Guidelines for Safe Handling of Powders and Bulk Solids

Powders and bulk solids, handled widely in the chemical, pharmaceutical, agriculture, smelting, and other industries present unique fire, explosion, and toxicity hazards. Indeed, substances which are practically inert in consolidated form may become quite hazardous when converted to powders and granules. The U.S. Chemical Safety and Hazard Investigation Board is currently investigating dust explosions that occured in 2003 at WestPharma, CTA Acoustics, and Hayes-Lemmerz, and is likely to recommend that companies that handle powders or whose operations produce dust pay more attention to understanding the hazards that may exist at their facility. This new CCPS guidelines book will discuss the types of hazards that can occur in a wide range of process equipment and with a wide range of substances, and will present measures to address these hazards.

Table of Contents:
Acknowledgments. 1. Introduction and Overview. 1.1 Purpose of Book. 1.2 Particulate Hazards. 1.2.1 Combustibility Hazards. 1.2.2 Instability Hazards. 1.2.3 Reactivity Hazards. 1.2.4 Toxicity Hazards. 1.3 Accident Data and Case Histories. 1.3.1 Dust Explosion Data and Case Histories. 1.3.2 Other Particulate Incident Databases. 1.3.3 Sample Case Histories for Particulate Instability, and Reactivity Incidents. 1.4 Particulate Handling and Storage Equipment Hazard Overview. 1.5 Historical and Regulatory Perspective. References. 2. Particulate Characteristics and Properties. 2.1 How Particulate Characteristics and Properties Affect Hazards. 2.2 Particulate Physical Characteristics. 2.2.1 Size Measurement Methods. 2.2.2 Particle Size Distribution. 2.2.3 Filter Characteristics. 2.2.4 Flake Characteristics. 2.2.5 Abrasiveness. 2.2.6 Hardness and Friability. 2.2.7 Agglomeration. 2.2.8 Particle Size Changes due to Friability and Agglomeration. 2.2.9 Bulk Density Measurements and Characterizations. 2.2.10 Dust Cloud Concentration Measurements. 2.2.11 Bulk Powder Moisture Measurements. 2.2.12 Fluidity and Dispersibility. 2.2.13 Electrical Resistivity. 2.3 Overview of Particulate Chemical Characteristics. 2.3.1 Flammability and Explosibility. 2.3.2 Thermal Degradation and Instability. 2.3.3 Chemical Reactivity: Incompatible Chemical Groups. 2.3.4 Corrosivity. 2.4 Overview of Particulate Toxicity. 2.4.1 Particulate Properties Pertinent to Respiratory Hazards. 2.4.2 Allergenic and Irritant Materials. 2.4.3 Systemic and Single Exposure Toxicity. 2.4.4 Carcinogenic Classifications. References. 3. Particulate Hazard Scenarios and Examples. 3.1 Thermal and Shock Instability Scenarios. 3.1.1 Exothermic Decomposition Explosions. 3.1.2 Shock/Friction Sensitive Instability Scenarios. 3.1.3 Self-Heating Hazard Scenarios. 3.2 Decision Trees for Assessing Thermal Instability Hazard Scenarios. 3.3 Chemical Incompatibility Hazard Scenarios. 3.3.1 Contamination Hazard Scenarios. 3.3.2 Water Entry Scenarios. 3.3.3 Container/Packaging Incompatibility Scenarios. 3.3.4 Air Access to Pyrophoric Particulates. 3.4 Chemical Compatibility Charts for Assessing Hazards. 3.5 Particulate Fire Scenarios. 3.5.1 Smoldering Fires in Storage Piles and Dust Collectors. 3.5.2 Dust Layer Fires. 3.5.3 Waterhouse Storage Fires. 3.5.4 Particulate Flash Fires. 3.6 Decision Trees for Assessing Particulate Fire Scenarios. 3.7 Dust Explosion Scenarios. 3.7.1 Primary Dust Explosions in Process Equipment. 3.7.2 Hybrid Explosion Scenarios. 3.7.3 Explosion Propagation to Connected Equipment. 3.7.4 Secondary Dust Explosions in Building. 3.8 Dust Explosion Decision Trees and Protection Flow Charts. 3.9 Toxic Material Exposure Scenarios. 3.9.1 Chronic Exposure Scenarios during Processing and Material Handling. 3.9.2 Acute Exposure Accident Scenarios. 3.9.3 Fire and Explosion Exposure Scenarios. 3.9.4 Incident Cleanup Exposure Scenarios. References. 4. Assessing Particulate Hazards. 4.1 Preliminary Assessment via Material Safety Data Sheets, Handbooks, Guidelines, Codes, and Standards. 4.1.1 Preliminary Assessment of Instability Hazards. 4.1.2 Preliminary Assessments of Reactivity Hazards. 4.1.3 Preliminary Assessments of Combustibility and Explosibility Hazards. 4.1.4 Preliminary Assessments of Toxicity. 4.1.5 Special Considerations and Cautions in Using MSDS and Generic Databases. 4.1.6 Publicly Available Computer Databases. 4.1.7 Company and Consortium Databases. 4.2 When Are More Detailed Particulate Hazard Data Needed? 4.3 Laboratory Test Methods for Detailed Assessments of Particulate Hazards. 4.3.1 Particulate Sampling and Conditioning for Testing. 4.3.2 Laboratory Testing for Instability Hazards. 4.3.3 Laboratory Test Methods for Chemical Incompatibility Hazards. 4.3.4 Self-Heating, Spontaneous Combustion, and Pyrophoric Solids Test Methods. 4.3.5 Dust Layer Combustibility Test Methods. 4.3.6 Electrostatic Charging and Discharge Testing for Particulates. 4.3.7 Dust Cloud Explosibility Test Methods. 4.3.8 Fire Exposure Tests. 4.3.9 Particulate Toxicity Testing. 4.3.10 UN Testing Scheme for Classification of Materials as Explosions. 4.4 Scaling Considerations in Applying Laboratory Test Data. 4.5 Larger-Scale Testing and Theoretical Modeling. References. 5. Equipment Hazards and Preventive/Protective Measures. 5.1 Introduction. 5.2 Safety Aspects of Batch versus Continuous Operation. 5.3 Particulate Solids Processing Equipment Hazards and Preventive and Protective Measures. 5.3.1 Bag Openers (Slitters). 5.3.2 Blenders/Mixers. 5.3.3 Drying Equipment. 5.3.4 Dust Collectors. 5.3.5 Extruders. 5.3.6 Feeders and Rotary Valves. 5.3.7 Hoses, Loading Spouts, and Flexible Boots and Socks. 5.3.8 Mechanical Conveyors and Bucket Elevators. 5.3.9 Pneumatic Conveyors. 5.3.10 Portable Containers. 5.3.11 Portable Container Emptying (Unloading) Equipment. 5.3.12 Portable Container Filling Systems. 5.3.13 Samplers and Sampling Systems. 5.3.14 Screens and Classifiers. 5.3.15 Silos and Hoppers. 5.3.16 Size Enlargement Equipment. 5.3.17 Size Reduction Equipment. 5.3.18 Solids Charging Systems. 5.3.19 Tableting Systems. 5.3.20 Values for Solids. 5.3.21 Weighing Systems. 5.4 Loading and Unloading of Railcars and Hopper Trucks. 5.4.1 Types of Railcars and Hopper Trucks. 5.4.2 Railcar and Hopper Truck Loading. 5.4.3 Railcar and Hopper Truck Unloading. 5.5 Instrumentation. 5.5.1 Flow Instruments. 5.5.2 Level Instruments. 5.5.3 Pressure Instruments. 5.5.4 Temperature Instruments. References. 6. Designing and Installing Systems to Prevent and Control Combustion, Explosions, Uncontrolled Reactions, and Release of Toxic Particulate Solids. 6.1 Introduction. 6.2 Causes of Fire and Deflagration. 6.2.1 The Fire Triangle. 6.2.2 Types of Ignition Sources. 6.3 Ignition Sources: Description, Control, and Removal. 6.3.1 Electrostatic Hazards and Their Control. 6.3.2 Spontaneous Combustion: Evaluation and Control. 6.3.3 Pyrophoric and Water-Reaction Solids. 6.3.4 Flames and Hot Gases. 6.3.5 Hot Work. 6.3.6 Hot Surfaces. 6.3.7 Hot Particles. 6.3.8 Friction and Impact. 6.3.9 Chemical Reactions. 6.3.10 Physical Sources. 6.3.11 Electrical Equipment. 6.3.12 Lightning. 6.3.13 Projectiles. 6.4 Electrical Equipment Hazards and Area Classifications. 6.4.1 Electrical Equipment Hazards. 6.4.2 Electrical Area Classification. 6.5 Deflagration Prevention Methods. 6.5.1 Prevention Minimization of Dust Clouds Formation. 6.5.2 Oxidant Concentration Reduction (Inverting). 6.5.3 Combustible Concentration Reduction (Air Dilution). 6.6 Deflagration Protection Methods. 6.6.1 Deflagration Venting. 6.6.2 Deflagration Suppression. 6.6.3 Deflagration Pressure Containment. 6.6.4 Deflagration Isolation Systems. 6.6.5 Spark Detection and Extinguishing Systems. 6.6.6 Prevention of Secondary Explosions. 6.7 Sitting of Equipment and Buildings to Minimize Damage from Fires and Explosions. 6.8 Blast Resistant (Damage-Limiting) Construction of Buildings. 6.9 Protection of Equipment and Buildings by Water Sprinkler/Deluge Systems. 6.10 Protection of Equipment and Buildings by Foam and Other Special Extinguishing Systems. 6.10.1 Foams. 6.10.2 Dry Chemical Systems. 6.10.3 Carbon Dioxide Systems. 6.10.4 Halon Replacement (Clean) Agents. 6.11 Containment for Control of Releases of Toxic Particulate Solids. 6.12 Identification of System-Wide Design, Protection, and Prevention Requirements. References. 7. Plant Operation and Maintenance. 7.1 Introduction. 7.2 Regulatory Requirements. 7.3 Management of Change. 7.4 Process Hazard Analyses. 7.5 Housekeeping Practices to Prevent or Minimize Dust Emissions and Accumulation. 7.6 Mechanical Integrity of Equipment. 7.6.1 Scheduled Inspections and Testing of Equipment. 7.6.2 Upgrading and Repairs of Equipment. 7.6.3 Documentation. 7.7 Corrosion, Erosion, and Materials of Construction. 7.7.1 Introduction. 7.7.2 Types of Corrosion. 7.7.3 Corrosion Detection and Measurement. 7.7.4 Corrosion Prevention and Minimization Methods. 7.7.5 Erosion and Its Effect on Equipment. 7.7.6 Materials of Construction. 7.8 Maintenance Practices. 7.8.1 Introduction. 7.8.2 Preventive Maintenance. 7.8.3 Predictive Maintenance. 7.8.4 Good Maintenance Practices for Particulate Solids Processes and Equipment. 7.9 Incident Investigations. References. 8. Occupational Health and Environmental Considerations. 8.1 Introduction. 8.2 Occupational Health and Environmental Concerns. 8.2.1 Protecting Employees and the Community. 8.2.2 Regulatory Requirements. 8.2.3 Product Stewardship. 8.3 Routine Operations Considerations. 8.3.1 Permitting Issues. 8.3.2 Monitoring Emissions from Equipment. 8.3.3 Employee Exposure Monitoring and Risk Assessment. 8.3.4 System Design to Eliminate or Minimize Employee Exposure. 8.3.5 Health Standards. 8.3.6 Employee Precautions When Handling Toxic Particulate Solids. 8.3.7 Selection, Storage, and Maintenance of Personal Protective Equipment (PPE). 8.3.8 Normal (Routine) Venting. 8.3.9 Environmental Issues during Maintenance. 8.3.10 Housekeeping/Cleanup Health Hazards. 8.3.11 Hazards of Asphyxiation from Inerting/Safe Vessel Entry. 8.3.12 Design and Operations of Isolation Rooms. 8.3.13 Design and Operation of Cleanrooms. 8.4 Nonroutine Operations Considerations. 8.4.1 Emergency Venting. 8.4.2 Measuring the Impact of a Nonroutine Release. 8.4.3 Permitting and Reporting Issues for Emergency Vents. 8.4.4 Emergency Response for Accidents with Powder and Dusts. 8.4.5 Determining the Cause of a Protective System Activation. 8.4.6 Disabling of Protective Systems by an Explosion. Appendix A. Commercial Testing Facilities for Powder/Dust Hazard Assessments. Appendix B. Equipment Overview. Acronyms and Abbreviations. Glossary. Index.