Procedures, Deviations & Human Factors

• Safe written operating procedures should be provided by the operating organisation to its staff and contractor personnel who are involved and working not only with the process being operated, but within its associated hazardous areas.
• How do you know your procedure is safe, and if personnel deviate from it, have the risks associated with these deviations been assessed?
• Incidents may occur because an operator working on a process has unintentionally changed the way the operation is meant to be carried out, or maintenance has been involved which has resulted in a dangerous and unsafe situation being created.
• An operator can interact with a process in a variety of different ways, which may have a positive and negative aspect on the safety of the process in question. Therefore elements of human factors should always be included when defining the Basis of Safety.
• For example, an operator may observe that equipment or the process is not functioning as intended and stop it, preventing a disaster happening, change a process to work outside its operating conditions, or unintentionally turn the wrong valve, or add the wrong material to the process etc.

Equipment

• Whether the equipment is new, modified, or upgraded or equipment is changed up or downstream, the Basis of Safety should be defined/redefined through the Management of Change (MOC) process, which will include a hazard identification and risk assessment study.

Material Properties

• These need to be defined and understood as per the ATEX and DSEAR Legislation prior to conducting a valid hazard identification or risk assessment.
• Therefore to define a Basis of Safety for the process, operations, personnel interaction, and equipment in question, the materials properties in terms of Ignition Sensitivity, Explosion Severity, and the Flammable Range characteristics need to be understood.

Risk Tolerability

• No process or operation is totally “Risk Free”. Therefore, it is important to establish the tolerability or acceptability of risk involved with an operation or process under investigation.
• For example, venting via a vent panel to the external safe area where no personnel or offsite community, which may be affected by a potential vented explosion maybe a valid Basis of Safety. However, if there are no safe areas nearby then venting an explosion may not be a valid Basis of Safety and suppression or containment maybe better suited.