Safety: Avenues to a safer working environment
06/01/2000
by Bruce G. Walker, Wanda R. Mattson and William R. Acorn
12 steps to creating a safer working environment in clean manufacturing facilities
Safety is paramount in all we do, particularly in the manufacturing work environment. Identifying implications of Environmental, Safety and Health (ES&H) challenges can prevent endangerment to workers and the environment. Clean manufacturing facilities present certain unique safety concerns that must be evaluated, quantified and dealt with by the ES&H professional and all associated with their design, construction and use.
A 12-step method can help identify and quantify a variety of risks in the facility and manufacturing environment, enabling you to develop a plan of action to correct the potential situations and improve your working environment.
Identify hazards
Hazards identification involves itemizing all hazards associated with the system. By itemizing, one can quickly formulate a clear picture as to the complexity of safety issues related to the system. To enhance the list of hazards, a brief description of each hazard should include the following:
- The hazardous characteristic — fire, toxicity, chemical burns, physical injury from moving parts, electrical shock, etc.
- The form and quantity of the hazard — catastrophic result (such as explosion), gradual degradation (such as inhalation of low levels of contamination), etc.
- Where and when in the system it is present — at what point in the process or manufacturing operation
- The probable likelihood of an incident — based on subjective or experiential analysis — e.g. highly likely, moderately likely, unlikely, etc.
- Under what conditions could the hazard propagate into an undesirable event (i.e., accident, during construction, at shift change, during a power failure, etc.)
STEP TWO:
Collect Data
To assess the hazards, one must understand the details of the particular area of concern, including its function, design and anticipated end-user installations and operations. For new products, one may review previous products with similar components, with similar hazards or those that perform similar tasks or processes. Safety design solutions may also be found within previous hazards analyses and an assessment of their success and applicability for the design under evaluation. Utilize the safety manuals of the equipment manufacturer as a starting point and include the equipment technician on your team, if possible.For mature systems, interview individuals currently using the system/components. Field service personnel with extensive experience can also assist in information gathering. They often develop their own set of concerns or observations about a product's shortcomings as well a description of useful features.
STEP THREE:
Identify hazardous energy sources
A primary step to identifying hazards is to pinpoint all energy sources. This activity leads to the majority of hazards associated with a system. Energy sources may include, but aren't limited to:
- Chemicals — solids, liquids and gases
- Spills and physical contact
- Inhalation of hazardous vapors
- Pressure
- Flammable and combustible materials
- Thermal
- Fire
- Explosion
- Electrical shock or short circuiting
- Radiation
- Biological
- Mechanical
- Moving parts
STEP FOUR:
Develop a hazards checklist
A hazards checklist becomes a prime starting point for identifying hazards. Every industry and most safety professionals have their own customized hazards checklists. These lists should be modified based on experience, new products and designs, and field experience with similar products or situations.The hazards checklists should become a part of your protocol for authorizing the use of a process, tool or facility. The checklists should be reviewed and approved by the various parties responsible for safety of the facility or subsystem, including facilities engineering, process engineering, operations, ERT, etc. The checklist should always be in a state of revision, as new hazards are identified by your safety team or the industry.
STEP FIVE:
Define the scope of the analysis
The scope simply defines which part of a system is being analyzed and the operating phases being considered. Defining what is being reviewed facilitates an understanding of the goals and the results of the analysis. For example, a flammable gas supply could cross the boundary of the scope of analysis since gases are typically provided from the facility gas pad. Therefore, one might define the boundary of the gas system as the point at which the gas is connected to the tool. The interfaces that cross the boundary must be examined for hazards as well. In this example, hazards that must be considered include excessively high-pressure delivery, loss of flow, leaks, materials of construction, adequate ventilation and possibly the wrong gas used or plumbed.
STEP SIX:
Assess operational phases
The presence of hazards often depends upon the operational phase of a tool. Some hazards may appear in several phases but may likewise be absent in others. When identifying and evaluating hazards, it is important to document the applicable phases. A basic list of phases would include the following:
- Installation/hook-up
- System qualification
- Hazardous material introduction
- Production
- Standby
- Planned shut down
- Facility infrastructure system failure (power, ventilation, etc.)
- Emergency stop and shut down
- Maintenance (preventative and troubleshooting)
- Decommissioning
STEP SEVEN:
Identify key ES&H controls
Understand existing safety controls and features. For new systems, few or no controls may be in place. However, for established systems that are introducing component changes or enhancements, there should be a well-documented list of hazard controls and features. Only those relevant to the system or component being evaluated need to be included. Examples of such controls and features may include:
- Ventilation and exhaust treatment systems
- Gas monitoring and alarm systems
- Spill containment provisions
- Physical clearances around hazardous features
- Fire suppression systems
- Warning signs and written instructions;
- Remote shut-off capabilities
- Emergency power off switches
- ERT equipment — extinguishers, emergency showers, respirators, first aid, etc.
STEP EIGHT:
Itemize ES&H design features
ES&H design features can directly or indirectly influence the safety of a system. Such design features are items integral to the product that reduce the consequence or likelihood of the hazard leading to an accident. Features that are factored into the overall safety of a product or tool should be explicitly described and recognized during the hazards analysis. These design features then become part of the safety basis for the product. Examples of safety features may include the following:
- Low flow rates for hazardous chemicals
- Small storage containers for chemicals
- Water lines routed below or away from electrical cables and connectors
- Separate manifolds for chemical segregation of incompatibles
- Substitution for robots using less force
- Guards around rotating equipment
- Insulation at hot or cold surfaces
STEP NINE:
Consider consequences of accident
Based on the sequence of failures and normal steps that cause a hazard to become an accident, determine the consequences of the hazard. The consequence(s) should be based on the worst credible case of the events. For example, if electrical wires are shorted, they can overheat. In such a situation, assume that a fire may occur, unless there is specific test data or other protective devices that would preclude a fire.
Because the consequence is likely to be only an estimate, it is important to quantify the material, energy or other items available to cause the consequence related to the incident. In determining the consequence, consider how the hazard is influenced by the potential sequence of events that leads to the accident to determine the quantity of the hazard released.
STEP TEN:
Determine likelihood of accident
Determining the likelihood of an accident provides a perspective on the plausibility of a hazard propagating into an accident. The likelihood of the accident is based on the likelihood or plausibility that the sequence of events and failures will propagate into an accident. The likelihood value represents the expected frequency with which the system will fail and cause a described consequence.
STEP ELEVEN:
Document the results
The safety analysis techniques are documented to provide the following output (deliverables) to the overall product safety review and evaluation team.
- Systematic and thorough analyses of potential hazards
- Assurance that credible hazards are identified
- Permanent record for hazard
isk data on compliance tracking database - Quick reference of critical systems safety and ergonomic areas
- Point of reference for third-party evaluations
STEP TWELVE:
Conduct a "What if?" analysis
The "What if?" analysis technique is an approach to hazards analysis that is directly reflected by its name. In using a What-if? analysis, use questions posed in the form of What-if? statements, such as; "What if the cooling water to the chamber stops?" "What if the power system fails?" A team continues to determine what the outcome would be. The purpose of the What-if? analysis methodology is to identify hazards, hazardous situations or specific accident events that could produce an undesirable consequence.
Employing a "12-step" or similar methodology assures that you have begun to assess your facilities to create a safer working environment. Because safety is paramount, assessing as well as addressing critical ES&H challenges demands everyone's attention. Understanding these challenges can prevent endangerment to individuals and the environment.
12th step plus one
The follow-up to the above analysis procedure is the most important step. A perfectly executed 12-step analysis is meaningless if it sits on the shelf without implementation of constructive change.
Bruce Walker is president of Technology Performance Group, Inc., of Boise, ID. He has more than 20 years experience with the total cleanroom environment and process equipment manufacturing.
Wanda Mattson is executive vice president of Technology Performance Group, Inc., of Reno, NV. She has extensive experience in the development of quality systems.
Bill Acorn is principal consultant of Acorn Consulting Services in Tucson, AZ. ACS specializes in providing assessment and advice to advanced technology manufacturers and owners of complex facilities related to facility system performance, code compliance strategies and project delivery strategies.
Fostering an ES&H mindset
The overriding goal to meeting ES&H challenges is to assess the working environment to gain knowledge and understanding of those components that will maintain a safe facility. Consider these elements:
Fume control — Control of hazardous fumes and vapors such that they are away from the operator's breath zone and out of the process envelope.
Dilution vs. capture — Dilution requires that hazardous fumes be mixed with enough air to reduce the chemical concentration to a value below the Threshold Limit Value (TLV) for that chemical. Fume capture in terms of equipment operation signifies that fumes are controlled and confined to a specific operating area, not merely diluted and allowed to progress into the operator's breath zone or into the process envelope.
Unknown contamination — Many colorless, odorless chemicals are hazardous. An unidentified puddle or an unlabeled squeeze bottle represents a definite hazard and must be treated with extreme caution.
Decontamination and detoxification — Decontamination indicates neutralization of hazardous materials. Detoxification requires the complete removal of toxins from material or equipment.
Balance and airflow — Exhausted equipment in the cleanroom exists in synergy with the laminar flow environment and the exhaust facility. The facility air management scheme must be well understood by all who are charged with safety. Supply air and exhaust must be carefully balanced to prevent fume loss from inadequate exhaust and fume spills caused by overpowering airstreams in the process area. The patterns of airflow in the space must be understood to ensure a safe working environment.
Maintenance, monitoring and record keeping — Vigilance is the price of safety. Accurate and consistent record keeping that communicates equipment maintenance and operations monitoring informs cleanroom personnel of the safe status of the everyday working environment.
If these essential elements are weighed against other potential hazards such as spills and related physical contact, electrical, mechanical and thermal mechanisms, as well as potential radiation exposure, one begins to establish a 'facility safety scorecard' that defines the working environment.
It then becomes a predictive tool to assess real and potential worker hazards.
Implementing a facility safety scorecard
- Hazards Analysis — Identifying hazards and characterizing the risks associated with potential mishaps arising out of the hazards.
- Risk Assessment — Determining the probability of a mishap and the severity of the resulting loss or harm.
- Hazard — A condition that is a prerequisite to a mishap.
- Likelihood — The expected frequency with which a mishap will occur. Usually expressed as a rate (e.g., events per year, per product, per wafer processed).
- Mishap — An unplanned event or series of events that results in death, injury, occupational illness, damage to or loss of equipment or property, or environmental damage.
- Risk — The expected losses from a mishap, expressed in terms of severity and likelihood.
- Severity — The extent of the worst credible loss from a mishap caused by a specific hazard.
- Residual Risk — The risk which remains after engineering, administrative, and work practice controls have been implemented.
Before one can properly implement a safety program, a datum point must be established. Education and communication are key elements in the program, so let us begin with understanding a few basic terms as defined in the Hazards Analysis Guide: A Reference Manual for Analyzing Safety Hazards on Semiconductor Manufacturing Equipment from International SEMATECH published in 1999.
Hazards identification involves itemizing all hazards associated with the system. By itemizing, one can quickly formulate a clear picture as to the complexity of safety issues related to the system. To enhance the list of hazards, a brief description of each hazard should include the following:
To assess the hazards, one must understand the details of the particular area of concern, including its function, design and anticipated end-user installations and operations. For new products, one may review previous products with similar components, with similar hazards or those that perform similar tasks or processes. Safety design solutions may also be found within previous hazards analyses and an assessment of their success and applicability for the design under evaluation. Utilize the safety manuals of the equipment manufacturer as a starting point and include the equipment technician on your team, if possible.For mature systems, interview individuals currently using the system/components. Field service personnel with extensive experience can also assist in information gathering. They often develop their own set of concerns or observations about a product's shortcomings as well a description of useful features.
A primary step to identifying hazards is to pinpoint all energy sources. This activity leads to the majority of hazards associated with a system. Energy sources may include, but aren't limited to:
A hazards checklist becomes a prime starting point for identifying hazards. Every industry and most safety professionals have their own customized hazards checklists. These lists should be modified based on experience, new products and designs, and field experience with similar products or situations.The hazards checklists should become a part of your protocol for authorizing the use of a process, tool or facility. The checklists should be reviewed and approved by the various parties responsible for safety of the facility or subsystem, including facilities engineering, process engineering, operations, ERT, etc. The checklist should always be in a state of revision, as new hazards are identified by your safety team or the industry.
The scope simply defines which part of a system is being analyzed and the operating phases being considered. Defining what is being reviewed facilitates an understanding of the goals and the results of the analysis. For example, a flammable gas supply could cross the boundary of the scope of analysis since gases are typically provided from the facility gas pad. Therefore, one might define the boundary of the gas system as the point at which the gas is connected to the tool. The interfaces that cross the boundary must be examined for hazards as well. In this example, hazards that must be considered include excessively high-pressure delivery, loss of flow, leaks, materials of construction, adequate ventilation and possibly the wrong gas used or plumbed.
The presence of hazards often depends upon the operational phase of a tool. Some hazards may appear in several phases but may likewise be absent in others. When identifying and evaluating hazards, it is important to document the applicable phases. A basic list of phases would include the following:
Understand existing safety controls and features. For new systems, few or no controls may be in place. However, for established systems that are introducing component changes or enhancements, there should be a well-documented list of hazard controls and features. Only those relevant to the system or component being evaluated need to be included. Examples of such controls and features may include:
ES&H design features can directly or indirectly influence the safety of a system. Such design features are items integral to the product that reduce the consequence or likelihood of the hazard leading to an accident. Features that are factored into the overall safety of a product or tool should be explicitly described and recognized during the hazards analysis. These design features then become part of the safety basis for the product. Examples of safety features may include the following:
Based on the sequence of failures and normal steps that cause a hazard to become an accident, determine the consequences of the hazard. The consequence(s) should be based on the worst credible case of the events. For example, if electrical wires are shorted, they can overheat. In such a situation, assume that a fire may occur, unless there is specific test data or other protective devices that would preclude a fire.
Determining the likelihood of an accident provides a perspective on the plausibility of a hazard propagating into an accident. The likelihood of the accident is based on the likelihood or plausibility that the sequence of events and failures will propagate into an accident. The likelihood value represents the expected frequency with which the system will fail and cause a described consequence.
The safety analysis techniques are documented to provide the following output (deliverables) to the overall product safety review and evaluation team.
isk data on compliance tracking database
The "What if?" analysis technique is an approach to hazards analysis that is directly reflected by its name. In using a What-if? analysis, use questions posed in the form of What-if? statements, such as; "What if the cooling water to the chamber stops?" "What if the power system fails?" A team continues to determine what the outcome would be. The purpose of the What-if? analysis methodology is to identify hazards, hazardous situations or specific accident events that could produce an undesirable consequence.
The follow-up to the above analysis procedure is the most important step. A perfectly executed 12-step analysis is meaningless if it sits on the shelf without implementation of constructive change.