Risk assessments of industrial facilities, especially offshore oil and gas companies, are required to consider safety, environmental, financial, and company reputation risks. Risk assessments of normally unmanned installation (NUI) facilities usually do not accommodate personnel or employees. Therefore, a risk value cannot be applied when there is a plan to deploy personnel at an NUI. Hence, this study aimed to determine the inherent risk value when security personnel are deployed at an NUI. The NUI to be assessed has two types of platforms with different conditions. Risk values were obtained using a semi-quantitative risk analysis method by determining the likelihood and consequence criteria, whose values ranged from 1 to 5 according to the 5 � 5 risk-matrix scale used. The risk-assessment results demonstrate that NUI is at a �low risk� and is broadly acceptable. © 2019, The Author(s).