CWI key terms

An arc welding process in which a covered consumable electrode supplies both filler metal and shielding. The flux coating produces gas and slag that protect the molten weld, and slag must be chipped between passes.

An arc welding process using a continuous solid wire electrode fed through a gun, with shielding supplied by an external gas. It produces no slag and is common for production welding of steel, aluminum, and stainless.

An arc welding process using a continuous tubular wire containing flux. The flux generates shielding gas and slag, and the process gives high deposition rates, especially in flat and horizontal positions.

An arc welding process using a nonconsumable tungsten electrode and a separately fed filler rod under inert gas shielding. It gives precise control and clean welds, especially on thin material and root passes.

An arc welding process in which the arc is struck beneath a layer of granular flux, hiding the arc from view. It is normally mechanized, uses high currents, and achieves high deposition on flat work.

A standard designation system for covered electrodes. In E7018, E means electrode, 70 is minimum tensile strength in ksi, 1 is usable position, and 8 indicates a low-hydrogen coating and the current type.

The electrical relationship between electrode and workpiece in direct current welding. Electrode negative concentrates heat in the work for deeper penetration; electrode positive concentrates heat at the electrode and suits lighter gauge work.

The energy delivered per unit length of weld, calculated as amperage times voltage times sixty divided by travel speed. High heat input slows cooling, widens the heat-affected zone, and changes mechanical properties.

Heating the base metal to a specified temperature before welding begins. Preheat slows cooling, helps remove moisture and hydrogen, and reduces the risk of cracking in thick or hardenable steel.

The temperature of the weld and surrounding base metal just before the next pass is deposited. Codes set a maximum to control cooling rate and toughness, and sometimes a minimum to avoid cracking.

A calculated value combining the percentages of carbon and other alloying elements to indicate how readily a steel hardens. Higher values mean greater susceptibility to cracking and usually require preheat.

The base metal next to the weld that is not melted but is changed by welding heat. It can harden, soften, or grow grains, and it is often where cracks and failures begin.

Deflection of the welding arc away from the intended path by magnetic forces, common in direct current welding near joint ends or with poor ground placement. It causes spatter and incomplete fusion.

The shortest distance from the root of a fillet weld to its face, excluding any convexity. It is the dimension used to calculate the design strength of the weld.

Unwanted change in the shape or dimensions of a welded assembly caused by uneven heating and shrinkage. It can be controlled by proper sequencing, balanced welding, restraint, and backstep techniques.

Examination of welds and components by eye, aided by lights, magnifiers, and gauges. It is performed before, during, and after welding and is the most widely used examination method.

A surface examination method in which a liquid penetrant enters surface-breaking openings and is then drawn out by a developer for visual detection. It works on nonporous materials including aluminum and stainless steel.

A surface and near-surface examination method for ferromagnetic materials. Magnetizing the part causes particles to gather at discontinuities that interrupt the magnetic field, forming a visible indication.

A volumetric examination method that sends high-frequency sound waves into the material and interprets reflected echoes. It detects internal flaws and measures thickness, and requires a trained operator and couplant.

A volumetric examination method that passes X-rays or gamma rays through the weld onto film or a digital detector. Differences in density reveal internal discontinuities, and radiation safety controls are essential.

A small device, also called a penetrameter, placed on the part during radiography to show whether the exposure achieved the required sensitivity. Its image must meet the code before a radiograph is accepted.

A substance such as oil, grease, or water applied between an ultrasonic transducer and the part surface. It removes the air gap so sound energy can pass into the material.

A hand tool with several blades used to check the leg size, throat thickness, and convexity or concavity of fillet welds. It gives an approximate field measurement rather than a precise dimension.

A response from a nondestructive test that may or may not come from a real discontinuity. Indications must be evaluated against the acceptance criteria before being judged acceptable or rejected.

An interruption in the normal structure of a weld or base metal, such as porosity, slag, or a crack. A discontinuity is not necessarily a defect; it becomes one only when it exceeds code limits.

A document supplied by the material producer listing the chemical composition and mechanical properties of a heat or lot. Inspectors compare it with code and specification requirements before accepting material.

A heated cabinet that stores low-hydrogen electrodes at a controlled temperature after the original container is opened. Proper holding keeps the coating dry and helps prevent hydrogen cracking in the finished weld.

A written document giving the welding variables, materials, joint details, and ranges a welder must follow to produce welds meeting the code. It must be supported by a qualified procedure qualification record.

A record of the actual welding and testing performed to qualify a welding procedure. It documents the variables used and the results of mechanical tests such as bend and tensile tests.

A test demonstrating a welder's ability to deposit sound welds to a given procedure and code. It is documented by a record and is usually limited in position, thickness, and process.

A welding condition in a procedure that, if changed beyond code limits, requires requalification. Examples include filler metal classification, preheat, current type, and base metal thickness or group.

A welding condition that may be changed in a procedure without requalification but must still be updated on the WPS. Examples include travel speed, nozzle size, and some cleaning methods.

The American Welding Society structural welding code for steel. It covers design, qualification, fabrication, inspection, and acceptance criteria for statically and cyclically loaded steel structures.

The section of the ASME Boiler and Pressure Vessel Code that governs qualification of welding procedures and welders. It sets essential variables and testing requirements but does not give acceptance criteria for production welds.

The American Petroleum Institute standard for welding pipelines and related facilities. It covers procedure and welder qualification, inspection, and acceptance criteria for transmission pipeline girth welds.

The limits stated by the applicable code or specification that define whether a weld is acceptable. Inspectors compare measured indications and dimensions with these limits rather than with personal judgment.

A stage in fabrication where work may not continue until an authorized inspector has reviewed and approved it. Hold points are agreed in the inspection plan and enforced by the quality program.

The percentage of welds or joints requiring repair compared with the number completed. Tracking repair rate shows trends in workmanship and can trigger retraining or additional examination.