4 replies to this topic

[JYO]

Dear Forum

I'm preparing a propsal project.There is a requirement in the ITB as below

"If the FIRE SAFETY ASSESSMENT result show that jet fire is an issue that needs to be managed, immediate isolation and depressurization for jet fire protection is required. If it is impractical due to flare capacity, only then secondary means of protection suach as pasive fire protection hsall be considered"

The plant I'm studying is Ethylene, Propylene, Butadiene, Benzene Toluene, Xylene and I have never experienced FIRE SAFETY ASSESSMENT.
To prepare the proposal, I need to estimate the impact of the result of FIRE SAFETY ASSESSMENT result for jet fire passive protection.


1) Would there be any simple way to estimate the area of Passive protection without doing the FIRE SAFETY ASSESSMENT?

2) If the jet fire duration time is 2 hours and depressurization time is 30 minutes, then the required passive protection of fire proofing would be 1hr 30minutes. Is this right?





For an example, when we do flare study for revamping projects, we check the increased relief loads and when it exceeds the existing design flare load, we find points to reduce the total releiving rate. Usually steam supply to the reboiler is the heat source of Pressure built up in the column. So if the steam is blocked, we can ignore the PSV reliving since there is no source of heat. When we block the steam, we considere 2 on/off valves on steam supply line of the column reboilers to meet SIL 3 requirement. When we reduce 10,00 kg/hr, there needs to be 2 pointd of 10,000kg/hr to be reduced for backup. and Actually 4 on/off valves are reuiqred, not 2. (Of course, a lot of study is needed but this will be a simple way to do the estimation at the proposal stage and it quite sure that this will be the recommendation of SIL study result

[Zauberberg]

First of all, if you don't have any experience in fire safety then it is quite irresponsible (both from you and from your company) to undertake such a task. People's lives, environment, and property can be at stake if ANY of the layers in major hazard management system are not done properly. If you don't believe me, Google "Bhopal disaster", "BP Texas City explosion", and many, many others.

 

Unless the plant is offshore, there is usually very little reason to consider jet fire as the cause to employ passive fire protection (PFP). PFP is typically applied only when there is a substantial danger from pool fires. However, if there is unacceptable level of damage anticipated to the pipe racks, structures, vessel supports etc., PFP may be applied.

 

API 2218 provides guidance on fireproofing.

 

As for the duration of time during which PFP must provide protection, fireproofing is required to protect equipment and structures from catastrophic failure (loss of structural integrity) up to the point where active fire fighting system can be deployed. This means either use of automatic deluge systems, fixed fire monitors, local or remote fire brigade, etc. You are required to determine the most risky scenario (which not necessarily needs to be the highest volume of spill / full bore rupture because they have low frequencies) and set up appropriate PFP to manage those circumstances and the fire envelope.

 

All in all, this is rather complex subject and it cannot fit within one forum thread. I definitely suggest you to undertake more thorough evaluation and employ a specialist to handle the subjects outside your areas of expertise.

[shvet]

 If you don't believe me, Google "Bhopal disaster", "BP Texas City explosion", and many, many others.

 

 

visual aids

[JYO]

Thank you Zauberburg

 

At the project execution stage, we would definitly have 3rd party with a specialist who would do the Fire Safey Assessment.

But I'm the in middle of bidding stage and my project team wants to include a budget for the the results of Fire Safety Assessment.

 

I thought if I had experience of Fire Safety Assessment with a similar plant, I would have a vague idea what the results would be.

I guess I simplified it too much.

 

Anyway Thanks for the reply~

[Zauberberg]

If you want to apply prescriptive criteria for fireproofing, you can follow API 2218 - although the document itself says that it should not be regarded as a fireproofing design manual, but rather as a collection of industry practices.

 

Each plant is different, even if they have similar configurations. The extent of fireproofing will differ between two example plants depending on many items: provision of safety isolation valves at convenient locations, depressurization facilities, surface drainage and spill containment, soil characteristics, operating volumes and fluid properties, availability and capacity of fixed firefighting systems, etc. etc. It represents a detailed risk assessment in case you want to develop a performance based fireproofing system.