Many of the properties of welds can be tested by weld inspection, some of which are related to weld size and others to weld defects. Weld size is often extremely important because it is usually directly related to weld strength, and undersized welds may not be able to withstand the stresses at work. Weld seam defects are equally important. Defects inside or adjacent to the weld may result in the weld not achieving its intended performance, depending on the size and/or location of the underfill. Unacceptable weld defects are often referred to as weld defects, which may result in weld failure due to insufficient weld strength or stress concentration.
There are many reasons why you need to perform a weld inspection. Perhaps the most fundamental reason is to determine if the weld meets the quality requirements of its intended application. In order to evaluate the weld quality, we must first prepare some form of gauge block and use it to compare various characteristics. The quality of the weld cannot be evaluated without specific quality acceptance markings.
Weld quality acceptance criteria can be based on a variety of sources. Welded assembly drawings/design drawings usually provide weld size and may also provide additional weld size information such as weld length and position. These dimensional requirements are typically determined by design calculations and can be borrowed from proven designs that meet known solder joint performance requirements.
Acceptable and unacceptable weld defect levels or quantities are usually specified by welding procedures and standards. There are many types of welding procedures and standards for different industries, so it is important to choose the right standard.
Welding inspections often require a wide range of knowledge from welding inspectors: welding drawings, welding symbols, weld design, welding procedures, procedures and standard requirements, and inspection and testing techniques. Therefore, many welding procedures and standards require welding inspectors to be formally certified or have the necessary knowledge and experience to perform welding inspections. There are a variety of welding inspection training courses and international welding inspector qualification certification items to choose from. The most popular in the United States is the Certified Welding Inspector (CWI) certification of the American Welding Society (AWS). Welding inspector certification usually requires passing the exam to prove an individual's knowledge of welding inspection.
In order to further understand the welding inspection, we need to understand the specific testing process and scope of application. I chose the following topics to briefly introduce the main weld inspection process:
Inspection and testing of welding procedure qualifications – methods of testing used and how they become part of the welding quality control system.
Visual inspection – often the easiest and cheapest way to inspect; if properly implemented, it may be the most effective welding inspection method for many applications.
Surface crack detection – methods such as penetration testing and magnetic particle inspection – methods of operation and scope of application.
Radiation and ultrasonic inspection – Also known as non-destructive testing (NDT), it is commonly used to inspect the internal structure of the weld to confirm weld quality without damaging the weld.
Destructive Testing – A method used to verify weld integrity or performance, usually by cutting and/or breaking welded components and evaluating various mechanical and/or physical properties.
One of the elements of a perfect welding quality control system is to establish, operate, and monitor a reasonable weld quality inspection system. It is an indispensable prerequisite to establish a reasonable weld quality inspection system, determine appropriate quality acceptance criteria, select appropriate test methods, and have certified and/or experienced test personnel.
