Welding qualification involves various testing procedures to ensure that the welded joints meet specified standards and requirements like AWS D1.1 or ASME Section IX. The procedures can be either destructive or non-destructive in nature. These procedures are crucial to guarantee the integrity and reliability of the welds.
DIY’s do not need to undergo these tests as they are not professional welders. But in case of professional cliental work or high end projects like bridge construction, construction of buildings and other big projects, the quality control and welding quality assurance standards must be followed by the fabricators.
14 Welding Procedure Qualification To Test Welding Quality
Here is a list of 16 common testing procedures in the welding quality assurance process.
1. Visual Inspection (VT)
Visual Inspection (VT) in welding is a fundamental method. It involves visually examining the surface of the welded joints for any defects or irregularities. This type of inspection is done before destructive testing and involves the welder inspector to check for surface defects, such as cracks, porosity, undercut, and incomplete fusion with eyes. Few discontinuities are allowed to some extend like porosity. However bigger issues like cracks are not allowed even a little bit.
This technique is non-destructive testing (NDT) technique and it relies on the inspector’s visual acuity and experience.
2. Radiographic Testing (RT)
Radiographic Testing (RT) is a non-destructive testing (NDT) method used in welding to examine the internal structure of welds. This volumetric inspection involves the use of X-rays or gamma rays known as radiographs, to detect any flaw of weld and its surrounding materials. These radiographs reveal any internal defects or irregularities within the weld that may not be visible through visual inspection.
In this method welded joint is put under the electromagnetic radiation similar to medical field, and an image of weldment is created. If there is any internal defects like porosity, lack of fusion, and incomplete penetration etc. all the problems would appear on x-ray film upon which the inspector would make a report.
3. Ultrasonic Testing (UT)
Ultrasonic Testing (UT) is another non-destructive testing (NDT) method used in welding. In the method high-frequency sound waves are used to detect internal and surface defects in welds. It allows to inspect the overall surface of the welding area, not only a single spot.
Ultrasonic testing is particularly useful for identifying issues like cracks, lack of fusion, and porosity.
4. Magnetic Particle Testing (MT)
Magnetic Particle Testing (MT) is also known as magnetic particle inspection (MPI). It is a non-destructive testing (NDT) method used in welding to detect surface and near-surface defects in ferromagnetic materials.
This method involves the application of a magnetic field and the use of magnetic particles to identify the defects on material. Here material is magnetized first with the help of yoke. If there is any defects on surface then magnetic field would cause the fluxes to leak and the inspector would determine the problem area.
This technique is particularly effective for identifying cracks, discontinuities, and other flaws that are parallel to the magnetic field.
5. Liquid Penetrant Testing (PT)
Another name of Liquid Penetrant Testing (PT) is Dye penetrant testing (DPT) or penetrant inspection. It is a non-destructive testing (NDT) method too. This method is used in inspection of welding quality to detect defects in a variety of materials, including metals, plastics, and ceramics.
A liquid penetrant is applied to the surface of the weld, and after a certain dwell time when the liquid penetrant is soaked, the defect would become visible to open eye. This technique is particularly effective for identifying discontinuities such as cracks, porosity, and other surface imperfections.
6. Tensile Testing
Tensile testing is a mechanical testing method widely used in the field of welding to assess the mechanical properties and performance of welded materials. This test provides valuable information about the tensile strength, yield strength, elongation, and other mechanical characteristics of a material, including those specific to the weld zone.
7. Charpy Impact Testing
Charpy Impact testing is a method used in welding and material science to assess the toughness and impact resistance of a material. The primary goal of Charpy Impact Testing is to measure the energy absorbed by a material during fracture under a standardized impact load.
It measures the toughness of the weld by subjecting it to a sudden impact at low temperatures. This test is particularly crucial in applications where the material may be subjected to sudden, dynamic loads or impact forces.
8. Hardness Testing
Hardness testing is a common method used in welding to assess the hardness of welded joints and the surrounding base material. This testing technique provides information about the material’s resistance to indentation or penetration, offering insights into its strength, durability, and suitability for specific applications.
9. Bend Testing
Bend testing is a mechanical testing method used in welding to assess the ductility and soundness of a welded joint or the base material. This involves bending a specimen, usually a coupon cut from the welded joint, to evaluate the ductility and soundness of the weld.
This test involves bending a prepared specimen to evaluate its ability to withstand deformation without cracking or failure. Bend testing is particularly important for ensuring the integrity and performance of welds, especially in applications where the material may experience bending or flexing.
10. Welding Procedure Qualification Test (WPQT)
The Welding Procedure Qualification Test (WPQT) is essential for ensuring that the welding process employed will consistently produce welds of the required quality and mechanical properties. This involves testing a specific welding procedure to ensure it can consistently produce welds that meet the required standards.
The WPQT is a critical step in the overall quality assurance and certification process in the welding industry.
11. Welder Performance Qualification Test (WPQ)
The Welder Performance Qualification Test (WPQ) is a procedure used in welding to assess the skill and competency of individual welders. This test is designed to ensure that welders have the necessary proficiency to consistently produce welds that meet specified standards and requirements.
These testing procedures are often governed by industry codes and standards, such as those provided by organizations like the American Welding Society (AWS) or the International Organization for Standardization (ISO).
12. The Fillet Break Test
Fillet Break Test is a mechanical testing method used in welding to evaluate the quality and integrity of fillet welds. Fillet welds are commonly used in various applications, and this test specifically assesses their strength and soundness.
The test involves subjecting a fillet weld to bend forces until it breaks, providing valuable information about the weld’s ductility, fusion, and overall performance.
13. Macro Etch
Macro etch, also known as macroscopic etching, is a crucial technique in welding metallurgy used to assess the overall weld quality and integrity. In this process, a cross-section of the welded material is chemically etched to reveal the macrostructure, allowing for a detailed examination of the weld zone.
Macro etching helps inspectors and welders identify potential defects such as weld discontinuities, inclusions, and improper fusion. This method plays a vital role in quality control, ensuring that welds meet industry standards and specifications for structural integrity and performance.
14. Tension Test
The tension test is a fundamental method in welding quality assessment, aiming to evaluate the mechanical properties of welded materials. During this test, a specimen taken from the welded joint undergoes controlled tensile loading until it fractures.
The resulting data, such as ultimate tensile strength, yield strength, and elongation, provide crucial information about the weld’s structural performance and its ability to withstand applied forces. It serves as a key quality control measure in the welding industry.
15. Vickers Hardness Testing
Vickers hardness testing is a method used to assess the hardness of a material by measuring the resistance to penetration of a specified shaped indenter, typically a diamond pyramid with a square base. Named after its inventor, Smithson Tennant Vickers, this technique involves applying a known force to the indenter and calculating the hardness based on the resulting impressions.
Vickers hardness testing is widely used in various industries to determine the hardness of metals, ceramics, and other materials, providing valuable information about their mechanical properties and suitability for specific applications.
16. Nick Break Test
Nick break tests are a crucial aspect of welding quality assessment, involving the deliberate creation of a notch or “nick” in a welded specimen. It is a destructive method of weld quality test. This test method helps to reveal the internal structure and soundness of the weld by breaking it open and examining the fracture surfaces.
Engineers often rely on nick break tests to ensure welds meet stringent quality standards, providing valuable insights into the integrity and reliability of the welded joint. The distinctive fracture patterns observed during a nick break test offer a visual indicator of weld quality, guiding professionals in fine-tuning welding parameters for optimal results.
FAQ (Frequently Asked Questions)
1. What is the first step in welding procedure qualification?
The initial step in welding procedure qualification involves defining the essential variables, such as material type, thickness, welding process, and filler metal. This meticulous identification sets the foundation for creating a standardized and reproducible welding procedure that can be thoroughly tested and certified for quality and reliability.
2. What is the qualification range for welding?
The qualification range for welding encompasses the specified limits within which a welding procedure is deemed acceptable. It ranges from 25 mm (or 1 inch) to 73 mm (or 2-7/8 inch) for outside diameter.
3. What is the welding qualification test?
A welding qualification test is a comprehensive examination designed to assess a welder’s or welding procedure’s ability to meet specific industry standards and requirements.
The testing specifications covered here are crucial for fabricators who want to work as professional welder. For quality control and high end welding result these tests are very important. A professional welder must know these standards and code to work in welding industry.