Application of the Combinatorial Inspection Method on the Buried Steel Pipelines in China

In general, the pipeline external corrosion direct assessment should be synchronously done by two or more inspection tools. Hence, it is very important to know how to develop the high-efficient and accurate combinatorial inspection techniques for engineering application. In this paper, the advantages, disadvantages and adaptabilities of the existing techniques and instruments are reviewed. Considering the technical difficulties in Chinese engineering practices, five different combinatorial inspection techniques were then brought forward. The proper selection of the combinational inspection technique can be determined by the inspection aim, servicing environment and type of the pipeline, soil, and so on. However, it should be noted that each combinatorial inspection technique can be used most of the time with some demerits. Engineering application showed that the proposed techniques can be directly and efficiently used to assess the pipeline external corrosion.