大型LNG储罐不锈钢外罐焊接防变形综合技术OA
Comprehensive welding deformation control technology for stainless steel outer tanks of large LNG storage tanks
目的 针对大型 LNG双金属全容储罐 S30408奥氏体不锈钢外罐壁板焊接时,因材料特性易产生变形,威胁储罐几何精度与结构安全的问题,探究其焊接热变形机理并构建控制技术体系.方法 以大同液化调峰储备集散中心二期项目30 000 m3 LNG双金属全容储罐(外罐材质 S30408)为工程实例,采用材料学理论与工程实践相结合的方法,分析 S30408不锈钢低导热、高线膨胀系数及无相变特性对焊接变形的影响;阐述了基于液压提升倒装法的施工工艺、针对不锈钢低热输入、多层多道焊的工艺规程、对称分段退焊的焊接顺序,以及刚性固定与反变形等防变形措施,通过现场实测数据验证控制效果.结果 匹配 S30408特性的焊接参数控制(线能量 8～15 kJ/cm),可有效抑制热影响区宽度与变形;应用控制技术体系后,外罐壁板焊接一次合格率达 98.9%,壁板椭圆度≤35 mm(优于 API 620—2022中 D/200即 50 mm的要求),垂直度偏差≤28 mm;明确了不锈钢外罐焊接变形核心控制因素与碳钢的差异.结论 针对 S30408材质外罐壁板,采用匹配材料特性的低热输入焊接工艺、精细化施工组织及全过程监控,可有效控制焊接变形.该技术体系保障了全容储罐的建造质量,可为同类不锈钢大型储罐工程提供技术参考.
Objective This study aims to investigate the welding thermal deformation mechanism of the outer tank wall plates of large-scale LNG double-metal full-containment tanks,which are made of S30408 austenitic stainless steel and prone to deformation during welding due to material properties,and to establish a comprehensive control technology system to mitigate deformation,thereby ensuring tank geometric accuracy and structural safety.Method In the second phase of the Datong LNG Peaking Regulating,Reserve and Distribution Center project,a 30 000 m3 double-metal full-containment LNG tank(outer shell:S30408 stainless steel)was used as an engineering case.By combining materials science theory with engineering practice,the influence of S30408's low thermal conductivity,high coefficient of linear expansion,and lack of phase transformation on welding deformation was analyzed.The construction technology based on the hydraulic lifting inverted erection method,the low-heat-input multi-layer and multi-pass welding procedure,the symmetrical segmented back-step welding sequence,as well as anti-deformation measures such as rigid fixing and reverse deformation was also described.The control effectiveness was verified by on-site measurement data.Result Control of welding parameters matching the characteristics of S30408(e.g.,welding heat input of 8-15 kJ/cm)effectively suppressed the width of the heat-affected zone and welding deformation.After application of the control technology system,the one-time welding qualification rate of the outer tank wall plate reached 98.9%,the ovality of the wall plate was controlled to≤35 mm(better than the D/200 requirement of 50 mm specified in API 620-2022),and the verticality deviation was≤28 mm.The differences in the core control factors for welding deformation between stainless steel outer tanks and carbon steel tanks were also clarified.Conclusion For the S30408 outer tank wall plate,welding deformation can be effectively controlled by adopting a low-heat-input welding process that matches the material characteristics,combined with refined construction organization and whole-process monitoring.This technology system ensures the construction quality of the full-containment tank and provides a technical reference for similar large-scale stainless steel storage tank projects.
张鹏
大同华新液化天然气有限公司
LNG全容储罐S30408不锈钢外罐壁板焊接变形低热输入焊接倒装法
LNG full containment tankS30408 stainless steelouter tank wall platewall platewelding deformationlow heat input weldingtop-down erection
《石油与天然气化工》 2026 (4)
46-54,9
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