QRA Report for IOCL – Doimukh Depot

M/s. Indian Oil Corporation Limited is having an establishment for Receipt, Storage and Distribution of petroleum products at Doimukh Depot, Arunachal Pradesh. The product will be received by Tank Wagon and Tank Truck (Normal/Sick), the product will be stored in storage tanks (HSD/SKO/MS) Tanks and the same will be delivered by Road to Dealers and bulk Customers / Consumers.

The Depot receives, stores and distributes Petroleum Products: Motor Spirit (MS), Superior Kerosene Oil (SKO) and High-Speed Diesel (HSD). Initially the product will be received at depot through Rail Wagon and TT Unloading facility including TWD/TLD Pump house to Tank farm and the same will be stored in storage tanks in Tank farm and from there it will be transferred to Tank truck through TLF Loading facilities which includes TLF Pump house for onward transfer to Dealer / Customer by Road.

The products will be dispatched to truck loading facility (TLF) through dedicated pumps, located in the Pump House (TLF P/H). At least, one pump of each product will be considered as redundant to ensure smooth operation of the depot. Dedicated pipeline for each product will be laid till TLF bays. MS, HSD, SKO tanks will be having recirculation lines through their respective standby pumps in the TLF pump house.

In case of any unavoidable circumstance the loaded truck tanker of MS/HSD/SKO will unload the product into underground tanks by gravity, which is dedicated to each product. From these tanks after decantation/unloaded the products are pumped back to their respective main storage tanks through submersible pumps. Products drained from line (with basket type strainers) will be transferred to the U/G tanks of respective products.

All the products will be received, stored and dispatched through the depot. Feed is received from Rail Wagon and TT. Product receipt shall have wagons of HSD, MS and SKO facility. Dispatch is through tank trucks by road mode only. Vapor recovery system is available for MS TLF bays.

Vapor recovery system available for storage depot to collect MS vapors from the TLF bays. In this system truck tanks vents are connected to a common header system which collects the MS vapors from the truck tanks and are routed to vapor recovery system.

The vapor recovery process consists of adsorber vessels for continuous operation, containing activated carbon as adsorbent which collects MS vapor from vapor stream. MS vapors are adsorbed onto surface of activated carbon. Carbon bed adsorbs a given quantity of MS vapors and nearly saturated bed is then regenerated by means of a deep vacuum. The regeneration vacuum is generated by means of vacuum pumps. The hydrocarbons then desorbed from the activated carbon by a negative pressure. These concentrated vapors are compressed through an absorption column where they are absorbed by virtue of counter current flow of liquid MS.

The Scope of the work is to carry out Quantitative Risk Assessment Study for Indian Oil Corporation Limited- Doimukh Depot with the latest version of software Using PHAST & SAFETI 8.7. The following facilities are covered under the QRA study for the Project.

  • Receipt of products through Rail Wagons and Tank Truck.
  • Sufficient capacity storage tanks for product storage
  • Facilities for loading products using loading arms into tank lorries.

The main objective of this study is to systematically and numerically evaluate the potential risks associated with a particular situation, process, or decision. The following are QRA’s objectives:

  • Involves the use of numerical data and analysis to evaluate and quantify risks in various scenarios.
  • Aids decision making by enabling informed choices.
  • Assigns numerical values to risks, facilitating comparison and prioritization.
  • Provide a clear and objective way to communicate risk information to stakeholders.
  • Provide a clear and objective way to communicate risk information to stakeholders.
  • Assess the cost-effectiveness of different risk management strategies by comparing the potential costs of risk mitigation measures with the expected benefits in terms of risk reduction.

This Facility has been divided into Isolatable sections. The Major credible outcome events of Jet fire, Fire Ball, Flash fire & Overpressure Explosion have been identified and their impacts/consequences for each scenario have been determined using DNV PHAST 8.7. The risk analysis was carried out using DNV SAFETI 8.7 to obtain risk results in the form of LSIR contours and F-N curve. These risk results were assessed based on the Risk Acceptance Criteria and IRPA was found to broadly lie in the acceptable and the societal risk falls broadly in the acceptable region.