FIRE SUPPRESSION
Petroleum Storage Tank Facilities – Part 3
by Brenna ShumbamhiniJune 9, 2022
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In earlier installments of this series we talked in regards to the types of petroleum storage tanks, their locations, frequent fireplace hazards, described the kinds of fires, and fireplace suppression methods that storage tanks might have.
In this third and last article we’ll focus on firefighting strategies and ways in addition to pre-incident response planning basics.
Firefighting Strategies and Tactics
Firefighting strategies and tactics begins with a well planned and examined pre-incident response plan. This might be mentioned later in the article. Storage tank fires are complicated occasions. These fires will require the implementation of plans, preparation, proper utilization of sources, and an extensive logistics section to ensure the resources 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 successful and safe extinguishment of tank fires can solely be achieved when based on planning and preparation, with all associated taking part in all elements of the process as properly as the exercising of the plan. Exercising the plan may be performed with desk prime eventualities as properly as periodic full scale exercises.
As soon as a fire division receives notification of an incident, measurement up and intelligence gathering ought to be began. Information should be gathered shortly to start the event of firefighting methods. The following should be thought of:
Rescue of personnel within the quick area
Life safety hazards to web site personnel
Extension
Confinement
Extinguishment
Environmental impression
Community influence
After the quick issues are addressed, we have to identify the type of fireplace current:
Vent fireplace
Seal hearth
Piping-connection hearth
Full floor involvement hearth
Once we’ve examined the above data we are ready to then start to develop our useful resource record and incident motion plan (IAP). Remember that the sort of product concerned may even influence our resource needs and techniques. The following are numerous forms of fires and firefighting ways:
Ground Spill or Dike Fires
These fires may be viewed as simple pool or spill fires. Calculate the area (length x width) and use the proper software fee based on NFPA 11, Standard for Low-, Medium-, and High-Expansion Foam. Knowing the product may also provide the right sort of froth focus and application methodology. Alcohol merchandise will require a mild software method. Firefighters should not enter the dike space until safe to take action and approved by the Incident Commander in consultation with the incident’s Safety Officer. Atmospheric testing must be conducted previous to and through entry. Exposures such as tanks, associated piping, and pumps should be protected with water by way of floor or fastened screens. Ground fires ought to be extinguished first, then using dry-chemical gear, valves and flanges extinguished. The best gear for these combined fires would be hydro-chem™ know-how whereby foam/water resolution in addition to dry-chemical can be delivered simultaneously through the same nozzle.
Specialized portable monitor positioned on lip of storage tank.
Rim Seal Fires
Rim seal fires can normally be extinguished using the fixed or semi-fixed foam methods if installed and properly maintained. On exterior floating roof tanks, if the mounted or semi-fixed fire protection techniques aren’t current, manual firefighting will have to be carried out. Under the protection of a water spray, a firefighting crew will ascend to the gauging platform with hand-held foam tools. The main technique must be using foam wands to capture the hearth (Photo 1- Foam Wand) which allows the location of specialised monitors to be positioned on the lip of the tank. (Photo 2- Specialized transportable monitor) The screens can then be used to extinguish the rim seal fireplace utilizing the attain of the monitor so that hoselines and personnel usually are not operating from the wind girder away from the ladder. If this gear is not obtainable, then foam hoselines might be used from the wind girder. This is a hazardous operation, and solely undertaken if there’s a structurally secure wind girder with handrails. (Photo 3- Foam chamber and Wind Girder) Personnel should be secured to forestall falling.
In some instances, elevated streams from fire vehicles have been used. This just isn’t a primary methodology of extinguishment. It has been famous that there is all the time an opportunity of sinking or tilting the roof underneath the surplus water/foam solution, thus creating a larger downside, which may embrace an obstructed /unobstructed full floor fire.
On tanks fitted with internal floating roofs, these fires may be thought-about rare, however they do happen. They shall be extremely troublesome to extinguish until fixed or semi-fixed fire protection methods are put in. Foam chambers and foam dams are the simplest, and the design of the system should be calculated on a full floor fireplace, particularly if the pan beneath is aluminum.
The most difficult method of extinguishment in a coated floating roof tank shall be to shoot foam water solution via the eyebrow vents. Using hydro-chem™ into these vents has confirmed efficient in the past.
Full Surface Fires
Staffing requirements for a significant tank fire will range depending on the sort of tank, location, water supplies, nature of the incident and the supply of trained personnel. Attacks on these fires will predominantly use the Type III “Over the Top” methodology of extinguishing agent supply. The product concerned will decide the required foam software fee and proportion of focus to water flowed. The measurement of the tank may also decide the application fee. For bigger tank diameters a larger software fee is required. The chart beneath is accepted by trade consultants to be the minimum utility rates primarily based on the tank diameter:
Table 1– Application rates
Foam solution (foam focus + water) flow rates to be established are based mostly on the following formulation:
Foam resolution move price = Tank floor space x application rate (as famous in table 1)
Tank surface space = three.14 x radius2
Application price = as per table below
Foam Concentration Flow Rate (lpm [gpm] of foam concentrate)
Foam focus flow rate = Foam answer move rate x foam percent
Foam % = 1%, 3%, 6% depending on kind of froth, product on fireplace and manufacturer’s suggestions
Foam Concentrate Quantities
Foam concentrate circulate price (lpm or gpm) x period
Duration = 65 minutes for Type III (over the top) functions
Please notice that these portions are for extinguishment purposes. For vapor suppression after extinguishment it is an accepted follow to double our extinguishment provides to keep up the suppression of vapors and prevent the possible reignition of the product.
Some of the above flows could additionally be nicely in extra of 37,854 lpm (10,000 gpm) and would require massive capacity delivery devices similar to massive trailer mounted screens and huge portable pumps.
Now that we know our circulate charges and foam concentrates required we need to also look at different elements such as:
Position and situation of roof drains
Volume of the product
Status of tanks and valves
Depth of water bottoms
Structural situation of tank
Product in tank and its bodily properties
Is there room in the tank to accept the total foam resolution without causing an overfill
What different tanks, piping, or constructions may be exposed
Wind path
Weather situations (present and expected)
Foam chamber on tank. Note the wind girder with applicable handrail. If the froth chamber was not current or didn’t function correctly, the wind girder could probably be used to advance foam hoselines for seal fireplace extinguishment.
In any hearth scenario we want to involve the native facility personnel in our planning section as technical specialists. They can also be at the command post advising the Incident Commander immediately. These fires aren’t our ordinary ‘bread and butter’ operations and must be treated as an incident that can change quickly and unexpectedly, typically with severe consequences. Do not attempt to extinguish a full floor fireplace with out all necessary resources on the scene. Cooling of adjoining tanks can be a tactic for use previous to all foam supply and personnel sources are on the scene. The cooling of the tank that is on fire isn’t beneficial until complete 360 degree cooling could 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 may shut down the streams and begin them up again when necessary. This will conserve 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 every tank cooled. In addition to the right delivery units and foam supplies, we have to be certain that our foam solution delivery zone on the surface will have the power to unfold out once it hits the floor and canopy the whole floor space. According to the National Fire Protection Association (NFPA) foam can journey successfully throughout a minimal of 30m (100 ft) of burning liquid. We believe that for calculating foam runs, this number should be reduced to 24m (80 ft), ensuring that our landing zones journey and overlap each other. Firefighters ought to pay consideration to the distance a master stream can reach as nicely as the landing zone size and width. These can be obtained from the producer of the screens and nozzles and verified within the area during drills and exercises. By figuring out this data we can pre-plan the positioning of our grasp streams. ร้านซ่อมเครื่องวัดความดันomron can be utilized during operations to gauge distances to the tank to assist with monitor positioning. There are a few occurrences that can happen at a storage tank fire that the fire service ought to concentrate on. These are:
Slopover
This event can occur when a water stream is utilized to the recent surface of burning oil, supplied that the oil is viscous and the temperature exceeds the boiling level of water. It causes a brief length of slopping of froth over the rim of the tank with a minimal of intensity.
Frothover
Frothover is a gradual, slow shifting froth over the rim of a tank without a sudden and violent reaction. Frothover may occur when the tank is not on hearth and water already contained in the tank comes in contact with hot viscous oil which is being loaded. An instance is when scorching asphalt is loaded into a tank automotive and comes into contact with water within the tank, inflicting the product to froth over the top. During a hearth with crude oil it may also happen when the heat 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 response of the hot-layer and the accumulation of water at the bottom of the tank. The gentle fractions of crude oil burn off, producing a heat wave in the residue. The residues with their associated warmth wave sink in direction of the underside of the tank. This heat wave will eventually attain the water that normally accumulates at 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 travel the space equivalent of ten tank diameters. Careful consideration ought to be given throughout pre-incident response planning of the situation of the command post, staging areas, rehab, tools placement, etc.
Pre-Incident Response Planning
When planning for a response to a petroleum storage tank facility it’s best that the data gathered is finished on-site and with the help of facility personnel. While on web site, entry roads that you can be use to access the world and place fire apparatus (appliances) should be driven by the automobiles that might be used throughout an incident. Many occasions the turning radius of apparatus is too nice to make the turns wanted within the facility. Swales or culverts may also impede apparatus. If the apparatus chassis is simply too lengthy and or low, it could hang up or ground while traversing a swale or culvert. Bridges on website could not enable the load restrict of new apparatus, preventing its use at an incident.
During pre-incident response planning data that should be gathered consists of the following:
Tank varieties, dimensions, contents and capacities
Pipe isolation valves, areas, and working mechanism
Fixed hearth protection systems out there
Access factors to facility and tank
Contact telephone numbers
Locations and operation of emergency shutdown gadgets (ESD’s)
Availability of firefighting sources
Water provides
Pumping requirements
Foam focus requirements
Mutual/automatic help out there
Other data may be obtained based on the needs and requirements of your division. While these articles aren’t totally inclusive of all information that a hearth division must know, it is a good begin. Other assets are listed at the finish of this text. It is essential that firefighters attend courses on this specialized firefighting, pre-plan these services, and train the pre-plans. Don’t enable these amenities to become part of the landscape. Visit these amenities and ask questions!
For extra 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 protecting hose stream in place.
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