A weld test is a quality control measure for welds to meet the specification of the weld. A weld test can be done any number of ways, including ultrasonic testing or liquid penetrant testing. There are three standards that are considered when performing weld tests: The ASTM, ISO, and ASME standards.

To perform weld tests, the weld sample is prepared by cutting it off from the rest of the welded metal at its weakest point where possible. The weld must be cut through to ensure that no other defects exist in other parts of the welded metal surface to avoid false readings. The weld sample is then cleaned with a solvent to remove any oils or dirt on its surface. It should also be free-cutting so that it can be welded to another piece of metal. It is then welded back together using the original weld bead with slight aberration for standardized weld tests.

There are many different weld test methods, including X-ray radiographic testing, metallography, ultrasonic testing, dye penetrant testing, magnetic particle flux leakage testing, and mechanical bend testing. Welding inspectors read weld test reports to ensure that the weld sample’s dimensions have been tested per the specification of the welded design.

X-ray radiographic testing is also known as “radiography”. This is a non-destructive type of weld inspection where an image of the overall part or defect area can be produced on photographic film or by digital imaging. Radiography is the most widely used weld testing method and it gives high accuracy in-depth and position measurements.

Ultrasonic testing can be performed using either ultrasonic thickness gauges or phased array instruments. This weld test method uses sound waves to inspect weld integrity without cutting into the weld metal or part surface. Ultrasonic weld tests are non-destructive and provide operating conditions such as weld size, weld area, weld profile, and residual stresses in the weld metal. It can detect internal defects, such as gas inclusions cracks, porosity, and cold lap positions in the weld if they happen below or after the fusion zone of penetration.

Liquid penetrant inspection (PT) is a wet non-destructive type of weld inspection where weld examination is performed by applying a colored dye to the weld surface. It is performed by submerging the weld in a tank of liquid penetrant, removing surface contaminants with solvent, and then wetting weld metal surfaces with penetrant. The weld is examined for weld defects through fluorescent or black light conditions that are exposed to it. Flaws within the weld will allow for dye penetration into them after being exposed to both the ultraviolet beam of fluorescent lights and black lights. These flaws can be caused by porosity, slag inclusion, lack of fusion, lack of penetration or cracks in welds.

Magnetic particle testing (MT) is a non-destructive type inspection done by creating an eddy current within a magnetic field created on the welded metal surfaces. Flaw detection is ascertained through the magnetic field created when metal particles adhere to weld flaws that are electrically conductive. This weld test can be performed with either handheld or automated equipment; depending on the weld inspection area and type of weld under review for defects. Welds in both ferromagnetic (steels, stainless steels) and non-ferromagnetic materials like Aluminum alloys, carbon steel copper alloys, titanium, etc.) can be tested because of high sensitivity towards gap detection in non-ferromagnetic welds.

Mechanical bend testing (MBT) is a weld quality control method used to detect internal weld defects such as cracks by measuring the weld’s resistance to severe stress bending action. Defects can be caused by weld underfill, weld heat-affected zones (HAZ), and weld cracks. Welders use this weld test method to ensure that weldments meet both mechanical design requirements and weldability requirements. Mechanical bend testing is done on bend specimens of the weld metal after it has cooled down; causing less distortion in the weld cross-section.

Radiation penetrant testing (PT) is another non-destructive weld inspection method where a film or spray is used to highlight potential flaws on the weld specimen. This process detects any discontinuities between the weld metals having atomic differences within their atomic structures. Flaws are indicated by dye penetration into these areas during fluorescent or black light conditions, becoming observable by inspectors as they fluoresce. This weld test is commonly used for welds in materials like ACSR, aluminum alloys, copper alloys, stainless steel, & many more.

Radiography (RT) is the most common weld test method because it provides a high accuracy in in-depth and position measurements when inspecting welded joints. It uses x-rays to provide images of the weld area which can be examined to find any flaws present underneath its surface. Piping systems use this weld inspection method extensively as it gives the best possible picture of the weld from outside or circumference view without cutting into it or making physical contact with it. Connections between pipes that are welded together also undergo radiographic testing before they are put into to ensure proper weld quality and weld inspection.

Ultrasonic weld testing (UT) is a weld test method used for welds that are not able to be inspected by other methods like radiographic testing and gas metal arc welding (GMAW). This weld test uses high-frequency sound waves to detect flaws present in the welded structure; which can include cracks, porosity, lack of fusion, or incomplete penetration. Ultrasonic weld testing works on ferromagnetic as well as non-ferromagnetic metals like aluminum alloys, copper alloys, carbon steel, etc.

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