This study is designed to evaluate quality management in mechanical construction projects in the oil and gas industry. This evaluation was done by assessing quality assurance, quality control and planning. Three hypotheses were postulated to answer research questions. The study adopted an audit method as an appraisal strategy. To this end, an audit checklist was designed using the Iso 9001 and the companies‘ specifications as audit criteria. An extensive literature review was undertaken with a view to explain quality management and relate it properly to this research work. Based on the above, it was found out that the overall level of quality management of one project (project B) is below average (Poor quality management) while the other project (project A) is above average (satisfactory quality management). The percentage of nonconformance recorded after auditing project A contractors is below 40% while the percentage of nonconformance recorded after auditing project B is above 50%.The study reveals that non-compliance to the requirements of ISO 9001 and owner‘s specification is the critical factor responsible for poor quality management in the oil and gas industry. Conforming to requirements of ISO 9001 and project owners‘ specification achieves satisfactory quality. The study therefore, recommends that requirements of Iso 9001:2008 should be documented and implemented throughout the project life cycle. Also, that mechanical construction projects should be awarded to mechanical construction companies that are ISO 9001:2008 compliant. Furthermore, quality management of mechanical construction project should be evaluated using quality audit throughout the life cycle of the project in order to detect nonconformance and implement corrective actions before the end of the project. Moreover, top management of construction project should be committed to set and achieve quality objectives of the project.