The development and implementation of a portable nucleonic computed tomography system with clamp-on-features, called “GammaSpider”, employing gamma-ray for engineering inspection is briefly discussed. Depending on the object to be inspected, a small isotopic gamma-ray source, in combination of a NaI(Tl) scintillation detector and an autonomous mechanical gantry set-up are used. The basic theoretical aspects, the system configurations and the other features are presented. This system is capable of generating high quality tomographic images and thus, offers great promise for in-situ engineering inspection. It is successfully used to inspect blockages in pipelines, to examine wooden electric poles and to study hydrodynamic behavior of multiphase flow in a bubble column. Some of the preliminary results are presented in this paper.