Rapid Risk Assessment (RRA) Study For NRMT MS Blend Component Tank Truck Unloading Facility

Rapid Risk assessment is proven valuable as a management tool in assessing the overall safety performance of the chemical process Industry. Even though Industry management such as checklists, engineering codes, and reviews by well experienced engineers have provided substantial safety assurances, major accidents involving numerous injuries, casualties and significant damage can occur. Risk assessment techniques provide advanced quantitative means to supplement other hazard identification, analysis, assessment, and control and management methods to identify the potential for such incidents and to evaluate control strategies. The underlying basis of rapid risk assessment is simple in concept.


Numaligarh Refinery Limited (NRL), which was set up at Numaligarh in the district of Golaghat (Assam) in accordance with the provisions made in the historic Assam Accord signed on 15th August 1985. Main facilities required for MS blend component tank trucks are TT checking, gross weighing, unloading, emptiness checking and tare weighing. TT checking shed, Weigh Bridge and unloading facilities are located along road no. 111, 102 and 103 respectively. After entering the terminal through material gate, TT goes to black oil sealing platform via road no. 102 and 111. After which TT moves to weigh bridge via road no.111 & 102 for gross weighing. Then it goes to MTBE/PyGas TT unloading area via road no. 102, 111, 110 & 103 for unloading. Post unloading it comes back to black oil sealing platform for emptiness checking and then again goes to weigh bridge along road no.102 for tare weighing. Moreover, only one operator is deputed for both TT checking and unloading activities.

The Objective of RRA study is

  • Identification of worst case accidental events
  • Risk assessment due to the hazards and consideration of its tolerability to personnel, refinery and the environment which includes the following
  • Analyze and Calculation of physical effects of accidental scenarios.
  • Identification and quantification of the impact caused by the scenarios and contour mapping on the layouts.
  • Safety and Risk reduction measures to prevent incidents, to control accidents.
    The general hierarchy of risk reducing measures is:
  • Prevention (by distance or design);
  • Detection (E.g. fire and gas, Leak detection);
  • Control (E.g. emergency shutdown and controlled depressurization);
  • Mitigation (E.g. firefighting and passive fire protection);
  • Emergency response (In case safety barriers fail).