FIRE SUPPRESSION
Petroleum Storage Tank Facilities – Part three
by Brenna ShumbamhiniJune 9, 2022
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In earlier installments of this series we talked about the types of petroleum storage tanks, their areas, frequent fire hazards, described the types of fires, and fireplace suppression systems that storage tanks may have.
In this third and last article we’ll talk about firefighting strategies and techniques in addition to pre-incident response planning fundamentals.
Firefighting Strategies and Tactics
Firefighting methods and ways begins with a properly deliberate and examined pre-incident response plan. This might be mentioned later in the article. Storage tank fires are complex occasions. These fires will require the implementation of plans, preparation, proper utilization of sources, and an in depth logistics part to make sure the sources are available and arrive on scene in a coordinated and well timed trend. The following methods and tactics for firefighting presume that the planning and preparation levels have been carried out by plant and hearth department personnel. Experience tells us that profitable and secure extinguishment of tank fires can solely be achieved when based mostly on planning and preparation, with all associated taking part in all features of the process as well as the exercising of the plan. Exercising the plan may be carried out with desk prime eventualities in addition to periodic full scale exercises.
As quickly as a fireplace division receives notification of an incident, measurement up and intelligence gathering should be began. Information ought to be gathered quickly to begin the development of firefighting strategies. The following must be thought-about:
Rescue of personnel within the immediate space
Life security hazards to website personnel
Extension
Confinement
Extinguishment
Environmental influence
Community impact
After the quick issues are addressed, we have to establish the kind of fire present:
Vent fire
Seal fireplace
Piping-connection hearth
Full floor involvement hearth
Once we’ve examined the above data we are in a position to then start to develop our resource list and incident action plan (IAP). Remember that the kind of product involved may also impression our useful resource wants and techniques. The following are numerous forms of fires and firefighting techniques:
Ground Spill or Dike Fires
These fires may be considered as easy pool or spill fires. Calculate the area (length x width) and use the proper utility fee based on NFPA 11, Standard for Low-, Medium-, and High-Expansion Foam. Knowing the product will also give you the appropriate type of foam concentrate and application method. Alcohol merchandise will require a delicate application methodology. Firefighters should not enter the dike space unless safe to take action and approved by the Incident Commander in consultation with the incident’s Safety Officer. Atmospheric testing must be performed prior to and through entry. Exposures similar to tanks, related piping, and pumps should be protected with water via floor or fixed screens. Ground fires should be extinguished first, then using dry-chemical tools, valves and flanges extinguished. The handiest tools for these combined fires would be hydro-chem™ expertise whereby foam/water resolution in addition to dry-chemical can be delivered simultaneously through the identical nozzle.
Specialized portable monitor placed on lip of storage tank.
Rim Seal Fires
Rim seal fires can usually be extinguished utilizing the fixed or semi-fixed foam systems if installed and properly maintained. On external floating roof tanks, if the fastened or semi-fixed fireplace safety techniques aren’t current, manual firefighting will have to be performed. Under the safety of a water spray, a firefighting crew will ascend to the gauging platform with hand-held foam gear. The main technique should be using foam wands to seize the fireplace (Photo 1- Foam Wand) which allows the location of specialised monitors to be positioned on the lip of the tank. (Photo 2- Specialized moveable monitor) The displays can then be used to extinguish the rim seal hearth using the attain of the monitor in order that hoselines and personnel aren’t operating from the wind girder away from the ladder. If this gear isn’t obtainable, then foam hoselines could be used from the wind girder. This is a hazardous operation, and only undertaken if there’s a structurally protected wind girder with handrails. (Photo 3- Foam chamber and Wind Girder) Personnel must be secured to prevent falling.
In some situations, elevated streams from hearth autos have been used. This isn’t a primary technique of extinguishment. It has been noted that there is always a chance of sinking or tilting the roof underneath the excess water/foam answer, thus creating a larger drawback, which can embody an obstructed /unobstructed full surface fire.
On tanks fitted with inner floating roofs, these fires may be thought of rare, but they do happen. They might be extraordinarily difficult to extinguish unless fixed or semi-fixed hearth safety techniques 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, especially if the pan under is aluminum.
The most tough methodology of extinguishment in a covered floating roof tank might be to shoot foam water resolution through the eyebrow vents. Using hydro-chem™ into these vents has confirmed efficient prior to now.
Full Surface Fires
Staffing necessities for a significant tank hearth will range relying on the sort of tank, location, water provides, nature of the incident and the provision of trained personnel. Attacks on these fires will predominantly use the Type III “Over the Top” method of extinguishing agent delivery. The product involved will determine the required foam utility rate and share of concentrate to water flowed. The dimension of the tank may even determine the appliance fee. For bigger tank diameters a bigger application rate is required. The chart under is accepted by trade experts to be the minimal application rates based on the tank diameter:
Table 1– Application charges
Foam answer (foam focus + water) flow rates to be established are based on the following method:
Foam solution flow rate = Tank floor area x application rate (as famous in desk 1)
Tank floor area = three.14 x radius2
Application fee = as per table under
Foam Concentration Flow Rate (lpm [gpm] of foam concentrate)
Foam focus flow rate = Foam resolution circulate fee x foam percent
Foam percent = 1%, 3%, 6% relying on sort of foam, product on fire and manufacturer’s recommendations
Foam Concentrate Quantities
Foam focus circulate fee (lpm or gpm) x period
Duration = sixty five minutes for Type III (over the top) purposes
Please observe that these portions are for extinguishment functions. For vapor suppression after extinguishment it is an accepted follow to double our extinguishment supplies to keep up the suppression of vapors and forestall the potential reignition of the product.
Some of the above flows may be properly in extra of 37,854 lpm (10,000 gpm) and would require massive capability supply units such as large trailer mounted monitors and huge moveable pumps.
Now that we know our move charges and foam concentrates required we have to also have a look at different 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 physical properties
Is there room in the tank to accept the entire foam solution without inflicting an overfill
What other tanks, piping, or buildings could additionally be uncovered
Wind path
Weather situations (present and expected)
Foam chamber on tank. Note the wind girder with appropriate handrail. If the foam chamber was not present or did not function correctly, the wind girder might be used to advance foam hoselines for seal hearth extinguishment.
In any hearth state of affairs we need to involve the local facility personnel in our planning part as technical specialists. They may also be at the command post advising the Incident Commander directly. These fires aren’t our ordinary ‘bread and butter’ operations and must be treated as an incident that can change rapidly and unexpectedly, often with severe consequences. Do not attempt to extinguish a full floor fireplace without all essential sources on the scene. Cooling of adjacent tanks can be a tactic for use prior to all foam delivery and personnel sources are on the scene. The cooling of the tank that is on fire is not beneficial except full 360 degree cooling may be accomplished, which is uncommon. Also, when cooling a tank, use solely the quantity of water essential. When the cooling water stops turning to steam, you might shut down the streams and start them up again when needed. 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) shall be required for each tank cooled. In addition to the correct supply units and foam supplies, we want to ensure that our foam answer supply zone on the surface will have the flexibility to spread out as quickly as it hits the floor and cover the entire floor space. According to the National Fire Protection Association (NFPA) foam can journey successfully throughout a minimum of 30m (100 ft) of burning liquid. We imagine that for calculating foam runs, this number ought to be reduced to 24m (80 ft), making certain that our touchdown zones journey and overlap one another. Firefighters should pay attention to the space a grasp stream can attain in addition to the touchdown zone size and width. These may be obtained from the producer of the monitors and nozzles and verified in the subject during drills and workout routines. By understanding this information we can pre-plan the positioning of our master streams. Range finders can be used during operations to gauge distances to the tank to help with monitor positioning. There are a few occurrences that may happen at a storage tank fireplace that the hearth service should pay attention to. These are:
Slopover
This event can occur when a water stream is utilized to the new 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 minimum of intensity.
Frothover
Frothover is a steady, sluggish shifting froth over the rim of a tank without a sudden and violent response. Frothover might happen when the tank isn’t on hearth and water already contained in the tank comes in contact with sizzling viscous oil which is being loaded. An instance is when hot asphalt is loaded right into a tank car and comes into contact with water within the tank, causing the product to froth over the top. During a fire with crude oil it could also occur when the warmth wave created by the burning crude oil reaches the water layers (stratums) within the crude oil. This warmth wave will convert the water to steam, causing a frothover.
Boilover
This occasion is a sudden and violent ejection of crude oil from the tank because of the reaction of the hot-layer and the accumulation of water at the backside of the tank. The mild fractions of crude oil burn off, producing a heat wave in the residue. The residues with their related heat wave sink in the path of the bottom of the tank. This warmth wave will finally reach the water that normally accumulates on the bottom 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 journey the gap equivalent of ten tank diameters. Careful consideration must be given during pre-incident response planning of the location of the command submit, staging areas, rehab, gear placement, and so forth.
Pre-Incident Response Planning
When planning for a response to a petroleum storage tank facility it’s best that the information gathered is finished on-site and with the help of facility personnel. While on site, access roads that you may use to access the world and place fireplace equipment (appliances) ought to be pushed by the autos that will be used throughout an incident. Many instances the turning radius of equipment is too great to make the turns wanted within the facility. Swales or culverts may impede apparatus. If the apparatus chassis is too long and or low, it may hang up or ground whereas traversing a swale or culvert. Bridges on site may not allow the load restrict of recent apparatus, preventing its use at an incident.
During pre-incident response planning data that must be gathered includes the next:
Tank varieties, dimensions, contents and capacities
Pipe isolation valves, areas, and operating mechanism
Fixed fireplace protection methods out there
Access factors to facility and tank
Contact cellphone numbers
Locations and operation of emergency shutdown units (ESD’s)
Availability of firefighting sources
Water provides
Pumping requirements
Foam focus necessities
Mutual/automatic assist 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 information that a fire division must know, it is a good begin. Other resources are listed on the end of this article. It is essential that firefighters attend courses on this specialized firefighting, pre-plan these services, and train the pre-plans. เกจวัดแรงดัน ’t enable these facilities to become a part of the landscape. Visit these services and ask questions!
For more data, 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 during coaching. Note the protecting hose stream in place.
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