Consequence Assessment - DNV tool PHAST

Managing risk... First need to quantify the risk (semi or quanlitative are other options) For that, we should identify the hazard, estimate severity and then how frequent it could happen [Risk = Severity x Frequency]. For severty estimation, the extent of consequence from the event is to be predicted.

PHAST (Process Hazard Analysis Software Tool) by DNV is a software tool that I often use for consequence assessment. The coding of the tool started almost two decades back (sometime in late eighties). PHAST has developed ever since and still improving. I believe the wide recognition for the tool is mainly due to the technical support DNV offers and the continuous thrive to perform/satisfy the industry need. SafetiNL (Phast-Risk) is the only tool approved by the authority to perfrom QRA in the Netherlands. In the UK also, Phast is a widely accepted tool by Health and Safety Executive (HSE) and often used for the Safety Reports (COMAH / Seveso).

DNV Software organise Phast user group meeting. It provides platform to learn about the new developments in the forth coming versions, share the experiences from fellow users and ofcourse a good place to meet contemporaries. The number of such events held a year (across globle) reflects the growth and acceptance of the software tools for consequence assessment and the importance, industry is giving for managing risk.

The current version of Phast is v6.53.1. The next version V6.54 is expected to be available to the users by the last quarter of 2008. Following version v6.6 is due by mid-2009. After that, DNV is going for a major overhaul in the structure of the tool with its v7.x (and thereon). So far the improvements were mainly on improving the basic codes and adding on to that. It is expected that from v7.x, the architecture itself is recreated whereby more cross functional features (with Risk, Leak, Orbital - all are related DNV software tools) will be incorporated.

Some of the main features added on to the forthcoming version, i.e. Phast v6.54:
- Support MS vista
- Additional options for modelling impinged releases (don't get too excited, this feature enables the user to change the velocity reduction following impinged releases only. Earlier it was fixed to 25%. The changes in jet pattern, droplet formation, atomisation etc.. are far away from realisation).
- Short duration effects will be available for some more model options (time-varying long pipeline, leak, line rupture, disc rupture and relief valve scenarios).
- Greater control over trapped droplets for indoor releases (mass modification factor changeable).
- Warehouse modelling: Added a feature which automatically generate scenarios for Dutch PGS-15 Directive. This is available in table form and quite helpful for quick editing. Also, more complicated structural details could be considered (warehouse that is a part of a larger building, area and height changes etc). New materials can be created (rather than limited to the Phast provided warehouse material!).
- Advancements in the risk: risk ranking reports (more options like selection of top event or similar consequences etc.), define the outcome with a new code (e.g. INDXOF = Instantaneous release, No rainout, Delayed ignition, eXplosion Only, Free field ignition).
- New version will provide warning on license expiry.
- Provision for adding solar radiation to flame radiation.
- Greater control over graphs and maps. e.g. possible to plot effect zone in the graphs as well.
and many other minor corrections and updates.

Now looking forward to use and explore the advantages of the new features.

SreeRaj R Nair
Process Safety