Measurement of pipe scaling using parallel beam gamma tomography

Scaling in pipeline or other process units may occur in the production process. Scaling in pipes can reduce the diameter of the pipe, thereby reducing the flow rate and even lead to clogged pipes. Measurement is needed to determine the existence of scaling and its percentage. Tomography is a technique used to investigate the inner structure of an object in a non-intrusive and non-invasive. In this work tomography system was used to conduct translational and rotational scan automatically. Collimated gamma-ray source ¹³⁷Cs transmit photons through the object and detected using NaI(Tl) scintillation detector. The projections data was built to image using filtered back projection (FBP) image reconstruction method. The reconstructed image is able to distinguish materials with adjacent density value such as water (1 g/cm³), paraffin (0.9 g/cm³), and pertalite (0.72-0.77 g/cm³). The pipes within scale image were analyzed to calculate percentage of flow area after scaling compared to normal pipe (pipe without scale). The image analysis results of remaining flow area in geothermal plant pipe are 10.06 % with 16 projections, 9.86 % with 32 projections, 9.75 % with 64 projections, and 9.76 % with 128 projections, while 26.08 % is in furnace pipe with 32 projections. Finally, the system successfully scans the object, acquires and collects data, builds and analyzes the image for pipe scale investigation. (author)