How to Conduct Welding Inspection in Oil and Gas Industry
Welding is one of the fundamental functions in constructing the infrastructure for oil and gas industry. In order to accomplish this important task, numerous finer points as well as insights should be taken into account. Proper welding inspection helps ascertain the quality, safety, strength, and several other important factors.
Many standard weld inspection methods are suitable for oil and gas industry. In these projects, weld inspection is done mostly during the execution as well as after completion. Discussed below are some of the most commonly used methods for welding inspection in oil and gas industry.
- Visual inspection: This type of inspection is carried out using the human eye and some simple inspection tools. Performed while the welding is in progress, it is the easiest and least expensive of all inspection methods. Visual inspection can effectively check factors such as joint preparation, current used, electrode condition, slag removal, and others. Though this method is simple and inexpensive, it is extremely reliable for identification of defects such as bulking, cracking, leaks, corrosion, and other issues affecting the integrity of oil and gas pipelines.
- Radiography testing: This non-destructive testing (NDT) methodology is used for the examination of a weld’s internal structure without causing any harm to the welded component. The underlying principle of this inspection is similar to medical radiography, and involves using iridium isotope to produce X-rays and passing them through the weld. Radiography can effectively determine defects such as excessive penetration, concavity, lack of fusion, cracks, etc.
- Ultrasound testing: In this method, ultrasound equipment is used to transmit high-frequency sound vibrations through a welded joint. If there are any defects in the welded joint, signals are received on a glass screen. This method helps detect, locate, as well as evaluate discontinuities because sound velocity through any given material remains almost constant.
- Liquid penetrant testing: This method is used extensively for the detection of weld defects such as porosity, hairline cracks, etc. The test involves the application of a liquid penetrant on the weld surface. The defects are then rendered visible by using a developer.
- Magnetic particle testing: This test is performed to find out a weld’s surface and slightly subsurface discontinuities. First, a magnetic field is formed by passing an electric current through the weld. Then, the defect areas are identified by applying iron particles in the magnetic field.
- Eddy current testing: Very small cracks in the weld structure can be identified by Eddy current testing. The testing method involves placing circular coils carrying an alternating current near the test specimen. The resultant magnetic field generates an eddy current by interacting with the test specimen. Any change in the eddy current indicates a flaw that can be measured by a receiver coil.
- Hardness testing: This test is conducted by placing an indicator on the weld and striking a specific load on it. The findings of this test helps determine properties such as ductility, strength, and wear resistance.
If you want to find out more about weld inspection, please contact our expert inspectors today at Coating Management Solutions.