Blast Protection System Design Considerations & Design Criteria

Blast protection and explosion protection are the terms used to describe the application of protection and defence systems against both intentional and unintentional explosions and blasts, including bombs.

BLAST PRESSURES IN OPEN AIR

The table below shows the blast effects of 0.45kg of high explosives detonating at varying distances.

BLAST OVERPRESSURE COMPARISONS

The table below shows the typical resulting effects of varying blast forces.

UNINTENTIONAL BLASTS AND EXPLOSION PROTECTION

Many modern day facilities present high risks of unintentional blasts or explosions occurring, in particular facilities housing high voltage power transformers and those that have highly combustible fuels and materials on-site. Common facilities that unintentional blasts and explosions occur in include:

• Power stations
• Petrochemical facilities
• Warehouses
• Off-shore platforms
• Airports
• Rail and metro stations
• Fuel storage facilities

It is essential that such facilities are sufficiently explosion and blast protected, in order to not only protect the personnel in these areas from injury and death, but also ensure that upon an explosion occurring, disruption and downtime is minimised.

Durasteel blast walls and transformer barriers provide exceptional blast protection.

INTENTIONAL BLAST PROTECTION / ANTI-TERRORIST PROTECTION

Devastatingly high explosive attacks by terrorist organisations have become very common around the world in recent years. Such blast and explosive attacks on public places are not only designed to cause severe injury to people, but also shock and disruption to the economy. Therefore sufficient blast protection of such facilities is paramount.

Common terrorist targets include:

• Public buildings
• Public areas containing large numbers of people
• Government buildings
• Embassies
• Defence establishments
• Transport infrastructure
• Supplies of water and fuel
• Financial districts

Estimated losses for the World Trade Centre terrorist attacks in the USA in 2001 were as follows:

• Business interruption – £7.2bn
• World Trade Centre property – £2.3bn
• Aviation liability – £2.3bn
• All other liabilities – £6.6bn
• All other property – £3.9bn
• Life – £1.7bn
• Worker compensation – £1.3bn
• Event cancellation – £0.7bn
• Aviation hull – £0.3bn
• Total estimated losses – £27bn

THE 3 KEY EFFECTS OF EXPLOSIONS

BLAST “PRESSURE” EFFECT

• Positive pressure phase
• Negative pressure phase

FRAGMENTATION “SHRAPNEL” EFFECT

• Detonation inside a casing (metal, wood, etc.)
• Fragments projected outwards

INCENDIARY “FIRE” EFFECT

• During an explosion, intense heat is released and any combustible material in the area will ignite

CLASSIFICATION OF EXPLOSIVES

HIGH EXPLOSIVE

Velocity of detonation is greater than 3,000 feet per second

• Dynamite – 12,000 feet per second
• C4 plastic explosive – 28,000 feet per second

LOW EXPLOSIVE

Velocity of detonation is less than 3,000 feet per second

• Black powder – 1,200 feet per second
• Smokeless powder – 1,000 feet per second

To learn more about how your business should be protected against blasts and explosions, please get in touch with a member of our team today – we’d be happy to help.