NFPA Journal®, May/June 2011 

By Guy Colonna 

Two important industrial dust standards — NFPA 484, Combustible Metals, and NFPA 664, Prevention of Fires and Explosions in Wood Processing and Woodworking Facilities — will be discussed at the upcoming Association Technical Meeting. The revisions proposed for those documents reflect dust issues identified by the U.S. Chemical Safety Board (CSB), as well as by the Occupational Safety and Health Administration (OSHA). In fact, those common issues form a theme for the revisions taking place on all five of NFPA’s dust standards. Both NFPA 484 and NFPA 664 have completed their revision process and now await the action of the membership and the Standards Council to determine when they will be issued as 2012 editions.

YOUTUBE VIDEO FEATURE Watch NFPA Division Manager Guy Colonna provide an overview of the industrial dust hazard issue and how safety standards are keeping pace. RELATED NFPA CONFERENCE LINKS  Latest conference information  Register for the NFPA Conference + Expo  Full list of Education Sessions (PDF, 588 kb)  Read the daily NFPA Conference blog RELATED CONFERENCE SESSIONS Dust Explosions 101 - John Cholin, J.M. Cholin Consultants, Inc. - Sunday, June 12, 8–9 a.m. This primer on dust explosions is updated for 2011 to reflect the most recent developments in dust explosion hazard management. It covers the fundamental definitions, the process and progress of dust explosions, and hazard recognition. The session concludes with a review of hazard management options outlined in NFPA 654, NFPA 664, NFPA 484, and NFPA 61. The Hazards of Combustible Metals: What You Don’t Know May Injure or Kill Someone - Tom Christman, CSP; Kevin Kreitman, City of Redding Fire Department - Sunday, June 12, 9:30–10:30 a.m. The hazards of combustible metals and metal dusts are well documented. NFPA 484, Combustible Metals, identifies the controls that are necessary for the prevention and control of fire and explosions involving combustible metals. This session will provide you with knowledge of the primary hazards of combustible metals and highlight the key controls that are necessary to maintain a safe working environment. NFPA Combustible Dust Standards Update - Guy Colonna, Division Manager, Industrial & Chemical Engineering, NFPA - Monday, June 13, 11 a.m.–12:30 p.m. The NFPA combustible dust hazard standards form the most comprehensive basis for identifying hazardous conditions and establishing controls. All five documents are currently undergoing revisions, with some changes intended to correlate common requirements. At this session, you will get an update on the changes, their basis, and the current status. Fire and Explosion Incidents Involving the Return of Filtered Air to a Manufacturing Facility - Bob Zalosh, Firexplo - Tuesday, June 14, 8–9 a.m. Filters are used in numerous manufacturing facilities to absorb combustible particulates and vapors. The clean air from many of these filters is often returned to the building. When a fire or deflagration occurs in the filter/collector, burning particulates and incomplete combustion products are also returned to the workplace. This session describes incidents where this has occurred, and offers guidance for dealing with this hazard. Explosion Prevention & Protection - Guy Colonna, Division Manager, Industrial & Chemical Engineering, NFPA - Friday, June 10, pre-conference seminar Industrial processes that handle flammable liquids, gasses, and combustible particulate solids are subject to combustion events that can lead to explosions. This one-day seminar looks at NFPA 68, Explosion Protection by Deflagration Venting, and NFPA 69, Explosion Prevention Systems, which provide methods to control and mitigate the explosions. Dust Explosion Hazards - Guy Colonna, Division Manager, Industrial & Chemical Engineering, NFPA - Saturday, June 11, pre-conference seminar This one-day seminar defines crucial terms used in explosion hazard management, outlines the process of a dust deflagration, and provides real-world examples of hazardous areas with key indicators for recognizing an explosion hazard when one is encountered. The seminar reviews the 2006 edition of NFPA 654, Prevention of Fire and Dust Explosions from the Manufacturing, Processing, and Handling of Combustible Particulate Solids, and shows how the provisions of this standard are used to manage the dust explosion hazard to a level that is deemed acceptable by the currently adopted building codes.

For NFPA 484, the work of the Combustible Metals Committee centered on establishing a consistent structure and organization of the document for each of the combustible metals covered, ranging from aluminum to magnesium to zirconium. As part of the development of the previous revision, a number of individual combustible metals documents were combined into a single combustible metals standard.

The committee has now created a template for each chapter so that subsections are consistently numbered for each topic within a chapter. For example, explosion protection will always be subsection X.9 for each of the specific metal chapters. This is the kind of feature that will make it easier for users of the standard to find requirements for the various metals covered by the document. 

Revisions developed by the Committee on Wood and Cellulosic Materials Processing for the next edition of NFPA 664 include some of the same topics covered by NFPA 484. A new definition for “deflagration hazard” was included to complement revisions in Chapter 4 of the standard that pertain to the determination of the allowable dust layer thickness for combustible wood dust accumulations. These changes reflect the need for each of the dust standards to establish the conditions required for a dust fire or explosion hazard to exist. The committee revised requirements applicable to dust collectors and the protection against deflagrations using methods of deflagration venting according to NFPA 68, Explosion Protection by Deflagration Venting, or suppression according to NFPA 69, Explosion Prevention Systems. Like NFPA 484, NFPA 664 includes provisions for protective clothing targeting personnel in the immediate area where combustible dusts are generated or handled.

The other three NFPA standards are in revision cycles that follow the Annual 2011 cycle. NFPA 655, Prevention of Sulfur Fires and Explosions, has completed its Report on Proposals (ROP) and Report on Comments (ROC) stages and will be scheduled for issuance at the end of this year, pending any issues that could be raised through the Notice of Intent to Make a Motion (NITMAM) process. The revisions to NFPA 655 include changes to better define the conditions required for a dust fire or explosion hazard to exist. Other changes include the addition of requirements for process hazard analysis and management of change, plus revised housekeeping practices. NFPA 61, Prevention of Fires and Dust Explosions in Agricultural and Food Processing Facilities, and NFPA 654, Fire and Dust Explosions from the Manufacturing, Processing, and Handling of Combustible Particulate Solids, have both completed the first stage of their revisions for the Annual 2012 cycle, the ROP. The ROP for each standard will be available on the document information pages by June 24, 2011.

CSB, OSHA, + NFPA
Three incidents involving fires and explosions in three separate industries in 2003 signaled the beginning of what has become a concerted focus by the industrial community to better recognize, evaluate, and control the fire and explosion hazards presented by combustible dusts. That focus exists in the various affected industry sectors, but also within the federal and state governments, regulatory agencies, and standards-development organizations.

Data from the CSB’s Combustible Dust Hazard Study, published in November 2006, documented combustible dust incidents from 1980 to 2005. The report notes that 281 incidents occurred during that period and contributed to the loss of 119 lives through the resulting fires and explosions. CSB pointed to a lack of awareness of the specific hazards posed by combustible dust generation and release, a lack of specific dust explosibility property information included on Material Safety Data Sheets (MSDSs), and deficiencies in the various engineering controls.  The report noted existing NFPA consensus standards applicable to various types of dust and suggested that compliance with the NFPA standards could have mitgated or even prevented the incidents. CSB also recommended that OSHA establish a National Emphasis Program (NEP) for combustible dusts and develop comprehensive federal regulations that incorporate the requirements of the NFPA standards for combustible dust hazard processes.

OSHA responded to the CSB report by announcing two events. First, in October 2007, OSHA published the NEP establishing a heightened inspection focus by the agency for facilities that generate or handle combustible dusts. In April 2009, OSHA announced its intention to develop a comprehensive federal standard on combustible dust. The combustible dust NEP will provide input for the agency as it develops its proposed rules for combustible dusts.

The combustible dust NEP was amended to expand the inspection coverage following the explosion and fire at the Imperial Sugar Refinery in Port Wentworth, Georgia, in February 2008, which killed 14 workers and injured dozens. Under that revised NEP, OSHA targeted 64 types of industries and reported in October 2010 that nearly 2000 inspections had been completed in those industries. During those inspections, more than 9,000 violations were discovered. The primary industries inspected by OSHA between October 2007 and July 2010 were wood products, food products, chemical industries, metal products, and rubber and plastic products. These industries match industries and dust types for which NFPA has specific standards, and the attention these documents have received has influenced some of the work of the various technical committees as they consider the next revisions to these standards.

One topic consistently finding its way on the agenda of all of those committees relates to determining where dust fire and explosion hazards exist. As noted by the CSB and confirmed by the OSHA combustible dust NEP, awareness that a dust hazard exists remains a key factor in moving forward with protecting workplaces and workers from the potential fire and explosion hazards that exist due to the generation and handling of combustible dusts of all types. The Combustible Metals Technical Committee has added a new Chapter 5 to address the determination of dust explosion hazard areas and dust flash-fire hazard areas. One means of determining whether the dust hazard condition exists is to perform a process hazard analysis; as part of the changes associated with this revision, a process hazard analysis will now be required for all the metal chapters. The CSB noted that some of the incidents resulted when changes were made in some aspect of the process, be it equipment, materials, or processing sequence. NFPA 484 now requires that management of change (MOC) procedures be followed for all combustible metals.

Another important aspect of the OSHA NEP inspections is to understand how compliance inspectors use the NFPA standards. Where no specific OSHA regulation exists, the agency is permitted to use its General Duty Clause [Section 5 (a)(1) of the OSHA Act] to identify the potential for serious hazards, such as fire and explosion, for which there are feasible means of abatement. NFPA’s dust standards represent potential means for abating combustible dust hazard conditions in the relevant industry sectors.

In addition, OSHA has relied on NFPA 499, Classification of Combustible Dusts and of Hazardous (Classified) Locations for Electrical Installations in Chemical Process Areas, to identify safe practices for electrical equipment used in hazardous (classified) locations, specifically in Class II locations, as well as NFPA 68 and NFPA 69 for explosion protection and prevention measures.

A summary of OSHA’s General Duty Clause violations reinforces the findings of the CSB and line up with the core requirements found in the various NFPA standards. Some of the violations from the OSHA NEP inspections include hazardous levels of dust accumulations in workplaces due to poor housekeeping practices; electrical equipment and powered industrial trucks not approved for locations handling combustible dusts; dust collectors located inside buildings without proper explosion protection systems, such as explosion venting or explosion suppression systems; the lack of deflagration isolation systems to prevent deflagration propagation from dust handling equipment to other parts of the plant; and air from dust collectors recycled through ductwork back into the work area without the protection of a listed spark detection system, high-speed abort gate, and/or functioning extinguishing system.

Starting in October 2009 with the publication of Advanced Notice of Proposed Rulemaking, OSHA continues its efforts to develop a proposed rule on combustible dusts. Based on the published Regulatory Agenda for this year, the agency is expected to issue a Notice of Proposed Rulemaking sometime during the second half of the year.

Going Forward: A Single Document?
Through the findings of the CSB and the inspections of the OSHA combustible dust NEP, the basic actions required by the five NFPA combustible dust standards have become even more apparent. Each standard establishes a protection program that incorporates three core elements: prevent the generation or release of the combustible dust (the fuel); control the ignition sources; and, in the event that a fire or explosion occurs, limit the consequences by containing the fire or explosion through construction or isolation and deflagration venting. This strategy, described differently in the various standards, requires awareness of the factors that characterize or define the hazardous dust condition. Once the hazard analysis has been performed, the severity of the hazard potential can be realized. In addition to the isolation measures, an effective housekeeping program can be implemented along with protective equipment and clothing to safeguard the personnel and the facility.

Additional change may be in store for NFPA’s combustible dust standards beyond the current cycle of revisions. NFPA is exploring the possibility of consolidating or combining aspects of the dust projects into a single document that would address the fundamentals for all the dust hazard process sectors and dust types. Working through the Standards Council, a task group of the committees was formed and asked to develop a plan for coordinating the requirements between the documents. At the March 2011 Standards Council meeting, the Council voted to establish a Technical Correlating Committee (TCC) on Combustible Dusts and a Technical Committee (TC) on Fundamentals of Combustible Dusts. NFPA is currently soliciting applications for membership from those interested in participating on the TCC and TC.

The Council has also voted to have the newly formed TC on Fundamentals of Combustible Dusts develop a document that will provide the generally applicable requirements for managing the fire and explosion hazards of combustible dusts and combustible particulate solids. Besides defining the fundamental requirements for all dust types, this document will direct users to the appropriate industry or commodity-specific standard.

A variety of education sessions and pre-conference seminars at the upcoming Conference & Expo will address a range of topics on combustible dust hazard safety. For more information, visit nfpa.org/conference.