The study titled comparative evaluation of the microstructure and corrosion effects of stainless steel pipes conveying saltwater and petrol has been investigated. The study revealed that there were several challenges associated with an ideal stainless steel pipe when not properly protected from corrosion effect. The study also indicated that stainless steel pipes when exposed to some factors, there are bound to corrode and pose reasonable health hazards to human beings. Experimental technique was used as method to observe the effects of concentration, temperature, salinity and pH on pipes used in conveying some selected liquids under controlled environment. The aim of the experiment was to discover the factors responsible for the formation of hydrated oxides which causes corrosion on metals. At the end of the experiment, it was discovered that high salt concentration, chlorine and pH, temperature and other environmental factors were mainly responsible for the formation of these oxides that brings about corrosion. Finally, the results generated showed significantly that corrosion rates were higher under some conditions which were as results of non-availability of corrosion inhibitors.