Jet fires are among the most aggressive fire situations in high-risk industrial environments such as offshore platforms, petrochemical refineries, and LNG terminals. Unlike pool fires, jet flames entail high-velocity flame impingement, higher heat flux (sometimes reaching 250kW/m²), and directional exposure.
Removable jet fire PFP (passive fire protection) blankets and jackets are developed to provide insulation and structural protection in those conditions while giving the advantage of being removable for inspections and maintenance.
The effectiveness of these removable PFP systems depends entirely on the materials used and their ability to resist thermal degradation, mechanical stress, and hydrocarbon exposure.
Multi-Layer Composition of Removable Jet Fire PFP Systems
The core science behind removable jet fire PFP systems lies in their layered construction, with each material chosen to serve a distinct purpose. A typical system comprises an outer weather- and chemical-resistant layer, a thermal barrier, a heat-dissipating middle layer, and an inner liner designed for equipment compatibility.
The outermost layer is usually made from high-performance silicone or PTFE-coated glass cloths that resist UV degradation, corrosion, and water ingress. This protective shell ensures long-term integrity of the internal materials under harsh environmental conditions.
Beneath this, mineral wool or microporous insulation provides the bulk of the thermal resistance, rated to withstand temperatures beyond 1000°C for extended durations.
These insulation layers are reinforced with stainless steel mesh or e-glass scrim to prevent structural collapse under flame impingement.
Thermal Conductivity and Material Density Considerations
The thermal performance of a removable jet fire PFP jacket depends not just on the material selection but also on the density and thickness of each layer. Higher density mineral wools (in the 100–140 kg/m³ range) are preferred due to their ability to delay heat transfer and maintain structural cohesion.
Additionally, aerogel composites or microporous panels are sometimes used in critical areas requiring thinner profiles. These advanced materials offer significantly lower thermal conductivity but come at a higher cost, making them suitable for compact installations with limited space.
Material selection also accounts for off-gassing behaviour under fire. Non-toxic, low-smoke emitting materials are critical to meet fire safety compliance and maintain personnel safety during emergencies.
Retention Hardware and Thermal Breaks
Removable PFP systems are only effective if their fastening systems can survive and retain the jacket’s position during a jet fire. Due to this, stainless steel hardware, such as buckles, D-rings, and threaded fasteners, is integrated into the design. These components are selected for their thermal expansion stability and corrosion-resistance.
Furthermore, thermal breaks must be engineered between the equipment and fasteners to prevent heat bridging, which could otherwise compromise the protected surface.
Manufacturers often test these components under simulated fire scenarios to ensure the system remains structurally intact for durations of 30 to 120 minutes, depending on specification.
Testing, Certification, and Material Ageing
Removable jet fire PFP products are validated through rigorous testing in accordance with ISO 22899-1 or bespoke third-party tests replicating jet fire conditions. These tests measure backside temperature rise, duration of flame exposure, and jacket retention.
Material ageing is another key concern. Over time, exposure to salt spray, moisture, and UV radiation can degrade the outer layers and compromise the fire-resisting capability. Due to this, removable PFP systems are subject to accelerated ageing tests and field maintenance protocols.
Some manufacturers embed tagging systems or RFID into the outer layers for digital tracking and compliance logging over the product’s lifecycle.
Conclusion
Removable jet fire PFP blankets and jackets are not generic insulating materials. Their design requires a careful balance of material science, engineering, and compliance standards to withstand one of the most severe fire hazards in industrial facilities. While asset owners continue to prioritise inspection accessibility and fire resilience, the demand for removable PFP solutions, backed by robust materials and certification, will remain strong.
Visit Ancloz Engineering and ensure your facility’s fire protection systems meet the highest safety benchmarks.
