Design process

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.