Blast Doors
Blast Doors
Buildings would be so much easier to design and build for protection against blast effect if we did not need doors and windows. The reality however is that we do. We need to use materials which can be made into doorsets, can accept locking ironmongery and door furniture and they also have to be thinner and lighter than the walls into which they usually fit.
A blast door under load will experience a ‘pushing’ force known as the ‘Positive Phase’ and that will be followed by, for want of a better description, a ‘pulling’ or ‘suction’ action which is known as the ‘Negative Phase’. Although the negative blast phase is less onerous that the positive blast phase, it is still something that we need to engineer for in our blast doorset designs. Some buildings in recent years have been subjected to both positive and negative blast phases and in one incident the negative phase ‘pulled’ the glass out of the window frames and left glass debris one metre deep outside the foot of the building.
Steel doorsets – often the material of choice particularly for commercial plant and similar industrial environments.
Timber doorsets – often used in internal applications where cosmetics are important.
Blast pressures are measured in several units and all can be cross referenced. Common units for blast pressure are kPa (Kilopascals) PSI (Pounds per Square Inch) and so forth but when stated in this format they generally refer only to the ‘peak’ or ‘side on’ pressure. Sometimes we might see the blast load described as kPa-msec for instance. This is telling us the pressure and for how long it will ‘push’ against the doorset. This is referred to as an ‘Impulse’ load.
A gas explosion will generally have a lower pressure than a high explosive detonation. However the ‘Duration’ of the blast is much longer and that can actually cause more damage.
A steel doorset may be able to sustain a particular high explosive blast wave. The pressure hits the door, it bends into the building and absorbs the pressure and then it is quickly ‘sucked’ back out with the negative pressure wave before it reaches its ‘plastic’ state and beyond which would cause ultimate failure. The gas explosion however may exert less pressure but because it is pushing against it for a much longer period it could push it passed its plastic limit and the door cannot recover.
How much of this do we need to understand ?
A customer needs to aware of the potential that blast effects can have upon their staff, their property and also their business going forwards. When ordering doors we will need to know some basic information. We will ask for information such as the size of the doors, the finish of the doors, how the customer will need the locks to operate (access control, escape only and so on) and sometimes what is the most difficult piece of information and that is the blast pressure itself.
The blast pressure is determined usually by a blast consultant whose judgement may initially be based upon local intelligence or a pre-determined threat level. Alternatively it may be possible to supply a charge size (the volume of explosive) and also the distance at which it may be set from the building. In summary therefore, charge and distance or peak pressure and impulse will both provide the information that we need to manufacture an appropriate doorset.
All of our blast doors are purpose made to any size and configuration you may require. We can create any blast door in any range of style and finishes to incorporate with any style or theme. All our doors are made to your exact specifications including Blast and/or Ballistic ratings. All doors come with different security locking depending on your requirements.
Specification
| Application | Product | Blast Threat |
|---|---|---|
| Petrochemicals | Steel doors & windows | >1000kg |
| Terrorist Attacks | Wood, Steel, Glass Doors, Windows, Screens | 1kg to >3000kg |
| Scanner Rooms & Post Rooms | Wood, Steel, Glass Doors, Windows, Screens | 200gms to 20kg |
| Fragmentation | Wood, Steel, Glass Doors, Windows, Screens | Common materials, Nails, Screws, washers and also hardened materials |
| Equivalent Values |
|---|
| - Charge weight & Dynamic Distance (Dynamic Load) eg 1000lbs @ 30ft or 500kg @ 29meters - EXV (Dynamic Load) -kN/m2 (Static Load) - PSI (Static Load) -Bar (Static Load) -kPa-msec (impulse) -lbs/ft2 -Other Ammunition or Fragmentation |
Ballistic Protection
Inward opening and outward opening blast, ballistic and security doorsets
Blast & Ballistic Venting Products
Concealed locking double blast, ballistic and security doorset
Ballistic Protection
High security multi point locking system with bullet ventilation grilles and internal tray to resist deliberate ingress of flammable liquids
Blast & Ballistic Venting Products
Double doorset with high security locking and removable overpanel and transom. Particularly useful when large equipment needs to be moved through door openings
Ballistic Protection
Double Doorset in our blast test cubicle
Blast & Ballistic Venting Products
Building our oversized steel doorleaves
Ballistic Protection
Describe some quality or feature of the company. Write a short paragraph about it and choose an appropriate icon.
Blast & Ballistic Venting Products
Steel ballistic doorsets being packed for export
Frequently Asked Questions
What is a blast door?
A blast door is a specialist explosion-resistant doorset designed to withstand the positive and negative pressure phases of an explosion, protecting people, structures and critical assets. Unlike a standard security door, a blast door from Blast & Ballistics is engineered to cope with both the initial “push” and the subsequent “suction” phase of a blast wave, so the doorset continues to perform even after a major incident
How are Blast & Ballistics blast doors specified and designed?
All of our blast doors are purpose made to your required size, configuration and finish, with blast performance based on defined loads. We normally work from data provided by a blast consultant, such as charge weight and stand-off distance or peak pressure and impulse (kPa, PSI, bar, kPa-msec, etc.), and then design a doorset to suit those parameters
Can blast doors also provide ballistic and fire resistance?
Yes. Blast & Ballistics can combine blast, ballistic and physical attack resistance in the same doorset, and where required we can also provide fire-rated performance to standards such as BS EN 1634, BS 476 Part 22 and UL 10C, with ratings up to 240 minutes in steel doors. This allows a single door to meet multi-threat requirements and support safe escape routes and fire planning.
Where are blast doors typically used?
Our blast doors are widely used in petrochemical and industrial plants, scanner and post rooms, and buildings at risk from terrorist or accidental explosions, where both blast pressure and fragmentation must be considered. They are suitable for steel, timber and glazed doorsets, covering everything from plant room entrances to internal doors where appearance is important as well as protection.
What options and configurations are available on blast doors?
Blast doors can be single or double leaf, inward or outward opening, with a full choice of styles and finishes to match the surrounding architecture. Options include concealed high-security locking, multi-point locking systems, bullet louvre vents and ventilation grilles, removable overpanels and transoms for moving large equipment, and glazed fanlights or vision panels that still provide blast, ballistic and security protection