Destructive weld testing is a method of weld inspection that involves removing the weld and examining it for defects. It can be used on any weld but is usually utilized in conjunction with non-destructive methods such as radiography and magnetic particle inspection (MPI). However, MPI cannot detect slag inclusions or porosity from inside weld beads. Destructive weld test are also often performed when there have been indications of welding problems during inspections using other techniques.
Destructive weld testing is typically performed by cutting through the weld to examine its internal condition including corrosion, slag inclusion, porosity, fusion quality and metal transfer. The cut exposes a cross-section of the weld which can then be examined under magnification or viewed directly using optical equipment.
weld test destructively which requires cutting the weld cross-section to examine its internal condition, etc…
In destructive weld testing, a weld is cut in half and analyzed for defects such as corrosion, slag inclusions, porosity, fusion quality and metal transfer.[1] This type of weld testing can only be done when a weld is located out of position or cannot be tested using non-destructive methods. Optical equipment can also be used to view the weld directly without having to cut it.[2] Destructive weld tests are often performed when there have been indications of welding problems during inspections using other techniques. For example, radiography will not detect slag inclusions from inside weld beads, and may also miss porosity on weld surfaces. Magnetic particle inspection (MPI) will detect these types of defects, but it cannot detect internal porosity or corrosion.[3]
One of the most common nondestructive weld tests is radiography. This method uses x-rays to produce an image of the weld. Because this test can be performed without cutting into the weld, it is often used first to inspect the quality of a weld. A radiographic image picks up any crack indications as well as many other defects such as lack of fusion and slag inclusions. If no problems are detected during a routine radiograph, destructive weld testing will not be necessary.[2] However if there are indications that indicate welding problems during these types of weld tests, destructive weld testing will need to be performed.
Magnetic particle inspection (MPI) can also be used to inspect welds without having to cut them open. In MPI, magnetic particles are applied directly onto the weld surface and a magnet is brought very close to the weld area. Any indications such as lack of fusion or inclusions in the weld will show up as a dark spot on the weld bead.[4] However, because this method does not view any defects from inside beads, cases, here slag inclusions exist, may not be visible in the cross-section created by MPI.[2]
A sound wave test uses sound waves that bounce off internal weld defects and travel back to a receiver. This test is similar to MPI in that no cutting of the weld is required. The weld area is filled with a fluid made of ultrasound-sensitive particles and a sound wave sender is placed against the weld area. Any defect in the weld, such as corrosion or slag inclusions, will reflect back sound waves that are then picked up by the receiver.[2]
Destructive weld testing can be performed using mechanical means including shearography, ultrasonic testing, and gas plasma arc cutting (GPAC). In GPAC, heat is generated from an oxyacetylene flame to cut through the weld so it may be examined under magnification.
Learn more: https://en.wikipedia.org/wiki/Welding
