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This project is funded by the European Union Projekat finansira Evropska Unija. EFFECTS TO PEOPLE AND STRUCTURES, DOMINO EFFECTS ANALYSIS Antony Thanos Ph.D. Chem. Eng. [email protected] Project implemented by Human Dynamics Consortium Projekat realizuje Human Dynamics Konzorcijum.

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This project is funded by the European Union

Projekat finansira Evropska Unija


Project implemented by Human Dynamics Consortium

Projekat realizuje Human Dynamics Konzorcijum

Initial event

Top event




















Toxic effects

Toxic effects

  • Probit functions

    • Relation of probability for a certain effect level to a cause level

    • Probit function defined per type of effect expected

    • For thermal radiation, example of effects :

      • death

      • 1st degree burns

    • For toxic substance, example of effects :

      • death

      • irreversible effects

  • Probit functions (cont.)

    • Origin from toxicology. Extension to thermal radiation, overpressure effects

    • Basic assumption: cause and effects follow Gaussian distribution.

    • Why Gaussian distribution ?

      • Population members are not identical :

        • age

        • sex,

        • health status

        • etc.

  • Probit functions (cont.)

    • Transformation to probit results in close to linear relationship of cause (dose) and probit parameter

  • Probit functions (cont.)

    • P = (Pr),

    • P : probability value

    • Pr : probit value

    •  : standard function of probability with probit value

    • function  calculated by numerical approximations using error function (erf), for probit value Pr such as :

use this

for Excel

  • Probit functions (cont.)

    • error function (erf) definition:

    • erf calculated readily, even in spreadsheets (excel)

    • Polynomial approximations of error function also are available:

  • Probit functions and cause levels

    • Generally :

      • Pr = A + B ln(D),

      • Pr : probit value

      • A, B : probit constants for a specific harm

      • D : cause value for specific harm

  • Cause value in many cases relates also with exposure time

  • Toxic substance effects (cont.)

    • Toxic effects via inhalation

    • Dose concept : Dose = Cn t

      • C, concentration

      • t, exposure time

      • n, exponent depending on substance :

      • available on literature for several toxics,

      • usually in the range 1-2

      • even higher values (NO2 : 3.7, SO2 : 2.4),

      • if not known, or no suitable data are available, n=2

  • ToxicEffects (cont.)

    • Exposure time :

      • Usually 30-60 min (assumed time for escape time to shelter)

      • Probit constants available in literature for several toxics

      • Toxic endpoints definitions must include exposure time, e.g. LC50 (30 min)

  • ToxicEffects (cont.)

    • Toxicity data vs species and exposure time :

      • Literature toxicity data must be adjusted to humans and for the required exposure time, e.g. literature data for LC1 (2 hours) on rats must be adjusted to LC50 (30 min) for humans

      • Adaptation for exposure time : via exponent n for same dose, example for exposure time ta, tb, e.g. :

  • ToxicEffects (cont.)

    • Conversion of data between species (TNO Green Book) :

      • In general, safety factors taken for conversion of animal data to human :

        • 5 for locally acting substances (lung damage), different breathing rate and lung surface taken also into account

        • 10 for systemic damage (damage to other organs via blood circulation), different body weight taken also into account

      • In emergencies, additional safety factor (2) is encountered, due to increased breathing rate

  • ToxicEffects (cont.)

    • Conversion of data between species (TNO Green Book) : (cont.)

      • Finally, extrapolation factors (fd) are calculated (0.2-0.5)

        • Toxicity parameter such as LC50, LC1 etc.

  • ToxicEffects (cont.)

    • Conversion of data between species (TNO Green Book) : (cont.)

      • Example results for extrapolation factors (Green Book)

  • ToxicEffects (cont.)

    • Endpoints used

      • LC50, concentration of toxic in air for lethal effect to 50% of exposed people (usually provided for 30 min)

      • LC1, concentration of toxic in air for lethal effect to 1% of exposed people (usually provided for 30 min)

      • LDx, dose for lethal effect to x% of exposed people, dose defined as toxic load per body mass (kg of toxic/kg of body weight)

      • LD cannot be directly be used in Seveso application, as consequence analysis results in estimation of toxic in air concentration. Conversions are required for exposure time, breathing rate, body mass

  • ToxicEffects (cont.)

    • Endpoints used : (cont.)

      • IDLH (Immediately Dangerous to Life and Health), concentration threshold of airborne toxic likely to cause death or immediate or delayed permanent adverse health effects or prevent escape.

        • Maximum exposure time of healthy worker 30 min

        • Damage affecting escape action (irritation of eyes or lungs) are taken also into account.

        • Threshold for high reliable breathing apparatus requirement


  • ToxicEffects (cont.)

    • Endpoints used : (cont.)

      • IDLH source : NIOSH

      • IDLH available for limited number of substances

      • If not available and required, approximations are used :

      • IDLH= 0.1 LC50 (EPA)

  • ToxicEffects (cont.)

    • Other endpoints used : (cont).

      • ERPG 1/2/3 (Emergency Response Planning Guidelines, USA). Exposure time up to 1 hour, general population.

      • AEGP 1/2/3 (Acute Exposure Guideline Levels, USA). General population, exposure times 10 min, 30 min, 1 hour, 4 hour, 8 hours)

      • …….

      • Safety report must not be a collection of toxicity parameters

  • ToxicEffects (cont.)

    • Endpoints used in legislation, risk acceptance criteria

      • Usually up to 3 different endpoints required

      • France : LC50/LC1/Irreversible effects

      • Greece : LC50/LC1/IDLH

      • Italy : LC50/IDLH

      • Portugal : AEGL 3/AEGL 2

  • ToxicEffects (cont.)

    • Endpoints used in legislation, risk acceptance criteria

      • Common characteristics in most cases :

        • Inner endpoint : LC50

        • Outer endpoint : irreversible effects

        • Tables with values of required toxicity endpoint provided in Guidance documents (NO REQUIREMENT FOR TOXICITY ENDPOINT CALCULATION FOR MOST COMMON TOXICS)

  • ToxicEffects (cont.)

    • Mixed Toxics (e.g. pesticide warehouse)

      • Toxics in same category (e.g. organophosphates)

        • act via the same route in organism (e.g. respiratory system damage, depletion of oxygen)

        • concentrations in air can be aggregated and treated as one substance, via weighted average using toxicological endpoints (LC50, LC1, IDLH etc.) for each one:

          Aggregated (equivalent) concentration relates to category member with maximum endpoint

  • ToxicEffects (cont.)

    • Mixed Toxics (e.g. pesticide warehouse)

      • Toxics in different category (e.g. organophoshates, carbamides, organochlorides)

        • act via the different route in organism

        • concentrations cannot be aggregated

  • Thermal radiation effects

    • Impacts depend on both thermal radiation flux and exposure time, e.g.

      • Thermal radiation flux 37,5 kW/m2 :

        • damage to equipment after 20 minutes

        • 100% lethality in 1 minute

        • 1% lethality for 10 seconds

  • Thermal radiation effects to people

    • Best practice the use of Thermal Dose :

      • TDU = Q4/3 t

      • Q (W/m2), emissive power (thermal radiation flux) from flame/fireball surface at point in interest

      • t (sec), exposure time

  • Thermal radiation effects to people (cont.)

    Pr = A + B ln(D), D : Thermal Dose

    • Probit constants A, B available in literature for several levels of harm from thermal radiation

      • lethal effects probit function

        • where : Q (W/m2), t (sec)

        • Q calculated by consequence analysis

  • Thermal radiation effects to people (cont.)

    • Exposure time :

      • Short time period phenomena, e.g.

        • BLEVE/fireball : duration of BLEVE (appr. up to 30 sec, even for very big tanks)

      • Longer period phenomena : assumed escape time (time to shelter), as for :

        • pool fires

        • jet flame

  • Thermal radiation effects to people (cont.)

    • Exposure time : (cont.)

      • Estimation of exposure time required

      • HSE GRAG for LPGs, flammables:

        • Escape speed for average public 2.5 m/sec

        • Escape speed for elderly, children 1 m/sec

        • Distance to shelter in suburban areas 50 m

        • Distance to shelter in rural areas 78 m

  • Thermal radiation effects to people (cont.)

    • Exposure time : (cont.)

      • In most cases, exposure time is defined in guidance documents (usually in the order of 0.5-1 min)

        • Netherlands : 20 sec

        • Greece : 40 sec

        • UK : 60 sec

    • Flash fire case :

      • death expected within flammable cloud section limits (UFL/LFL) due to ignition of clothes

      • no effects expected outside flammable cloud

  • Thermal radiation effects to people (cont.)

    • Endpoints for thermal radiation to be reported in Safety Report defined usually for effects to humans (e.g. lethal effects, irreversible damage), inline with acceptance criteria

    • Be careful !!!!!

      • Thermal Dose in endpoints could require Q expressed in kW/m2

      • Typical case when thermal dose is expressed with TDU units ((kW/m2)4/3 sec)

  • Thermal radiation effects to people (cont.)

    • Endpoints in Greece :

      • 1500 TDU : 3rd degree burns (lethal effects) in 50% of exposed people

      • 450 TDU : 3rd degree burns in 1% of exposed people

      • 170 TDU : 1st degree burns in significant part of exposed people

    • Endpoints in France :

      • 1800 TDU : Significant lethal effects

      • 1000 TDU: Lethal effects threshold

      • 600 TDU : Irreversible effects threshold

  • Thermal radiation effects to people(cont.)

    • Endpoints in UK :

      • 1800 TDU : Significant likehood of death (12.8 kW/m2 for 1 min)

      • 1000 TDU : Dangerous dose for average people (8.2 kW/m2 for 1 min)

      • 500 TDU : Dangerous dose for vulnerable people (4.9 kW/m2 for 1 min)

  • Thermal radiation effects to structures

    • Damage type :

      • Level 1. Ignition of surfaces, breakage of structure elements

      • Level 2. Optical deterioration of material (discoloration, paint peeling off), structural element deformation

    • For Safety Reports, effects to structure elements are in primary interest, as no combustible (wood) buildings are expected

  • Thermal radiation effects to structures (cont.)

    • Parameters affecting effects :

      • Thermal radiation flux on exposed surface

      • Material of construction and shape

      • Exposure time

        • Surface and bulk material temperature rises

        • Deterioration of material properties (e.g. yield strength)

        • Potential to exceed the capability of material to carry the structural loads present

  • Thermal radiation effects to structures (cont.)

    • For buildings, severe damage referred in literature for 12.6 kW/m2 and 20 min. For which buildings ???

    • TNO Green Book clarifies :

      • 25 kW/m2, wood ignition for prolonged exposure

      • 12.5 kW/m2, piloted ignition of wood, plastics melt

      • 4 kW/m2, glass breakage

  • Thermal radiation effects to structures (cont.)

    • France : 16 kW/m2 generic for structures (excluding reinforced concrete)

    • UK, SRAG documents:

      • 25.6 kW/m2, spontaneous ignition threshold

      • 14.7 kW/m2, piloted ignition threshold

    • What about steel/equipment ??

  • Thermal radiation effects to structures (cont.)

    • Generic threshold for equipment : 37.5 kW/m2 and 20 min exposure time

    • TNO Green Book for beam profiles :

      • Level 1 damage expected for 100 kW/m2

      • Level 2 damage expected for 25 kW/m2

      • Exposure time for critical temperature to be reached, depends strongly on beam (geometry and orientation to heat source)

      • Level 2 damage for exposure time in the range of 10-50 min, depending on beam type.

  • Overpressure effects to structures (cont.)

    • Some examples for equipment damage (note that 100 kPa=1000 mbar) :

      • Destruction of sphere support structure : 100 kPa

      • Movement of cylindrical tank, failure of connecting piping : 50 –100 kPa

      • Damage in distillation column : 35 – 80 kPa

      • Rail tank turnover: 50 kPa

      • Piperack destruction : 40 – 55 kPa

      • Crack in empty oil tank : 20 –30 kPa

      • Destruction of tank roof : 7 kPa

  • Overpressure effects to structures (cont.)

    • Some examples for buildings :

      • Total destruction : 70-83 kPa

      • Partial destruction : 35-50 kPa

      • Severe and repairable damage (partial collapse of walls and roofs): 15-20 kPa

      • Partial demolition, made inhabitable : 8 kPa

      • Limited damage (windows break, small cracks in walls) : 3-5kPa

  • Overpressure effects to structures (cont.)

    • Apparently effect to buildings are strongly related with building elements construction characteristics, as for example:

      • shape

      • dimensions

      • material of construction (brick wall, reinforced concrete wall etc.),

      • type of window used (old type-single ones versus modern-double ones)

    • Effects are related also with probit functions for damage to both human and structures



  • Overpressure effects to structures (cont.)

    • Effects are related also with probit functions for damage to either human and structures

    • Some probit functions use in addition to overpressure, the impulse parameter (is)

  • Overpressure endpoints in Safety Reports

    • Usually, impulse parameters is not taken into account for endpoints defined in legislation, guidance for Safety Reports (especially for non-probabilistic approach)

    • Common characteristic : endpoints defined for effects only to structures

  • Overpressure endpoints in Safety Reports (cont.)

    • France :

      • 200 mbar : significant lethal effects

      • 140 mbar : lethal effects threshold

      • 50/20 mbar : irreversible effects (direct/indirect)

    • Greece :

      • 350 mbar, severe and not repairable damage to bearing structure and walls

      • 140 mbar, damage to bearing structure and walls

      • 50 mbar, simple cracks in walls, damage to doors, windows

  • Overpressure endpoints in Safety Reports (cont.)

    • Italy :

      • 300 mbar, high lethal effects

      • 140 mbar, lethal effects threshold

      • 70 mbar, irreversible effects

      • 30 mbar, reversible effects

    • Portugal :

      • 140 mbar : lethal effects

      • 50 mbar : irreversible effects

  • Overpressure effects. What about people ?

    • Effects to humans are present at similar or higher overpressures than for effects to structures. Examples :

      • 1000 mbar : Probability of death due to lung hemorrhage 0.5%. Fatality to people expected for extremely high overpressures

      • 350 mbar : Probability of 5% of ear drum rupture

    • More severe effects expected to people due to building collapse, window fragments injuries (indirect effects)

  • Domino effects

    • Evaluation of secondary accidents expected due to initial accident (internal primary accident, or known external accident)

  • Domino effects (cont.)

    • Example case : PEMEX Mexico City 1984

    • Initial LPG pipeline rupture lead to 19 successive BLEVEs

  • Domino effects (cont.)

    • Analysis outcome expectations :

      • Accident sequences

      • Comment for accident escalation (secondary accident results in more extended consequences)

      • Review if all secondary accidents had been included in risk assessment of establishment in the first place

      • Re-evaluation of safety measures for primary accident










Domino radius

Domino radius

Domino radius



Identification of equipment

within Domino radius












  • Domino effects (cont.)

  • Domino effects (cont.)

    • Domino effects expected due to

      • Thermal radiation (pool fire, jet flame)

      • Overpressure

      • Missiles (BLEVE/fireball)

    • No Domino effects attributed from flash fire or toxic effects

      • Indirectly only effects could be expected from deaths of operators

  • Domino effects (cont.)

    • Thermal radiation : Domino effects due to effect to support structures and equipment (steel) (not for buildings). Both L1 and L2 (deformation of structures) damage levels under interest

    • No detailed missiles (fragment) analysis expected. Stochastic phenomenon :(fragment size, energy, direction) with inherent analysis difficulty

  • Domino effects causes (cont.)

    • BLEVE/fireball

      • Thermal radiation not considered to cause secondary accidents due to very limited duration (up to 30 sec)

      • Missiles contribute to loss of containment with expression of secondary accidents (pool fire, jet flame) which can also lead even to BLEVE

      • Missiles can be expected up to appr. 1 km away

  • Domino effects endpoints

    • France :

      • 8 kW/m2, thermal radiation

      • 200 mbar, overpressure

    • Greece :

      • 37,5 kW/m2, thermal radiation (pool fire/jet flame)

      • BLEVE radius, jet flame length

      • 500 mbar, overpressure

  • Domino effects (cont.)

    • Italy :

      • 12.5 kW/m2, thermal radiation

      • 200-800 m, BLEVE

      • 300 mbar

    • Spain :

      • 8 kW/m2, thermal radiation

      • 160 mbar, overpressure

  • Domino effects (cont.)

    • Primary accident in establishment

      • Straight forward calculation of Domino effects within installation based on defined Domino endpoints

      • What if Domino distance extends to third party establishments ?

  • Domino effects example

    • Comment Domino effects from tanker BLEVE

  • Domino effects example (cont.)

    • “Internal” effects

      • Domino radius includes LPGSITE tanks. Secondary accidents expected in LPGSITE tanks, resulting, in worst-case, in more severe consequences compared to primary accident (tanker BLEVE), due to higher capacity of tanks (100 m3) than tanker capacity (appr. 40 m3)

      • Domino radius includes other LPGSITE areas (e.g. cylinder filling station, piping network). Not significant secondary accidents, due to less severe consequences in those areas

  • Domino effects example (cont.)

    • “External” effects

      • Domino radiusincludes areas of GASCOMP site

      • GASCOMP must be informed in order to take the relevant risk into account in its own risk assessments

      • Usually no detailed map of neighbour site is available, nor details of operation

      • Not detailed comments to be made from LPGSITE for accidents in GASCOMP

  • Domino effects example (cont.)

    • Example of comments to be made from GASCOMP (owner and responsible for risk analysis) on “external” effects from LPGSITE primary accident

      • Domino area does not include GASCOMP tanks area, or road tanker station. No secondary accidents expected in this area (excluding fragment effects)

      • Domino area includes pump station

      • GASCOMP must examine accidents in pump station (and in piping included in domino area)

  • “External” Domino effects summary

    • For primary accident in establishment A

      • No information on neighbor establishment B available (operation data, drawings)

      • No requirement for A to carry out consequence analysis for affected area of neighbor B

      • Authorities must provide the information to the neighbor B for its affected area

      • The neighbor B (owner and responsible for risk analysis) completes its own risk assessment, taking into account the additional source of accident in its establishment from primary accident in establishment A

  • Literature for Effects to People & Structures, Domino Effects Analysis

    • Lees’ Loss Prevention in the Process Industries, Elsevier Butterworth Heinemann, 3nd Edition, 2005

    • Methods for the Determination of Possible Damage to People and Objects Resulting from Releases of Hazardous Materials , Green Book, CPR 16E, TNO, 1992

    • Guidelines for Quantitative Risk Assessment, Purple Book, CPR 18E, VROM, 2005

    • Methods for the Calculation of Physical Effects due to Releases of Hazardous Materials (Liquids and Gases), Yellow Book, CPR 14E, VROM, 2005

    • Guidelines for Chemical Process Quantitative Risk Analysis, CCPS-AICHE, 2000

  • Literature for Effects to People & Structures, Domino Effects Analysis (cont.)

    • Safety Report Assessment Guides (SRAGs), Health and Safety Executive, UK

    • HSE, Research Report 182, Development of methods to assess the significance of domino effects from major hazard sites, 1998

    • Guidelines for Evaluating the Characteristics of Vapour Cloud Explosions, Flash Fires and BLEVEs, CCPS-AICHE, 1994

    • Assael M., Kakosimos K., Fires, Explosions, and Toxic Gas Dispersions, CRC Press, 2010

    • C. Delvosalle, F. Benjelloun, C. Fiévez,, A Methodology for Studying Domino Effects, Faculté Polytechnique de Mons,Ministere Federal de l’;Emploi et du Travail, July 1998

    • RIVM, Instrument Domino Effecten, May, 2003 (in Dutch)

  • Literature for Effects to People & Structures, Domino Effects Analysis (cont.)

    • Taylor J., Risk Analysis for Process Plant, Pipelines and Transport, E&FN SPON, 1994

    • Prugh R., The effect of Explosive Blast on Structures and Personnel, Process Safety Progress, p.5, Spring 1999

    • N. Markatos, NTUA, Chemical Engineering Department, Methodology of Assessment of Consequence from fire in Pesticide installations, 2001 (in Greek)

    • Derivation of IDLH values, NIOSH 2014

    • Technical Guidance for Hazards Analysis Guidance for Hazards Analysis - Emergency Planning for Extremely Hazardous Substances, U.S. EPA, FEMA, DoT, December 1987