Explosion Vented Equipment System Protection Guide. Robert C. Comer

Data

      Names: Comer, Robert Charles, 1934– author.

      Title: Explosion vented equipment system protection guide / Robert Charles Comer.

      Description: First edition. | Hoboken, NJ, USA : John Wiley & Sons, 2020. | Includes index.

      Identifiers: LCCN 2020022867 (print) | LCCN 2020022868 (ebook) | ISBN 9781119640035 | ISBN 9781119640066 (adobe pdf) | ISBN 9781119640073 (epub)

      Subjects: LCSH: Dust control–Equipment and supplies. | Fire prevention–Equipment and supplies.

      Classification: LCC TD884.5 .C655 2020 (print) | LCC TD884.5 (ebook) | DDC 628.9/22–dc23

      LC record available at https://lccn.loc.gov/2020022867 LC ebook record available at https://lccn.loc.gov/2020022868

      Cover design : Wiley

      Cover Images: (background) © Jose A. Bernat Bacete/Getty Images (graph) Courtesy of Robert Comer

       This book is dedicated to my beautiful, extraordinary wife Jean and the beautiful, talented family that we have been blessed with. Daughter Lynn, her husband Jack, their son Adam, his wife Jessica, their son Andrew, his wife Sarah; daughter Donna, her husband George, their son Jonathan, their daughter Jacqueline; and daughter Kerry Ann, her husband John, their daughter Samantha, their sons Christopher and Stephen.

      Preface

      This book presents practical applications and guidance for engineers. It provides a reference to meet the needs of a company licensed or competent unlicensed engineer, that by education or experience understands the concepts presented in this book. It provides guidance to analyze and design or retrofit dust collection equipment to resist dust explosions, to protect employees and reduce production down time. The intent of the book is not to encourage licensed or competent unlicensed engineers to practice outside of their field of expertise, but to provide guidance to competent engineers to enhance their knowledge and approach to the narrow area of dust handling explosion venting and system reinforcing. Dust collector systems are not very complicated in scope and design. The reinforcing of thin panels is common to all square/rectangular dust collectors as are cylindrical dust collector roofs and access doors. Bolted flange connections, hinges, and latches are common and easily analyzed. This book provides guidance for these conditions. Licensed engineers and engineering consulting firms may find this book to be an advantage in obtaining the business of mitigating hazards for the many facilities that will have their hazards exposed by the National Fire Protection Association (NFPA) mandate of providing a dust hazard analysis of all facilities by September 2020. Many facilities do not have an engineer on staff, and they will be obligated to hire an outside consultant to mitigate their hazards.

      Detailed explanations of formulas and tedious derivations are not necessary and are avoided. The data are presented in tables and graphs along with examples to illustrate the actual applications.

      For each topic, the general principles and theories are stated, followed by extensive tables and worksheets for use in calculations of stress and strain and to design reinforcing of equipment with adequate and economical reinforcing members.

The examples are based on actual proven designs developed by the author by analyzing over 200 systems to clearly illustrate application of the information provided.

      The book is arranged to provide a means of solving practical engineering problems.

      Although every effort has been made to avoid errors, it is possible some could exist. I will be grateful for any needed corrections.

      Robert C. Comer

      Rockaway, NJ

      09 June 2020

      Introduction

      Be aware: Your dust collection system, though properly vented per National Fire Protection Agency, NFPA 68 (2013) “Standards on Explosion Protection by Deflagration Venting,” may not survive the vented explosion without having permanent deformation or catastrophic failure allowing hot gasses or shrapnel to be expelled into the surrounding area causing personnel injury or death, and exceedingly long production lost time while new equipment is ordered or failed equipment is rebuilt. The new NFPA 652 “Standard on the Fundamentals of Combustible Dust,” applies to all agriculture and food production facilities. All facilities must complete a Dust Hazard Analysis (DHA) by September 2020. Required is a systematic review to identify and evaluate potential dust fire, flash fire, and explosion hazards in a process or facility where combustible/explosible material is handled or processed. There are over 130 000 plants that handle sugar, flour, starch, dried milk, egg whites, gluten, and artificial sweeteners and are dealing with combustible dusts and potential dust explosions. Milling, grinding, spray drying of liquids, and handling of grains are processes that generate combustible dust. Combustible dusts are common in the food, plastics, metals, agriculture, chemical, and wood industries. There are many documented cases of dust explosions causing injury and death to workers due to a lack of understanding of the equipment requirements. Many plants have been in operation for years without an explosion and without being cited by OSHA. This does not mean that they are in compliance, and their facility processes will not injure or cause death to employees.

The expense of retrofitting equipment is justified when, in the event of a dust explosion, there is major production down time, or employees have not been protected properly. A recent minor dust explosion in a 3D printing company caused third degree burns on an employee. The fine by OSHA was US$ 64 500. Proper equipment reinforcing design would have cost a small fraction of that fine. The US Chemical Safety Board reports 316 dust explosions over the last 30 years that caused 145 workers killed and 846 injured with extensive damage to facilities. Damage to facilities and lost production time has been extensive. The most deadly 2017 event occurred when corn dust exploded at a milling plant in Wisconsin, killing 5 and injuring 14. OSHA has levied a fine of US$ 1.8 million citing 19 violations at the mill. According to the independent 2019 (mid‐year) Combustible Dust Incident report from DustEx Research Ltd., there were 80 dust‐related fires, 19 dust related explosions, 22 injuries, and 1 fatality in the United States from January through July 2019. This could have been avoided with proper design of the equipment.

      This manual provides the design criteria and guidance to ensure safe venting of dust collection systems. Purchasers of dust collection systems as well as manufacturers of the equipment can ensure that the equipment is not only vented safely and correctly but also would not contribute to lost production time. The equipment would be able to be put back in service with only a cleaning and replacement of the dust explosion relief elements. Analysis performed by a licensed engineer consultant would cost US$ 8000.00 or more for each system. This book will allow a licensed or competent unlicensed engineer, that by education or experience, understands the concepts presented in this book. It provides guidance to analyze, design, and supervise the installation or retrofit reinforcing of dust handling equipment. This manual also provides analysis and design of the explosion relief ductwork required to vent the hot gasses outside to a safe location.

      Note: An alternative to the explosion relief ductwork is the use of a device called a flameless vent that is installed over the standard explosion vent to extinguish the flame front as it exits the vented area. This allows the venting to be inside without a duct to the outside when access to the outside is remote or venting to a safe location is not possible. Flameless devices are not recommended for toxic dusts because dust can be released into the room. Consult the manufacturer for safe application of this device.

      It is essential that no catastrophic failure of the equipment occurs that could injure