FIRE SUPPRESSION
Petroleum Storage Tank Facilities – Part 3
by Brenna ShumbamhiniJune 9, 2022
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In previous installments of this collection we talked concerning the types of petroleum storage tanks, their places, frequent fire hazards, described the kinds of fires, and fire suppression methods that storage tanks could have.
In this third and last article we will talk about firefighting methods and techniques as nicely as pre-incident response planning fundamentals.
Firefighting Strategies and Tactics
Firefighting strategies and tactics begins with a nicely planned and examined pre-incident response plan. This will be discussed later in the article. Storage tank fires are complex events. These fires would require the implementation of plans, preparation, proper utilization of assets, and an extensive logistics part to ensure the sources can be found and arrive on scene in a coordinated and well timed style. The following strategies and techniques for firefighting presume that the planning and preparation levels have been performed by plant and fire division personnel. Experience tells us that profitable and secure extinguishment of tank fires can only be achieved when based on planning and preparation, with all associated collaborating in all aspects of the method as properly as the exercising of the plan. Exercising the plan could be conducted with desk top scenarios in addition to periodic full scale workout routines.
As soon as a fire department receives notification of an incident, measurement up and intelligence gathering should be began. Information must be gathered shortly to start the event of firefighting strategies. The following ought to be thought of:
Rescue of personnel within the quick area
Life security hazards to website personnel
Extension
Confinement
Extinguishment
Environmental impact
Community influence
After the immediate points are addressed, we have to determine the type of fire present:
Vent fire
Seal fireplace
Piping-connection hearth
Full surface involvement fireplace
Once we’ve examined the above info we can then start to develop our useful resource record and incident action plan (IAP). Remember that the sort of product concerned may even impact our useful resource needs and tactics. The following are varied kinds of fires and firefighting techniques:
Ground Spill or Dike Fires
These fires could be considered as easy pool or spill fires. Calculate the realm (length x width) and use the right utility rate based mostly on NFPA eleven, Standard for Low-, Medium-, and High-Expansion Foam. Knowing the product may even provide the right kind of foam concentrate and software methodology. Alcohol merchandise would require a gentle application method. Firefighters shouldn’t enter the dike space except protected to take action and accredited by the Incident Commander in session with the incident’s Safety Officer. Atmospheric testing must be performed prior to and through entry. Exposures similar to tanks, related piping, and pumps must be protected with water by way of ground or fixed displays. Ground fires must be extinguished first, then using dry-chemical equipment, valves and flanges extinguished. The best gear for these mixed fires would be hydro-chem™ expertise whereby foam/water answer in addition to dry-chemical could be delivered concurrently through the same nozzle.
Specialized transportable monitor placed on lip of storage tank.
Rim Seal Fires
Rim seal fires can often be extinguished utilizing the fixed or semi-fixed foam systems if installed and correctly maintained. On external floating roof tanks, if the fastened or semi-fixed fire protection techniques usually are not present, guide firefighting will have to be carried out. Under the safety of a water spray, a firefighting crew will ascend to the gauging platform with hand-held foam tools. The major methodology should be the use of foam wands to seize the fireplace (Photo 1- Foam Wand) which allows the placement of specialised displays to be placed on the lip of the tank. (Photo 2- Specialized transportable monitor) The screens can then be used to extinguish the rim seal fire using the attain of the monitor so that hoselines and personnel aren’t working from the wind girder away from the ladder. If this tools is not available, then foam hoselines could be used from the wind girder. เพรสเชอร์เกจ is a hazardous operation, and solely undertaken if there is a structurally protected wind girder with handrails. (Photo 3- Foam chamber and Wind Girder) Personnel must be secured to forestall falling.
In some instances, elevated streams from fire automobiles have been used. This isn’t a primary methodology of extinguishment. It has been noted that there is at all times an opportunity of sinking or tilting the roof underneath the excess water/foam answer, thus creating a bigger drawback, which may embrace an obstructed /unobstructed full floor hearth.
On tanks fitted with inner floating roofs, these fires may be considered uncommon, but they do occur. They will be extraordinarily troublesome to extinguish except fastened or semi-fixed hearth protection systems are installed. Foam chambers and foam dams are the simplest, and the design of the system ought to be calculated on a full floor hearth, particularly if the pan under is aluminum.
The most troublesome technique of extinguishment in a lined floating roof tank will be to shoot foam water resolution through the eyebrow vents. Using hydro-chem™ into these vents has confirmed effective in the past.
Full Surface Fires
Staffing necessities for a major tank fire will range depending on the kind of tank, location, water provides, nature of the incident and the availability of educated personnel. Attacks on these fires will predominantly use the Type III “Over the Top” technique of extinguishing agent supply. The product involved will decide the required foam application rate and percentage of focus to water flowed. The size of the tank may also decide the application rate. For bigger tank diameters a larger software rate is required. The chart below is accepted by trade experts to be the minimal utility rates primarily based on the tank diameter:
Table 1– Application rates
Foam resolution (foam focus + water) move charges to be established are primarily based on the next formulation:
Foam answer flow fee = Tank floor area x application price (as famous in table 1)
Tank floor area = three.14 x radius2
Application price = as per desk below
Foam Concentration Flow Rate (lpm [gpm] of foam concentrate)
Foam concentrate move rate = Foam resolution circulate price x foam %
Foam % = 1%, 3%, 6% depending on kind of froth, product on fireplace and manufacturer’s suggestions
Foam Concentrate Quantities
Foam concentrate circulate fee (lpm or gpm) x length
Duration = 65 minutes for Type III (over the top) functions
Please note that these quantities are for extinguishment purposes. For vapor suppression after extinguishment it’s an accepted practice to double our extinguishment supplies to maintain up the suppression of vapors and forestall the possible reignition of the product.
Some of the above flows may be nicely in extra of 37,854 lpm (10,000 gpm) and will require massive capability delivery gadgets such as massive trailer mounted displays and enormous transportable pumps.
Now that we all know our flow charges and foam concentrates required we have to additionally take a glance at other elements corresponding to:
Position and situation of roof drains
Volume of the product
Status of tanks and valves
Depth of water bottoms
Structural condition of tank
Product in tank and its bodily properties
Is there room in the tank to simply accept the entire foam answer without inflicting an overfill
What other tanks, piping, or buildings may be exposed
Wind course
Weather circumstances (present and expected)
Foam chamber on tank. Note the wind girder with applicable handrail. If the foam chamber was not current or did not operate correctly, the wind girder might be used to advance foam hoselines for seal fire extinguishment.
In เพรสเชอร์เกจ want to contain the native facility personnel in our planning section as technical specialists. They may be at the command publish advising the Incident Commander instantly. These fires are not our ordinary ‘bread and butter’ operations and must be treated as an incident that can change quickly and unexpectedly, usually with severe consequences. Do not try and extinguish a full surface hearth with out all necessary resources on the scene. Cooling of adjoining tanks would be a tactic to be used prior to all foam delivery and personnel resources are on the scene. The cooling of the tank that is on fireplace is not recommended except complete 360 diploma cooling can be completed, which is rare. Also, when cooling a tank, use solely the amount of water necessary. When the cooling water stops turning to steam, you might shut down the streams and start them up again when necessary. This will preserve water supplies for extinguishment and scale back the water flowing into the dike areas. Generally between 1,893 lpm (500 gpm) and three,785 lpm (1,000 gpm) will be required for each tank cooled. In addition to the correct supply devices and foam supplies, we want to ensure that our foam answer supply zone on the floor will be capable of unfold out as quickly as it hits the floor and canopy the complete surface space. According to the National Fire Protection Association (NFPA) foam can travel effectively throughout at least 30m (100 ft) of burning liquid. We imagine that for calculating foam runs, this number must be decreased to 24m (80 ft), ensuring that our touchdown zones travel and overlap each other. Firefighters ought to concentrate on the distance a master stream can attain as well as the landing zone length and width. These may be obtained from the manufacturer of the screens and nozzles and verified in the area throughout drills and exercises. By figuring out this info we are in a position to pre-plan the positioning of our master streams. Range finders can be utilized during operations to gauge distances to the tank to help with monitor positioning. There are a quantity of occurrences that may happen at a storage tank fireplace that the fireplace service should pay consideration to. These are:
Slopover
This occasion can happen when a water stream is utilized to the recent floor of burning oil, offered that the oil is viscous and the temperature exceeds the boiling point of water. It causes a brief duration of slopping of froth over the rim of the tank with a minimal of intensity.
Frothover
Frothover is a gentle, sluggish moving froth over the rim of a tank without a sudden and violent response. Frothover could occur when the tank is not on hearth and water already inside the tank comes in contact with hot viscous oil which is being loaded. An example is when hot asphalt is loaded into a tank automotive and comes into contact with water within the tank, inflicting the product to froth excessive. During a hearth with crude oil it could additionally occur when the warmth wave created by the burning crude oil reaches the water layers (stratums) within the crude oil. This heat wave will convert the water to steam, causing a frothover.
Boilover
This event is a sudden and violent ejection of crude oil from the tank because of the response of the hot-layer and the accumulation of water on the backside of the tank. The mild fractions of crude oil burn off, producing a heat wave in the residue. The residues with their associated warmth wave sink in the direction of the bottom of the tank. This heat wave will ultimately attain the water that normally accumulates on the backside of the tank, and when the two meet the water is superheated and subsequently boils, increasing explosively inflicting a violent ejection of the tank contents and hearth. The expanding contents being expelled can travel the gap equivalent of ten tank diameters. Careful consideration must be given during pre-incident response planning of the location of the command publish, staging areas, rehab, tools placement, etc.
Pre-Incident Response Planning
When planning for a response to a petroleum storage tank facility it is best that the knowledge gathered is completed on-site and with the help of facility personnel. While on web site, entry roads that you may use to entry the world and place fire apparatus (appliances) ought to be pushed by the automobiles that shall be used during an incident. Many instances the turning radius of equipment is just too great to make the turns needed within the facility. Swales or culverts may impede equipment. If the equipment chassis is simply too long and or low, it might grasp up or floor whereas traversing a swale or culvert. Bridges on website could not enable the load restrict of recent equipment, stopping its use at an incident.
During pre-incident response planning data that ought to be gathered consists of the following:
Tank types, dimensions, contents and capacities
Pipe isolation valves, places, and working mechanism
Fixed hearth protection systems out there
Access points to facility and tank
Contact cellphone numbers
Locations and operation of emergency shutdown gadgets (ESD’s)
Availability of firefighting assets
Water provides
Pumping necessities
Foam focus necessities
Mutual/automatic help obtainable
Other information can be obtained based on the needs and requirements of your division. While these articles usually are not completely inclusive of all info that a fireplace department needs to know, it’s a good start. Other sources are listed on the finish of this article. It is necessary that firefighters attend lessons on this specialized firefighting, pre-plan these services, and train the pre-plans. Don’t permit these services to turn out to be a part of the landscape. Visit these facilities and ask questions!
For more information, go to www.worldsafeinternational.com
[su_note]Resources
American Petroleum Institute [API]. API Recommended Practice 2021: Management of Atmospheric Storage Tank Fires. Washington, DC: API, 2001, Reaffirmed 2006 Hildebrand, M. S. & Noll, G. G. Storage Tank Emergencies: Guidelines and Procedures. Annapolis, MD: Red Hat Publishing, 1997 Institution of Chemical Engineers [IChemE]. BP Process Safety Series: Liquid Hydrocarbon Tank Fires: Prevention and Response. Rugby, UK: IChemE, 2005 Shelley, C. H., Cole, A. R. and Markley, T. E. Industrial Firefighting for Municipal Firefighters. Tulsa, OK: PennWell, 2007References 1.
Shelley, C. H., Cole, A. R. and Markley, T. E. Industrial Firefighting for Municipal Firefighters. Tulsa, OK: PennWell, 2007.[/su_note]
Top Image:- Foam wand being placed throughout training. Note the protective hose stream in place.
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