TANK FARM FIRE PROTECTION. EXTINGUISHING FIRE IN TANKS

The Pozhneftehim supports the designing of fire protection systems and manufactures equipment and foam concentrates for tank farms’ extinguishing systems.

Over 10-year experience in cooperation with leading oil and gas and petrochemical organizations allows creating economically feasible and efficient systems with due concideration of facility characteristics and legal requirements.

ORDER TYPICAL PROJECT DESIGN

Fire protection of tank farms

Tank farm fires are dangerous both for the industrial facility itself and for settlements located in the immediate vicinity. Inaccuracies in design, installation and maintenance of fire extinguishing systems may have social, financial, environmental, and infrastructural consequences.

The fire protection of the oil and oil products tank farm depends on the specifics of the facility: what tanks are installed on the site, what flammable and combustible liquids are stored therein and in what amounts. The main section of the project «Fire safety measures» (MOPB) should contain both regulatory and technical justification for decisions. Pozhneftehim has experience in developing MOPB for hazardous production facilities and carries out a range of works to ensure fire safety under the license of the Ministry of Emergencies of the Russian Federation.

The fire safety system includes not only fire extinguishing means, but also the organization’s internal regulations to prevent fire. Among them:

• Organization policy in the field of industrial safety, labor, environment protection
• Organization standards for emergency preparedness and corporate training on fire safety
• Requirements for contractors, instructions for organizing safe conduct at open fire, gas hazardous and other works

The internal organization security documents are mandatory for all employees and invited specialists.

Methods of fighting fire in a tank

According to SP 155.13130.2014 “Warehouses for oil and oil products”, the main means of extinguishing fires in oil and oil products tanks is medium- and low expansion foam applied to the surface of a combustible liquid.

The main provisions for foam fire extinguishing systems are prescribed in federal law 123-FZ "Technical regulation on fire safety requirements". Other official standards and codes of practice regulate the use of fire extinguishing systems, firefighting equipment, foam concentrate (extinguishing agent), foam generators, etc.

The Pozhneftehim recommends using the following foam extinguishing methods for fire protection of tank farms:

• application of a film-forming low or medium expansion foam from the top downward onto the surface of the oil product using heat and explosion resistant chambers of low expansion foam in the tank upper zone;
• application of a low expansion foam through subsurface nozzles into the stratum of the oil product to reduce the burning area in the tanks;
• universal method with application of foam to the surface and/or into the stratum of flammable and combustible liquids.

The working solution of foam concentrate is applied to the surface of the fuel from the top downward through the wall of the tank using the Vega low expansion foam produced by the Pozhneftehim. For the method of subsurface application, a Shturm high back pressure foam generator, a burstable membrane and an Interlayer subsurface nozzle are recommended. Aquafom AFFF and AFFF/AR fluorosynthetic foam concentrates are recommended to use depending on the type of combustible/flammable liquid in the tank. Non-polar liquids shall be extinguished with AFFF foam concentrate, polar liquids – with AFFF/AR.

The principle of action of fire extinguishing systems (firefighting) and water cooling in tanks

Cooling of a burning tank and adjacent tanks of the RVS type (vertical steel tank) is the first priority of stationary installations and fire units. For this end, a water cooling unit with a pump station is created. In the event of a fire, it begins to work both on the ignited tank, and on the tanks adjacent to it. An installation of water cooling requires an underground circular water line with fire hydrants. Water also flows from it to the foam proportioners (BK-PT Vityaz) of the foam fire extinguishing systems.

Depending on the required response time of the system (the time span for the foam fire extinguishing system to start functioning), a centralized or decentralized storage and proportioning system of the foam concentrate (SKhDP) can be used in the tank farm. The point of storage and preparation of the foam concentrate solution may be located at a greater or lesser distance from the tank.

The response time of the foam fire extinguishing system directly depends on the length of the solution line that connects the foam concentrate storage and propotioning system and a protected tank. The main reason for the system failure is the use for extinguishing a non-heat/non-explosion-proof generators of medium expansion foam and low-quality foam concentrate. If the foam concentrate is non-compliant with GOST, it loses its properties before the expiration date. When stored in a pipeline, the premix decomposes within one to two months. It is possible to check the fire extinguishing properties of the foam concentrate only during expensive fire tests in accredited laboratories equipped with a test site.

The traditional top-down fire fighting technique developed in the 1960s consists in the use of a medium expansion foam, a GPS foam generator and a synthetic foam concentrate. Medium expansion foam can enter the tank by rigid application method which is one of its drawbacks. In addition, the foam premix solution of synthetic foam concentrate S-type does not protect the tank from burn back.

The risk of re-ignition of a combustible or flammable liquid (for some substances the flash point is less than 28 °C) is the main reason for choosing fluorosynthetic foam concentrate.

Fluorosynthetic foam concentrates require using low expansion foam generators and gentle foam application on the walls inside the tank. Another advantage of AFFF and AFFF/AR foam concentrates is that fluorosynthetic foam concentrates are used for both top and subsurface fire extinguishing, they do not mix with oil and effectively cool the walls of the tank at fan application with Vega foam chambers KNP.

The foam fire extinguishing systems (installations) with turbine inline and balanced pressure proportioners require the AFFF and AFFF/AR foam concentrates.

It is important that the selected foam concentrate meets the requirements of the fire equipment available at the facility, and the fire extinguishing efficiency is confirmed by testing at the test stand, taking into account the quality of water and fuel at the facility. When choosing the volume concentration, frost resistance and viscosity of a fluorosynthetic product, we recommend you to consult a specialist of the manufacturing company.

Contact information to order Pozhneftehim complex supplies

Questions concerning the choice of foam concentrates for fire extinguishing

Tatyana Potapenko, foam project manager +7 (499) 703 01 32, ext.172

Questions concerning the choice of firefighting equipment

Sergey Vypritsky, Project Manager +7 (499) 703 01 32, ext.153

Questions on documentation regarding Fire safety measures (MOPB) and Special technical conditions (STU)

Sergey Titenkov, Head of Regulatory and Technical Department +7 (499) 703 01 32, ext.159