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) – – 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.