Accidents in a chemical plant can be divided into fires and explosions (42%), fires (29%), vapour cloud explosions (22%) with the remaining 8% attributed to floods and windstorms. Economic loss is consistently high for accidents that involved explosions. The most damaging type of explosion is an unconfined vapour cloud explosion, where a large cloud of volatile and flammable vapour is released and dispersed through the plant site followed by ignition and explosion of the cloud. Toxic release typically results in little damage to capital equipment, although the resulting personnel injuries, employee losses, legal compensation, and cleanup liabilities can be significant. The most common root cause for toxic release is mechanical failures such as pipe failures due to corrosion, erosion, high pressure and seal/gasket failures. Failures of this type are usually due to poor maintenance or the poor utilisation of the principles of inherent safety and process safety management.
(Source: Crowl & Louvar  Chemical Process Safety, 3rd Edition, Prentice Hall). As experienced plant hazard simulation specialists, we provide plant safety simulation services, including major hazard facility simulation, to support plant hazard, risk and consequence assessment in chemical, petrochemical, hydrocarbon, oil refinery, LNG plants and all major hazard facilities. Our in-house PhD-qualified chemical process engineers ensure the boundary conditions employed are accurate, the numerical setup is appropriate to the problem, the simulation results are realistic and the recommendations are feasible.
Our blast consultancy firm provides third-party independent blast effects analysis (BEA) assessment to determine the adequacy of a bunker's design with respect to the storage of munitions or high pressure piping and pressure vessels, often located in a major hazard facility. Our blast consultants begin by studying the existing storage facility, researching on the explosives being stored, building the 3D model and simulating various scenarios such as the locations of detonation and the amounts of explosive charge.
UFC-3-340-02 guideline stated that the overpressure produced by an explosion that occurred inside a confined space would be amplified. This statement was supported by an independent study of urban blasts which determined that the confinement provided by the street buildings could increase the peak reflected overpressure by a factor of 4 times. In other study, it was determined that the blast wave propagation inside a tunnel or chamber had also showed that not only the peak overpressure generated in a confined space was higher than those produced from an explosion that occurred in open space, the duration of the blast wave was longer. This also enhanced the impulse, which was defined as the area under the overpressure history and was representative of the total energy imposed on the structure, thus the opportunity of survivability of the structure, or its elements were reduced.
From the simulation results, our comprehensive blast effects analysis report will answer the following questions:
- What is the degree of damage due to the blast wave and
where are the damages located?
- What is the maximum amount of explosives that can be
safely stored to avoid damage to the bunker?
- Are the concrete walls and its underlying reinforcement bars
capable of containing the blast waves?
- Will the bunker's walls be breached or collapse?
- Can the bunker's door withstand the blast wave?
- Are the door frame effective against the door being punched
out of the bunker by the blast wave?
- How far and how fast will the fragments fly?
- Will personnel working around the bunkers be injured by
flying fragments if an explosion was to occur?
- What is the degree of collateral damage on neighbouring
buildings or structures?
- What are the values of blast load?
- What is the probability of sympathetic detonation occurring?
- What reinforcement design is required to ensure personnel
working outside the bunkers are protected?
- How effective is the reinforcement design?
Major hazard facilities (MHFs) are industrial sites such as:
- Military explosive storage facility
- Chemical manufacturing and storage
- Commercial explosive storage depots
- Explosive and munitions manufacturing facilities
- Gas processing plants
- LPG and LNG storage and distribution facilities
- Facilities that store oxidisers, peroxides, toxic solids and liquids materials
- Selected warehouses and transport depots
- Flammable and combustible fuel storage depots
A few examples of major accidents that occurred in a major hazard facility are:
- Release of toxic material
- Release of flammable material
- Explosion or dispersion of hazardous materials
- Fire and major structural failure
- An incident that leads to environmental damage
- Incidents due to sabotage
The first step in the hazard identification process is a process hazard analysis, which identifies potential major accidents at the major hazard facility and possible initiating events. Common methods used include:
- Analysing process material properties and process conditions
- Reviewing organisation and industry experience
- Safety checklists
- Conducting what-if analysis on various scenarios
- Developing interaction matrixes
- Hazard and operability studies (HAZOPs)
Our consultans provide modelling and simulation services of cryogenic materials for the purpose of providing consequence analysis. One of the flammable cyrogenic materials is liquefied natural gas (LNG), particularly during its storage and distribution. The consequence analysis services we provide include: (1) Simulate gas pipe explosion. For example, our simulation will show that since LNG has a high vapour pressure and if left unchecked the pressure build up can rupture the pipe and the blast wave may compromise the bunker’s structural integrity. (2) If there is an LNG leakage but no explosion, the escaped LNG will form a pool. We have the experience to simulate LNG vapour cloud dispersion and through our comprehensive LNG gas dispersion analysis, we will determine, based on the environmental condition, how far and at what concentration does the LNG vapour cloud spread. (3) For the methane gas that vaporised from the LNG pool with concentration between LFL and UFL, we can simulate vapour cloud explosion and determine the consequence with respect to nearby structure and personnel.
(4) Our in-house chemical engineers will perform all necessary calculations to ensure the boundary conditions are appropriate and accurate. Then, the same chemical engineers will analyse the results to determine whether these results make engineering sense and realistic.
As for explosion scenarios in an MHF, we provide blast effects analysis and blast mitigation design to any major hazard facility or critical infrastructure and most importantly human lives from being attack by blast waves and flying fragments. We provide blast simulation as part of process hazard analysis and our report reveals what are the consequence if an explosion in a major hazard facility occurs. As for incidents due to sabotage, we help to protect a major hazard facility and we achieve this by conducting impartial 3rd-party independent threat and vulnerability analysis on any major hazard facility or critical infrastructure and human lives supported by advanced explicit dynamics modelling and simulation. Through an in-depth analysis of material, and structural behaviour (including large deformation, material fragmentation, solid-solid and gas-solid interactions), we are able to predict how a major hazard facility or critical infrastructure responds to threats such as explosive blast wave and fragment attack. The three pictures on the right show the contour of pressure magnitude which arose from a denotation occurring at the centre of the major hazard facility. This was conducted as part of the what-if analysis. With the results from this analysis, we proposed blast mitigation measures. From there, our mechanical and structural engineers performed detailed plant infrastructure reinforcement design.