Many different types of welding inspection exist to keep pipes and structures safe and secure. Countless building codes require strict adherence to project plan specifications and inspection guidelines, according to Weld Procedures. The American Weld Institute usually produces code for multiple story structures, while the American Petroleum Institute issues construction and inspection guidelines for pipelines and refineries.
Visual inspection is an important preliminary method of welding inspection. According to Weld Procedures, inspectors will observe welding with the naked eye to analyze the material for corrosion or cracking. Visual inspection is an expedient way to catch major problems with welding jobs. If problems are spotted they can be fixed before additional inspections commence. Succeeding a thorough visual evaluation is a good indicator that the welding may withstand additional non-destructive inspections.
X-ray inspection is a critical, non-destructive evaluation method allowing the inspector to see the inside and underside of welded materials, according to Weld Procedures. Recorded on radiographic film, x-ray readings give the inspector a clear indication of how durable and well-constructed welded materials are -- well beyond what can be viewed with the naked eye. Once analyzing the x-ray film, the inspector has the right to give the welding job a failing grade if too many sizeable holes or exposed fibers exist in the weld.
Ultrasonic testing is a third method of weld inspection. Ultrasonic inspection uses audio waves to test for proper echoing and vibration within welded pipe, according to Weld Procedures. Essential methods of non-destructive inspection, ultrasonic waves are generated into the pipe to match the density and length of the materials being tested. If an inspector notes any abnormalities in sound wave frequency -- such as hearing reflected sound in the a portion of the pipe where no echo should be heard -- it may be grounds for rejecting the weld.