in all welding, cutting, and related work. No activity is satisfactorily completed if someone is injured. The hazards that may be encountered, and the practices that will reduce personal injury and property damage, are discussed here. The most important component of an effective safety and health program is leadership support and direction. Management must clearly state objectives and show its commitment to safety and health by consistent support of safe practices. Management must designate approved safe areas for conducting welding and cutting operations. When these operations are done in other than designated areas, management must assure that proper procedures are established and followed to protect personnel and property. Figure 2.1—Personal Protective Equipment (PPE) tion Standard (29 CFR 1910.1200). Welders and other equipment operators work most safely when they are properly trained in the subject. Management must also be certain that only approved welding, cutting, and allied equipment are used. Such equipment includes torches, regulators, welding machines, electrode holders, and personal protection devices (see Figure 2.1). Adequate supervision must be provided to assure that all equipment is properly used and maintained. Proper training includes instruction in the safe use of equipment and processes, and the safety rules that must be followed. Personnel need to know and understand the rules and the consequences of disobeying them. For example, welders must be trained to position themselves while welding or cutting so that their heads are not in the gases or fume plume. A fume plume is a smoke-like cloud containing minute solid particles arising directly from the area of melting metal. The fumes are metallic vapors that have condensed into particulates. Thorough and effective training is a key aspect of a safety program. Adequate training is mandated under provisions of the U.S. Occupational Safety and Health Act (OSHA), especially those of the Hazard Communica- 2-2 WELDING INSPECTION TECHNOLOGY CHAPTER 2—SAFE PRACTICES FOR WELDING INSPECTORS (TLV), and any other exposure limit used or recommended by the manufacturer. TLV is a registered trademark of the American Conference of Governmental and Industrial Hygienists (ACGIH). Before work begins, users must always read and understand the manufacturers’ instructions on safe practices for the materials and equipment, and the Material Safety Data Sheets (MSDSs). Certain AWS specifications call for precautionary labels on consumables and equipment. These labels concerning the safe use of the products should be read and followed (see Figure 2.2). Employers that use consumables must make all applicable MSDS data available to their employees, and also train them to read and understand the contents. The MSDS contain important information about the ingredients contained in welding electrodes, rods, and fluxes. These sheets also show the composition of fumes generated and other hazards that may be caused during use. They also provide methods to be followed to protect the welder and others who might be involved. Manufacturers of welding consumables must, upon request, furnish a Material Safety Data Sheet that identifies materials present in their products that have hazardous properties. The MSDS provides OSHA permissible exposure limits, known as the Threshold Limit Value Under the OSHA Hazard Communication Standard, 29 CFR 1910.1200, employers are responsible for employee hazardous material training in the workplace. Many welding consumables are included in the definition of hazardous materials according to this standard. Welding employers must comply with the communication and training requirements of this standard. WARNING: PROTECT yourself and others. Read and understand this label. FUMES AND GASES can be dangerous to your health. Proper use and maintenance of the equipment must also be taught. For example, defective or worn electrical insulation in arc welding or cutting should not be used. Also, defective or worn hoses used in oxyfuel gas welding and cutting, brazing, or soldering should not be used. Training in equipment operation is fundamental to safe operation. ARC RAYS can injure your eyes and burn your skin. ELECTRIC SHOCK can KILL. • Before use, read and understand the manufacturer’s instructions, the Material Safety Data Sheets (MSDSs), and your employer’s safety practices. Personnel must also be trained to recognize safety hazards. If they are to work in an unfamiliar situation or environment, they must be thoroughly briefed on the potential hazards involved. For example, consider a person who must work in confined spaces. If the ventilation is poor and an air-supplied helmet is required, the need and instructions for its proper use must be thoroughly explained to the employee. The consequences of improperly using the equipment must be covered. When employees believe that the safety precautions for a given task are not adequate, or not understood, they should question their supervisor before proceeding. • Keep your head out of fumes. • Use enough ventilation, exhaust at the arc, or both, to keep fumes and gases from your breathing zone and the general area. • Wear correct eye, ear, and body protection. • Do not touch live electrical parts. • See American National Standard Z49.1, Safety in Welding, Cutting, and Allied Processes, published by the American Welding Society, 550 N.W. LeJeune Road, Miami, FL 33126; and OSHA Safety and Health Standards, available from U.S. Government Printing Office, Washington, DC 20402. Good housekeeping is also essential to avoid injuries. A welder’s vision is often restricted by necessary eye protection, and personnel passing a welding station must often shield their eyes from the flame or arc radiation. This limited vision makes both the welder and passersby vulnerable to tripping over objects on the floor. Therefore, welders and supervisors must always make sure that the area is clear of tripping hazards. A shop production area should be designed so that gas hoses, cables, mechanical assemblies, and other equipment do not cross walkways or interfere with routine tasks (see Figure 2.3). DO NOT REMOVE LABEL Figure 2.2—Typical Warning Label for Arc Welding Processes and Equipment 2-3 CHAPTER 2—SAFE PRACTICES FOR WELDING INSPECTORS WELDING INSPECTION TECHNOLOGY Figure 2.3—Designated Welding Area Figure 2.4—Protective Screening Between Workstations When work is above ground or floor level, safety rails or lines must be provided to prevent falls because of restricted vision from eye protection devices. Safety lines and harnesses can be helpful to restrict workers to safe areas, and to restrain them in case of a fall. Unexpected events, such as fume releases, fire and explosions do occur in industrial environments. All escape routes should be identified and kept clear so that orderly, rapid, and safe evacuation of an area can take place. Employees must be trained in evacuation procedures. Storage of goods and equipment in evacuation routes must be avoided. If an evacuation route must be temporarily blocked, employees who would normally use that route must be trained to use an alternate route. having low reflectivity of ultraviolet radiation. Paint finish formulated with certain pigments, such as titanium dioxide or zinc oxide, have low reflectivity to ultraviolet radiation. Color pigments may be added if they do not increase reflectivity. Pigments based on powdered or flaked metals are not recommended because they reflect ultraviolet radiation. In most welding, cutting, and allied processes, a hightemperature heat source is present. Open flames, electric arcs, hot metal, sparks, and spatter are ready sources of ignition. Many fires are started by sparks, which can travel horizontally up to 35 ft from their source. Sparks can pass through or lodge in cracks, holes, and other small openings in floors and walls. Equipment, machines, cables, hoses, and other apparatus should always be placed so that they do not present a hazard to personnel in passageways, on ladders, or on stairways. Warning signs should be posted to identify welding areas, and to specify that eye protection must be worn. Occasionally, a “fire watch” person must be assigned to maintain safety during welding or cutting operations. The risk of fire is increased by combustibles in the work area, or by welding or cutting too close to combustibles that have not been shielded. Materials most commonly ignited are combustible floors, roofs, partitions, and building contents including trash, wood, paper, textiles, plastics, chemicals, and flammable liquids and gases. Outdoors, the most common combustibles are dry grass and brush. Personnel in areas next to welding and cutting must also be protected from radiant energy and hot spatter. This is accomplished with flame-resistant screens or shields, or suitable eye and face protection and protective clothing. Appropriate radiation-protective, semi-transparent materials are permissible. Where operations allow, work stations should be separated by noncombustible screens or shields (see Figure 2.4). Booths and screens should allow circulation of air at floor level and above the screen. The best protection against fire is to do welding and cutting in specially designated areas or enclosures of noncombustible construction kept free of combustibles. Combustibles should always be removed from the work area or shielded from the operation. Common combustibles found in welding manufacturing include fuels for both equipment engines and welding or cutting operations. These fuels should be stored and used with care. Equipment manufacturers’ instructions should Where arc welding or cutting is regularly performed next to painted walls, the walls should be painted with a finish 2-4 WELDING INSPECTION TECHNOLOGY CHAPTER 2—SAFE PRACTICES FOR WELDING INSPECTORS Flammable gases, vapors, and dust mixed with certain proportions of air or oxygen present explosion and fire dangers. To prevent explosions, avoid all sources of ignition. Welding, brazing, soldering, cutting, or operating equipment that can produce heat or sparks must not be done in atmospheres containing flammable gases, vapors, or dusts. Such flammables must be kept in leaktight containers or be well removed from the work area. Heat or sparks may cause otherwise low-volatility materials to produce flammable vapors. be followed because fuels and their vapors are combustible and can be explosive under some conditions. Acetylene, propane and other flammable gases used in cutting and welding areas require careful handling. Special attention should be given to fuel gas cylinders, hoses, and apparatus to prevent gas leakage. Combustibles that cannot be removed from the area should be covered with tight fitting, flame-resistant material. These include combustible walls and ceilings. Floors around the work area should be free of combustible materials for a radius of 35 ft. All doorways, windows, cracks, and other openings should be covered with a flame-resistant material. If possible, the work area should be enclosed with portable flame-resistant screens. Hollow containers must be vented before, and during, any application of heat. Heat must not be applied to a container that has held an unknown material, a combustible substance or a substance that may form flammable vapors without considering the potential hazards. Such containers must first be thoroughly cleaned or filled with an inert gas. Adequate eye and body protection must be worn if the operation involves explosion risks. Burns of the eye or body are serious hazards in the welding industry. Eye, face, and body protection for the operator and others in the work area are required to prevent burns from ultraviolet and infrared radiation, sparks, and spatter. Combustibles on the other side of metal walls, ceilings or partitions must be moved to safe locations when welding or cutting is done on or next to the location. If this cannot be done, a fire watch should be stationed near the combustibles. Welding heat can conduct through metal partitions and ignite combustibles on the opposite side. A thorough examination for evidence of fire should be made before leaving the work area. Fire inspection should be continued for at least 30 minutes after the operation is completed. Eye and Face Protection Welding or cutting should not be done on material having a combustible coating or internal structure, as in walls or ceilings. Hot scrap or slag must not be placed in containers holding combustible materials. Suitable fire extinguishers should always be available nearby, and the fire watch trained in their use. Arc Welding and Cutting Welding helmets or handshields containing appropriate filter plates and cover plates must be used by welders and welding operators and nearby personnel when viewing an arc. Standards for welding helmets, handshields, face shields, goggles, and spectacles are given in ANSI publication Z87.1, Practice for Occupational and Educational Eye and Face Protection, latest edition. Welding, brazing, or cutting should not be done on combustible floors or platforms that may readily be ignited by heat from the operation. Welders and inspectors must be alert for traveling vapors from flammable liquids. Vapors are often heavier than air. Vapors from flammable liquid storage areas can travel several hundred feet along floors and in depressions. Light vapors can travel along ceilings to adjacent rooms. Safety spectacles, goggles, or other suitable eye protection must also be worn during other welding and cutting operations (see Figure 2.6). Such devices must have full conforming side shields when there is danger of exposure to injurious rays or flying particles from grinding or chipping operations. Spectacles and goggles may have clear or colored lenses. Shading depends on the intensity of the radiation that comes from adjacent welding or cutting operations when the welding helmet is raised or removed. Number-2 filter plates are recommended for general purpose protection (see Table 2.1). When welding, cutting or similar hot working operations are to be performed in areas not normally assigned for such operations, a “hot work permit” system should be used (see Figure 2.5). The purpose of the hot work permit system is to alert area supervisors to an extraordinary danger of fire that will exist at a particular time. The permit system should include a checklist of safety precautions. A checklist often includes fire extinguisher inspection, establishes the fire watches if necessary, a flammable material search, and area safety instructions for personnel not involved in the hot work. When a hot work permit is issued, the welding inspector must be aware of and adhere to all its requirements. Oxyfuel Gas Welding and Cutting, Submerged Arc Welding Safety goggles with filter plates and full conforming side shields must be worn while performing oxyfuel gas welding and cutting (see Table 2.1). During submerged arc welding, the arc is covered by flux and is not readily 2-5 CHAPTER 2—SAFE PRACTICES FOR WELDING INSPECTORS WELDING INSPECTION TECHNOLOGY PERMIT NO. __________ INSTRUCTIONS TO OPERATORS For electric and acetylene burning and welding with portable equipment in all locations outside of shop. This permit is good only for the location and time shown. Return the permit when work is completed. _____________________________________________ Date _________________________________________ PRECAUTIONS AGAINST FIRE Time Started___________ Finished ______________ 1. Permits should be signed by the foreman of the welder or cutter and by the safety supervisor or plant superintendent. Building_______________________________________ Dept._________________ 2. Obtain a written permit before using portable cutting or welding equipment anywhere in the plant except in permanent safe-guarded locations. Floor_________________ Location on Floor _______________________________ 3. Make sure sprinkler system is in service. Nature of job___________________________________ 4. Before starting, sweep floor clean, wet down wooden floors, or cover them with sheet metal or equivalent. In outside work, don’t let sparks enter doors or windows. _____________________________________________ Operator ______________________________________ Clock No. _____________________________________ 5. Move combustible material 25 feet away. Cover what can’t be moved with asbestos curtain or sheet metal, carefully and completely. All precautions have been taken to avoid any possible fire hazard, and permission is given for this work. 6. Obtain standby fire extinguishers and locate at work site. Instruct helper or fire watcher to extinguish small fires. Signed _______________________________________ 7. After completion, watch scene of work a half hour for smoldering fires, and inspect adjoining rooms and floors above and below. Foreman Signed _______________________________________ 8. Don’t use the equipment near flammable liquids, or on closed tanks which have held flammable liquids or other combustibles. Remove inside deposits before working on ducts. Safety supervisor or plant superintendent _____________________________________________ 9. Keep cutting and welding equipment in good condition. Carefully follow manufacturer’s instructions for its use and maintenance. _____________________________________________ PERMIT NO. OU812 Date _________________________________________ Bldg _________________ Floor_________________ Nature of Job __________________________________ Operator ______________________________________ _____________________________________________ _____________________________________________ Figure 2.5—National Safety Council “Hot Work Permit” Figure 2.6—Eye, Ear, and Face Protective Equipment 2-6 WELDING INSPECTION TECHNOLOGY CHAPTER 2—SAFE PRACTICES FOR WELDING INSPECTORS Key Words—Eye protection and lens shade AWS F2.2:2001 Table 2.1 Lens Shade Selector Shade numbers are given as a guide only and may be varied to suit individual needs. Electrode Size in (mm) Arc Current (Amperes) Minimum Protective Shade Suggested* Shade No. (Comfort) Less than 3/32 (2.4) 3/32–5/32 (2.4–4.0) 5/32–1/4 (4.0–6.4) More than 1/4 (6.4) Less than 60 60–160 160–250 250–550 7 8 10 11 — 10 12 14 Gas Metal Arc Welding (GMAW) and Flux Cored Arc Welding (FCAW) Less than 60 60–160 160–250 250–500 7 10 10 10 — 11 12 14 Gas Tungsten Arc Welding (GTAW) Less than 50 50–150 150–500 8 8 10 10 12 14 Less than 500 500–1000 10 11 12 14 Plasma Arc Welding (PAW) Less than 20 20–100 100–400 400–800 6 8 10 11 6–8 10 12 14 Plasma Arc Cutting (PAC) Less than 20 20–40 40–60 60–80 80–300 300–400 400–800 4 5 6 8 8 9 10 4 5 6 8 9 12 14 Torch Brazing (TB) — — 3 or 4 Torch Soldering (TS) — — 2 Carbon Arc Welding (CAW) — — 14 Process Shielded Metal Arc Welding (SMAW) Air Carbon Arc Cutting (CAC-A) (Light) (Heavy) Plate Thickness Oxyfuel Gas Welding (OFW) Light Medium Heavy Oxygen Cutting (OC) Light Medium Heavy in mm Suggested* Shade No. (Comfort) Under 1/8 1/8 to 1/2 Over 1/2 Under 3 3 to 13 Over 13 4 or 5 5 or 6 6 or 8 Under 1 1 to 6 Over 6 Under 25 25 to 150 Over 150 3 or 4 4 or 5 5 or 6 *As a rule of thumb, start with a shade that is too dark to see the weld zone. Then go to a lighter shade which gives sufficient view of the weld zone without going below the minimum. In oxyfuel gas welding, cutting, or brazing where the torch and/or the flux produces a high yellow light, it is desirable to use a filter lens that absorbs the yellow or sodium line of the visible light spectrum. 2-7 CHAPTER 2—SAFE PRACTICES FOR WELDING INSPECTORS WELDING INSPECTION TECHNOLOGY visible; therefore, an arc welding helmet is not needed. However, because the arc occasionally flashes through the flux burden, the operator should wear tinted safety glasses. Sparks or hot spatter in the ears can be particularly painful and serious. Properly fitted, flame-resistant ear plugs should be worn whenever operations pose such risks. Torch Brazing and Soldering Noise Safety spectacles with side shields and appropriate filter plates are recommended for torch brazing and soldering. As with oxyfuel gas welding and cutting, a bright yellow flame may be visible during torch brazing. A filter similar to that used with those processes should be used for torch brazing (see Table 2.1). Excessive noise, particularly continuous noise at high levels, can severely damage hearing. It may cause either temporary or permanent hearing loss. U.S. Department of Labor Occupational Safety and Health Administration regulations describe allowable noise exposure levels. Requirements of these regulations may be found in General Industry Standards, 29 CFR 1910.95. Other Brazing Processes and Resistance Welding In welding, cutting, and allied operations, noise may be generated by the process or the equipment, or both. Hearing protection devices are required for some operations (see Figure 2.6). Additional information is presented in Arc Welding and Cutting Noise, American Welding Society, 1979. Air Carbon Arc and Plasma Arc Cutting are processes that have very high noise levels. Enginedriven generators sometimes emit a high noise level, as do some high-frequency, and induction welding power sources. Operators and helpers engaged in these processes must wear safety spectacles, goggles, and a face shield to protect their eyes and face from spatter. Filter plates are not necessary but may be used for comfort (refer to Table 2.1). Protective Clothing Sturdy shoes or boots, and heavy clothing should be worn to protect the whole body from flying sparks, spatter, and radiation burns. Woolen clothing is preferable to cotton because it is not so readily ignited. Cotton clothing, if used, should be chemically treated to reduce its combustibility. Clothing treated with nondurable flame retardants must be treated again after each washing or cleaning. Clothing or shoes of synthetic or plastic materials, which can melt and cause severe burns, should not be worn. Outer clothing should be kept free of oil and grease, especially in an oxygen-rich atmosphere. Machinery Guards Welders and other workers must also be protected from injury by machinery and equipment they are operating or by other machinery operating in the work area. Moving components and drive belts must be covered by guards to prevent physical contact (see Figure 2.7). Cuffless pants and covered pockets are recommended to avoid spatter or spark entrapment. Pockets should be emptied of flammable or readily ignitable material before welding because they may be ignited by sparks or weld spatter and result in severe burns. Pants should be worn outside shoes. Protection of the hair with a cap is recommended, especially if a hairpiece is worn. Flammable hair preparations should not be used. Durable gloves of leather or other suitable material should always be worn. Gloves not only protect the hands from burns and abrasion, but also provide insulation from electrical shock. A variety of special protective clothing is also available for welders. Aprons, leggings, suits, capes, sleeves, and caps, all of durable materials, should be worn when welding overhead or when special circumstances warrant additional protection of the body. Figure 2.7—Machinery Guard 2-8