Get the Hazardous Area Classification wrong on an offshore platform and the consequences can be severe — equipment installed in areas classified as Zone 2 that should have been Zone 1; ignition sources present in locations where a flammable atmosphere can form; electrical systems that fail to meet the protection requirements of the zone they operate in. These are not abstract risks. Fires and explosions on offshore facilities have historically been traced, at least in part, to failures in hazardous area identification and equipment specification.
Elixir Engineering carried out the Hazardous Area Classification (HAC) assessment for the Drilling Platform (DP) and Living Quarters (LQ) of the Kalamkas-Sea and Khazar Field Development Project during the FEED phase. The assessment was conducted in compliance with the requirements of the Republic of Kazakhstan regulations, client specifications, and applicable international standards — including IEC 60079-10-1, the primary international framework for gas atmosphere classification.
The Kalamkas-Sea and Khazar fields are located in the Northern Caspian Sea, approximately 132 km and 160 km south-west of the Kashagan field respectively. Both fields are in shallow water, with water depths of around 6 to 7 metres, and the operating environment includes seasonal ice conditions between December and March. The HAC assessment covered the full platform scope: all process areas, utility areas, enclosed rooms, and any other areas on the DP and LQ where flammable inventories are present or could accumulate.
Hazardous Area Classification is a systematic engineering process that identifies every location on a facility where a flammable gas, vapour, or liquid could be released into the atmosphere, assesses how likely that release is to occur and how long it is likely to persist, and then maps the resulting hazardous zones across the facility. Those zone maps form the basis for a series of critical engineering decisions: what type of electrical equipment can be installed where, how ventilation systems need to be designed, and where ignition sources must be excluded.
The underlying logic is straightforward. A spark that is harmless in a well-ventilated open area can be fatal in a room where a flammable vapour has accumulated. The HAC assessment is the process that tells you which rooms are which — and ensures that the electrical and mechanical equipment installed in each area is appropriate for the risk level that area presents. On an offshore platform handling hydrocarbons, the range of flammable inventories is considerable. Natural gas under pressure in the process systems, hydrocarbon vapours in the vicinity of pumps and compressors, hydrogen from battery charging, diesel vapour near fuel handling equipment — all of these need to be identified, characterised, and classified before a single electrical fitting is specified. The HAC study is the engineering tool that makes that characterisation systematic and auditable
The HAC assessment for the Kalamkas-Sea and Khazar platforms had five specific objectives, each contributing directly to the safety design of the facility at FEED stage.
The first was to identify every potential source of release of flammable material on the platforms. This is the inventory side of the work — reviewing process descriptions, PFDs, and P&IDs to build a complete picture of where hydrocarbons and other flammable materials are present, under what operating conditions, and at what pressures and temperatures.
The second was to classify identified hazardous areas into appropriate zones. Not every area where a release could theoretically occur needs to be classified as Zone 0 or Zone 1. The classification depends on how likely the release is and how long it is likely to last — which is why the release grade determination (continuous, primary, or secondary) and the ventilation assessment are both integral parts of the methodology.
The third was to define the spatial extent of each hazardous zone. It is not enough to say 'this area is Zone 2' — the classification has to define the horizontal and vertical boundaries of each zone so that equipment selection and layout decisions can be made with precision.
The fourth was to support compliance with the applicable regulatory framework. For this project, that meant satisfying both the Republic of Kazakhstan regulations and the relevant international standards. The assessment had to be defensible against both sets of requirements simultaneously.
The fifth was to generate the input that the electrical engineering team needed. The HAC study is not an end in itself — its outputs feed directly into electrical equipment selection, instrument selection, and the detailed engineering drawings that govern what gets installed on the platforms.
The methodology followed IEC 60079-10-1 principles, supplemented by API RP 505 and the Republic of Kazakhstan Electrical Installation Rules. The assessment was structured as a five-stage process, each stage building on the outputs of the previous one.
The starting point is always the process. We reviewed the process descriptions, Process Flow Diagrams, and Piping and Instrumentation Diagrams for the Drilling Platform and Living Quarters, along with operating conditions data covering pressures, temperatures, and fluid compositions. From that review, we built a complete inventory of the flammable gases, vapours, and liquids present on the platforms — identifying not just what they are but their physical properties, flash points, vapour pressures, and explosive limits. These properties directly influence how a release behaves and therefore what zone classification is appropriate.
On a drilling platform in the Caspian Sea, the flammable inventory is substantial and varied. Hydrocarbons from the well streams, diesel for power generation and fuel systems, gas to the flare, battery charging hydrogen — each requires individual consideration rather than a blanket assumption.
With the inventory established, the next stage was to identify every potential source of release — every point in the system where a flammable material could escape into the surrounding atmosphere. The assessment classified these into three categories as defined by IEC 60079-10-1.
Continuous sources are those where release is effectively ongoing — open vents, open interfaces with the atmosphere, or any point where a flammable atmosphere exists by design rather than by accident. On a drilling platform, an open hydrocarbon sump is a typical continuous source.
Primary sources are those where release is expected as part of normal operation, but not continuously. Pump seals and flanged connections operating under normal process conditions are primary sources — they will release flammable material periodically through normal wear and minor leakage, but not all the time.
Secondary sources are those where release is not expected during normal operation but could occur during abnormal conditions or maintenance activities. Most flanges, valves, and instrument connections on a well-maintained facility are secondary sources — they should not be releasing flammable material under normal operations, but they must be accounted for in the classification because abnormal conditions are credible.
Each identified source was assigned a release grade — continuous, primary, or secondary — based on the expected frequency and duration of release from that source under the operating conditions of the platforms. This step is where the specifics of the project matter. The same type of equipment at the same pressure and temperature does not necessarily have the same release grade on every project; operating context, maintenance philosophy, and the availability of isolation systems all influence the grade assigned to a given source.
Ventilation is the other half of the zone classification equation. A secondary source of release in a well-ventilated open area produces a very different risk from the same source in a poorly ventilated enclosed room. The ventilation assessment evaluated each area of the platform against three criteria: the type of ventilation (natural or mechanical), the degree of ventilation (high, medium, or low), and the availability and reliability of the ventilation system.
Natural ventilation in the exposed Northern Caspian environment is usually effective for open deck sections on the Drilling Platform; wind conditions play a role in this ventilation assessment, and the seasonal variation between summer and ice-affected winter conditions was considered. For enclosed rooms — including battery rooms, UPS rooms, and other equipment spaces — mechanical ventilation systems were assessed for their capacity to dilute potential releases and prevent flammable atmosphere accumulation.
With release grades and ventilation effectiveness established for each area, the zone classification followed the IEC 60079-10-1 framework: Zone 0 where a flammable atmosphere is present continuously or for very long periods; Zone 1 where it is likely to occur in normal operation; Zone 2 where it is unlikely in normal operation but credible under abnormal conditions; and non-hazardous where the ventilation is sufficient to prevent any significant accumulation of a flammable atmosphere.
Crucially, the classification did not stop at zone type — it also defined the spatial extent of each zone: how far does the Zone 2 boundary extend horizontally and vertically from a given source? Those dimensional limits are what translate the classification into something the structural and electrical engineers can actually use.
One of the specific challenges of this project was the regulatory context. The Republic of Kazakhstan has its own set of electrical installation and hazardous area requirements — the ST RK IEC series and GOST standards — that run alongside the international IEC framework. The assessment had to satisfy both sets of requirements, which meant working within the IEC 60079-10-1 methodology while simultaneously verifying compliance with the Kazakhstan national standards. The four principal references applied are listed below:
| Document | Standard | Role in This Assessment |
| IEC 60079-10-1 | Explosive Atmospheres — Classification of Areas — Gas Atmospheres | The primary classification standard. Defines Zone 0, 1, and 2, sets out the release grade and ventilation framework, and provides the annexes used to determine zone type and spatial extent. |
| ST RK IEC 61892-7 | Mobile and Fixed Offshore Units — Electrical Installations — Hazardous Areas | Kazakhstan national standard governing electrical installations in hazardous areas on offshore units, required for regulatory compliance under the Republic of Kazakhstan framework. |
| GOST 31610.0 / 31610.20-1 | Explosive Atmospheres — Equipment and Material Characteristics | Applied for equipment and material characterisation requirements under Kazakhstan national regulations, complementing the IEC framework. |
| API RP 505 | Classification of Locations for Electrical Installations at Petroleum Facilities — Zone 0, 1, and 2 | Supplementary petroleum industry guidance on zone classification for facilities handling flammable gases and vapours. Used for cross-referencing source of release scenarios and zone extent guidance. |
The interaction between the IEC and Kazakhstan national standards is worth noting. Where the Republic of Kazakhstan regulations are more conservative than IEC 60079-10-1 — in particular for certain enclosed room classifications — the more conservative requirement was applied. This is not unusual for international projects that span multiple regulatory jurisdictions, but it requires explicit attention during the methodology development rather than an assumption that international standards automatically satisfy local requirements.
The HAC assessment produced a complete zone classification for the Drilling Platform and Living Quarters, covering all areas with identified flammable inventory. The findings broke down into two clear categories.
The majority of open and well-ventilated areas on the Drilling Platform were classified as Zone 2. This reflects the prevalence of secondary sources of release — flanged connections, valve stems, instrument connections — in areas where natural ventilation is effective. A Zone 2 classification in a well-ventilated open area means that a flammable atmosphere is not expected during normal operation; it is the classification for an area where you need protection against abnormal releases, not continuous hazard management.
This is the expected result for a well-designed offshore facility with an open deck configuration, and it is a positive finding in engineering terms. Zone 2 classification allows the use of equipment certified to Equipment Protection Level Gc — a broader and less expensive equipment range than Zone 1 — which has direct implications for procurement costs and the range of certified equipment available.
Selected enclosed rooms on the platforms — specifically UPS rooms and battery rooms — were classified as Zone 1. This is the outcome defined by IEC 60079-10-1 and the Republic of Kazakhstan regulatory requirements for spaces of this type. Battery charging produces hydrogen, which is highly flammable and lighter than air. In an enclosed room where hydrogen can accumulate, even with mechanical ventilation, the classification is Zone 1 because a flammable atmosphere from a primary source — the battery charging process — can develop under normal operating conditions.
Zone 1 classification has direct consequences for equipment selection in those rooms. Equipment must meet Equipment Protection Level Gb at minimum — flameproof (Ex d), increased safety (Ex e), intrinsically safe (Ex i), or another IEC 60079 protection concept appropriate for Zone 1. That specification goes directly into the electrical engineering deliverables for detailed design.
The Zone 1 classification for battery and UPS rooms is not a surprise — it is consistent with standard industry practice for enclosed spaces housing battery systems on offshore platforms. What matters is that it is formally documented, that the zone extents are defined, and that the equipment selection requirements are clearly stated so that the detailed engineering team cannot inadvertently specify inappropriate equipment.
For each classified area, horizontal and vertical zone boundaries were defined. These are the dimensions that populate the hazardous area zone drawings — the engineering documents that physically show where each zone begins and ends on each deck of the platform. Those drawings become the reference documents for all subsequent electrical, instrumentation, and mechanical engineering decisions on the project.
The classification outputs were accompanied by a set of recommendations addressing the areas where design decisions at detailed engineering stage will be most directly influenced by the HAC findings.
Electrical equipment selection: For all Zone 1 areas — battery rooms and UPS rooms in particular — equipment must carry the appropriate IEC 60079 certification for Equipment Protection Level Gb or above. The HAC deliverable provides the zone classification schedule that the electrical engineering team uses to specify Ex-certified equipment from vendors. No standard (non-Ex) equipment can be installed in classified areas.
Ventilation system requirements: For enclosed rooms classified as Zone 1, the mechanical ventilation systems must be designed and maintained to the performance levels assumed in the classification. If ventilation availability drops below the assumed level, the zone classification may become more severe. The recommendation included explicit performance criteria for the ventilation systems in classified enclosed rooms, so that the mechanical engineering team has clear targets for the detailed design.
Layout optimisation: Where the defined zone extents extended into areas originally intended for equipment or personnel access routes, layout adjustments were recommended to ensure that ignition sources — including non-Ex certified portable equipment and hot work activities — are excluded from classified zones during operations. These recommendations were integrated into the FEED layout drawings.
Hazardous area drawings: The zone extents defined in the assessment provide the input for the formal hazardous area drawings that form part of the FEED deliverable package. These drawings carry statutory weight under the Republic of Kazakhstan regulatory framework and form the reference document for all subsequent electrical and instrumentation engineering work.
HAC is sometimes treated as a detailed engineering activity — something to be done once the layout is fixed and the P&IDs are mature. That approach is a mistake, and it is a mistake that tends to be expensive to correct.
The most significant reason to do HAC at FEED is that the zone classifications directly influence the platform layout. If a process area comes out as Zone 1 rather than Zone 2, the equipment selection requirements for that area change significantly — and if the area is adjacent to a control room or a living quarters module, those results may require layout changes. Discovering Zone 1 requirements during detailed engineering, when the layout has been optimised around Zone 2 assumptions, is the kind of finding that generates RFIs, potential delays, and cost impacts.
A second reason is the interface with electrical engineering procurement. FEED is when the electrical philosophy for the platform is being established and when vendor interactions for major electrical equipment begin. If the HAC classification is not available at FEED, the electrical philosophy cannot be finalised, and the procurement process for Ex-certified equipment — which typically has longer lead times than standard equipment — cannot start with confidence.
A third reason is regulatory. For projects in Kazakhstan, the HAC study forms part of the regulatory submission package. Having a completed and reviewed HAC at FEED provides the regulatory authority with a documented basis for the electrical safety design of the platforms — a basis that can be reviewed and approved in parallel with the detailed engineering work rather than sequentially after it.
The Hazardous Area Classification assessment for the Kalamkas-Sea and Khazar Drilling Platform and Living Quarters delivered a complete, standards-compliant zone map for both facilities. The classification framework — built on IEC 60079-10-1 as the primary international standard, supplemented by API RP 505 and the applicable Republic of Kazakhstan national standards — gave the project team a defensible, auditable basis for every electrical, instrumentation, and mechanical equipment decision that follows.
The key finding — that most open and ventilated areas are Zone 2 while selected enclosed rooms with battery and UPS systems are Zone 1 — is consistent with a well-designed offshore facility of this type, and reflects the thoroughness of the ventilation assessment that underpins those classifications. The defined zone extents, spatial boundaries, and equipment selection inputs were delivered as part of the FEED package, giving the detailed engineering team clear and complete inputs before they begin specifying equipment and producing installation drawings.
If your project requires a Hazardous Area Classification study, whether at FEED stage or during detailed engineering, Contact us to discuss how we can support your safety design work.
