【Haichuan’s Insights from Others】Application of submerged arc automatic welding in the welding of two equipment units on-site

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Shi Jian’s Innovative Construction Methods Improve Quality and Efficiency 2019-01-15 Source: Sinopec News Network. The methanol-to-olefins unit of the 1.7 million tons per year methanol and converted olefins project built by Shi Jian is a key component of the Anhui United Coal-to-Olefins facility. The welding of pressure vessels in the reaction and regeneration areas represents a challenging aspect of this unit’s construction. In order to make up for the more than three months of delay caused by various factors, the Shi Jian project team began developing innovative construction techniques as soon as the necessary components arrived at the end of 2017. They compared the quality and efficiency of different welding methods, and ultimately decided to use submerged arc automatic welding for welding the longitudinal seams of the equipment. Over the course of several months, it was proven that this method not only ensured stable quality but also helped reduce costs and increase construction efficiency, earning high praise from the project owner, general contractor, and supervisors. During actual construction, the personnel involved in the Ten Construction Project keep a close watch on and promptly monitor the quality of submerged arc automatic welding. After several rounds of tuning and quality testing, confidence in the application of these devices in submerged arc automatic welding grew, and batch production was initiated. Ultimately, the welding results for the circumferential welds of the \"two vessels\" assembly were satisfactory. Among them, the cumulative welding length for the submerged arc automatic welding of the transverse seams on the regenerator cylinder was 96.2 meters, with a first-pass qualification rate of 97.35% ； The cumulative welding length for the submerged arc automatic welding of the ring seams in the reactor cylinder was 265 meters, with a qualification rate of 99.34%. For the automatic submerged-arc welding of the circumferential seams of the smoke gas three-spinning cylinder, the total welding length was 71 meters; 295 radiographs were taken, with a qualification rate of 97.97%. For the automatic submerged-arc welding of the circumferential seams of the process gas three-spinning cylinder, the total welding length was 139.5 meters, 510 radiographs were taken, and the qualification rate was as high as 99.8%. Zhang Bo, head of the Engineering Management Department at the Shijian Zhong’an Project Team, summarized by saying: “When using submerged arc automatic welding for welding the transverse seams of equipment, since the equipment needs to be suspended at a certain height, its use is limited during the initial stages of equipment assembly as well as when the assembly is carried out in multiple stages; as a result, there is no significant improvement in efficiency.” It is recommended to promote submerged arc automatic welding in the welding of similar equipment in other projects; by making appropriate improvements to the suspension devices of submerged arc welders and organizing modular construction in a rational manner, the application scope of submerged arc automatic welding can be expanded, thereby enhancing its advantages. ” It is estimated that submerged arc automatic welding can save 10 hours of labor per meter of weld, offering a significant advantage over manual welding. The Zhongan MTO facility has a total of 571.7 meters of pre-made transverse seams in its two reactors and three spinners; just this aspect alone results in savings of 750 man-days and 6,002.85 hours of labor, as well as cost savings of up to 300,000 yuan in labor costs. (Liu Chun)