“Separation Distances in NFPA Codes and Standards”[1]

Cassio Ahumada

M.S. in Chemical Engineering

Mary Kay O’Connor Process Safety Center

Texas A&M University, College Station.

October 26, 2015

Steering Committee Meeting

Outline

Introduction

Motivation

Literature Review

Case Study

Separation Distances Development

Conclusion

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Introduction “NFPA 400 consolidates fundamental safeguards for the storage, use, and handling of hazardous materials in all occupancies and facilities. The Code does not apply to storage or use of hazardous materials for individual use on the premises of one- and two-family dwellings”

(NFPA 400, 2106)

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2010 2013 2016 • NFPA 430, NFPA 432

and NFPA 490; • Hazardous material

found in building and fire codes.

• Maximum allowable quantity (MAQ);

• Oxidizer Table.

• Ammonium Nitrate requirements;

• Oxidizers were reclassified;

• MAQ tables.

Introduction Separation Distances

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Table obtained from NFPA 5000[3]

Motivation Recent accidents have highlighted a problem with storage of hazardous materials regulation and related separation distances around the facilities.

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Blast radius of the fertilizer plant explosion[5]. Aerial photos of damage by fertilizer plant explosion[4].

Literature Review Types of Approach[6]

Consequence-Based: Maximum credible scenarios (MCE);

Worst case scenario;

Results might not be economic viable[7,1].

Risk- based: Range of all credible hazard scenarios;

Separation distance is obtained according to the risk acceptance criteria;

Requires a good understanding of the frequency and consequence of each potential scenario[8].

Lookup tables: Based on historic events and good engineering practice;

Fire and explosion scenarios;

Dow Fire and Explosion Index[7];

Its efficacy is not confirmed[1].

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Literature Review Consequence-Based:

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Toxic Release

Explosion Hazards

Fire Scenarios

Dispersion Modeling

Overpressure quantification

Thermal Dosage

Effect on People

Building response and occupant

vulnerability[8,9]

Exposure criteria[10]

Scenario Identification

Consequence Estimation Evaluation

Evaluation

Overall Risk

Societal/ individual Risk

Criteria[11]

Dispersion Modeling

Overpressure quantification

Thermal Dosage

Effect on People

Building response and occupant

vulnerability[8,9]

Consequence Estimation Scenario Identification

Toxic Release

Explosion Hazards

Fire Scenarios

Likelihood

Literature Review Risk-Based:

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Literature Review Ammonia Release Example[12]

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Parameter Value

Wind speed= 3 m/s

Cross-sectional Area = 490 mm2

Release Duration= 10 min

Concentration < ERPG2 = 150ppm Distance > 398 m

Consequence-based

Risk-based

Case Study: Ammonium Nitrate[1] Objective

Test both process-to-process separation distance and process-to-personnel separation distance.

Materials

Hazard Source: Ammonium Nitrate Fuel Oil (ANFO)

industrial explosive mixture used in mines and quarry operation[13];

85-95 % porous Ammonium Nitrate (NH4NO3) and 4-7% of fuel oil[14];

3,000 lb (TNT equivalent= 2,460) [1];

More predictable and reliable during detonation.

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Case Study: Ammonium Nitrate[1] Materials

Stored Materials: Industrial Grade Ammonium Nitrate (1,600 lb)

Melting point: 337◦F

Stability: Stable under normal conditions. May explode when subjeted to fire, supersonic shock, or high-energy projectile impact[15];

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@ high T: explosive decompositions [16]:

2NH4NO3 →2N2(g)＋O2 (g)＋4H2O (g), ΔH=-1057 kJ/mol

8NH4NO3 →5N2 (g)＋ 4NO＋ 2NO2 (g)＋16H2O (g), ΔH=-600 kJ/mol

Case Study: Test Setup[1]

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ARA’s Pecos Research and Testing Center (PRTC)

Google maps view[8]

Case Study: Instrumentation[1]

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Sensors

AN Storage ANFO Donor

Steel Wall

Camera

Data Aquisition System

Case Study: Qualitative Results[1]

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Bag 1 (42’) Bag 2 (54’) Bag 3 (66’)

Case Study: Qualitative Results[1]

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t = 5.06 ms

Distance is not adequate!

Case Study: Process-to-personnel results[1]

Qualitative

No damage was observed to the wall or witness plate;

Slight movement was captured;

No Failure of the structure.

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Quantitative

Not reliable;

No discernable blast wave arrivals;

Lost of communication.

Serious Injuries and fatalities are not expected!

Time-pressure histories for the sensors near wall

Overpressure Estimation

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[18] Sochet, I., et al., Blast wave parameters for spherical explosives detonation in free air. Open journal of safety science and technology, 2011. 1(02): p. 31.

Blast Wave Parameters of ANFO[18]

Spherical explosives denotation; It depends on physical and chemical properties.

Overpressure Estimation

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Component ΔP (kPa)

Bag 1 (13.4m) 564

Bag 2 (17.0m) 306

Bag3 (20.1m) 212

Wall (353.6m) 2.1

“Safe Distance”(95% probability of no serious damage) [19]

Case Study: Conclusion[1]

Low effect to personnel due to overpressure is expected if the separation distance for inhabited buildings is implemented;

Serious injuries and deaths could occur if the workers are in the process area;

Separation distance for storage of AN solids are inadequate;

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Separation Distances Development[1]

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Consequence-Based Approach

Tests similar to the case study presented;

Measurement of the damage during a catastrophic failure;

Central charge positioned in the center of a pad;

Place storage containers according to standards.

Risk-Based Approach

Statistical analysis to test general design elements;

Probability of damage as a function of distance;

Risk of exposure is evaluated.

Summary

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Concerns regarding the safe distances of NFPA 400;

Methodologies to calculate separation distances;

Case study for Ammonium Nitrate;

Experimental methods to determine the separation distances.

References

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1. Argo, T. and E. Sandstrom, Separation Distances in NFPA Codes and Sandards. 2014, The Fire Protection Research Foundation NFPA Website

2. NFPA, Fire protection guide to hazardous materials. 2015: National Fire Protection Association.

3. NFPA, Building Construction and Safety Code. 2015: National Fire Protection Association.

4. Gutierrez, T., Arial photos of damage by fertilizer plant explosion in West, Texas 2013: The Associated Press.

5. CBS News, A map showing the blast radius of the fertilizer lant explosion in West, Texas, F.s.f.s.a.d.T.f.p. blast, Editor. 2013.

6. API, R., 752. Management of Hazards Associated with Location of Process Plant Buildings–, 2003.

7. Prophet, N. The benefits of a risk‐based approach to facility siting. Process Safety Progress 2012 [cited 31 4]; 377-380].

8. CCPS, Guidelines for Evaluating Process Plant Buildings for External Explosions, Fires, and Toxic Releases (2nd Edition). Center for Chemical Process Safety/AIChE.

9. Zipf, R.K. and K. Cashdollar, Effects of blast pressure on structures and the human body. National Institute for Occupational Safety and Health (NIOSH), 2006.

10. US Environmental Protection Agency, Risk Management Program Guidance for Offsite Consequence Analysis 1999.

11. Safety Progress, 2011. 30(4): p. 408-409. CCPS, Guidelines for Developing Quantitative Safety Risk Criteria. Center for Chemical Process Safety of the American Institute of Chemical Engineers, New York, 2009. 210.

12. Gawlowski, M., et al., Deterministic and Probabilistic Estimation of Appropriate Distances: Motivation for Considering the Consequences for Industrial Sites. Chemical Engineering & Technology, 2009. 32(2): p. 182-198.

13. Sharma, P.D. Low density, porous ammonium nitrate granules( for ANFO)-COst effective low cots technology [cited 10/11/2015; Available from: https://miningandblasting.wordpress.com/.

14. ANFO. MSDS 1009 [cited 2015 10/11]; Available from: http://www.dynonobel.com/~/media/Files/Dyno/ResourceHub/Safety%20Data%20Sheets/North%20America/1009%20ANFO_Fragpak-Waterblock.pdf.

15. Ammonium Nitrate. MSDS 1020 2015 [cited 2015 10/11]; Available from: http://www.dynonobel.com/~/media/Files/Dyno/ResourceHub/Safety%20Data%20Sheets/North%20America/1020%20SuperPrill.pdf.

16. Han, Z., et al., Ammonium nitrate thermal decomposition with additives. Journal of Loss Prevention in the Process Industries, 2015. 35: p. 307-315.

17. Google Maps. Texas 2015 Available from: https://goo.gl/maps/a9E7AZmRP9L2.

18. Sochet, I., et al., Blast wave parameters for spherical explosives detonation in free air. Open journal of safety science and technology, 2011. 1(02): p. 31.

19. Crowl, D.A. and J.F. Louvar, Chemical Process Safety-Fundamentals with Applications, (2011). Process Safety Progress, 2011. 30(4): p. 408-409.

Acknowledgement • Dr. Sam Mannan

• Dr. Noor Quddus

• Dr. Hans Pasman

• Dr. Sonny Sachdeva

• Dr. William Pittman

• Ms. Valerie Green

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• Dushyant Chaudhari

• Juliana Guarguati

• Yue Sun

• All members of SC

• All members of MKOPSC

Thank you & Questions?

Cassio Ahumada M.S. in Chemical Engineering

Mary Kay O’Connor Process Safety Center cassioahumada@tamu.edu

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