HAZOP Revalidation Study For Various Area's of SOHAR REFINERY

Elixir Engineering  was awarded to perform HAZOP Revalidation Study for SR1 (AREA-100, AREA-200, AREA-300, AREA-400, AREA-500 and utilities for SOHAR REFINERY


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 OQ Sohar Refinery is located in the industrial area of Sohar, in the northern part of Oman. The refinery was originally built in the 2000s as a joint venture between Oman Oil Company and Aromatics Oman LLC. However, in 2011, Oman Oil Company acquired Aromatics Oman LLC, and the OQ Sohar Refinery became a fully owned subsidiary of Oman Oil Company.

The OQ Sohar Refinery has undergone significant expansions and upgrades in recent years to increase its capacity and improve its efficiency. In 2017, the refinery completed its $3.6 billion Sohar Refinery Improvement Project (SRIP), which involved the construction of a new crude oil unit, a new hydrocracker unit, and upgrades to existing units.

The OQ Sohar Refinery is a critical component of Oman's economy, providing the country with a reliable source of refined products for domestic consumption and for export to other countries in the region. It also supports Oman's growing petrochemical industry, providing feedstocks for the production of plastics, chemicals, and other products

Hazard & Operability study (HAZOP)

Hazard and Operability (HAZOP) Study is a structured and systematic evaluation of a planned and/or existing operation to identify and evaluate potential hazards in design and operation. This study is carried out by a team of engineers from different disciplines. The team looks at each section of a plant or system or operation (node), considers potential deviations from intended operation and analyses their consequences against any existing safeguards. Impact of identified hazards on safety, asset and environment are assessed.

HAZOP is a guideword driven brainstorming technique. Team members contribute based on their collective experience and lessons learnt from past projects.

HAZOP study records the identified hazards without proposing any solution, unless a solution is obvious. Proposed solutions may include additional safeguards or operational procedures as necessary. The study record serves as a guide to determine the Health, Safety and Environment (HSE) issues to be resolved during the project.

Purpose of HAZOP:

HAZOP for any project or modification serves many purposes including

  • Identify the hazards inherent to the proposal.
  • Identify the credible equipment instrument failure likely to lead to accident scenarios / hazards / operability problems
  • In addition to these issues, HAZOP occasionally identified items which could improve unit operations and efficiency


The HAZOP focuses on the process / utility system and associated interfaces. The basic concept of a HAZOP study is to take full description of the process and question every part of it during brain storming meetings attended by the different specialists involved in the process design to discover firstly what deviations from the intention of design can occur and what their causes and consequences may be.

The main steps involved in a HAZOP study are as follows:

  • Select the node (Line, equipment or a system) on the P&ID;
  • List of the intention & process parameters, guidewords for the nodes;
  • List all deviations an ignore deviations that are not meaningful and apply the deviation;
  • Brainstorm and list various causes of the deviation and ignore causes that are not credible;
  • Determine the consequences of the deviations due to each listed credible cause;
  • Identify safeguards already provided in the system
  • Suggest recommendations / actions, should the safeguards be inadequate;
  • Repeat steps 3 to 7 for each deviation
  • Repeat steps from one (1) to eight (8) on the next node until all the nodes are covered.

Elements of HAZOP study:

Node definition

The HAZOP study progresses through the plant node by node. The selection of the node sizes and the route through the plant is made before the study by the facilitator. The node should be described in terms of: -

  • Brief description of the node
  • Typical operating and design conditions
  • Method of operation and maintenance, and requirement for operator intervention


Flow, Pressure & temperature are usually regarded as the main parameters/elements. Additional parameters relate to general considerations like maintenance, safety, relief, corrosion/ erosion, instrumentation, start-up & shutdown, etc. Some of these may be selected for nodes in a study as appropriate based on relevance and concerns expressed by team members.


Guide words are simple words or phrases used to qualify or quantify the intention and associated parameters in order to suggest deviations.

Standard guide words; No/less, more/Less, As Well As/Part of, Reverse/Other Than, Early/Late, Before/After are applicable to each parameter. ‘Other Than’ is a very popular ‘catch all’ guide word at the end of each parameter.



All credible/ plausible scenarios leading to the deviations, should be considered when determining causes. The Causes should be “Local” to the node being studied. The consequences are deliberated only after listing all the Causes. Two events happening simultaneously without any correlation should not be considered.


“Global” effects should be considered for the consequences i.e., keep researching the resulting reactions till you reach the Ultimate Consequence of a deviation.


Risk is a function of both Probability and Consequence. Safeguards reduce either Probability or Consequence. These could be either related to hardware or operator practices & intervention., While selecting safeguards, you may consider engineering or administrative safeguards, but it is necessary to check whether these are existing & functional for the operating plant

Risk matrix

Risk assessments should be carried out to quantify the risks associated with deviations and their potential consequences, and to assist in determining the adequacy of planned safeguards and the possible need for further action. An initial informal risk assessment should be carried out on each case – Consequence scenario based on the inherent risk in the unprotected state.

The risk matrix included in the below table should be used as a guide. The risk should then be reassessed taking into consideration the planned safeguards and risk reduction measures. For less important risks, the need for further action can be based on the experience and judgement of the HAZOP study team.


Once the reasonable consequence and likelihood of each potential unwanted event is determined, the risk can be ranked using the above “Risk Assessment Matrix” and recorded on the HAZOP study Worksheet.


Recommendations should be reported using action-based words (such as Check, Provide, Consider, Ensure, Review etc.), and assigned to specific work groups. It should be verified whether three chief questions have been explained, viz.

  • What is to be done?
  • Where is it to be done?
  • Why is it to be done?

Elixir Engineering

Elixir Engineering is a multi-disciplinary Engineering services company.
With our strong technical team, we have proven to be effective for our Clients.
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