Safety triangle

Accident investigation indicates that there are often many individual causes to an accident, and that a series of incidents occur simultaneously to cause the accident. The following figure is called the safety triangle", and shows the approximate ratios of occurrence of accidents with different severities. This is based on industrial statistics. 

The safety triangle shows that there are many orders of magnitude more unsafe acts than LTIs and fatalities. A combination of unsafe acts often results in a fatality. Addressing safety in industry should begin with the base of the triangle trying to eliminate the unsafe acts. This is simple to do, in theory, since most of the unsafe acts arise from carelessness or failure to follow procedures. In practice, reducing the number of unsafe acts requires personal commitment and safety awareness. 

Procedures are written to ensure that activities are performed in a systematic way. Accident investigation shows that the majority of accidents occur because procedures are not followed, and this contributes mostly to the base of the safety triangle introduced at the end of Section 4.1. 

The statistical pattern seen in the BUS data and in many individual companies calls into question one of the core assumptions of modern safety science. For the past 80 years the safety community has assumed that the Heinrich Safety Triangle (HST), first introduced in 1931, is an accurate depiction of the relationship among types of injuries, and how to prevent SIFs. 

Most people involved with workplace safety are aware of the iceberg theory, the safety triangle, or its correct terminology, the accident ratio. For every recorded injury or loss sitting above the surface, there are many unrecorded near miss incidents submerged below the surface. This was first proposed by H. W. Heinrich in 1931 when he published his 1 29 300 ratios. 

Figure 1.7. Safety triangle shows relationship between unsafe work situations and injuries.

The implication of the safety triangle is that many unsafe acts and conditions occur before an injury results. The frequency of these events reflects the probability at each level of the triangle. The probability of getting injured is often simply too small to sustain a consistent level of safe work practices. Each time employees shortcut a safety procedure and do not get hurt, they lose a bit of the fear that typically motivates safety. 

National Electrical Code, No. 70, National Fire Protection Association, Boston, Mass., 1993 Electrical Installations in Chemical Plants, No. 497A, 1992. Electrical Safety Practices, Monograph Nos. 110—113, Instmment Society of America, Research Triangle Park, N.C., 1965—1972 Electrical Safety Abstracts, 4th ed., 1972. 

ISA S12.16.01 (lEC 79-7 MOD), Electrical Apparatus for Use in Class I, Zones 1 and 2 Elazardous (Classified) Locations Type of Protection—Increased Safety e . Instrument Society of America, Research Triangle Park, N.C. 

Instrument Society of America (ISA) (1996). ISA-S84.01. Application of Safety Instrumented Systems for the Process Industries. Research Triangle Park, NC Instrument Society of America. 

The problem must be simplified considerably to permit solution in the context of this book. Suppose an equilateral triangle is subjected to some loads in the vertical direction as in Figure 7-22. A load P of 100 lb (445 N) is applied to the top joint, and that load can go in either the downward or upward direction (in the diagram, not in space ). This truss must take its reversible load with, say, a factor of safety of two against whatever event would cause it to fail. What material, size, and weight of truss element would you select to satisfy the design requirements that include building the structure for the lowest cost ... 

FIG. 23-2 The fire triangle showing the requirement for combustion of gases and vapors. [D. A. Crowl, Understanding Explosions, Center for Chemical Process Safety (CCPS) of the American Institute of Chemical Engineers (AIChE) copyright 2003 AIChE and reproduced with permission. ]... 

The agreement between the Committee on Safety of Medicines and the ABPI on the use of the black triangle is that ... 

Chemical Industry Institute of Tjxicology CUT Chemical Safety Studies Dinitrotoluene Final Report, docket No. 12362. Research Triangle Park, NC, CIIT, 1979... 

For analytical properties to be consistent with the quality expected from an analytical process and the results derived from it, they should be considered in a hierarchical way [4,50]. Thus, there are three primary types of analytical properties, namely (a) capital properties (accuracy and representativeness), which are directly related to quality of the results (b) basic properties (sensitivity, selectivity and precision), which support accuracy and are related to the analytical process and (c) accessory properties (expeditiousness, cost-effectiveness and personnel safety/comfort), which are also related to the properties are related to one another in an additive or contradictory way. The best way of envisaging the ensuing relationships is by means of two analytical tetrahedra sharing a common apex (see Fig. 1.16.A). The apices of the tetrahedron on the left hold the basic analytical properties that define the accuracy triangle, whereas those of the tetrahedron on the right accommodate the accessory analytical properties, which delimit the analytical... 

NTP. 1995. Long term technical reports and short term toxicity study reports. National Toxicology Program. National Institute of Occupations Safety and Health, Research Triangle Park, NC. 

Dr Terri Damstra, International Programme on Chemical Safety, World Health Organization, Research Triangle Park, North Carolina, USA... 

Application of Safety Instrumented Systems for the Process Industries, ISA-S84.01, Instrument Society of America, ISBN 1-55617-590-6, Research Triangle Park, NC, 1996. The objective of this document is to define the requirements for Safety Instrumented Systems (SIS) for the process industries. The SIS addressed here includes electrical, electronic, and programmable electronic technology. 

Newly licensed POMs would not be considered for reclassification until the safety profile had been established. Drugs under intensive safety surveillance are indicated by a black triangle in the British National Formulary, which generally continues for approximately two years, dependent on whether any issues related to safety are discovered. 

Comparison of the Safety Margin and the Triangle Method for Linear Isotherms 815... 

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