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Engineering Safety in Design. Bo Hu John Nieber. Safety. Damage from an unsafe process or product A defective automobile brake system: Collision: driver, passengers, other drivers, pedestrains, vehicles, buildings, other facilities Customer and employee lawsuits, criminal penalties
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Engineering Safety in Design Bo Hu John Nieber
Safety • Damage from an unsafe process or product • A defective automobile brake system: • Collision: driver, passengers, other drivers, pedestrains, vehicles, buildings, other facilities • Customer and employee lawsuits, criminal penalties • Unethical
Safety hazards • Life cycle of the products • Manufacturing • Use • Retirement • Hazard: sources of danger • Fire and explosions • Toxic release and dispersion models • Entrapment • Contact (hot surface) • Impact (machine part collide with body part) • Ejection (dangerous debris particles) • Entanglement (hair or loose clothing) • Noise and vibration • Heat or cold • Radiation, inhaled fibers • Bacteria, fungi, molds, insects, bites etc
Legal Responsibility • Product liability • Civil action • Criminal action • Occupational liability • Occupational Health and Safety Act of 1970
Prevention through Design • “Addressing occupational safety and health needs in the design process to prevent or minimize the work-related hazards and risks associated with the construction, manufacture, use, maintenance, and disposal of facilities, materials, and equipment.” (NIOSH)
Benefits of Safety by Design • Reduced site hazards fewer injuries and fatalities • Reduced workers compensation premiums • Increased productivity • Fewer delays due to accidents during construction allow continued focus on quality • Encourages designer-constructor collaboration
Approaches • Techniques to prevent fires and explosions • Inerting • Well ventilated • Relief devices • Material safety and data sheet (MSDS) • http://hazard.com/msds • http://www.ilpi.com/msds • Hazards identification and risk assessment
Hazard Analysis • Causal analysis • involves identifying various cause-effect sequences of hazardous events that may combine to cause the identified hazards. • Consequence analysis • identifies the sequences of events that could lead from a hazard to an accident or incident. • A safety case • relates to the assurance that the system is relatively safe.
Guidelines for Engineering Design for Process Safety • Inherently Safer Plants • Plant Design • Equipment Design • Materials Selection • Piping Systems • Heat Transfer Fluid Systems • Thermal Insulation • Process Monitoring and Control • Documentation • Sources of Ignition • Electrical System Hazards • Deflagration and Detonation Flame Arresters • Pressure Relief Systems • Effluent Disposal Systems • Fire Protection • Explosion Protection
Homework V • Identifying the possible hazards in your process • Check the safety lists provided at Page 44, Guidelines for Engineering Design for Process Safety; and discuss the possibilities to make your projected process inherent safe process • Topic Discussion: It is a commonly acknowledged that safety should be placed in the top priority in the engineering design; However, many barriers are slowing this effort in the field, for example 1. Fear of undeserved liability for worker safety; 2. Increase both direct and overhead costs for designers industries; 3. Few design professionals possess sufficient expertise in construction safety. Please play a role and provide suggestions on how we as a society to address this problem?
Safety Hierarchy • Eliminate the hazard • Protect against the hazard • Warn against the hazard • Provide training • Provide personal protection
Safety Design Principles • Safe-life design principle • Fail-safe design principle • Redundant design principle
Barrier: Designers' Fear of Liability • Barrier: Fear of undeserved liability for worker safety. • Criminal actions: Fail to • Perform appropriate analysis • Comply with published standards • Make use of state-of-the-art technology, owing to ignorance • Include reasonable safety features or devices • Take into account how the user might misuses the product • Consider hidden dangers that might surprise the user • Consider variations in materials, manufacturing processes, or effects of wear • Carry out appropriate testing, or interpret results correctly • Provide adequate warnings.
Barrier: Increased Designer Costs • Barrier: Safety before design processes will increase both direct and overhead costs for designers.
Barrier: Designers' Lack of Safety Expertise • Barrier: Few design professionals possess sufficient expertise in construction safety.