The form of transportation of energy from the sources to the consumers is the concern of the researchers across the world, this is due to the consequences upon the failures. Some of these failures causing economical losses and environmental damages. Both are worth to be investigated and studied to reduce the risks and losses. In this paper the effects of cracks in pipelines has been investigated, it is found that the crack is causing the decrease in pressure. Several pipes were used in the experiment, one without crack and the rest with different crack size. The pressure drop in the area around the crack (named crack zone) was bigger in the up and down stream zones. Computational fluid dynamics CFD package ANSIS (Fluent) was used in the analysis and the results presented. Because the fluid used in the research is crude oil, so the paper is mainly for the benefit of the oil and gas industries and the pipeline designers and manufacturers.