Hazards & risk assessment

Hazard

Substance, object or situation that can give rise to injury or damage

Risk

Combination of the size of hazard and the probability of its occurrence i.e. the likelihood that an accident or damage of a particular type and severity that will occur

Flammability

Flash-point - measure of ease of ignition of liquid
Autoignition temperature (spontaneous ignition, without external source)
Flammability limits - lowest/ highest concentrations in air at which flame will propagate through a mixture
Energy release in combustion

Toxicity

Distinguish between acute & chronic

Common hazards

Explosion
CVCE
UCVCE
BLEVE
Dust explosion

Sources of ignition

Electrical equipment
Static electricity
Process flames

Temperature deviation - mitigations

High temp alarms/ interlocks to shut down reactor feeds/ heating systems
Emergency cooling systems for reactors where heat is still generated after shut-down
Structural design of equipment
Selection of intrinsically safe heating systems for hazardous materials

Excessively noisy equipment

Compressors, fans, burners, steam relief valves

HAZOP Level 1

Aims to ensure that the understanding of the project, process and materials involved is sufficient to enable safety, health and environmental issues to be properly addressed. It is carried out early in the project when the scope is reasonably well understood.

HAZOP Level 2

Helps to identify significant hazards which the detailed design then has to eliminate/ otherwise address. Output is identifying features which must be built into next stage of design

HAZOP Level 3

Thorough line-by-line study which seeks to determine issues missed or forgotten during design process