Understanding Maximum Credible Loss Scenarios: How Do They Work and Who Conducts Them?

Understanding Maximum Credible Loss Scenario Study

What is meant by the maximum credible loss scenario study? Why is it to be conducted? Who can conduct this? Is there any standard/guideline to conduct this internally by a safety person with the HAZOP team?

Regards,
Abhay

Dear Abhay,

What is meant by maximum credible loss scenario study?

The studies are carried out by assessing the existing conditions of the workplace, process, operation, plant, and equipment. Based on the observations made and results obtained, the industries are advised to minimize or eliminate hazards in the form of a study report. The total duration for carrying out the study and submitting the report depends on the size of the plant, number of locations, number of samples collected, type of analytical method adopted, etc. As such, the study may be completed, and the report prepared within 4 months.

This includes the determination of the affected distance for the identified maximum credible loss scenarios using computer-aided software. This distance would indicate the radiation and overpressure levels for flammable substances and vapor concentration for toxic chemicals. By using this technique, one can relocate areas of the site that would be affected in the event of an emergency. Consequence analysis distances are incorporated into the on-site as well as off-site emergency management system.

Dear all,

Wait for commands. . .

Thanks in advance.

Thanks & Besafe,

Raghu

Dear all seniors, please come forward and help to provide a solution to our member, Mr. Abhay's query. More than 50 viewers but no replies. Hope for your earliest reply. Thanks in advance.

Dear Abhay,

Maximum credible (loss) accident analysis is one of the most widely used concepts in risk assessment of chemical process industries, which involves the following steps -

1. Development of credible accident scenarios. For the units of any industry being analysed, a set of scenarios are developed for accidents which are ‘credible'; the credibility being qualitatively understood as a combination of likelihood (of occurrence) and scale (of damage potential).

2. Delineation of maximum credible accident scenario. Based on the credibility of the accident scenarios they are ranked, and maximum credible accident scenarios are identified.

3. Damage calculations through mathematical modelling. The impact of these scenarios—for example explosion followed by a fire ball—is then studied using available models of explosion, boiling liquid expanding vapour cloud explosion (BLEVE), confined vapour cloud explosion (CVCE), vapour cloud explosion (VCE) and fire ball.

4. Risk estimation. Based on the damage potential estimated in the previous step and the probability of occurrence of these credible accident scenarios, risk factors are estimated.

Central to these steps is the aspect of ‘credibility'. A ‘credible' accident is one which is within the region of possibility and which is also likely to be severe enough to cause significant damage.

Hope this answers you.

Once again, I'm late, due to tight schedule. Kindly regret, as it cannot be avoided in my current schedule.

But I'm happy to see many good questions arising from you. Keep on asking (with patience to get reply).

Dear Ragu,

Once again thank you for your valuable contribution. Keep on contributing. Even though I'm not answering all the posts, I'm having a look on the posts atleast during alternate days...

But due to current tight work schedule I'm unable to reply or take part immediately.

Dear Penney, thanks for your consideration and response.

Dear Abhay, please let me know!

Conducting an MCLS Study

Dear All, thank you for the response. We have storage tanks containing Toluene, Methanol, TBA, Hexane, and caustic lye. We want to conduct a Maximum Credible Loss Scenario (MCLS) study for these. Kindly suggest a standard operating procedure to be followed by our internal team. If you have a sample or guideline, please post it.

Regards,
Abhay