Following the August 2012 fire and chemical release at a San Fransico Bay Area refinery, the Governor of CA formed the Interagency Working Group on Refinery Safety to examine ways to improve public and worker safety through enhanced oversight of refineries, and to strengthen emergency preparedness in anticipation of any future incident. The Interagency Working Group found gaps in the regulatory schemes, noting that the regulations did not cover all aspects of process safety. The report recommended that existing CalARP regulations be strengthened to ensure that more data and information are provided to agencies, workers, and the public. The final CalARP Program 4 regulations were adopted and became effective on October 1, 2017. In addition to the expanded prevention program requirements, the refineries are required to perform a Hierarchy of Hazard Control Analysis (HCA) of a process or of recommendations from a PHA, in which the team applies INHERENT SAFETY MEASURES AND SAFEGUARDS in a structured sequence and priority order in order to identify the safest feasible alternative for a specific purpose. This is a nice explanation of what is necessary to perform a Hierarchy of Hazard Control Analysis (HCA).
Inherent safety is defined as:
“an approach to safety that focuses on eliminating or reducing the hazards associated with a set of conditions. A process is inherently safer if it reduces or eliminates the hazards associated with materials or operations used in the process, and this reduction or elimination is permanent and inseparable from the material or operation. A process with reduced hazards is described as inherently safer compared to a process with only passive, active, and procedural safeguards. The process of identifying and implementing inherent safety in a specific context is known as inherently safer design.”
“Safety Instrumented Systems” is a type of active safeguard. “Safety Instrumented Systems” mean
systems designed to achieve or maintain safe operation of a process in response to an unsafe process condition.
Industrial safety concepts that underlie this section include the distinction between hazard and risk. HAZARD is an INTRINSIC PROPERTY of a chemical or process, such as toxicity or flammability, whereas risk is a concept that incorporates both hazard and other issues such as exposure and probability. Although risk reduction is desirable, hazard reduction is much more desirable because low-frequency/high-consequence incidents can result in significant harm to workers and communities.
In facilities such as refineries, it is not feasible to eliminate all hazards, so a combination of hazard and risk reduction is necessary to protect health and safety. The HCA is a well-established structured approach to industrial safety that has been used in numerous industrial sectors, mostly for the purpose of worker protection, but also in the area of general safety and incident prevention. The HCA framework incorporates BOTH hazard reduction and risk reduction in FIVE (5) prioritized tiers:
- “First Order Inherent Safety measure” is a measure that eliminates a hazard. Changes in the chemistry of a process that eliminate the hazard(s) of the chemicals used or produced are usually considered First Order Inherent Safety measures; for example, by substituting a flammable chemical with an alternative chemical that can serve the same function but with lower vapor pressure and narrower flammable range.
- “Second Order Inherent Safety measure” is a measure that reduces the severity of a hazard or the likelihood of a release without the use of add-on safety devices. Changes in process variables to minimize, moderate and simplify a process are usually considered Second Order Inherent Safety measures; for example, redesigning a high-pressure, high-volume, and high-temperature system to operate at lower temperatures, volumes, and pressures.
- “Passive Safeguards” means minimizing the hazard through process and equipment design features that reduce either the frequency or consequence of the hazard without the active functioning of any device; for example, by providing a diked wall around a storage tank of flammable liquids.
- “Active Safeguards” means using controls, alarms, safety instrumented systems, and mitigation systems to detect and respond to deviations from normal process operations; for example, by using a pump that is shut off by a high-level switch in the downstream tank when the tank is 90% full.
- “Procedural Safeguards” means using policies, operating procedures, training, emergency response and other administrative approaches to prevent incidents or to minimize the effects of an incident. Examples include hot work procedures and permits and emergency response procedures implemented by employees.
For each process hazard that the HCA team identifies, the team is required to develop written recommendations in the above sequence and priority order. To the greatest extent feasible, the team must recommend first order inherent safety measures to eliminate the hazard. If the hazard cannot be eliminated, the team must develop recommendations to reduce the hazard to the greatest extent feasible using second-order inherent safety measures. Only if both of these are infeasible does the team need to continue their analysis to recommend safeguards that can reduce risk. For example, to address pipe corrosion caused by high-temperature sulfidation, the following are possible corrective actions:
(1) eliminate the sulfur that exists in the hydrocarbons as early in the refinery process as possible to eliminate the corrosive effects on the pipe downstream of the sulfur elimination—a first-order inherent safety measure;
(2) change the process conditions to reduce the corrosive effects so they are less intense or less likely to occur—a second-order inherent safety measure;
(3) upgrade the piping material for sections of pipe — a passive safeguard;
(4) install instrumentation that monitors the thickness of the pipe—an active safeguard;
(5) routine inspections of the thickness of the pipe — a procedural action; or
(6) take various combinations of these actions.