Large diameter stainless steel cylinders are critical components in boilers, nuclear energy vessels, and other heavy-duty equipment. Their welding process is characterized by high technical challenges and stringent quality requirements. For example, a large-diameter stainless steel cylinder is made from 06Cr19Ni10N steel with a plate thickness of 22 mm. The inner diameter of the cylinder is 12 meters, and its height is approximately 17.6 meters. After welding, the verticality and ellipticity of the cylinder must not exceed 10 mm.
The cylinder body consists of 11 individual sections. The grooves on the four sides of the steel plates are machined using a planer and then rolled with a coiling machine to ensure that the dimensions and shape meet the design specifications. One of the main challenges in manufacturing such large-diameter stainless steel cylinders is controlling the ovality and verticality, as well as ensuring the quality and tightness of the welds.
The cylinder is assembled and welded using a vertical assembly method, with the first section serving as a reference plane. To maintain welding quality, several control measures are implemented during the process.
First, the ellipticity of the cylinder is carefully controlled. During welding, it's essential to ensure that the lateral shrinkage on both the inner and outer sides of each longitudinal weld is equal or similar. To achieve this, large or equally stiff П-shaped plates can be welded to the inner, outer, and upper, middle, and lower parts of the weld. Each weld is designed with an asymmetrical X-shaped groove, with a larger opening on the inside. The inner side is first welded with back-capping and the second layer, while the outer side is deeply rooted. Once the outer side reaches the surface weld layer, the inner weld is also completed. By controlling the welding sequence and the thickness of each layer, the deformation at the inner and outer corners of the weld is balanced. Finally, the П-shaped plates help make the inner and outer corners almost equal, ensuring that the cylinder’s ellipticity remains below 10 mm.
Second, the lateral shrinkage of the longitudinal seams is controlled. To ensure the verticality of the barrel section, the amount of lateral shrinkage on the upper and lower parts of the vertical joint should be uniform. This requires the top and bottom surfaces of the cylinder sections to be parallel and horizontal. With these precautions, the verticality of the 17.6-meter cylinder fully meets the design requirements.
During the initial welding of the inner side, each vertical joint is divided into four or five equal parts. Both the inner and outer sides are welded using a top-down section back-welding method, which results in less lateral contraction at the top than at the bottom. From the third layer onward, bottom-up through-welding and symmetrical welding are used, causing the upper part to contract more than the lower part. This compensates for the initial contraction differences and is further supported by rigid fixation using inner, outer, and upper, middle, and lower II plates, ensuring uniform lateral shrinkage across all welds.
Third, the lateral contraction of the circumferential seam is strictly controlled. In addition to uniform lateral contraction along the length of the longitudinal joints, the lateral contraction of the annular joints between sections must also be tightly managed. Rigid shaped panels are evenly spaced along the entire length of the weld, and eight welders simultaneously use identical welding parameters—such as current, speed, rod diameter, thickness, strip movement method, and direction—to perform segmented jump welding. This ensures precise control over the lateral contraction of the circumferential weld, keeping the center of each barrel ring within a horizontal plane.
By employing the II-plate rigid fixing method, combined with different welding sequences and groove shapes, along with the use of segmental back-welding and through-welding techniques, the verticality and ellipticity of the cylinder are guaranteed to meet both design and operational requirements.
Vision SE is our specialist vision solution offering a wide range of classification services. Through advanced image processing, we realize professional-level visual technology, which is suitable for medical image processing, scientific research and other fields. We focus on performance optimization to make it an industrial-grade solution that is widely used in factory automation and high-demand application scenarios. At the same time, we pay attention to data security and privacy protection, ensuring that the highest standards are met when processing images and data. Vision SE's classified services exceed expectations, providing high-performance and professional-grade vision solutions to various industries.
vision services,vision sensor,vision sense,vision se,vision se review
Ningbo Autrends International Trade Co., Ltd. , http://www.visionsemr.com