A nonstandard term for OXYFUEL GAS WELDING TORCH. 


    An insulated conductor, usually copper, that carries electric current from the welding power supply to the torch and then from the workpiece back to the power supply. Cables should be inspected periodically to assure that insulation is not cracked or damaged and that fittings are tight.

    The diameter or size of cable required for a given application depends on the welding or cutting current and the distance from the power supply to the work site. 

    The use of the steel frame of a building in place of a copper workpiece cable is a widespread but poor practice. This is especially true if the frame of the building is riveted. In this case there is likely to be a considerable voltage drop across riveted joints, and this drop will vary as the riveted connections warm up due to 12R heating. Weld quality is almost certain to suffer from this practice; it is far better to use a copper cable as the workpiece lead. 




    Current for welding is controlled by a welding power source. The typical output of a welding power source may be alternating current, direct current, or both. It may be either constant current, constant voltage or both. It may also provide a pulsing output mode. Selecting the correct power source depends on the current output required for each of the arc welding processes. See VOLT-AMPERE CURVE.


    The complete series of events involved in the making of a weld.  


    Poor Fusion

    Causes of poor fusion: Low welding current; improper weaving technique; improper electrode diameter; poor joint preparation; hurried welding speed.

    Corrections: The electrode should be small enough to reach the bottom of the joint; for a given electrode, current should increase with plate thickness to properly deposit metal and penetrate the plates; weaving should sweep outward enough to melt sides of the joint; deposited metal should fuse into the plates, not curl away.


    Causes of porosity: Excessive arc length; insufficient puddling; unsound base metal; moisture in electrode coating.

    Corrections: Shorter arc required, especially on stainless steels; sufficient puddling of molten metal to allow trapped gas to escape; proper weaving technique; appropriate welding current; sound base metal selection; dry electrodes.

    Incomplete Penetration

    Causes of incomplete penetration: Improper joint preparation; electrode too large; insufficient welding current; hurried welding speed.

    Corrections: Allow proper free space at bottom of weld; use electrodes of appropriate diameter in narrow groove; use sufficient welding current and proper welding speed; use a backup bar; chip or cut out the back of the joint and deposit a backing bead. 


    Causes of brittleness: Air-hardening of base metal; improper heating; unsatisfactory electrodes.

    Corrections: Preheating of medium-carbon and certain alloy steels at 150 to 260°C (300 to 500°F); proper preheating; controlled cooling. Multiple-layer welds tend to anneal hard zones; stress relieving at 600 to 650°C (1100 to 1200°F) after welding generally softens hard areas formed during welding. Austenitic electrodes are sometimes desirable on air-hardening steels; the increased weld ductility compensates for the brittleness of the heat-affected areas in the base metal.

    Arc Blow

    Causes of arc blow: Magnetic fields force the arc in a different direction than the point at which it is directed, particularly at the ends of joints and in comers when welding with direct current.

    Corrections: Place the workpiece connection in the direction of arc blow; clamp the workpiece cable to the work at two or more locations; weld toward the direction of the blow; hold a short arc; change the magnetic path around the arc by using steel blocks, or magnetic shunts; use a-c welding.


    Causes of undercutting: Excessive welding current; improper electrode technique; mismatch between electrode design and weld position.

    Corrections: Use a moderate welding current and proper welding speed; use an electrode that produces a puddle of the proper size; proper weaving technique; proper positioning of the electrode relative to a horizontal fillet weld. See UNDERCUT.


    Causes of distortion: Improper joint preparation or clamping; non-uniform heating of the parts; improper welding sequence.

    Corrections: Clamp or tack parts properly to resist shrinkage; pre-form parts to compensate for weld shrinkage; distribute welding deposit to avoid localized overheating; preheat heavy structures; remove rolling or forming strains before welding; proper welding sequence, determined by a study of the structure. See DISTORTION.

    Cracked Welds

    Causes of cracked welds: Joint too rigid; welds too small for size of parts joined; poorly executed welds; improper joint preparation; unsuitable electrode.

    Corrections: Design the structure and develop a welding procedure to eliminate rigid joints; design weld size appropriate to parts; make a full size weld in short sections; develop a welding sequence that leaves the ends of the joint free to move as long as possible; proper fusion; preheating; prepare uniform joints.

    Irregular Surface

    Causes of irregular surface: Excessive welding current; improper weaving technique; improper voltage; overheating of the workpiece; inherent characteristics

    of the electrode.

    Corrections: Change to proper welding technique; use proper welding current; use proper voltage; use proper welding speed.

    Irregular Weld Quality

    Causes: Wrong electrode: improper technique; excessive current; electrode used in wrong position; improper joint design.

    Corrections: Prepare the joint properly; match the electrode to the weld position; weld with uniform weave, proper rate of travel, and proper welding current.

    Residual Stresses

    Causes of residual stress: Joints are too rigid; improper welding sequence.

    Corrections: Make the weld in several passes; peen each deposit; stress relieve finished product at 600°C to 650°C (1100°F to 1200°F) for one hour per inch of thickness; develop procedure that permits all parts to be free to move as long as possible.


    Causes of corrosion: improper type of electrode diminishes corrosion resistance of the weld compared to the parent metal; improper weld deposit for the corrosive media; the metallurgical effect of welding; and improper cleaning of the weld.

    Corrections: Use electrodes that provide equal or better corrosion resistance than the parent metal; when welding austenitic stainless steel the analysis of the steel and the welding procedure should be correct to avoid carbide precipitation: this condition can be cor rected by heating to 104°C-115O°C (1900 to 2100°F) followed by quenching; proper cleaning of materials such as aluminum to prevent corrosion.


    Causes of spatter: The inherent properties of certain electrodes; excessive welding current; the type or diameter of rod used; an excessively long arc; arc blow.

    Corrections: Use proper type of electrode; proper welding current; proper arc length; reduce arc blow; use anti-spatter adjacent to the weld to prevent the welding of spalls to the work.

    Warping of Thin Plates

    Causes of warping: Shrinkage of the deposited weld metal; local overheating at the joint; improper joint preparation; unsuitable clamping of the parts.

    Corrections: Select electrode with high welding speed and moderate penetrating properties; weld rapidly to prevent over-heating of the plates adjacent to the weld; do not permit excessive space between the parts; clamp parts adjacent to the joint; use a back-up bar to cool them rapidly; use a welding sequence such as the backstep or skip procedure; peen the joint edges thinner than the body of the plate before welding. The elongated edges will pull back to the original shape when the weld shrinks. 


    A component of the welding circuit through which current is conducted and that terminates at the arc, molten conductive slag, or base metal. See ARCWELDING ELECTRODE, CARBON ELECTRODE, COVERED ELECTRODE, ELECTROSLAG WELDING ELECTRODE, FLUX CORED ELECTRODE, METAL CORED ELECTRODE, METAL ELECTRODE, RESISTANCE WELDING ELECTRODE, and TUNGSTEN ELECTRODE.

    Electrodes used for welding carbon steels and alloy steels have been standardized by the specifications of the American Welding Society. ANSIJAWS A5.1, Specification for Carbon Steel Electrodes for Shielded Metal Arc Welding covers electrodes for welding mild steel. Low-alloy steels appear under ANSUAWS A5.5, Specification for Low Alloy Steel Covered Arc Welding Electrodes.

    ANSUAWS A5.4, Specification for Stainless Steel Welding Electrodes for Shielded Metal Arc Welding covers stainless steel arc welding electrodes with various nickel and chromium contents. See STEEL, STAINLESS, Arc Welding.

    Copper and copper bearing alloy arc welding electrodes appear under ANSUAWS A5.7, Specification for Copper and Copper Alloy Bare Welding Rods and Electrodes. See COPPER ALLOY WELDING.

    Aluminum arc welding electrodes appear under ANSIIAWS A5.3, Specification for Aluminum and Aluminum Alloy Electrodes for Shielded Metal Arc Welding. See ALUMINUM. See also ELECTRODES. 


    The metal or alloy to be added in making a weld joint that alloys with the base metal to form weld metal in a fusion welded joint. 


    Welders, welding operators, and other persons in the area must be protected from overexposure to fumes and gases produced during welding, brazing, soldering, and cutting. Overexposure is exposure that is hazardous to health, and exceeds the permissible limits specified by a government agency. Such recognized authorities arethe U.S. Department of Labor, Occupational Safety and Health Administration (OSHA), Regulations 29 CFR 1910.1000; the American Conference of Governmental Industrial Hygienists (ACGIH) in its publications Threshold Limit Values for Chemical Substances and Physical Agents in the Workroom Environment. Persons with special health problems may have unusual sensitivity that requires even more stringent protection.

    Fumes and gases are usually a greater concern in arc welding than in oxyfuel gas welding, cutting, or brazing because a welding arc may generate a larger volume of fume and gas, and greater varieties of materials are usually involved.

    Protection from excess exposure is usually accomplished by ventilation. Where exposure would exceed permissible limits with available ventilation, respiratory protection must be used. Protection must be provided not only for the welding and cutting personnel but also for other persons in the area.

    Refer to Industrial Ventilation, A Manual of Recommended Practice, Cincinnati: American Conlference of Governmental Industrial Hygienists (latest edition).

    Arc Welding- Fumes and gases from arc welding and cutting cannot be classified simply. Their composition and quantity depend on the base metal composition; the process and consumables used; coatings on the work, such as paint, galvanizing, or plating; contaminants in the atmosphere, such as halogenated hydrocarbon vapors from cleaning and degreasing activities; and other factors.

    Various gases are generated during welding. Some are a product of the decomposition of fluxes and electrode coatings. Others are formed by the action of arc heat or ultraviolet radiation emitted by the arc on atmospheric constituents and contaminants. Potentially hazardous gases include carbon monoxide, oxides of nitrogen, ozone, and phosgene or other decomposition products of chlorinated hydrocarbons, such as phosgene.

    Helium and argon, although chemically inert and nontoxic, are simple asphyxiants, and could dilute the atmospheric oxygen concentration to potentially harmful low levels. Carbon dioxide (COz) and nitrogen can also cause asphyxiation.

    Ozone may be generated by ultraviolet radiation from welding arcs. This is particularly true with gas shielded arcs, especially when argon is used. Photochemical reactions between ultraviolet radiation and chlorinated hydrocarbons result in the production of phosgene and other decomposition products.

    Exposure Factors- The single most important factor influencing exposure to fume is the position of the welder’s head with respect to the fume plume. When the head is in such a position that the fume envelops the face or helmet, exposure levels can be very high. Therefore, welders must be trained to keep their heads to one side of the fume plume. In some cases, the work can be positioned so the fume plume rises to one side.

    Ventilation- Ventilation has a significant influence on the amount of fumes in the work area, and hence the welder’s exposure. Ventilation may be local, where the fumes are extracted near the point of welding, or general, where the shop air is changed or filtered. The appropriate type will depend on the welding process, the material being welded, and other shop conditions. Adequate ventilation is necessary to keep the welder’s exposure to fumes and gases within safe limits.

    The bulk of fume generated during welding and cutting consists of small particles that remain suspended in the atmosphere for a considerable time. As a result, fume concentration in a closed area can build up over time, as can the concentration of any gases evolved or used in the process. The particles eventually settle on the walls and floor, but the settling rate is low compared to the generation rate of the welding or cutting processes. Therefore, fume concentration must be controlled by ventilation.

    Adequate ventilation is the key to control of fumes and gases in the welding environments. Natural, mechanical, or respirator ventilation must be provided for all welding, cutting, brazing, and related operations. The ventilation must ensure that concentrations of hazardous airborne contaminants are maintained below recommended levels. These levels must be no higher than the allowable levels specified by the U.S. Occupational Safety and Health Administration or other applicable authorities.

    Respiratory Protective Equipment- Where natural or mechanical ventilation is not adequate or where protection from toxic materials require a supplement to ventilation, respiratory protective equipment must be used. Respirators with air lines, or face masks that give protection against all contaminants are generally preferred. Air-supplied welding helmets are also available commercially. Filter-type respirators, approved by the U.S. Bureau of Mines for metal fume, give adequate protection against particulate contaminants that are less toxic than lead, provided they are used and maintained correctly. Their general use is not recommended, however, because of the difficulty in assuring proper use and maintenance. They will not protect against mercury vapor, carbon monoxide, or nitrogen dioxide. For these hazards an air line respirator, hose mask, or gas mask is required.

    Special Ventilation Situations

    Welding in Confined Spaces- Special consideration must be given to the safety and health of welders and other workers in confined places. Gas cylinders must be located outside of the confined space to avoid pos sible contamination of the space with leaking gases or

    volatile material. Welding power sources should also be located outside to reduce danger of engine exhaust and electric shock.

    A means for removing persons quickly in case of emergency must be provided. Safety belts and lifelines, when used, should be attached to the worker’s body in a manner that avoids the possibility of the person becoming jammed in the exit. A trained helper should be stationed outside the confined space with a preplanned rescue procedure to be put into effect in case of emergency.

    Welding of Containers- Welding or cutting on the outside or inside of containers or vessels that have held dangerous substances presents special hazards. Flammable or toxic vapors may be present, or may be generated by the applied heat. The immediate area outside and inside the container should be cleared of all obstacles and hazardous materials.

    When repairing a container in place, entry of hazardous substances released from the floor or the soil beneath the container must be prevented. The required air-supplied respirators or hose masks are those accepted by the U.S. Bureau of Mines or other recognized agency. For more complete procedures, refer to AWS F4.1, Recommended Safe Practices for the Preparation for Welding and Cutting Containers that Have Held Hazardous Substances. Miami: American Welding Society (latest edition). When welding or cutting inside of vessels that have held dangerous materials, the precautions for confined spaces must also be observed.

    Highly Toxic Materials- Certain materials which are sometimes present in consumables, base metals, coatings, or atmospheres for welding or cutting operations, have permissible exposure limits of 1.0 mg/m3 or less. Among such materials are the following metals and their compounds:

    (1) Antimony

    (2) Arsenic

    (3) Barium

    (4) Beryllium

    (5) Cadmium

    (6) Chromium

    (7) Cobalt

    (8) Copper

    (9) Lead

    (10) Manganese

    (11) Mercury

    (12) Nickel

    (13) Selenium

    (14) Silver

    (15) Vanadium

    Base metals and filler metals that may release some of these materials as fume during welding or cutting are shown in Table W-2.

    Manufacturer’s Material Safety Data Sheets should be consulted to determine if any of these highly toxic materials are present in welding filler metals and fluxes being used. Material Safety Data Sheets should be requested from suppliers. However, welding filler metals and fluxes are not the only source of these materials. They may also be present in base metals, coatings, or other sources in the work area. Radioactive materials under Nuclear Regulatory Commission jurisdiction require special considerations. 

    When toxic materials are encountered as designated constituents in welding, brazing or cutting operations, special ventilation precautions must be takea to assure that the levels of these contaminants in the atmosphere are at or below the limits allowed for human exposure. All persons in the immediate vicinity of welding or cutting operations involving toxic materials must be similarly protected. Unless atmospheric tests under the most adverse conditions establish that exposure is within acceptable concentrations, the following precautions must be observed.

    Confined Spaces- Whenever any toxic materials are encountered in confined space operations, local exhaust ventilation and respiratory protection must be used.

    Indoors- When any toxic materials are encountered in indoor operations, local exhaust (mechanical) ventilation must be used. When beryllium is encountered, respiratory protection in addition to local exhaust ventilation is essential.

    Outdoors- When any toxic materials are encountered in outdoor operations, respiratory protection approved by the Mine Safety and Health Association (MSHA) the National Institute of Occupational Safety and Health (NIOSH), or other approving, authority may be required.

    Persons should not consume food in areas where fumes that contain materials with very low allowable exposure limits may be generated. They should also practice good personal hygiene, such as washing hands before touching food, to prevent ingestion of toxic contaminants.

    Fluorine Compounds- Fumes and gases from fluorine compounds can be dangerous to health, and can bum the eyes and skin on contact. Local mechanical ventilation or respiratory protection must be provided when welding, brazing, cutting, or soldering in confined spaces involving fluxes, coatings, or other material containing fluorine compounds.

    When such processes are employed in open spaces, the need for local exhaust ventilation or respiratory protection will depend upon the circumstances. Such protection is not necessary when air samples taken in breathing zones indicate that all fluorides are within allowable limits. However, local exhaust ventilation is always desirable for fixed-location production welding and for all production welding of stainless steels when filler metals or fluxes containing fluorides are used.

    Fumes Containing Zinc- Compounds may produce symptoms of nausea, dizziness, or fever (sometimes called “metal fume fever”). Welding or cutting where zinc may be present in consumables, base metals, or coatings should be done as described for fluorine compounds.

    Measurement of Exposure

    The American Conference of Governmental Industrial Hygienists (ACGIH) and the U.S. Department of Labor, Occupational Health and Safety Administration (OSHA) have established allowable limits of airborne contaminants. They are called threshold limit values (TLVs), or permissible exposure limits (PELS).

    The TLV (a registered trade mark of the ACGIH) is the concentration of an airborne substance to which most workers may be repeatedly exposed, day after day, without adverse effect. In adapting these to the working environment, a TLV-TWA (Threshold Limit Value-Time Weighted Average) quantity is defined. TLV-TWA is the time weighted average concentration for a normal 8-hour workday or 40-hour workweek to which nearly all workers may be repeatedly exposed without adverse effect. TLV-TWA values should be used as guides in the control of health hazards, and  should not be interpreted as sharp lines between safe and dangerous concentrations.

    TLVs are revised annually as necessary. They may or may not correspond to OSHA permissible exposure limits (PEL) for the same materials. In many cases, current ACGIH values for welding materials are more stringent than OSHA levels.

    The only way to assure that airborne contaminant levels are within the allowable limits is to take air samples at the breathing zones of the personnel involved. An operator’s actual on-the-job exposure to welding fume should be measured following the guidelines provided in ANSVAWS Fl.l, Method for Sampling Airborne Particulates Generated by Welding and Allied Processes. This document describes how to obtain an accurate breathing zone sample of welding fume for a particular welding operation. Both the amount of the fume and the composition of the fume can be determined in a single test using this method. Multiple samples are recommended for increased accuracy. When a helmet is worn, the sample should be collected inside the helmet in the welder’s breathing zone. 


    A generator used for supplying current for welding. 


    Goggles with tinted lenses, used during welding or oxygen cutting, which protect the eyes from harmful radiation and flying particles.


    A nonstandard and incorrect term for WORKPIECE CONNECTION. 


    The part of a welding machine in which a welding gun or torch is incorporated. 


    A device equipped with a filter plate designed to be worn on the head to protect eyes, face, and neck from arc radiation, radiated heat, spatter or other harmful matter expelled during some welding and cutting processes.  .

    Helmets are generally constructed of pressed fiber or fiberglass insulating material. A helmet should be light in weight and should be designed to give the welder the greatest possible comfort. Some helmets have an optional “flip lid,” a dark filter plate covering the opening in the shield. It can be flipped up so the welder can see to chip slag from the weld and be protected from flying slag. Slag can cause serious injury if it strikes a person, particularly while it is hot. It can be harmful to the eyes whether it is hot or cold. 


    A nonstandard term for WELDING HELMET. 


    The workpiece lead and electrode lead of an arc welding circuit. See Figure D-5. 


    Equipment used to perform the welding operation. For example, spot welding machine, arc welding machine, and seam welding machine. 


    One who operates adaptive control, automatic, mechanized, or robotic welding equipment. 


    When welding under the specifications of the ASME Boiler and Pressure Vessel Code, each employer is responsible for qualifying all the welders and welding operators employed by the company with responsibility for welding according to specifications of a code. However, to avoid duplication of effort, the employer may accept a Weldermelder Operator Performance Qualification (WPQ) made by a previous employer (subject to the approval of the owner or the agent of the owner) on piping using the same or an equivalent procedure in which the essential variables are within the limits established in Section IX of the ASME Boiler and Pressure Vessel Code.

    An employer accepting such qualification tests by a previous employer is required to obtain a copy of the WPQ showing the name of the employer by whom the welders or welding operators were qualified, the dates of such qualification, and evidence that the welder or welding operator has maintained qualification with Q-322 of Section IX of the Code. The employer then prepares and signs the record accepting responsibility for the ability of the welder or welding operator.


    The relationship between the weld pool, joint, joint members, and welding heat source during welding. See FLAT WELDING POSITION, HORIZONTAL WELDING POSITION, OVERHEAD WELDING POSITION, and VERTICAL WELDING POSITION. 




    The detailed methods and practices involved in the production of a weldment.. See also WELDING PROCEDURE SPECIFICATION. 


    A record of welding variables used to produce an acceptable test weldment and the results of tests conducted on the weldment to qualify a welding procedure specification.  


    A document providing the required welding variables for a specific application to assure repeatability by properly trained welders and welding operators.

    A WPS document contains all of the instructions required to produce a weldment. Standards such as ANSYAWS B2.1, Specification for Welding Procedure and Peflormance Qualification; ANSIJAWS D1.1, Structural Welding Code-Steel; ASME Boiler and Pressure Vessel Code, and others specify the welding variables that are required to be addressed on the WPS. See STANDARD WELDING PROCEDURE SPECFICATION. 


    A device in a welding power source for converting alternating current to direct current. 


    A form of welding filler metal, normally packaged in straight lengths, that does not conduct the welding current.  Welding rods, like welding electrodes, are designed to meet the needs of the industry. In some instances the same rod is suitable for use with either the GTAW process or oxyacetylene welding (OAW).

    The use of a bare welding rod for either application is satisfactory, since the molten weld puddle is shielded. In oxyfuel gas welding, the gas envelope around the weld puddle may be carburizing, oxidizing, or neutral, depending on the gas regulation. In gas tungsten arc welding, an inert gas shields the weld puddle.

    Nonferrous materials such as aluminum or bronze, when used with OAW, generally require a flux to shield the weld puddle and to clean the base metal to ensure a more satisfactory weld. The flux may be externally applied or, in some instances, may be applied by coating the rod with the flux.

    The American Welding Society maintains specifications for welding rods, including those used for iron and steel, copper and copper alloy, corrosion-resistant

    chromium and chromium nickel, aluminum and aluminum alloy, nickel and nickel alloy, cast iron, titanium and titanium alloy, magnesium alloy, and composite surfacing. Specifications for steel rods are available from the American Welding Society in AWS A5.2, Specifcation for Carbon and Low Alloy Steel Rods for Oxyfuel Welding.