Professional welds are often carefully regulated based on blueprints and designs that ensure they will perform well under pressure and have a clean appearance. Weld inspections will take into account the weld’s location, the size and shape of the weld, and the materials used for the weld.
Understanding the types of welding inspection tests can give welders some clues about how to make stronger, more reliable welds.
Beginning Welds the Right Way
Welding inspectors will review the materials used, the preparation of the metal, and the quality of the weld, ensuring that the weld achieves the right amount of penetration and doesn’t have any cracks or discontinuities. In light of that, make sure you’ve gone through all of the proper steps to prepare the metal, to get the right consumables and filler material, and reviewed the standards for shielding gas.
If necessary, review your blueprints and documentation about the welds in question to make sure you’ve followed all of the necessary guidelines, especially if the weld is in a challenging position or uses unfamiliar materials.
Tests for Detecting Surface Cracks in Welds
Welding inspectors can perform visual inspections of welds in order to evaluate their safety. However, a visual inspection may not detect the deeper or finer issues in a weld since they are primarily able to determine the overall quality of the weld. In addition, welds in certain positions or on certain materials may require more rigorous tests.
Liquid penetration tests are a simple and effective way to evaluate a weld, testing the weld to ensure that it doesn’t have cracks or defects that could cause issues in the future. Using a either “visible dye” or fluorescent dye, inspectors apply the dye to the weld’s surface and then apply a light or black light to determine if any small or hairline cracks are visible in the weld.
Besides liquid tests, magnetic tests are also useful for detecting cracks in ferromagnetic materials. If there are no cracks or discontinuities in the weld, then the magnet applied to the weld will not be attracted to it.
Destructive Welding Tests
Whether you’re being tested for your welding technique or an inspector can remove a section of a welding production line for a test, there are a number of destructive weld tests that give insights into the penetration of the weld and the presence of cracks throughout the weld joint. The macro etch version of this test applies a mild acid mixture to the weld joint, which enables inspectors to evaluate the quality of the weld’s fusion, bond, and stability.
The fillet weld test breaks off a portion of a weld and then applies pressure to it until the weld breaks. This is especially useful to determining how much slag is in the weld and the amount of porosity in the weld. The transverse tension test is another version of this approach to testing the stability of a weld until it hits its breaking point.
If you take a welding test or exam for your certification, there’s a good chance that you’ll have a guided bend test performed on your weld to ensure that the weld has excellent fusion. The weld’s bend radius helps determine the quality of the work.
Radiographic and Ultrasonic Welding Tests
These tests for welds aren’t destructive, sending waves into a finished weld and recording how well they travel through the weld in order to determine if there is any distortion from a discontinuity in the weld. Porosity, cracks, and slag will all appear as dark outlines in the final film for this test. While they require the right equipment, they have the distinct advantage of accurately testing finished welds without destroying them.