The management of electrical equipment in hazardous areas (EEHA) is a key safety concern for oil and gas operators, requiring risk mitigation strategies, protective measures, comprehensive incident response protocols, and mandatory compliance around monitoring and reporting
Desspite their rarity, fire hazards or explosions cannot be overlooked, with historical data showing that about half of the largest offshore oil and gas incidents resulted in fire explosions.
EEHA regulations pertain to work areas where an explosive atmosphere is present or may be anticipated. In such environments, electrical equipment must be appropriately rated and effectively earthed to ensure that any ignition risks are effectively managed.
Whenever flammable liquids, vapours, gases and/or combustible dusts are used, stored, handled, or generated, a hazardous area classification is needed to assess the risk of fire and explosion.
Identifying the various explosion risks is the first step in effective EEHA management. There are numerous factors to consider, especially in the oil and gas industry, particularly in offshore facilities.
Explosions can occur under certain conditions when a mixture of air and released hydrocarbon gases is present. This may result from blowouts, the use of inadequate equipment or equipment malfunctions, negligence, insufficient training, and poor or incomplete maintenance.
Best practice EEHA management in the oil and gas sector should utilise a hybrid approach that combines prescriptive and goal-oriented methods, with regularly updated prescriptive standards to keep pace with technological change, proactive risk management, and a safety culture focused on continuous improvement, ensuring adaptability.
It also requires consideration of all potential emission sources, including natural gas pneumatic device venting, natural gas-driven pneumatic pumps, acid gas removal units, dehydrators, well venting for liquid unloading, and gas well completions and workovers, with or without hydraulic fracturing.
Other sources include blowdown vent stacks, atmospheric and transmission storage tanks, well testing, flare stacks, offshore production facilities, and centrifugal and reciprocating compressors.
Sources of ignition relevant to oil and gas can include naked flames, electrical sparks, static electricity, hot surfaces, friction, ionising radiation, ultrasound, and hot gases.
Another important aspect of effective EEHA management in the oil and gas sector is arc flash hazard analysis. This analysis evaluates the risks associated with light and heat generated from electrical explosions or discharges.
Ageing explosion-protected electrical equipment in hazardous areas, both onshore and offshore, can become a potential concern for operators and maintenance supervisors, as their degradation can lead to eventual failure to meet certification requirements and possibly even catastrophic failure.
Equipment can be impacted by corrosion, water ingress, and insufficient gasket or seal protection. Additionally, degradation of plastics due to UV exposure or other environmental factors, along with the lack of proper labelling or identification to confirm the type of protection relevant to its location, can also pose significant risks.
LESSONS SORELY LEARNED
A key turning point for process safety and EEHA management in Australia was the 1998 Longford disaster. This incident involved the rupture and leak of a pressure vessel at the Esso natural gas plant in Victoria, which ignited and rapidly escalated to a deflagration that took two days to extinguish.
One of the key events leading up to the incident was the rupture of a heat exchanger, which had become embrittled due to a stoppage in the flow of the heating medium into the exchanger.
A faulty pump had tripped earlier in the day, causing the stoppage of heated lean oil into the exchanger, which then experienced temperatures as low as -48 degrees Celsius, in contrast to its normal operating range of 60 to 230 degrees Celsius.
The rupture released approximately 10 tonnes of hydrocarbons, which then flashed, creating a partial vapour after a saturated liquid stream lost pressure. This formed a cloud that drifted 170 metres downwind before igniting 60 to 90 seconds later on a set of fired heaters.
There was no explosion, but rather a deflagration, a subsonic combustion where a flame propagates through a mixture of fuel and oxidiser. This deflagration quickly moved toward the leak source, reaching the ruptured heat exchanger and resulting in a jet fire.
This jet fire burnt beneath a critical pipe rack section and led to a domino effect, with three further releases of large flammable inventories and a full-blown plant conflagration.
Two workers lost their lives, and eight others suffered serious injuries.
The major finding of the subsequent Royal Commission was that the training of employees and the operating procedures of the plant were inadequate for dealing with hazardous processes, particularly for disruptions such as the loss of lean oil circulation.
It was found that the rapid escalation of the fire was exacerbated by the plant’s design, particularly concerning the isolation of its hazardous inventories.
A study published this August in the journal Process Safety and Environmental Protection proposed a new hazard-accident causal analysis method, based on extensive offshore incident data, that combined domino effects with trajectory intersection theory.
The new method utilises a three-level hazard classification system to build a directed network of relationships among hazards, with Bayesian estimation methods filling data gaps while grey relation analysis and dynamic entropy weighting help quantify hazard-accident relationships.
More specifically, complex network analysis was used to identify key hazard nodes and critical pathways, providing practical recommendations for hazard control.
The analysis of 209 offshore platform accidents found that equipment-related hazards were most frequent, accounting for 40 per cent of primary hazards.
Electrical failures and production interruptions were common secondary and tertiary hazards, respectively, while crude oil leakage accounted for 42 per cent of the sample.
Six main categories of equipment (with partial overlap) were identified: drilling, well intervention, material handling, well control, and electrical equipment, plus other equipment that operates under pressure.
The researchers explained that current research on offshore oil and gas production platform accidents had gradually shifted from the traditional technical safety system to the comprehensive consideration of man-made, organisational, and dynamic factors.
They said: “Traditional models usually consider the impact of man, equipment, environment, and management factors side by side, failing to effectively reveal their common effects and subsequent co-evolutionary hierarchical relationships and specific impact paths.
“Moreover, it is difficult to reflect the systematic diffusion characteristics of accident development in a single impact analysis of the evolution of various hazards.
“This integrated approach offers practical risk control recommendations, demonstrating scientific innovation and practical applicability for offshore oil and gas industry safety.”