Hazard and Operability (HAZOP) Revalidation Study for OQ Sohar Refinery

HAZOP Revalidation study is a comprehensive evaluation of potential risks associated with exposure to hazardous substances in a specific environment. HAZOP revalidation study has been conducted for OQ refinery SR1. The purpose of the HAZOP Revalidation Study is to ensure that a process plant is designed, operated, and maintained in a safe and reliable manner. Click here to learn more on HAZOP Rules in Process Industry

HAZOP studies are crucial because they provide valuable insights into identifying risks and operational issues in a structured and systematic way. The resulting knowledge obtained from these studies proves highly beneficial in determining suitable remedial action. Click here to learn more on What is HAZOP Study?

OQ Sohar Refinery is a major oil and gas processing complex located in Oman. It is one of the largest and most complex refineries in the Middle East, producing a wide range of refined products, including gasoline, diesel, jet fuel, naphtha, LPG, and petrochemical feedstocks.

The objective is to identify potential hazards involved in the process/operation, evaluate their likelihood and severity based on cause & consequence identified by the HAZOP study, and propose effective control measures to enhance safety and operational efficiency.

The Scope of work awarded to Elixir Engineering is to conduct HAZOP Revalidation study that includes only the SR1 Unit of OQ refinery. HAZOP revalidation study covers the following facilities:

1.Crude Distillation Unit (CDU)
2.CDU LPG Merox Unit
3.Kerosene Merox Unit
4.RFCC RX-Regen Section
5.RFCC Main Frac. Section
6.RFCC Gas Concentration
7.RFCC Flue Gas Section
8.RFCC LPG Merox Section
9.Propylene Recovery Unit
10.Fuels Selective Hydrogenation
11.Indirect Alkylation Unit
12.Distillate Union fining Unit
13.Hydrogen Generation Unit
14.Sour Water Stripping Unit
15.Amine Regeneration Unit
16.Sulfur Recovery Unit (SRU-1/2)
17.Tail Gas Treating Unit
18.Sulfur Granulation Unit
19.TAME Selective Hydrogenation
20.Process (TSHP) & TAME Unit
21.Gasoline Hydro-desulfurization
1Power Plant, Electricity Receiving and Distribution System.
2Sea Water Intake Station
3Water system
4Steam and Condensate system
5Fuel Gas and Natural Gas System
6Instrument Air and Plant Air system
7Nitrogen System
8Chemical Preparation and Injection Facilities
9Offsite Common
10Feedstock and Slop Tankage
11Product and Component Tankage
12Truck Loading Facilities
13Marine Loading Facilities
14Waste Water Treatment
15Flare System
16Flushing Oil System
17LPG Vaporizer

HAZOP Revalidation  Procedure


HAZOP Revalidation study is performed by a multidisciplinary team experienced in Engineering, Operations, and Maintenance. Other relevant Experts should be included as required.

The HAZOP Revalidation study for OQ Refinery SR1 consisted of the following Personnel

  • Two HAZOP leaders
  • Two HAZOP scribes
  • Process Engineers from the respective area
  • Engineer Operations from the respective area
  • Instrumentation Engineers from the respective area
  • Safety Engineers
  • Corrosion Engineer (if required)
  • Mechanical Engineer(if required)
  • Rotary Engineer (if required)


During  HAZOP analysis conducted for OQ Refinery SR1, the initial step involves dissecting the process being examined into manageable sections called Nodes. These Nodes represent logical segments with clearly defined design objectives. Each Node is then meticulously examined by applying appropriate Guidewords to design parameters, so as to pinpoint potential hazards and operability issues that may arise as a result. Various factors, such as Equipment malfunction, Human error, Engineering, and administrative controls, as well as external events, are all taken into account as potential sources of hazards. By employing a Risk Ranking Matrix, the severity, and likelihood of each hazard are assessed, ultimately leading to the assignment of a numerical risk ranking for each identified hazard.


A detailed list of Questions, written from knowledge and experience is used to assess the acceptability or status of the process, system, or operation compared to standard design and operating practices. Checklist analysis is done for OQ refinery SR1 considering human factors and fire safety.  During Checklist analysis for Human factors, Questions based on Housekeeping and General Work Environment, Accessibility/Availability of Controls and Equipment, Workload and Stress Factors, Training procedures, etc. were captured. During checklist analysis for fire safety, Questions based on spacing between Process Components, Location, and Construction of Control rooms, Location of Engineering, Lab, Administration or other occupied buildings, Unit Layout, etc. were captured.

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