The engineering task
A horizontal storage vessel contains a liquefied gas under pressure. External fire transfers heat into the wetted wall and vaporises liquid. The relief valve must discharge the generated vapour without vessel pressure exceeding the permitted limit.
The fire case is coupled to fill level, wetted area, insulation or passive fire protection. At the same time, wall heating reduces material strength. Relief capacity, discharge backpressure, saddle/shell verification and safe disposal form one protection concept.
Required design data
- Vessel geometry and maximum/minimum fill
- Properties of the liquefied gas
- Fire assumption, insulation and fire protection
- Relieving pressure, backpressure and disposal system
Technical solution approach
Define the fire scenario
Set exposed area, heat flux, shielding and effectiveness of passive protection.
Determine wetted area
Calculate the thermally effective surface from geometry and governing liquid level.
Balance vaporisation rate
Use net heat input and latent heat to determine required relief mass flow.
Size the relief system
Design valve area, inlet, backpressure and discharge piping for the fire case.
Check vessel condition
Reconcile shell, heads, saddles and allowable pressure with fire temperature and operating/test cases.
Expected deliverables
Suitable SOL ALPHA modules
The modules form a technically plausible toolchain. Their final selection and sequence will be confirmed during the later calculation against the applicable code and project conditions.