In the Oil and Gas Industry, maintenance is done using a device or tool called a pig, chiefly to remove solids, dirt, and liquids from the pipelines. The aim of this work is to design and retrofit a pig which will clean 3 identical underground transfer pipelines linking 2 depots The movement of this tool is basically through the action of the fluid in the pipeline pushing it along as it is pumped from one point to another, hence no external power is needed in the device to help in its movement. Calculation based model analysis of the tool together with Solidworks simulations and results are included in detail, with all assumptions and limitations clearly stated and listed. The results show that the pig will move inside the pipe at a lower speed than the mean flow velocity which is good for the performance of the electronic systems installed on its body for pipeline inspection. Bypass hole is added on the central part of the pig body to control the speed as well as keep the cleaned dirt stirred and moving, being pushed by the pig as it performs its cleaning process.