Post-heat treatment
After welding, the weldment is kept warm and slowly cooled to reduce the cooling rate and prevent cold cracks. It is suitable for materials such as low-alloy high-strength steel.
Overall heat treatment
After the weldment is heated and kept warm as a whole or partially, it is furnace cooled or air cooled to reduce welding residual stress and improve the structure and performance of the weld and heat-affected zone.
Weld cleaning
After welding, remove slag, spatter and other impurities on the weld surface in time. You can use tools such as wire brushes and flat shovels for cleaning. For slag that is difficult to clean, mechanical grinding can also be used. The weld surface after cleaning should be smooth and neat, which is convenient for subsequent quality inspection and anti-corrosion treatment.
Non-destructive testing
According to the requirements of API 5L standard and relevant specifications, non-destructive testing is carried out on the weld. Commonly used non-destructive testing methods include radiographic testing (RT), ultrasonic testing (UT), magnetic particle testing (MT), etc. Radiographic testing can intuitively detect whether there are defects such as pores, slag inclusions, cracks, etc. inside the weld; ultrasonic testing can quickly detect defects inside the weld; magnetic particle testing is mainly used to detect defects such as cracks on the surface and near the surface of the weld. The proportion and qualification standards of non-destructive testing should comply with the standard regulations. For example, for some important pipelines, 100% radiographic testing may be required.
Appearance inspection
Inspect the appearance of the weld, including the weld's excess height, width, surface flatness, undercut, etc. The weld reinforcement should generally not exceed 3mm, the width should be uniform, the surface should not have obvious defects such as pores, slag inclusions, cracks, and lack of fusion, the undercut depth should not be greater than 0.5mm, and the continuous length should not exceed 100mm, and the total length of the undercut on both sides should not exceed 10% of the weld length. Through the appearance inspection, it can be preliminarily judged whether the quality of the weld meets the requirements.
API 5L X52 PSL1/PSL2 Spiral welded pipe
