Blast doors: ask the experts

In-depth understanding, experience and forward-thinking have enabled our team to create industry-leading blast doors. Here, our team answers some of the common questions around blast doors and their manufacturing process.

Do designers and engineers producing blast doors need to have specialist abilities or qualifications? 

To function effectively, all structural elements of a blast door must be designed to withstand the loads imposed during a blast event. Depending on the magnitude of the blast event, the design process can be complex, as different elements of the door construction will be loaded in different ways and will have different performance limits. 

Blast designers thus require extensive static and dynamic structural design capability, as well as the ability to analyse how a door will behave in a blast. 


What information is needed from clients in order to correctly design a blast door? 

It’s important to receive as much information as possible from clients when they are specifying a blast door, to avoid assumptions and over- or under-estimation of the proposed door. 

To correctly assess and design a blast door, the following performance criteria needs to be known, and understood: 

  1. Peak (reflected) Pressure – This is the maximum pressure that the door will see during a blast, and this will vary depending on how far away the door is from the source of the blast.
  2. Blast Waveform – The way that the peak pressure is achieved, and how it reduces, is absolutely critical for the design of the door. Gaseous-type explosions will typically see a linear rise to peak pressure, and a linear decay, whereas explosives (e.g. TNT) are often considered as instantaneous rise, linear decay. Instantaneous rise in pressure is more onerous to deal with, as are extended durations of blast.
  3. Rebound – If a blast door deforms elastically under the blast (i.e. it returns to its original shape without permanent deformation), the door will rebound and impose additional loads on the frame/structure that need to be considered and allowed for.
  4. Operability – If the door is a primary exit or subject to repeated blast events, clients may want the door to be fully operable after a blast, and with no damage. At the other extreme, it may be acceptable for the door to be inoperable after the blast, provided that the door has prevented the blast from passing through.
  5. Seated or unseated – Which side of the door does the blast come from? If the blast pushes the door leaf on to the frame (seated), this is easier to deal with than if only the hinges/locks are available to transfer the loads to the frame (unseated). 

What are the individual components that make up a blast door? 

A blast door must be designed to withstand the blast event as a complete unit. There would be little point in having a blast door where the door leaf and frame withstood the initial positive blast loads, only for the door to be pulled open under the rebound loads which follow a positive blast. 

All structural elements of the door must therefore be designed to withstand the loads imposed by the blast event and to transfer these loads to the supporting structure. These door elements include the door leaf, the door frame and the hinge and latching system which secures the door leaf in the closed position. 


How long is the process of producing a blast door, from design through to manufacture? 

This depends on the magnitude of the blast load and the complexity of the door construction – blast doors are often designed to provide additional capabilities such as fire resistance and the ability to remain secured when subjected to physical attack.  

The design and engineering process can therefore take anywhere from two weeks to several months, whilst the manufacturing process can typically take from six weeks to four months. 

Where design loads are particularly onerous or complex, the designs are sometimes also analysed with the aid of computers using Non Linear Finite Element Analysis (NLFEA). Whilst this process can validate the design of doors subject to extreme blast loads, it also adds to the time required to produce the final design. 

What kind of sites are blast doors most commonly found in? And are there unexplored applications within different sectors? 

Blast doors are found wherever containment of a blast event or protection from the effects of a blast event may be required.  

Example sites include petrochemical and pharmaceutical sites and military installations, such as munitions storage facilities, as well as building elements that may be subject to loads from a comparatively distant terrorist attack or the catastrophic failure of high-power electrical equipment. 

It is incumbent on all architects and facility designers to be aware of such potential threats and to specify the potential for these events in their design. 


Are blast doors manufactured to withstand any blast or are there calculations involved to ensure the door is at the relevant standard to withstand specific blasts? 

For lower levels of blast, a ‘standard’ design may be produced to provide protection up to that particular blast load and door size. However, for more onerous blast loads, a project-specific set of design calculations would be produced, incorporating the specific blast load and door design. 

Are blast doors routinely tested and certified? 

It is unusual to physically blast test a door, simply because of the variability of blast scenarios that may exist and the prohibitive cost of testing. However, it does happen as required, on occasion.  

More often, however, calculations are produced to demonstrate that the proposed door design meets the design criteria, and these are then peer reviewed by the client’s consulting engineers (or insurers) to confirm performance compliance. 


There are many factors to take into account when designing and procuring blast doors, but our team is always here to answer any questions to help establish what you need.