High voltage testing is also known as spark testing. This type of testing utilizes electrically conductive medium to coat the weld. After the weld is coated, the weld is exposed to a high voltage probe. This test shows an indication of a leak in the weld when an arc is observed through the weld. This type of testing is advantageous in the fact that it allows for quick detection of the flaws inside the weld joint and that you only have to have access to one side of the weld. One disadvantage with this type of testing is that there is not a way to evaluate the weld seam quality. Additionally, the weld has to be coated with conductive material.