Most legacy studies use round holes because they are conservative for release rate but not always for consequence . For toxic gases (like H2S or chlorine), a crack's directional jet can send a plume directly toward an air intake that a round hole might miss.
How to use PHAST not just for compliance, but for predicting the unpredictable.
PHAST can help validate LBB strategies. If your crack model shows that the leak will be detected (via gas detection or pressure drop) before the crack reaches critical size, you can avoid a catastrophic rupture. If the model shows the opposite, you need better inspection intervals. dnv phast crack
Demystifying the “PHAST Crack”: What DNV’s Consequence Modeling Tool Reveals About Real-World Failures
If you’ve spent any time in process safety or quantitative risk assessment (QRA), you’ve likely heard the term . It’s the gold standard for modeling the consequences of hazardous releases—fires, explosions, and toxic dispersions. Most legacy studies use round holes because they
If your process safety studies only consider round holes, you are missing the scenarios that actually cause domino effects. The next time you open PHAST, don't just reach for the default "10 mm hole." Ask yourself: Could this fail as a crack?
Because in the real world, it usually does. Have you run crack scenarios in PHAST? Share your findings or questions in the comments below. PHAST can help validate LBB strategies
Let’s break down what the "crack" actually means and why it changes how we think about risk. In the context of DNV PHAST, “crack” refers to a pressurized leak from a small, slit-like opening —such as a fatigue crack in a pipe weld, a partially open valve, or a corroded seam.