Risk Assessment. Georgi Popov
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is considered the center piece for machine safety and risk assessments. It is one of more than 30 standards and technical reports for metal working machinery published by ANSI and B11 Standards, Inc., known as the B11 series. In the absence of machine‐specific standards, ANSI B11.0, along with ANSI B11.19‐2019, Performance Requirements for Risk Reduction Measures: Safeguarding and other Means of Reducing Risk combine to form the foundation for the B11 series of machine‐specific (Type‐C) standards, and for other industrial machinery lacking a machine‐specific safety standard. The B11 standards and technical reports are organized with the ISO A‐B‐C level structure briefly summarized below:
Type‐A standards (basis standards) provide basic concepts, principles for design, and general aspects that can be applied to machinery.
Type‐B standards (generic safety standards) address one or more safety aspects or one or more types of safeguards that can be used across a range of machinery.
Type‐C standards (machinery‐specific safety standards) address detailed safety requirements for a particular machine or group of machines.
Since it applies to an array of machines and contains general requirements, ANSI B11.0 is considered a Type‐A standard. Its applies to new, existing, modified, and rebuilt power‐driven stationary machines used to shape or form materials through cutting, impact, pressure, electrical, and other processing methods. ANSI B11.0 also states that machinery suppliers and users are responsible for defining and achieving acceptable risk and that any risks associated with the operation, maintenance, dismantling, and disposal of machinery shall be reduced to an acceptable level. The standard includes a formal method to conduct and document the risk‐assessment process, and also identifies some preparations that must be made before a risk assessment begins. The standard presents the basic risk‐assessment process in a step‐by‐step approach to assist in achieving this goal.
The ANSI B11.TR3‐2000 (R2015), Risk assessment and risk reduction – A guide to estimate, evaluate and reduce risks associated with machine tools is an ANSI Technical Report. As part of the ANSI B11 series of technical reports and standards, TR3 pertains to the design, construction, care, and use of machine tools. The report defines a method for identifying hazards associated with a particular machine or system when used as intended, and provides a procedure to estimate, evaluate, and reduce the risks of harm to individuals associated with these hazards under the various conditions of use of that machine or system. Examples of tasks and machine hazards, as well as risk‐reduction methods are included in the technical report.
In addition, ANSI has adopted ISO 12100, Safety of Machinery – General Principles for Design – Risk Assessment and Risk Reduction. This standard specifies the basic terminology, principles, and a methodology for achieving safety in the design or machinery. It specifies principles of risk assessment and risk reduction to help designers in achieving this objective. While this is an international standard, it is an ISO standard that safety professionals in the United States should be aware of even if they do not have international responsibilities or involvement.
2.11 NFPA 70E
With 2015 and 2018 editions of NFPA 70E, a major shift occurred in how stakeholders evaluate electrical risk. The National Fire Protection Association’s 2018 NFPA 70E: Standard for Electrical Safety in the Workplace, the latest edition of the voluntary consensus standard, addresses workplace electrical safety and includes guidance for performing risk assessments of arc flash, shock, and electrical hazards exposures.
The 2018 edition carries over several significant changes over previous editions. Where an arc flash, shock, or electrical “hazard analysis” was required before, now a “risk assessment” is required. Further, the standard has expanded the “risk assessment procedure” to include the requirement of hazard identification, assessment of risks, and the implementation of risk controls according to hierarchy of risk control methods specified in ANSI/ASSP Z10.0. The addition of the Informative Annex F, Risk Assessment Procedure, provides information regarding the process steps, risk estimation, risk reduction, and risk evaluation in alignment with ANSI/ASSP/ISO 31000. This shift from “hazard analysis” to “risk assessment” reflects a change in awareness about the potential for failure, moving from a hazard‐based to a risk‐based focus. In support of this shift, new definitions for hazard, hazardous, risk, and risk assessment are now included.
2.12 MIL‐STD‐882E, 11 May 2012, Department of Defense Standard Practice, System Safety
This official Department of Defense (DoD) standard, originally published in 1969, provides detailed guidance on system safety including the risk assessment process. It has been updated numerous times since and MIL‐STD 882E, 11 May 2012 is the current version at the time of this writing. The standard is approved for use by all Departments and Agencies within the DoD and it is used by many contractors and others outside the DoD.
MIL‐STD‐882 is one of the earliest US standards on risk assessment that was publicly available. General requirements of the standard include the identification and documentation of hazards, and assessment and documentation of risk. The standard defines severity categories and probability levels for application in a risk matrix. Below are all eight system safety elements of MIL‐STD‐882E.
1 Document the System Safety Approach
2 Identify and Document Hazards
3 Assess and Document Risk
4 Identify and Document Risk Mitigation Measures
5 Reduce Risk
6 Verify, Validate and Document Risk Reduction
7 Accept Risk and Document
8 Manage Life‐Cycle Risk
This standard clearly includes a significant risk assessment provision and it is one of the earliest US standards to do so as mentioned previously. It has been referred to by safety professionals for decades.
2.13 Key Terms and Definitions
Found within the aforementioned standards and others related works are a number of important terms and definitions related to the practice of hazard analysis, risk assessments, and risk management. The following are selected risk‐related terms and how they are defined in their context. Many of the definitions are taken from referenced standards, which in some cases have multiple variations. These variations have been provided to illustrate subtle differences and similarities for certain terms used in the standards.
Acceptable Risk:
The risk level that is considered as low as reasonably practicable (ALARP) by the organization and acceptable in its current context. This level of risk is generally lowered as the organization matures and the control technologies improve. (Authors)
That risk for which the probability of an incident or exposure occurring and the severity of harm or damage that may result are ALARP in the setting being considered. (ANSI/ASSP Z590.3‐2011(R2016))
A risk level achieved after risk reduction measures have been applied. It is a risk level that is accepted for a given task (hazardous situation) or hazard. For the purpose of this standard, the terms – acceptable risk and – tolerable risk are considered to be synonymous. (ANSI B11.0‐2020)
Risk that the appropriate acceptance authority (as defined in DoDI 5000.02) is willing to accept without additional mitigation. (MIL‐STD‐882E‐2012)
As Low as Reasonably Achievable (ALARA):
ALARA is an acronym for “as low as (is) reasonably achievable,” which means making every reasonable effort to maintain exposures to ionizing radiation as far below the dose limits as practical, consistent with the purpose for which the licensed activity is undertaken,