Ade, Are you sure your figures are correct? 150 millibar, as written, is a tiny pressure.

150mbar is more than enough to do damage to structures, given the large surface area of buildings / walls etc Structural element Typical failure pressure (mbarg) Glass windows 20-70 Room doors 20-30 Light partition walls 20-50 50 mm thick breeze block walls 40-50 Unstrained brick walls 70-150

I'm not sure what unstrained means in this context. Maybe a free standing wall, with no additional loading or supporting bracing/buttress? Various methodologies are available for calculating blast effect - TNO method, Multi energy method. Strehlow, Tang & Baker are the usual authors quoted when undertaking blast analysis. Blast effects are also influenced by how confined and congested a work area is. Lots of pipework etc increase the likely over pressure and hence possible damage.

Thanks everyone for your reply. The original explosion assessment was done with DNV PHAST Multi Explosion Model. This gave a worst case scenario of 150 mbar overpressure within a radius of 56metres. The blast wall between the control room and the gas turbine hall where there is a risk of explosion due to the congestion is within this 56 metre radius. Hence, the need to conduct some analysis on this blast wall to ascertain the maximum overpressure it can withstand. There is no record of the design data for the blast wall as it was installed in 1979.

when oh when can we edit Missed off to reinforce or rebuild the wall. Bob

Would be interesting to know the source of release or scenarios considered as a part of your assessment.

Was thinking more along the lines of was this an assessment considering DSEAR or COMAH. Release due to failure at flange or guillotine rupture from a pipe. Frequency of overpressure scenario may be tolerable and blast wall may not be required depending on scenario. If enclosure is provided, the design should preclude an explosive atmosphere. Similarly, what levels of ventilation are provided within the turbine hall if enclosures are not provided. Is LEL detection provided so as to shut off gas supply and possibly ramp up ventilation in the event of release. As we do not know the details involved, it is difficult to comment, as previously stated, there are other counter measures available and pressure resistant design may not be the most suitable.