Gas Offtake stations are located on ground level that number of pipes exposure in open area is huge. Dirty dust and moss always stick on pipe surface which may damage pipe surface coating and obstruct inspection process during maintenance. The removal of stains requires huge amount of human resources and time, which is time-consuming and cost-wasting. The diameter of pipe varies around 450-600mm and there are obstacle along the pipe likes flange or support base. The orientation of pipe is restricted by API 5L specification of pipe. The surface of pipe is covered by a specific paint coating and then a layer of stains. Main goals of the device are to clean stain along a pipe (both vertical and horizontal), which contains 3 special features-a curved length, a flange and a supporting base. How can I design a robot to clean this huge pipe?? It is a big challenge.