Petroleum Storage Tank Facilities – Part 3
by Brenna ShumbamhiniJune 9, 2022
In previous installments of this collection we talked in regards to the forms of petroleum storage tanks, their locations, frequent hearth hazards, described the kinds of fires, and fire suppression systems that storage tanks may have.
In this third and ultimate article we are going to focus on firefighting strategies and ways in addition to pre-incident response planning basics.
Firefighting Strategies and Tactics
Firefighting methods and ways begins with a well deliberate and tested pre-incident response plan. This might be mentioned later in the article. Storage tank fires are complex occasions. These fires would require the implementation of plans, preparation, correct utilization of sources, and an in depth logistics part to make sure the assets can be found and arrive on scene in a coordinated and timely fashion. The following strategies and ways for firefighting presume that the planning and preparation stages have been performed by plant and fireplace department personnel. Experience tells us that successful and protected extinguishment of tank fires can solely be achieved when primarily based on planning and preparation, with all associated collaborating in all aspects of the process in addition to the exercising of the plan. Exercising the plan may be carried out with table top eventualities as nicely as periodic full scale workouts.
As quickly as a hearth department receives notification of an incident, size up and intelligence gathering must be started. ที่วัดแรงดันน้ำ ought to be gathered quickly to begin the event of firefighting strategies. The following should be thought-about:
Rescue of personnel in the instant space
Life safety hazards to web site personnel
After the quick issues are addressed, we have to identify the sort of fire current:
Full surface involvement fire
Once we now have examined the above data we can then begin to develop our useful resource listing and incident action plan (IAP). Remember that the kind of product concerned will also impact our useful resource wants and ways. The following are varied forms of fires and firefighting techniques:
Ground Spill or Dike Fires
These fires could be seen as simple pool or spill fires. Calculate the world (length x width) and use the right application price primarily based on NFPA eleven, Standard for Low-, Medium-, and High-Expansion Foam. Knowing the product may also give you the appropriate sort of froth concentrate and utility methodology. Alcohol merchandise will require a gentle software methodology. Firefighters shouldn’t enter the dike space until secure to do so and approved by the Incident Commander in consultation with the incident’s Safety Officer. Atmospheric testing ought to be conducted prior to and during entry. Exposures similar to tanks, associated piping, and pumps should be protected with water through ground or mounted screens. Ground fires ought to be extinguished first, then utilizing dry-chemical tools, valves and flanges extinguished. The most effective tools for these combined fires could be hydro-chem™ know-how whereby foam/water resolution in addition to dry-chemical can be delivered concurrently through the same nozzle.
Specialized moveable monitor placed on lip of storage tank.
Rim Seal Fires
Rim seal fires can often be extinguished using the fastened or semi-fixed foam methods if put in and correctly maintained. On exterior floating roof tanks, if the fastened or semi-fixed fire protection systems aren’t current, guide firefighting will need to be carried out. Under the safety of a water spray, a firefighting crew will ascend to the gauging platform with hand-held foam equipment. The major methodology should be the utilization of foam wands to capture the hearth (Photo 1- Foam Wand) which allows the position of specialized displays to be positioned on the lip of the tank. (Photo 2- Specialized moveable monitor) The monitors can then be used to extinguish the rim seal fire using the attain of the monitor so that hoselines and personnel usually are not operating from the wind girder away from the ladder. If this tools is not out there, then foam hoselines might be used from the wind girder. This is a hazardous operation, and only undertaken if there is a structurally protected wind girder with handrails. (Photo 3- Foam chamber and Wind Girder) Personnel must be secured to prevent falling.
In some cases, elevated streams from hearth autos have been used. This is not a main method of extinguishment. It has been famous that there is always an opportunity of sinking or tilting the roof under the excess water/foam solution, thus creating a bigger problem, which can 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 shall be extraordinarily troublesome to extinguish until fastened or semi-fixed hearth protection techniques are put in. Foam chambers and foam dams are the simplest, and the design of the system must be calculated on a full surface fireplace, particularly if the pan beneath is aluminum.
The most difficult methodology of extinguishment in a covered floating roof tank shall be to shoot foam water answer through the eyebrow vents. Using hydro-chem™ into these vents has confirmed efficient prior to now.
Full Surface Fires
Staffing requirements for a serious tank hearth will range relying on the kind of tank, location, water provides, nature of the incident and the provision of skilled personnel. Attacks on these fires will predominantly use the Type III “Over the Top” method of extinguishing agent supply. The product concerned will determine the required foam software fee and percentage of focus to water flowed. The measurement of the tank may even decide the application rate. For larger tank diameters a bigger software rate is required. The chart below is accepted by industry specialists to be the minimal software charges primarily based on the tank diameter:
Table 1– Application charges
Foam resolution (foam concentrate + water) move charges to be established are based mostly on the next formulation:
Foam answer circulate fee = Tank surface area x software fee (as famous in table 1)
Tank surface space = 3.14 x radius2
Application price = as per table under
Foam Concentration Flow Rate (lpm [gpm] of foam concentrate)
Foam focus circulate fee = Foam resolution move rate x foam percent
Foam percent = 1%, 3%, 6% depending on kind of foam, product on hearth and manufacturer’s suggestions
Foam Concentrate Quantities
Foam concentrate circulate rate (lpm or gpm) x duration
Duration = 65 minutes for Type III (over the top) functions
Please note that these portions are for extinguishment purposes. For vapor suppression after extinguishment it is an accepted follow to double our extinguishment provides to maintain the suppression of vapors and prevent the attainable reignition of the product.
Some of the above flows could also be properly in extra of 37,854 lpm (10,000 gpm) and will require large capacity supply devices similar to massive trailer mounted displays and enormous portable pumps.
Now that we all know our circulate charges and foam concentrates required we need to also have a glance at other factors 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 within the tank to simply accept the whole foam answer without causing an overfill
What different tanks, piping, or buildings could additionally be exposed
Weather conditions (present and expected)
Foam chamber on tank. Note the wind girder with applicable handrail. If the froth chamber was not current or did not operate correctly, the wind girder might be used to advance foam hoselines for seal hearth extinguishment.
In any fire state of affairs we want to contain the native facility personnel in our planning section as technical specialists. They may also be at the command post advising the Incident Commander instantly. These fires are not our strange ‘bread and butter’ operations and ought to be treated as an incident that can change quickly and unexpectedly, usually with severe penalties. Do not try to extinguish a full floor fire without all necessary resources on the scene. Cooling of adjoining tanks could be a tactic for use previous to all foam supply and personnel resources are on the scene. The cooling of the tank that’s on fire isn’t beneficial unless complete 360 diploma cooling may be completed, which is rare. Also, when cooling a tank, use only the amount of water needed. When the cooling water stops turning to steam, you could shut down the streams and start them up once more when essential. This will preserve water provides 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) might be required for every tank cooled. In addition to the right delivery gadgets and foam provides, we need to make sure that our foam solution delivery zone on the surface will be able to unfold out as soon as it hits the surface and cover the entire surface space. According to the National Fire Protection Association (NFPA) foam can journey effectively throughout at least 30m (100 ft) of burning liquid. We consider that for calculating foam runs, this quantity must be reduced to 24m (80 ft), guaranteeing that our landing zones travel and overlap one another. Firefighters should pay consideration to the distance a grasp stream can attain in addition to the touchdown zone length and width. These may be obtained from the producer of the displays and nozzles and verified within the field during drills and workouts. By understanding this information we will pre-plan the positioning of our grasp streams. Range finders can be used throughout operations to gauge distances to the tank to help with monitor positioning. There are a quantity of occurrences that may occur at a storage tank hearth that the fire service ought to be conscious of. These are:
This event can happen when a water stream is utilized to the recent surface of burning oil, provided that the oil is viscous and the temperature exceeds the boiling point of water. It causes a short period of slopping of froth over the rim of the tank with a minimal of depth.
Frothover is a gentle, slow transferring froth over the rim of a tank without a sudden and violent response. Frothover might occur when the tank is not on fireplace and water already inside the tank comes in contact with sizzling viscous oil which is being loaded. An example is when hot asphalt is loaded into a tank automobile and comes into contact with water within the tank, inflicting the product to froth excessive. During a fireplace with crude oil it could additionally happen when the warmth wave created by the burning crude oil reaches the water layers (stratums) in the crude oil. This warmth wave will convert the water to steam, causing a frothover.
This occasion 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 bottom of the tank. The mild fractions of crude oil burn off, producing a warmth wave in the residue. The residues with their associated heat wave sink towards the underside of the tank. This heat wave will eventually reach the water that usually accumulates at the bottom of the tank, and when the two meet the water is superheated and subsequently boils, expanding explosively causing a violent ejection of the tank contents and fire. The increasing contents being expelled can journey the space equivalent of ten tank diameters. Careful consideration must be given throughout pre-incident response planning of the location of the command submit, staging areas, rehab, equipment placement, etc.
Pre-Incident Response Planning
When planning for a response to a petroleum storage tank facility it’s best that the knowledge gathered is finished on-site and with the assist of facility personnel. While on web site, entry roads that you can be use to access the realm and place hearth apparatus (appliances) ought to be pushed by the vehicles that might be used during an incident. Many occasions the turning radius of equipment is merely too nice to make the turns needed within the facility. Swales or culverts can also impede equipment. If the equipment chassis is too long and or low, it could hold up or floor whereas traversing a swale or culvert. Bridges on website might not permit the load restrict of latest equipment, stopping its use at an incident.
During pre-incident response planning information that ought to be gathered contains the following:
Tank varieties, dimensions, contents and capacities
Pipe isolation valves, places, and working mechanism
Fixed hearth protection methods obtainable
Access points to facility and tank
Contact cellphone numbers
Locations and operation of emergency shutdown devices (ESD’s)
Availability of firefighting sources
Foam focus necessities
Mutual/automatic help out there
Other info could be obtained based on the wants and necessities of your department. While these articles usually are not totally inclusive of all info that a hearth division needs to know, it’s a good start. Other sources are listed at the end of this text. It is essential that firefighters attend lessons on this specialized firefighting, pre-plan these facilities, and train the pre-plans. Don’t enable these services to turn into part of the panorama. Visit these facilities and ask questions!
For extra data, go to www.worldsafeinternational.com
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 positioned throughout coaching. Note the protecting hose stream in place.