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 in regards to the kinds of petroleum storage tanks, their locations, frequent hearth hazards, described the types of fires, and fireplace suppression techniques that storage tanks could have.
In this third and last article we’ll discuss firefighting methods and techniques as well as pre-incident response planning fundamentals.
Firefighting Strategies and Tactics
Firefighting methods and ways begins with a properly planned and tested pre-incident response plan. This shall be mentioned later in the article. Storage tank fires are complex occasions. These fires would require the implementation of plans, preparation, correct utilization of assets, and an extensive logistics part to ensure the resources can be found and arrive on scene in a coordinated and well timed trend. The following strategies and ways for firefighting presume that the planning and preparation phases have been performed by plant and fire division personnel. Experience tells us that profitable and secure extinguishment of tank fires can solely be achieved when primarily based on planning and preparation, with all related collaborating in all elements of the process in addition to the exercising of the plan. Exercising the plan may be carried out with desk top eventualities in addition to periodic full scale workout routines.
As soon as a fireplace division receives notification of an incident, size up and intelligence gathering must be started. Information must be gathered shortly to start the development of firefighting strategies. The following should be thought of:
Rescue of personnel in the instant space
Life safety hazards to site personnel
Extension
Confinement
Extinguishment
Environmental impact
Community impact
After the quick issues are addressed, we want to identify the type of fireplace current:
Vent fire
Seal fire
Piping-connection hearth
Full surface involvement hearth
Once we’ve examined the above information we are in a position to then start to develop our useful resource record and incident motion plan (IAP). Remember that the kind of product concerned will also influence our useful resource wants and ways. The following are varied forms of fires and firefighting techniques:
Ground Spill or Dike Fires
These fires can be considered as simple pool or spill fires. Calculate the area (length x width) and use the right utility rate based mostly on NFPA 11, Standard for Low-, Medium-, and High-Expansion Foam. Knowing the product may also provide the correct kind of foam focus and software method. Alcohol merchandise would require a gentle software methodology. Firefighters should not enter the dike area until secure to do so and permitted by the Incident Commander in session with the incident’s Safety Officer. Atmospheric testing should be conducted previous to and during entry. Exposures similar to tanks, associated piping, and pumps must be protected with water through floor or mounted displays. Ground fires ought to be extinguished first, then using dry-chemical tools, valves and flanges extinguished. The best tools for these combined fires would be hydro-chem™ know-how whereby foam/water solution as properly as dry-chemical can be delivered simultaneously via the same nozzle.
Specialized transportable monitor placed on lip of storage tank.
Rim Seal Fires
Rim seal fires can normally be extinguished utilizing the fastened or semi-fixed foam systems if put in and correctly maintained. On external floating roof tanks, if the mounted or semi-fixed fire protection methods are not current, guide firefighting will must 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 main technique should be the use of foam wands to capture the fire (Photo 1- Foam Wand) which permits the placement of specialised displays to be positioned on the lip of the tank. (Photo 2- Specialized portable monitor) The displays can then be used to extinguish the rim seal fireplace utilizing the attain of the monitor so that hoselines and personnel aren’t working from the wind girder away from the ladder. If this gear isn’t obtainable, then foam hoselines could presumably be used from the wind girder. This is a hazardous operation, and solely undertaken if there is a structurally secure wind girder with handrails. (Photo 3- Foam chamber and Wind Girder) Personnel ought to be secured to prevent falling.
In some cases, elevated streams from hearth automobiles have been used. This isn’t a main method of extinguishment. It has been famous that there is all the time a chance of sinking or tilting the roof beneath the excess water/foam answer, thus creating a bigger downside, which may embody an obstructed /unobstructed full surface hearth.
On tanks fitted with inner floating roofs, these fires may be thought-about rare, however they do happen. They might be extraordinarily troublesome to extinguish until mounted or semi-fixed fireplace protection techniques are put in. Foam chambers and foam dams are the best, and the design of the system must be calculated on a full surface fire, especially if the pan under is aluminum.
The most troublesome method of extinguishment in a covered floating roof tank will be to shoot foam water answer via the eyebrow vents. Using hydro-chem™ into these vents has confirmed effective prior to now.
Full Surface Fires
Staffing requirements for a significant tank fire will range depending on the type of tank, location, water provides, nature of the incident and the provision of educated personnel. Attacks on these fires will predominantly use the Type III “Over the Top” method of extinguishing agent supply. The product involved will determine the required foam software price and proportion of concentrate to water flowed. The dimension of the tank may also determine the application fee. For larger tank diameters a larger software price is required. The chart below is accepted by trade consultants to be the minimum application charges primarily based on the tank diameter:
Table 1– Application rates
Foam solution (foam focus + water) flow rates to be established are primarily based on the following method:
Foam solution flow fee = Tank surface area x utility price (as noted in table 1)
Tank floor space = 3.14 x radius2
Application rate = as per desk beneath
Foam Concentration Flow Rate (lpm [gpm] of foam concentrate)
Foam concentrate flow rate = Foam resolution flow fee x foam percent
Foam percent = 1%, 3%, 6% relying on sort of froth, product on hearth and manufacturer’s suggestions
Foam Concentrate Quantities
Foam focus move rate (lpm or gpm) x duration
Duration = sixty five minutes for Type III (over the top) functions
Please notice that these quantities are for extinguishment purposes. For vapor suppression after extinguishment it’s an accepted follow to double our extinguishment provides to take care of the suppression of vapors and stop the attainable reignition of the product.
Some of the above flows may be nicely in excess of 37,854 lpm (10,000 gpm) and will require massive capacity supply devices similar to giant trailer mounted screens and enormous portable pumps.
Now that we know our flow charges and foam concentrates required we have to additionally take a look at other elements similar 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 within the tank to simply accept the total foam solution without causing an overfill
What different tanks, piping, or constructions may be uncovered
Wind direction
Weather circumstances (present and expected)
Foam chamber on tank. Note the wind girder with appropriate handrail. If the foam chamber was not current or didn’t perform correctly, the wind girder could be used to advance foam hoselines for seal hearth extinguishment.
In any fireplace state of affairs we want to contain the native facility personnel in our planning section as technical specialists. They can also be on the command post advising the Incident Commander instantly. These fires usually are not our odd ‘bread and butter’ operations and ought to be handled as an incident that can change quickly and unexpectedly, usually with extreme penalties. Do not attempt to extinguish a full floor fire without all needed resources on the scene. Cooling of adjacent tanks can be a tactic to be used prior to all foam delivery and personnel assets are on the scene. The cooling of the tank that is on fireplace isn’t recommended except complete 360 diploma cooling may 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 may shut down the streams and begin them up again when essential. This will conserve water supplies for extinguishment and cut back the water flowing into the dike areas. Generally between 1,893 lpm (500 gpm) and 3,785 lpm (1,000 gpm) shall be required for each tank cooled. In addition to the proper delivery devices and foam supplies, we have to be certain that our foam resolution supply zone on the surface will be succesful of unfold out as quickly as it hits the floor and cover the whole floor space. According to the National Fire Protection Association (NFPA) foam can travel successfully across at least 30m (100 ft) of burning liquid. We imagine that for calculating foam runs, this quantity must be decreased to 24m (80 ft), guaranteeing that our touchdown zones journey and overlap each other. Firefighters should be conscious of the gap a grasp stream can attain as well as the landing zone length and width. These can be obtained from the manufacturer of the monitors and nozzles and verified in the area throughout drills and workouts. By understanding this data we are able to pre-plan the positioning of our master streams. Range finders can be used throughout operations to gauge distances to the tank to assist with monitor positioning. There are a number of occurrences that can happen at a storage tank fireplace that the fireplace service should concentrate on. These are:
Slopover
This occasion can happen when a water stream is applied to the new surface of burning oil, supplied that the oil is viscous and the temperature exceeds the boiling point of water. It causes a short duration of slopping of froth over the rim of the tank with a minimal of depth.
Frothover
Frothover is a gentle, gradual moving froth over the rim of a tank with no sudden and violent reaction. Frothover may happen when the tank is not on fire and water already contained in the tank is out there in contact with sizzling viscous oil which is being loaded. An example is when sizzling asphalt is loaded right into a tank automobile and comes into contact with water within the tank, causing the product to froth excessive. During a fireplace with crude oil it may also 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, inflicting a frothover.
Boilover
This event 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 light fractions of crude oil burn off, producing a heat wave within the residue. The residues with their related heat wave sink in the course of the underside of the tank. This heat wave will eventually attain the water that normally accumulates at the backside of the tank, and when the 2 meet the water is superheated and subsequently boils, expanding explosively inflicting a violent ejection of the tank contents and hearth. The increasing contents being expelled can travel the gap equal of ten tank diameters. Careful consideration must be given during pre-incident response planning of the situation of the command post, staging areas, rehab, equipment placement, and so forth.
Pre-Incident Response Planning
When planning for a response to a petroleum storage tank facility it is best that the information gathered is finished on-site and with the help of facility personnel. While on website, access roads that you may use to entry the realm and position fireplace equipment (appliances) ought to be pushed by the automobiles that might be used during an incident. Many times the turning radius of equipment is simply too nice to make the turns wanted in the facility. Swales or culverts may impede equipment. If the equipment chassis is just too long and or low, it may hang up or floor whereas traversing a swale or culvert. Bridges on site may not allow the load limit of latest apparatus, stopping its use at an incident.
During pre-incident response planning data that must be gathered includes the following:
Tank varieties, dimensions, contents and capacities
Pipe isolation valves, places, and operating mechanism
Fixed hearth protection systems obtainable
Access factors to facility and tank
Contact phone numbers
Locations and operation of emergency shutdown devices (ESD’s)
Availability of firefighting resources
Water provides
Pumping requirements
Foam focus requirements
Mutual/automatic help available
Other information can be obtained based on the needs and necessities of your department. While these articles are not totally inclusive of all data that a hearth division needs to know, it’s a good start. Other sources are listed on the end of this text. It is essential that firefighters attend courses on this specialised firefighting, pre-plan these facilities, and exercise the pre-plans. Don’t permit these facilities to become a half of the panorama. 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. pressure gauge 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 positioned throughout training. Note the protecting hose stream in place.
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