Fire integrity analysis of process systems

Legislation, industry standards, and company-specific risk acceptance criteria impose strict requirements on the design of process facilities to ensure their ability to withstand fire scenarios.
We have developed specialized tools and methodologies to address these challenges, supported by a strong track record of reference projects.

The fire integrity of pressurized pipework and equipment depends on several factors – including fluid properties, process conditions, material characteristics, the presence of passive fire protection (PFP), and the design of blowdown and depressurization systems.
When a hydrocarbon fluid is exposed to heat, its components vaporize according to their thermodynamic properties, causing a pressure rise within the equipment. This increased internal pressure imposes additional mechanical load on the system.
At the same time, as the material temperature increases, the strength of the metal decreases, reducing its ability to resist these loads.

The required fire integrity of a process system is determined by how long the system must retain its inventory to ensure safe personnel evacuation and prevent escalation of the event.
This required duration can vary — typically from 15 minutes to one hour, depending on the facility design and safety criteria.

VessFire has been developed to help engineers verify that process plants have adequate blowdown capacity and structural integrity (i.e., time to rupture) under defined fire scenarios.
The tool performs blowdown rate calculations in accordance with the advanced methodologies described in ISO 23251:2006 / API 521, ensuring compliance with international standards and best practices.

Fire Integrity of Flanges

One of the main hazards on oil & gas installations — both onshore and offshore — is the leakage of flammable or explosive substances.
Most leaks originate from flanges and fittings, making their fire integrity critical for preventing escalation once a fire starts.

When exposed to heat, bolts quickly lose their load-bearing capacity.
Since the threads between the bolt and nut carry the tension, elevated temperatures can weaken them — eventually causing nut loosening and leakage.

Standards such as NORSOK S-001 (Section 8.4.3) highlight the importance of preventing leaks from flanges and connections in fire scenarios. To meet this requirement, we’ve developed a specialized procedure for fire integrity analysis of flanges. Through experiments at SINTEF’s fire laboratory (now RISE Fire Research), the behavior of ASME weld neck and compact flanges was studied, and detailed 3D models were built in Brilliant.By combining these models with VessFire simulations, we can accurately assess flange performance and leakage risk under high-temperature, high-stress fire conditions.