Introduction
In order to meet the challenges that arise due to the production of oil, the oil has to be protected from fire. This procedure requires highly developed systems in order to overcome the challenges in the oil production system. Therefore, this research paper deals with offshore oil rigs and the various fire protection systems used to provide safety to the oil industry.
The systems to be discussed under this paper should be able to persevere with any environment such as the marine environments. They should also require minimum and easy maintenance. Also, they should be able to deal with rapid occurrence of fires that may release high amounts of heat energy.
Again, the systems should be reliable and should be approved by various authorities of regulation or safety. In order to meet these qualifications, the paper provides a discussion of a number of products and new designs which have been used in industries in order to meet the standards of fire protection.
A number of the fire protection systems discussed can be applied in various fields and industries to meet the standards of fire protection (Cote and Bugbee, p. 270).
Fire protection for offshore oil rigs is concerned with various conditions that are almost similar to protection of the oil refinery system. However, the former is somehow complicated. Any uncontrolled gases like carbon dioxide may cause overwhelming of the oil suppression systems.
Any operation meant for fire protection should be performed by the trained personnel on site. This is because evacuating the facilities for protection of the fires may result to high risks and consequences than any operation that is done on land. The fires that release high amounts of heat greatly reduce the amount of fuel available for combustion.
Fire protection for offshore oil rigs should first emphasize on protection of fire and also provision of training to the personnel who respond to the same. The goals of the systems must be keenly viewed before coming up with the decision to install fire protection systems.
For example, the goal of the systems of fire protection that deals with hazards of low heat release are to detect the occurrence of fire control or put off the fire before the trained firefighters arrives. This trained administration is the personnel to whom the lease belongs or the personnel whose flag is registered under that vessel.
Another, factor to consider before having a fire protection system is the process used for regulating facilities in the offshore. This is because, for offshore setting, the process of regulation is different from the facilities on land.
This is done by the provision of features that are able to meet the requirements of the society as well as the government regulations. It is important to understand the major types of oil rigs before going to the fire protection systems used in oil rigs. This will enable one to know where and when to install the fire protection systems (Cote and Bugbee, p. 268).
Description of an oil rig
An oil rig can be defined as a large structure that contains facilities used for drilling of wells. It also contains facilities for the extraction and manufacturing of oil and gas from its natural state.
Oil rigs are used for storage of products like oil temporarily until the time it is brought to the shore for refining and to taken for marketing. The oil rig, in other terms, may be called an oil platform.
There are many places where the oil rig can be fixed. These areas include the floor of the sea, float on the sea, or it can consist of an artificial island that is established on the sea or ocean (Ardley, p. 40).
Types of oil rigs
One of the common types of oil rigs is the fixed type which is built on concrete of steel legs and connected with a strong support from the bed of the sea. They provide support to rigs for drilling and facilities used for production of oil and other products. These types of oil rigs are usually designed to be used for quite a long time because they are immobile.
There is a variety of structures used under this oil rig such as steel jackets and floating steel among others. Steel jackets are made using steel tube members, which lie in piles on the bed of the sea where they are being constructed. The water tight structures called the concrete caisson have oil storage tanks which are in- built below the surface of the sea.
These tanks allow the oil rigs to be constructed close to the sea shore; they also allow the oil rigs to be floated to the last position where they are deeply sunk to the bed of the sea. They can only be installed to water depths of 500m and above (Ardley, p. 42).
The second category of the oil rig is the compliant towers majorly used for offshore gas or oil production. The compliant towers are used for sustaining some significant deflections and forces in a lateral manner due to their design. They are majorly used where water goes to a depth of 450m and above.
The third category of oil rig is the semi-submersible rig which has a hull with buoyancy sufficiency for easy floatation. The weight of the structure is sufficient enough to keep it always upright during its operation. The semi-submersible rigs are mobile and thus they can be relocated from place to place.
When the hull structure is submerged, this oil rig is rarely affected by loads from sea waves. This category of oil rig is very sensitive to changes in load.
This means that care must be taken when trimming in order to maintain stability. Its sufficient buoyancy is obtained by placing a heavy material on the in built tanks. In addition, it has the capacity to move from deep to shallow enabling substantial materials to be moved to the surface.
The fourth category of oil rig is the jack – up oil rig, which is mobile just like the semi submersible and can be upright on the floor of the sea. It usually rests on several legs that are for its support and anchorage. These legs can be raised or lowered to any position.
When it is lowered to its location to start working, the legs are jacked down on to the floor of the sea. The weight of the barge and the ballast water drives the support legs to the bottom of ocean or the sea in order to avoid further penetration when the rig is in operation.
This process is called preloading. All types of oil rigs are self sufficient in terms of water and energy. They also provide necessary equipment for processing of the oil so tat it can be transferred through a pipeline to a tanker loading facility (Hyne, p. 153).
Fire protection systems
These are systems which are meant for mitigation of the insignificant effects of highly destructive fires. Fire protection entails careful investigation of fire occurrences and the related emergencies which includes detailed research and application of systems for mitigation.
It is critical for the fire protection systems to be maintained in tandem with the basis of their design. Usually, the design is done according to laws and the fire code regardless of whether they are land based or offshore.
This is done to ensure that the fire protection systems serve the intended function as required and at the stated period. Whenever a fire accident happens, fire experts should be summoned to conduct investigation to establish the cause and damage of the fire accident. The fire protection aims at protection of property and the safety of life (Lambert, p. 25).
Types and categories of fire protection systems
in a broader sense, the fire protection systems can be grouped into two. The two categories include: (a) active fire protection systems, and (b) passive fire protection systems. In passive fire protection, the fire compartments are formed by fire resistance rated walls and floor assemblies.
These are meant to limit the spreading of fire and keep fire as well as high temperatures within the fire compartment to enhancing fire fighting. In active fire protection, fire is detected by the equipment both manually and automatically. The fire protection systems are put in to other categories.
The first category is the fire sprinkler system. In this system water flows through pipes and must be connected to a fire detection system which detects heat or fire. This category has got various types of fire protection systems.
One of the most common protection systems is the wet fire sprinkler system which is often installed. This is a simplified system consisting of a sprinkler and an automated alarm valve. When it is subjected to a high degree of heat, there is a retraction of a certain in-built element which is highly sensitive. This allows water to flow from the sprinkler. In this system, there are two categories.
The first one supplies the system with water once it required whereas the other is pressurized in a continuous manner. The latter is disadvantageous because the water within the pipes may stagnate and become infested by bacteria and mold. The same water in these pipes can break the pipes due to continued freezing.
This is the reason why such systems require regular maintenance. The second category of fire protection system is the dry pipe system which is commonly used where cold is a major consideration. It does not involve water storage like the wet system. This helps in preventing freezing of water in pipes.
In such fire protection system, water is released only when the operation starts. This is only in case of any occurrence of fire. This system uses pressurized oxygen instead of water in the pipes, which is only released when the sprinklers are started. This operation allows the pressurized water to push the valve open so as to let the water pass through the pipes to reach the sprinklers.
This system has one disadvantage that it has a longer response time in case of fire. The third type is the pre-action fire protection system which is further categorized in to three other types. The single, interlocked system; where water flows into the closed sprinkler system when the detection unit is activated.
A pre-action valve in the system functions to keep the pipes free from water. When the pre action valve is released, water is made to fill the pipes, which is then released by the sprinklers (Cote, p. 460).
Another pre-action system is the double interlocked pre-action system. This is where water does not flow in to the pipes. In this system water only flows in to the system when there is activation of both the system for detection and also the sprinklers. This is to reduce any discharge of water.
The third pre-action system is the non-interlocked pre-action system where unlike the double interlocked, it allows water to flow in the pipes. All the above fire sprinkler systems involve pipes that run through the whole system. They use sprinklers which release water to enable putting out fire when it occurs.
This is achieved by separation of heat from the oxygen and cooling down the fire. Again, in such systems the sprinklers must always be connected to a fire detection system. The sprinkler pipes can either be of a plastic or steel material.
The second category of fire protection system is the pull alarms. This is open to everyone because even individuals with visual problems can make use of such alarms. This is enabled by braille signs that are placed on the pull buttons.
These alarms are placed near exits to allow the occupants of the room where it is installed to pull out the fire alarm in case of fire occurrence. The pulling of the fire alarm not only alerts the occupants but also sends a signal to any fire department locally in order to give an alert of fire occurrence (Cote, p. 463).
The third category is the fire extinguishers. This mitigates fire by spreading of a certain material which brings a cooling effect or causes separation of fire from the source of fuel. Although fire extinguishers are used in fire protection, they cannot be used to put out large fires. The fourth category is the use of fire proofing materials which resist the process of combustion.
These materials keep the building off from burning when any fire arises. They are not good conductors of heat; therefore, they cannot conduct heat easily and cannot be destroyed by heat unless subjected to very high temperatures. Another category of fire protection system is the smoke detectors, which act as fire protectors by sending a signal to any local fire department.
When the fire occurs it burns materials releasing a considerable amount of smoke in the atmosphere which alert of a fire occurrence. Apart from this they detect any high temperatures that occur to show that there is incoming fire.
Lastly, fire escapes are also fire protection systems which provide escape when fire occurs unexpectedly. These types of fire protection systems are used for domestic and small scale purposes (Cote, p. 461).
Fire protection systems for Offshore oil rigs
Most of the above discussed fire protection systems are used for domestic purposes. However, there are others which can be used where there are large fires. In offshore oil rigs, since there is a high risk of fire occurrence, high fire detectors should be installed.
This is to ensure both safety of the machines and safety of the operators of the machines in use. Since offshore oil rigs are used in oil production, they require special fire protection systems and equipment in order to reduce high risks of fire. The offshore oil rigs mostly make use of passive fire protection to provide protection for the equipment (Cote, p. 465).
The oil rig structures are protected with fire proofing so that the fire boundaries can be adequate. One of the fire proofing materials used is the standard rock wool commonly found in water structures. Other products used are those that can fit well in an oil rig environment.
Such products are moisture and oil resistant and can be used in the offshore environment without any effect. Some of the sections of the oil rigs which require maximum protection are the control rooms, accommodation areas where the operators live, the places where the machines are kept and the area where oil processing is done.
The exit ways are the other places that may need protection from fire. Just like the operations that are based on land, the bulkheads, which have pipes and ducts for proper ventilation, should be highly protected. The other most commonly used fire protection system is the water mist system which is quite effective. It is the best for places where flammable liquids are the common products.
This is because they provide high fire suppression and fire extinguishing capabilities even if the area contains ordinary combustibles. This provides fire protection by use of various mechanisms.
These include cooling mechanism, depletion of oxygen which is also “inerting,” and also radiant heat blocking. In such fire protection system, water is the basic agent that is used for extinguishing any fire that occurs within the system.
This is because it has exemplary cooling properties that can be used in this system. This water is usually converted to steam which is more efficient than the water in liquid form. This steam is what causes depletion of oxygen in the flames of fire hence causing the fire to be extinguished.
Again, this system also cools down the oil in the system to ensure that the fire does not re-flash in to the system. The most important area to be given fire protection is an area that generates power to the system. That is the area with generator modules because these water mist systems provide fire extinguishing in a very excellent way.
These systems are advantageous because they require very little space to occupy. Once the fire has been extinguished, the whole system should be placed back to its normal service. This is done by refilling the cylinders used to store water and replacement of the cylinder that contains nitrogen.
Though most people think that these systems can cause harm to the turbines or the diesel engines, they have been tested by several agencies to prove that there is no harm from thermal shocks. This means that when choosing the fire protection system for the oil rigs care must be taken because of the high cost of turbines and engines.
Again, another important consideration is the safety of the people operating the system. For the case of the water mist system, it is very efficient and does not have an effect on personnel. This system is more advantageous over other fire protection systems that utilize gases like carbon dioxide as far as personal safety is concerned. This is because breathing the mist is not harmful to human health.
Again, the maintenance of a water mist system is very cheap especially in terms of cleaning the system. It is also advantageous over other systems because it does not cause any harm to the environment (Cote, 470).
Some fire protection systems that utilize carbon dioxide cause depletion of the ozone layer hence increased global warming. On the other hand, the living areas with accommodation facilities are protected by use of conventional sprinklers.
The areas used for food preparation are protected from fire by use of dry or wet chemical fire extinguishing systems. The production areas, areas for pumps storage, and areas for machinery make use of clean agents, deluge or foam systems. The areas where flammable liquids are stored are protected using dry chemical or using clean agent systems.
For all the above mention areas, a single pump based water mist system can be used to cater for the fire protection. In a single pump based system; stainless steel tubing is connected within the protection spaces. The mist from the system is delivered through nozzles in the method known as total deluge.
The areas mentioned above usually utilize the water mist nozzles that are open in order to bring down any strength that accompanies fire occurrence. The system that provides water for the water mist system should ensure that there is supply of water through out the facility.
The fire pumps used in the system should provide a reliable water supply. When working on the installation, care should be taken to ensure that all conductors are routed. This is made so because events taking place in the facilities can cause danger to the fire pumps.
It is also important to note that sea water causes corrosion and fouling on the fire pumps, so fresh water is significant. The pump materials are upgraded with aluminum bronze material, and the pipes are upgraded to copper nickel of fiber glass so as to prevent corrosion and fouling. This increases the reliability and integrity of the fire pump system and increases its lifespan (Cote and Bugbee, p. 272).
Another fire protection system is the deluge system which is used for areas like production, off loading, drilling and the well head areas. These types of fire protection are majorly used where fire is noticed to occur after a short period. They make use of open spray nozzles which are usually supplied by use of pipes containing water from the sea.
This water goes through a valve called a deluge valve. When an alarm is sent, the valve opens, and water is delivered through the spray nozzles over the hazard that has occurred. Water should be supplies at a high flow rate to cater for the high, challenging fire hazards. Although the fire protection system is quite effective, corrosion is a major setback in this system.
This is because pipes in this system are exposed open to the atmosphere hence they easily corrode making them non-functional. In order to ensure the integrity and efficiency, it is highly recommended that copper nickel pipes are used where possible. Fiber glass can be used in these systems to increase resistance when water is not yet flowing in to the system (Paik and Thayamballi, p. 3).
The other fire protection system for oil rigs includes the monitors and hose stations that are commonly used in the drilling areas or well test areas. These systems are very significant because they usually provide additional protection to the system.
It is highly preferable to look for a suitable place to locate them due to too much congestion on offshore oil rigs. They are commonly used in accommodation areas where fire occurrence is not highly expected. The hose stations are usually placed throughout the facility in order to ensure that all places can be reached within a short duration.
In this system, hose reels can also be used. These contain special provisions for delivery of certain foam stored in sealed buckets that can be pierced with an induction nozzle device. This nozzle is always connected to hose reels.
There is also another fire protection system called the fire suppression system and the fire extinguishers. These utilize clean agent to enhance fire protection within the oil rigs. Fire extinguishers are usually connected throughout the oil rig system.
This depends on the hazard of the protected space in the system. Another important fire protection unit is the fire and gas detection alarms. These operate by sending an alarm accompanied by a response from the fire brigade facility which causes an emergency shut down.
Apart from detecting fire occurrence within the system, the alarm system also detect poisonous gases, which are usually produced as by products of the system. Combustible detectors of toxic gases are also put in place especially in areas suspected to have leakages.
The areas that are protected by such systems are wellhead, the processing equipment, well floor and the degasser. Again, there is provision of smoke detectors in the control rooms and most of the enclosed areas within the system. This is because as said earlier smoke detectors are commonly used where fire occurrence is not often (Jones, p. 20).
Conclusion
From the discussion on fire protection, it can be concluded that almost al fire protection systems available can be suitable for oil rig fire protection. It is also important to note that not any fir protection system can fit in any part of the oil rig system. All the factors should be put in to consideration before installing any fire protection system.
It can also be concluded that oil rig fire protection, has its own regulations which should coordinate well with the marine and fire codes. Again, on operation skilled and highly qualified personnel are employed in order tom ensure safety of the oil rig facilities.
This is because most of the realized risks of fires arise from poor operation of the equipment or carelessness in oil handling. This means that a lot of concern should be put on safety management techniques so as to reduce risks of fire. Again, it is important to ensure that, after installation of any fire protection system, testing should be carried out.
This assures the management of total safety within the systems. Also, a design that is appropriate to a certain hazard is required. Finally, it can be concluded that as the oil industry expands on quality oil production, it should also ensure high protection of hazards.
Works Cited
Ardley, Neil. Oil Rigs. Ada, OK: Garrett Educational Corp, 1990. Print.
Cote, Arthur E. Operation of Fire Protection Systems: A Special Edition of the Fire Protection Handbook. Quincy, Mass: National Fire Protection Association, 2003. Print.
Cote, Arthur E, and Percy Bugbee. Principles of Fire Protection. Quincy, MA: National Fire Protection Association, 1988. Print.
Hyne, Norman J. Dictionary of Petroleum Exploration, Drilling & Production. Tulsa, Okla: PennWell Pub Co. 1991. Print.
Jones, Maurice A. Fire Protection Systems. Clifton Park, NY: Delmar Cengage Learning, 2009. Print.
Lambert, David. Fires and Floods. London: Evans Brothers, 1997. Print.
Paik, Jeom K, and Anil K. Thayamballi. Ship-shaped Offshore Installations: Design, Building, and Operation. New York: Cambridge University Press, 2007. Print.