Industrial-size fire protection

Fire protection engineers must become familiar with the idiosyncrasies of industrial fire safety design.

03/17/2010


 

 

 

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Designing fire and life safety systems for industrial occupancies almost always poses a challenge to a design team. Depending upon the nature of the raw materials, the processes involved, and the nature of the final products, the hazards vary from minor risks to conditions that are or can become immediately dangerous to life and health—not just within the facility itself but also the wider community.

As a result, the responsibility for designing fire protection and life safety systems for industrial occupancies cannot be transferred from the engineering professionals to builders and contractors.

 

The one factor that makes industrial buildings different from all others is the focus of their use. The majority of buildings are people-centered. Whether residential, assembly, educational, or business, the focus of the facility is how it ultimately serves its future human tenants' needs. In industrial facilities, on the other hand, the focus is on the movement of incoming raw materials, parts, or components through a variety of processes to create final products. These products can be everything from raw steel to pharmaceuticals to electrical power.

 

When industrial applications are mentioned, many people think of the large-scale production facilities that make up our popular consciousness: the sprawling steel mills, the automotive assembly lines, the high-tech production facilities for computer chips, or refineries. But the fact is that these large facilities comprise the minority of our world's industrial facilities. The great majority of the industrial base is made of smaller facilities and businesses, often specialized in particular products or components. And these facilities dot the landscape in every conceivable urban and rural environment.

 

Regardless of size or the nature of the products or processes involved, the needs of the human occupants in industrial facilities are almost always a secondary consideration, limited to meeting only the most basic human needs. In addition, the hazards of the raw materials, the processes, the by-products produced during manufacturing, and the storage and handling of the finished product need to be part of the design process. Chemical process safety management is mandated by federal laws and must be part of the design process in applicable industries.

 

Trying to delineate a single concise methodology to ensure that a facility has a solid fire safety design is simply not possible. The breadth of what comprises “industry” is part of that problem. But there are a number of factors often given limited consideration that prudent design and engineering professionals can add to help ensure that adequate fire protection and life safety objectives are achieved.

 

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While production lines are often designed with simplicity and flexibility of operation in mind, they often do not take into account the potential hazards that could result when incompatible materials are used in close proximity. All photos: Hughes Assocs. Inc.

 

 

Understand the building's risks

In order to ensure that a facility or even single process is adequately protected, the design team, and in particular the person charged with designing the fire and life safety features, must be thoroughly familiar with every aspect of the operation. Every material, component, or process presents an inherent risk that depends on its nature, quantity, and configuration.

 

Fire protection engineers should ask: What are the raw materials? What are their inherent hazards? How and where will they be stored, dispensed, and conveyed into the production process? Does that process create any new or special hazards unto itself, and what about any hazards created by the final products where they are stored or dispensed?

 

At every point in the process, the engineering team needs to address the risks and the relative actions that can be taken to eliminate, limit, or respond to the risks. Some items can be addressed in the design of the process itself. For example, static electricity can be dissipated through proper bonding and grounding, vapors can be captured and removed, and interlocks can be installed. But even in the best design, safety features can fail or conditions are such that a deviation of the process can result in a fire or explosion. What strategies, technologies, or procedures can be taken to limit the resulting damages?

 

The prevalence of flammable and combustible liquids and gases in industrial facilities makes the recognition of a potential hazard seemingly self-evident. Moreover, the history of the inherent hazards presented by such materials has led to the development of a range of well-recognized codes and standards to help engineers mitigate these risks. Whether the hazard is primarily the quantity and configuration of the storage or the generation of flammable or combustible vapors, the engineering team must have complete knowledge of the configurations to determine what controls are needed to control the risk.

 

But what about the range of other processing, where the materials processes present less commonly recognized hazards?

 

For example, consider a facility that will be using a heat transfer fluid to warm a special adhesive used to attach a laminate to the base. The transfer fluid may be a combustible liquid that is circulated through a direct-fired heater, raising its temperature above its flash point. Similarly, the adhesive itself might emit both combustible and toxic vapors as it is applied and cured. All of these are hazards need to be addressed not only by automatic fixed fire suppression systems and exhaust systems, but also by control systems and trained operators. Fire protection engineers must consider all of these aspects—and not just suppression and detection. Failure to analyze the entire production process can result in large property loss, long periods of business interruption, injury or fatality to operators, and extensive litigation.

 

The International Code Council (ICC) and the National Fire Protection Assn . (NFPA) publish codes and standards that address a broad range of the commonly encountered industrial hazards. Insurance and or industry-specific organizations, such as Factory Mutual or the American Petroleum Institute also publish standards. Collectively, many of these documents are considered the “standard of care” when designing specific facility types and, in some cases, the documents are adopted as law within the governing jurisdiction. In addition to these “design standards,” other regulation such as that linked to worker health and safety (like OSHA) can contain reference to yet other specific standards that must be accounted for in design.

 

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Process design traditionally isn’t part of the fire protection engineer’s role, but engineers must be aware of the entire process so as to address potentially hazardous conditions, like this one.

Other factors that play a part

 

Environmental and process conditions are often-overlooked contributors to fire and life safety. Weather-related heat or cold, pressure, and humidity can alter the physical characteristics of materials, particularly those transported and used at outdoor ambient temperatures. Similarly, the process itself can use or add heat, pressure, or humidity that can create or exacerbate potentially hazardous conditions. The most common contributing factor in industrial fires is often tied to facility housekeeping. While a large portion of managing such concerns is a facility management function, there are plenty of conditions that good facility design can help address.

 

Due in large part to a number of recent high-profile fires and explosions involving combustible dusts, this subject has become a prominent topic within the design community as well as several of the more prominent worker-safety enforcement agencies. While a number of NFPA and other industry standards address design to prevent and mitigate the effects of these explosions, the most effective prevention method is to prevent the accumulation of dust in the first place. This usually involves both fixed systems to capture and remove dust at its source and continuous housekeeping to control fugitive emissions that often seem to escape.

 

A simple rule of thumb for dust: If a layer of combustible dust develops that is deep enough to write your name in, it is more than enough fuel to be a significant dust explosion hazard. The level and extent of the hazard is a function of the amount, distribution, and material properties of the dust itself. But in many cases, even a thin layer of dust, particularly if distributed about the room or building, can be more than enough fuel to level the building. Therefore, the fire protection engineer must insist that the material properties of the dust be fully defined through testing, and not simply make generalizations from readily available standards.

 

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Anything the design team can do to improve housekeeping will provide a greater degree of fire safety to the facility, as poor housekeeping is often the most comon fire hazard.Anything the design team can do to improve housekeeping will provide a greater degree of fire safety to the facility, as poor housekeeping is often the most comon fire hazard.

 

 

Employing codes and standards

For most industrial projects, the basis of the physical building design is governed by the needs of the facility. The basic fire protection and life safety provisions that must be incorporated into that design are mandated by a locally adopted building code, such as the ICC's International Building Code. While adopted building codes provide basic framework and legally required minimums for general life safety and property protection considerations, they are often too generically written to address the specific hazards (and the means to mitigate them) that may be present in an industrial facility.

 

The building codes expand the extent of applicable requirements through the adoption or reference of other codes and standards. The most commonly adopted references include a fire code, such as a version of the ICC's International Fire Code (IFC), as well as many of the model codes and standards published by the NFPA.

 

Conflicts between codes and standards are not unusual. While many codes, such as the ICC's, are drafted with the intent of being well-coordinated, conflicts do exist among them. Conflicts are far more prevalent when the building and fire codes reference codes and standards produced by third parties such as the NFPA. Moreover, care must be taken to acknowledge when referenced standards are only partially adopted, limited to specific aspects or provisions within the references.

 

For example, code confusion exists in the latest version of NFPA 30 Flammable and Combustible Liquids Code , which identifies a range of storage configurations and corresponding fire protection schemes for flammable and combustible liquids. However, the IFC does not adopt the entire NFPA 30 standard and the two are often not in sync regarding technology changes. Instead, the IFC contains many of its own requirements and limitations. As a result, while many design professionals would consider use of NFPA 30 as a standard of care for the design of facilities that store and handle flammable and combustible liquids, use of NFPA 30 as a basis for design in some instances could actually be in violation of the jurisdiction's adopted laws.

 

Therefore, when using code-referenced documents or third-party design standards such as those produced by Factory Mutual, American Petroleum Institute, or other standards-writing entities as a basis of design, be sure to present the design basis in detail to the authorities having jurisdiction as soon as practicable. While many will accept these referenced documents in principle, some jurisdictions may not have the legal authority to approve them, and a formal variance process may be required prior to employing them. If a formal variance is not obtained and a subsequent loss occurs, the design team can be saddled with the difficult task of trying to defend their design when it is clear violation of locally adopted law.

 

One code-related item that is often overlooked in the design of industrial facilities is the development and maintenance of adequate egress access throughout the building. As the majority of industrial buildings have large open floor plans, the principal means of achieving code-compliant egress travel distances is to employ a relatively large number of exit doors directly to the building exterior. However, in large-footprint buildings, processing (assembly) lines and storage configurations are commonly oriented in a manner that significantly increases exit access travel. Such issues are even more prevalent when processes are modified or expanded within existing facilities. Therefore, it is the fire protection engineer's responsibility to evaluate and reevaluate the egress system as part of the process and storage design process.

 

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Fire protection engineers take a great interest in flammable vapor capture and control; other vapors, like corrosives, can generate false alarms, system corrosion, or other performance problems.

Specify the automatic sprinkler protection

It has become common practice for design professionals to pass on the details of fire suppression design to third parties, particularly contractors, through broadly worded performance specifications. While this practice may work well within the majority of buildings and occupancies, doing so in an industrial facility can, at the least, limit the future use and flexibility of the facility for the owner or, at worst, result in the design and installation of a totally inadequate fire suppression system.

 

Proper design of fire suppression systems must account for both the quantity and nature of the materials being stored, handled, and processed within the facility. The specifying engineer should clearly establish a basis of design for each area within the building and present this information within the design documents.

 

This information should include two distinct components. The first is a detailed description of the hazards to be present in the space (types of materials present, their configuration, and the nature of the processes therein). The second is a full designation of the applicable standard(s) being referenced, the applicable version of that standard, and a specific reference to precise design parameters being employed. This often includes reference to other NFPA standards such as NFPA 30, Flammable and Combustible Liquids Code; NFPA 33, Standard for Spray Application Using Flammable or Combustible Material; or NFPA 34, Standard for Dipping and Coating Processes Using Flammable or Combustible Liquids ; or NFPA 430, Code for the Storage of Liquid and Solid Oxidizers .

 

As an added precaution, the engineer should review this information with the owner/tenant to be sure that the specified protection meets the owner's expectations. Failure to fully document these details not only creates ambiguity in the design documents, potentially causing confusion for the construction contractors, but could also be a source of future liability for the design team if the owner changes operations under an assumption that the design team factored the flexibility into the base design.

 

You may also find that a single layer of fire suppression may not be adequate for the process or the hazards. For example, the process may employ a fire suppression agent other than water. Yet, the building may need automatic sprinklers to satisfy other code requirements.

 

NFPA 13, Standard on the Installation of Sprinkler Systems , requires the owner or its authorized agents to provide the details on the design requirements for automatic sprinkler protection. In order to meet this code requirement, the specifying engineer must provide information on the intended use of the building, the materials and operations to be conducted within the building, information on the storage method (including height of any storage), preliminary design concepts to perform the layout, and any special knowledge of the water supply. Because NFPA 13 is an adopted reference to most building codes, meeting this requirement is a duty of the owner and its design professionals, and cannot be delegated to the contractors.

 

Fire alarm system considerations

Fire alarm systems are not usually required in small single-story industrial occupancies, other than the limited capability provided by sprinkler system monitoring systems (where a building is sprinklered). But for larger facilities or those handling significant amounts of hazardous materials, such systems, even if not required, are often desirable. While NFPA 72, National Fire Alarm Code generally governs the design and layout of these systems, two items are often poorly addressed.

 

The first is system audibility. NFPA 72 mandates that visual notification be provided when audible levels within the building are in excess of 105 db. But with the increasing prevalence of mandatory hearing protection in the industrial workplace, if a fire alarm design spaces devices in a manner that would normally provide adequate audibility, the sound output could be significantly masked by industrial background noise and rendered inadequate though the employees' use of hearing protection. For industrial facilities where hearing protection is widely used, it is a good strategy to design in a manner that is more heavily dependent on visual notification.

 

Similarly, as a result of the same high noise environments, industrial process designers and the manufacturers themselves often employ horns and strobes (or other flashing lights) to convey operating conditions to employees. In many parts of the country there are other auxiliary communications for emergency notification systems such as emergency alarm systems, tornado warnings, etc. Fire alarm design team members need to take these other signals and means of communication into consideration, particularly in existing facilities, to design the fire alarm system with a distinctive audible and visual signal.

 

In some situations and with the authority having jurisdiction's support, using one notification system for normal and emergency use may be the better solution. Note that IBC Chapter 4 requires a separate hazardous materials pull station/alarm system in certain situations. Also, a facility may need special detection such as organic vapor monitoring to meet explosion prevention requirements of IBC and IFC.

 

Just the beginning

 

This article raises only a few of the more typical fire protection and life safety concerns found in industrial occupancies. For every common practice, there will always be an exception to the rule. It cannot be emphasized enough that to craft a successful fire protection and life safety design basis, the facility designers, engineers, and owner have to work together to clearly delineate each and every inherent risk from every component, process, and product.

 

While the locally adopted building code is often used as the baseline for fire protection and life safety design, the designers must recognize that such a document is only a minimum standard and may not meet the needs of the owners. Moreover, as a minimum standard, the code may not adopt or reference a range of other documents that form the “standard of care” for a particular industry or process. Therefore, the fire protection engineer for each project needs to understand the needs of the facility owners and operators to develop a comprehensive design basis.

 

Finally, the process of providing for adequate fire and life safety design must be recognized as an ongoing process. As the facility changes the processes or the storage configurations, each change must be evaluated for its specific impacts as well as its impact on the overall facility.

 

 

Author Information

Sincaglia is director of Midwest operations for Hughes Assocs. Inc.

 



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