Dec 2020

Paper Making Fire Hazards

Every day we touch something made from paper. The box we got our internet order in, the paper you put in the printer, the carton your cereal is in and so many other items. Paper is an item we now just take for granted, but making paper is a complex operation which requires large manufacturing facilities sometime valued in the several billions of dollars. Property loss exposures come in a variety of ways in what is basically a mechanical/chemical process used to breakdown trees (most often used raw material) into usable fiber and then mechanically manipulated to form that sheet of paper you are familiar with. Since this one article cannot discuss the operation and exposures to property loss in great detail, the following will provide a basic list of exposures and some general guidance regarding associated property protection systems.

Combustible Dusts – A by-product of just about every phase of the paper making process is combustible dust. From the wood yard where the trees are de-barked, cut and chipped into usable wood chips, to the transportation of the chips to be made into pulp and bark to the power house, in the paper machines where to pulp is made into a rolls of paper to the converting area where the rolls are made into sheets or other forms of paper. Many operations include the use of other combustible dusts such as corn or similar starch which would include truck/rail unloading equipment, storage silos and material handling and processing equipment. All equipment and processes that produce, handle and use combustible dust should be identified and a Dust Hazard Analysis performed to identify the risk of a combustible dust explosion with this information used to take measures to reduce or eliminate the exposure to a combustible dust explosion. Documents such as NFPA 652, NFPA 654 and NFPA 664 provide guidance in addressing the exposure to combustible dusts. Protective systems such as automatic sprinkler systems, dust collection and separation systems properly equipped with explosion venting and possibly fixed fire/explosion suppression systems, methods to separate dust processes form the remainder of the facility and procedural requirements such as housekeeping and handling procedures should be considered.

Another form of a combustible dust exposure is the accumulation of paper dust within the paper machine enclosure. This enclosure, normally referred to as the paper machine hood, accumulates paper dust which is exposed to moisture from the heated steam drums steam system and the oil residual from the minor oil system leaks. If this paper dust is allowed to accumulate in the hood, a fire involving this residue can quickly spread outpacing the operation of installed sprinkler systems. The installation of automatic sprinklers throughout the paper machine hood along with a good housekeeping and continued maintenance are the primary protection and fire prevention measures in addressing this exposure.

Heat Transfer Hot Oil Roll Systems – Depending on the paper being made, the surface of the paper may be enhanced by using heated press rolls to give the paper a specific finish. Some locations use Heated Thermal Oil Transfer Roll systems to perform this function. This is a subject on its own but in

general the heating system, transfer system and associated equipment present a high fire hazard if the heated thermal oil is released due to a failure or if the heating system malfunctions. The systems are usually operated at about 60 psi and the oil may be heated above its flash point. Roll rotary joints present a system failure point and these joints must be properly designed and maintained as would apply to the entire system. In general, automatic sprinkler systems should be provided over the entire system including distribution piping and heater system and on the operating floor around the heated roll but not directly over the heated roll. The system equipment should be provided with automatic shutdown interlocks and the heating system should be provided with temperature controls arranged to shut the system down upon an overheating condition. FM Global Data Sheet 7-99 may be used as guidance.

Hydraulic systems – As in many manufacturing settings, a paper mill has many hydraulically operated production equipment. The hydraulic systems range in size and operating pressures but most of the systems have a hydraulic fluid capacity in excess of 100 gallons (379 liters). These systems are located in every manufacturing area in a paper mill and present the same type of fire exposure as in any other manufacturing operation; that of a high pressure ignitable liquid spray fire upon failure of the piping system. Of particular concern are those hydraulic systems that are used as hydraulic equipment drives, which are usually located in the wood yard and pulp mill, and the hydraulic units that operate systems on the paper machine. These hydraulic systems usually have a larger fluid capacity and are located in close proximity and sometimes within the confines of the equipment enclosures. Due to the location and size, a hydraulic system fire exposes multi-million dollar machinery and can cause major damage and equipment downtime brining the mill operation to a standstill. General fire protection includes the installation of automatic fire sprinkler systems, hydraulic system automatic shutdowns and physical separation of the hydraulic reservoir and pumping system from surrounding areas.

Lubrication Systems – Paper machines include large rotating rolls and steam drums that require lubrication systems. The systems are usually operate at lower pressures (about 30 to 50 psi) pumping lubricating oil up to the rotating roll and steam drum bearings with the oil then gravity fed back to the oil storage tanks. Since the system is operated at a relatively low pressure, the primary fire exposure is the quantity of oil and the location of the tanks and pumping system. A paper machine will generally have multiple lubrication systems each with a tank capacity about 5,000 to 8,000 gallons (about 18,900 to 30,300 liters). The tanks and pumps are generally located on the building grade level within the building adjacent to the paper machine. Due to the many heated surfaces and other ignition sources, an oil leak can easily be ignited and can expose the entire machine to severe damage and extended downtime. General fire protection includes the installation of automatic fire sprinkler systems, tank and pumping system spill containment and fire detection systems to alert operators of a possible fire near the tanks and pumping systems. Good housekeeping and system maintenance are needed to prevent system leakage or to reduce the amount of leakage accumulation until the system can be repaired during paper machine outages.

Ignitable Liquids and Other Chemicals – A paper and pulp mill can in many ways be compared to a chemical processing operation. Paper and pulp mills, besides using use lubricating and hydraulic oils in their equipment, also use ignitable liquids such as methanol in the production operation while turpentine is a by-product of the pulping process. The turpentine recovery operation includes decanting and distillation operations. Bulk storage and handling of ignitable liquids must be done in accordance with codes and standards and include storage tank space separation with spill containment, along with automatic and manual firefighting capabilities. Decanting and distillation structures must be provided with adequate space separation and automatic fire sprinkler or similar systems installed throughout the process structures along with proper spill containment. Other chemicals used in the paper and pulp making process include (this list is not all inclusive) acids, caustics, oxygen, ozone, chlorine dioxide, hydrogen peroxide, sodium chlorate, sodium hypo-chlorite and sulfur. All these chemicals include different and specific types of hazards and exposures and each must be evaluated and provided with proper protection safeguards.

Storage – From incoming wood logs, to in-process storage and to the storage of finished products such as Roll Paper and sheet paper in corrugated cartons, a paper and pulp mill have many different storage fire exposures. Tree length and cut length logs can be stored in bulk piles up to 80 ft. (24 m) in height and up to several thousand feet (meters) in length. Fires can start at the base of the log pile due to decomposition of wood fiber with these types of fires are very difficult to extinguish. Firefighting includes the re-positioning of logs and the application of great amounts of water. These fires can take weeks to control and extinguish. Similarly, wood chip piles, which can be 100 ft. (30 m) in height and many hundred feet (meters) long, have deep seated fires that require the movement of the chips and the application of large amounts of firefighting water. This can be a dangerous operation since mechanical equipment must be place on and adjacent to the pile to move the chips. Deep seated fires can create voids in the chip piles allowing for pile collapse. These fires must be very carefully addressed to assure proper safety is adhered to while combating the fire. In both the wood log and chip pile fires, much of the pile may become unusable due to fire contamination.

In-process storage of concern is at the exit end of the paper machine where the continuous paper sheet is wound into large paper rolls called “Parent Rolls.” These rolls weigh about 20 tons and are stored on horizontally on stands or on the floor waiting to be cut into smaller rolls. Fires have occurred on these rolls and can be very difficult to control since roof level sprinkler protection is normally about 30 to 50 ft. (9 to 15 meters) above the rolls. Manual firefighting is the primary method of fire control in these instances. These parent rolls are cut to smaller size rolls that are either converted into sheets of paper or are shipped to customers for their use.

Finished products are primarily roll paper storage and storage of paper products in corrugated cartons. Roll paper presents one of the most challenging type fires with automatic fire sprinkler protection being the primary method of protection for this storage. Sprinkler system design is based the base

weight and coating of the paper, storage configuration, storage height and other variables. These sprinkler systems require large water discharge capabilities at relatively high operating pressures.

Packaged paper products are considered to be a Class 3 commodity and can be protected following NFPA code requirements.

The above provides a basic introduction to the fire exposures that can be found at a typical paper and pulp mill. All these exposures require detailed review to provide an understanding of specific site fire exposures and the methods that should be taken to reduce or eliminate the facility to a large loss potential. Please contact Risk Logic if you would like such a review for your paper plant.

References:

NFPA 13, Standard for the Installation of Sprinkler Systems NFPA 30, Flammable and Combustible Liquids Code

NFPA 652, Standard on the Fundamentals of Combustible Dust

NFPA 654, Standard for the Prevention of Fire and Dust Explosion from the Manufacturing, Processing and Handling of Combustible Particulate Solids

NFPA 664, Standard for the Prevention of Fires and Explosion in Wood Processing and Woodworking Facilities

FM Global Data Sheet 7-4, Paper Machines and Pulp Dryers FM Global Data Sheet 7-57, Pulp and Paper Mills

FM Global Data Sheet 7-73, Dust Collectors and Collection Systems

FM Global Data Sheet 7-76, Prevention and Mitigation of Combustible Dust Explosion and Fire FM Global Data Sheet 7-88, Ignitable Liquid Storage Tanks

FM Global Data Sheet 7-98, Hydraulic Fluids

FM Global Data Sheet 7-99, Heat Transfer by Organic and Synthetic Fluids FM Global Data Sheet 7-103, Turpentine Recovery in Pulp and Paper Mills FM Global Data Sheet 8-9, Storage of Class 1, 2, 3, 4 and Plastic Commodities FM Global Data Sheet 8-21, Roll Paper Storage

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