Gastech

Offshore oil and gas facilities operate in some of the most complex and hazardous industrial environments in the world. Floating Production Storage and Offloading vessels (FPSOs), semi-submersible platforms, and subsea riser systems handle large volumes of hydrocarbons under high pressure, in corrosive marine conditions, and often far from immediate emergency support.

This article is based on internal application research conducted by Gastech's NSW Regional Manager, Andrew Gibson, focused on fixed gas detection for offshore FPSOs, platforms, and riser moorings. It is written for professionals working in offshore operations who are responsible for managing safety, compliance, and asset protection in high-risk environments.

Who This Application Impacts Offshore

Fixed gas detection on offshore facilities directly supports the safety and operational responsibilities of:

• Rig Managers and Operations Managers
• Drilling Rig Superintendents
• HSE Officers and Safety Specialists
• Rig Electricians and Mechanical Supervisors
• Engineering and Procurement Teams

These roles are accountable for ensuring that hazardous atmospheres are identified early, controlled effectively, and managed in compliance with offshore safety regulations.

Summary of Exposure and Risk

Offshore FPSOs and platforms present continuous exposure risks from both combustible and toxic gases. These hazards can lead to fires, explosions, acute poisoning, and long-term health impacts, including exposure to carcinogens.

Workers may be exposed during normal operations such as drilling, processing, storage, and offloading, as well as during maintenance, commissioning, or upset conditions. Because offshore facilities are confined, elevated, and subject to weather conditions, gas accumulation can escalate rapidly if not detected early.

Causes of Gas Risk on FPSOs and Riser Systems

Subsea risers are pipelines designed to vertically transport crude oil, LNG, or LPG from beneath the seafloor to surface facilities such as FPSOs or semi-submersible platforms. These risers, along with processing and storage systems, create multiple potential release points for hazardous gases.

Combustible gases commonly present include methane, propane, butane, and other hydrocarbons. Hydrogen sulphide is particularly dangerous due to its toxicity and flammability, with concentrations capable of becoming life-threatening very quickly.

Toxic gases of concern offshore include hydrogen sulphide, benzene, mercury vapour, nitrogen dioxide, and oxygen-deficient atmospheres. In addition, offshore workers may be exposed to hazardous drilling fluids, fire suppression foams, and chemical retardants, which can cause skin, eye, respiratory, and long-term health effects.

The combination of pressurised systems, volatile products, and harsh marine conditions significantly increases the consequence of any gas release event.

Contact Gastech to speak with a Technical Consultant or Engineer today.

Why Fixed Gas Detection Is Critical Offshore

Unlike portable instruments, fixed gas detection provides continuous, automatic monitoring in high-risk zones without relying on human presence. On offshore facilities, this is essential due to the scale of operations and the speed at which conditions can deteriorate.

Fixed gas detectors are typically installed in and around:

• Riser moorings and collars
• Processing and separation modules
• Platform storage areas
• Offloading pipelines and manifolds

In some locations, point-to-point or open-path detection is also required to monitor larger areas where gas dispersion is influenced by wind and structure.

Fixed systems allow gas detection controllers to trigger alarms, activate deluge systems, and initiate emergency responses through relay outputs and 4–20 mA signals, providing critical time for intervention.

Offshore Environmental and Certification Challenges

Gas detection equipment offshore must operate reliably in extreme conditions. High winds can affect gas dispersion and complicate sensor calibration. Saltwater exposure, humidity, and deluge fire suppression systems place additional stress on housings and electronics.

Temperature extremes vary significantly, from sub-zero conditions in southern waters such as Bass Strait to sustained heat and humidity in northern offshore regions. Equipment must remain stable and accurate across these ranges.

Certification is mandatory. Fixed gas detection systems must meet offshore and hazardous area requirements, including ATEX or IECEx approval, Ex d protection, and marine certification such as the Marine Equipment Directive. Systems must also align with the Offshore Petroleum and Greenhouse Gas Storage Act and current offshore safety regulations.

How Gastech Supports Offshore Gas Detection

Gastech provides fixed gas detection solutions specifically selected and configured for offshore oil and gas environments. Our systems support the detection of combustible hydrocarbons, hydrogen sulphide, oxygen deficiency, nitrogen dioxide, benzene, and mercury vapour, depending on the application.

Area gas detectors are deployed across riser moorings, processing areas, platform storage, and offloading systems to provide continuous monitoring. These detectors integrate with multi-gas controllers that support standard 4–20 mA outputs and hard relay contacts, allowing connection to alarm sirens, strobes, deluge systems, and platform control systems.

All solutions are specified with marine durability, hazardous area certification, and long-term serviceability in mind. Gastech works closely with offshore engineering, operations, and procurement teams to ensure systems are compliant, practical, and fit for purpose throughout the asset lifecycle.

Learn more about our fixed gas detection solutions for offshore FPSOs and risers.

Common Questions

What gases are most critical to monitor on offshore FPSOs?

Combustible hydrocarbons such as methane and propane, as well as toxic gases including hydrogen sulphide, benzene, mercury vapour, nitrogen dioxide, and oxygen deficiency.

Why is fixed gas detection preferred offshore?

Fixed systems provide continuous monitoring, faster response times, and integration with alarms and safety systems, which is critical in confined and high-risk offshore environments.

Where should fixed gas detectors be installed offshore?

Common locations include riser moorings, processing modules, storage areas, and offloading pipelines. Some applications also require open-path detection.

What certifications are required for offshore gas detection equipment?

Typical requirements include ATEX or IECEx approval, Ex d protection, marine certification, and compliance with offshore petroleum safety legislation.

Conclusion

FPSOs, offshore platforms, and riser systems operate in environments where combustible and toxic gas risks are ever-present. Fixed gas detection is a fundamental safety control that provides continuous monitoring, early warning, and integration with emergency systems.

With proven application knowledge and offshore-ready gas detection solutions, Gastech supports operators in protecting personnel, maintaining compliance, and safeguarding critical offshore assets.

If you are responsible for gas detection on an FPSO, offshore platform, or riser system, speak to a Gastech Technical Consultant today. Our team can help assess your risks, specify compliant detection systems, and support your operation with confidence. Contact Gastech today.