This study is related to the risk-based inspection (RBI) of pressure relieving devices (PRD) for Malaysian petrochemical plant. The PRD RBI study was executed utilizing the API RBI software, which follows the API 581: 2008, Risk-Based Inspection Technology standard. API 581 specifies the quantitative approach in determining the risk for PRD. PRD technical datasheet, inspection reports, process flow diagram, protecting equipment technical datasheet, piping and instrumentation diagram, and mass and energy balance are among the essential documents required to perform this analysis. A total number of 169 PRD were analyzed. The PRD testing interval at an oil refinery is currently between 1 and 3 years. From the study, 72% (122 units) of PRD interval can be extended from existing interval practiced by PP(T)SB. Another 18% (31 units) of PRD interval needs to be reduced from existing interval practice and 10% (16 units) of PRD interval is unaffected. Several significant findings were noted throughout this study such as set pressure higher than equipment design pressure and data discrepancy on technical documents. PP(T)SB is strongly recommended to take all the necessary actions to ensure PRD is operating as intended.