Substation Firewall

[SKJ25POL]

Hi Everyone,

Any information in design and analysis of the Firewalls?
Any design examples, any handbooks have solved an example.

I appreciate any help if possible.

Thank you
Skj

 

[r13]

You need to gather information on equipment and fire protection requirement, which are required in setting fire wall configuration (Height, Width, Length), and select wall material based on fire rating criteria. The structural design aspect is the same as designing a free standing wall for the material selected (concrete, masonry).

Online Training: "Understanding of Firewall Basics",

https://pdhonline.com/courses/g125/g125content.pdf

.

References:
IEEE National Electrical Safety Code
IEEE 979 Guide for Substation Fire Protection
NFPA 70 National Electric Code

 

[SKJ25POL]

Thank you very much retired13.

Any educational and practical examples? Details?

Thank you

 

[JLNJ]

Fire barriers between uses is complicated and depends on a myriad of factors. Some are building code related (read through the IBC sections on fire rated construction and fire separations). The permutations are too many to bake into a few "worked examples". Some fire barriers or separations might be specified in the NEC. Again, there are many factors in play. Many substations don't need barriers - you see them outside and inside all the time with just a chain link fence around them.

The phrase "fire wall" is used generically (and improperly) to refer to almost any fire rated wall construction. The Code (I'm referring to the IBC) has very specific and extensive requirements for a true "fire wall" but I doubt any kind of substation will need a Fire Wall.

Building uses and separations between uses are normally the realm and responsibility of the architect. Talk to your architect about what is required.

 

[Ron]

The building code you're under gives the basic requirements. Follow that up with UL fire resistance guides that give the specific assemblies to comply with time ratings, and then look at the National Fire Protection Association for further guidance if needed.

If you need specific analysis guidelines, consult publications by the late Armand Gustaferro. He was the guru.

 

[SlideRuleEra]

The Code (I'm referring to the IBC) has very specific and extensive requirements for a true "fire wall" but I doubt any kind of substation will need a Fire Wall.

Substation fire walls have nothing to do with buildings, it's about protecting adjacent transformers and switchgear from an oil-filled transformer fire:

SKJ25POL - See this T&D (Transmission and Distribution) World article for a brief overview: "Fire Protection in Substation Transformers"

http://www.SlideRuleEra.net

 

[SKJ25POL]

SlideRuleEra (Structural),
Thank you very much for the information and I have had seen that but I guess my questions more specifically are that, if using a concrete wall what shall be the fire rating for it and is there any specific concrete with certain properties and strength we have to use? Any specific detailing that we have to follow like if you design a wall in high seismic area that we must follow the specific details/ rebar sizes/ cover?

Are we allowed to use "post-tensioned concrete" for Fire wall? Whats the benefit if able to use post-tension concrete?

retired13 (Civil/Environmental,
Thank you for the link with pictures.

Ron (Structural,
Thank you so much introducing Mr. Armand Gustaferro. I havent had heard from him before.
Do you know if he has papers on non post-tensioned concretes exposed to fire and high temp.
I just found the post -tension concrete paper from him.

 

[r13]

A search, on the pictures contained through the link provided, yields this article "Fire protection for power plants (NFPA 850)". THe things concerning you are extracted below for your convenience. Please read, understand the scope, and do further research as required. (Link to the complete article, Link)

Fire protection for oil-insulated outdoor type transformers
It is strongly recommended that any oil-insulated outdoor type transformer containing 500 gal (1890 liters) or more of oil is separated from nearby structures by a 2-hour–rated firewall or by specific spatial separation in accordance with NFPA 850 recommendations.
Wherever a firewall is installed between transformers (please refer to the picture below), it should extend at least 1 ft (0.31 m) above the top of the transformer shell and oil tank and at least 2 ft (0.61 m) beyond the width of the transformer and cooling radiators.
Fire protection for indoor transformers
Dry-type transformers are strongly preferred for use inside buildings. In case however, an oil-insulated transformer is installed indoors, then if its oil content exceeds 100 gal (379 liters), then it should beseparated from nearby areas by a fire barrier of 3-hour fire resistance rating. In case an automatic fire extinguishment system is installed, then it is allowed that the fire restistance rating of the fire barrier is reduced to 1 hour.
Construction materials for power plants
With the exception of roof materials, materials used in critical buildings of the power block shall be either non combustible or limited combustible. Roof covering is recommended to be be Class A, in compliance with NFPA 256, whereas metal roof deck construction, should be either “Class I” or “fire classified.”

 

[SKJ25POL]

retired13 (Civil/Environmental),

Sure. I appreciate it.

Skj

 

[SlideRuleEra]

A search, on the pictures contained through the link provided, yields this article "Fire protection for power plants (NFPA 850)". THe things concerning you are extracted below for your convenience.

There is a problem with this advice, it does not apply to substations. The main transformer yard supporting an electric generating station:

1) Is near the generator (generator is often inside a building). The building needs to be protected from a transformer fire. Most substations have only small, or no, buildings.

2) A large generating station is typically an "essential facility" (high risk category). A substation may or may not be, depending on what services it supports.

3) Transformers at generating stations tend to be larger (more oil to feed a fire) than transformers at substations.

4) Transformers at generating stations still use rock-filled oil containment reinforced concrete pits to contain oil spills (a fire in a containment pit is possible). Substations may not use containment pits.

Instead of NFPA 850, see "IEEE 979 Guide for Substation Fire Protection"..

SKJ25POL - For our generating station (not substation) fire walls, we used the same concrete mix design that was used for other structures. The fire walls are designed for the same high-seismic and high-wind requirements as the rest of the plant.

http://www.SlideRuleEra.net

 

[SKJ25POL]

SlideRuleEra (Structural),

Thank you for your comment. So, if the concrete mix design was the same, then what can we do for the "fire wall" to make it more resistant compare to the normal(non fire resistant) walls?

 

[SlideRuleEra]

...what can we do for the "fire wall" to make it more resistant compare to the normal(non fire resistant) walls?

In our case (for generating station fire walls, not substations)... nothing. Because of seismic and wind requirements, the walls are heavily built anyway. Also, if there is a significant fire, the (one and only) multi-million dollar main transformer for the station is destroyed... the fire walls, as long as they protect adjacent structure and equipment, are expendable.

Repair / replacement of the main transformer will take many months... build new fire walls. This type of fire at a generating station is rare. We do keep one spare main transformer on hand at our largest station (4 units @ about 600 MW each).

http://www.SlideRuleEra.net

 

[JLNJ]

SlideRuleEra is of course correct about protecting a building from large transformers placed near the building's exterior. These type of substation fire walls are not covered by the IBC.

My recent experience made me think of a smaller, distribution substation like one might find inside a building. Some of these type might require fire rated construction, some might not. I was thinking Fire Walls like these Link which provide separation inside a building.

 

[Lifter123]

I can help with a precast concrete modular wall system using columns and panels.