大型落地式LNG储罐承台电伴热管施工技术

Construction technology of electric tracing pipes installed in foundation slab of large-scale LNG storage tank

上海LNG项目20万m^3储罐因地质原因采用了落地承台结构,由于储罐地基内部没有空气对流途径,为了防止储罐中的LNG冷量传入基础导致基础冻裂,因此确定采用电伴热方式抵消冷量。储罐承台电伴热系统由加热电缆、保护套管及控制设备组成,其保护套管预埋在钢筋混凝土中。在简要介绍该储罐承台电伴热管布置要求的基础上,较为详细地论述了储罐承台电伴热管的施工工艺,重点叙述了电伴热管材料进场验收、下料预制、焊接安装和吹扫通球等各个关键施工工序。工程实践证明,储罐承台电伴热管安装按照上述流程和措施施工后各项质量指标均符合设计和规范要求。

For geological reasons, the 200 000 m^3 storage tank in Shanghai LNG Project adopts the structure of foundation slab.Because there is no air convection way inside the tank foundation, in order to prevent LNG cool in the tank from entering the foundation and causing the foundation to freeze and crack, it is determined to install the electric tracing system in the tank foundation to eliminate the cooling.The electric tracing system of the foundation slab is composed of heating cables, protective pipes and control equipment.The protective pipes are embedded in reinforced concrete of the slab.On the basis of a brief introduction to the arrangement requirements of the electric tracing pipes, the construction technology of the electric tracing heat pipes is discussed in detail, and the emphasis is placed on the key construction procedures such as field check and acceptance of the electric tracing pipes, material cutting and prefabrication, welding installation and purging.The engineering practice proves that all quality indexes of the construction of the electric tracing pipes in the tank foundation slab meet the requirements of design and specifications.