Bi-rigid guide wire enables endoscope insertion into winding small gas pipelines

Abstract

Bi-rigid guide wire enables endoscope insertion into winding small gas pipelines 1. Introduction Pipelines are indispensable for supplying resources to cities and homes (Takeshima and Takayama, 2018; Y. Li et al., 2019). In Japan, the underground gas pipeline extends for more than 1.5 billion km (Gas Pipe Overview, 2018). Generally, gas is sent through main pipes under the public road and branches into external gas pipes at residential sites (Fig. 1). The main pipes are of size "50A" (diameter: 52.9 mm), whereas the external gas pipes are of size "25A" (diameter: 27.6 mm) (Gas Pipe Overview, 2018). External gas pipes have four sets of two turns consisting of a bend and an elbow (Gas Pipe Overview, 2018). The total length of an external pipe is about 7.0 m. Because these pipes are installed underground, they are not being maintained. Therefore, corrosion often appears inside the pipes as they age (Cole and Marney, 2012). The most widespread method of inspecting the interior of a gas pipe is visual inspection using an endoscope. One example is using a flexible microscope, as shown in Fig. 2. The operator uses the hand console to manipulate the tip with the microscope camera. However, it is impossible to insert a microscope into a buried pipe because the microscope buckles and stops in the pipe. Thus, when an accident occurs at an external gas pipeline, the buried pipes are dug up randomly until the staff finds the causes. This requires stopping the gas flow and digging up the branch pipe extending from the load (Ogai and Bhattacharya, 2018). The entire process takes more than 1 day, and the gas cannot be used while the pipes are being inspected. Furthermore, digging up and refilling the load has a high cost, which includes personal expenditure and catering (Cole and Marney, 2012).

Current Trends and Perspectives of Detection and Location for Buried Non-Metallic Pipelines

“…(2) The robustness of the wire and mobility of the probe has been enhanced. Miura et al [37] designed a hollow conductive filament that can improve the toughness of the wire to detect and locate the farther pipeline path. Kim et al [38] developed the magnetic flux leakage (MFL) system structure to reduce the friction on the pipeline wall.…”