Abstract: Risk analysis, a new and developing science of pratical value, deals with the evaluation on how much risk exists in a project, and eventually reveals the proper orientation for cost and management needed for risk reduction.Hazard is defined as a characteristic or a set of characteristics of having potential losses, while risk is the combination of the probability that hazard results in failure and the degree of losses.A project having a very severe loss in case of failure will have a high risk even though its failure probability is very low; by contrast, if it is a minor loss, the risk will be low regardless of its high probability, and it will not pay to allocate excessive resource for risk reduction.Risk is usually controlled to an acceptable level.W?Kent Muhlbauer introduces a relatively complete set of method for pipeline risk scoring.During scoring each risk factor is assummed to be an individuality and the worst case is considered.The scores are characterized by subjectivity and relativity.The factors that contribute to pipeline risk are catalogued into four classes: third party damage, corrosion, design and incorrect operations.A score is assigned to each factor, and the relative risk score is then obtained with the considerations for the hazard and importance of the medium transported.The higher the score, the smaller the risk represented.In U.S.A, third party damage accounts for 40% or so in pipeline failures.There are six factors in third party damage, for which scoring method is introduced.