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40th Annual Engineering Insurance ConferenceOctober 10, 2013 , Toronto, Canada

Ali Reza, P.E., CFI1What is an Explosion?Does an explosion require a fire?What is a fire?Why is this relevant?A pressure vessel in natural gas processing failed in service. Head separated from vessel because attachment pins failed. Extensive damage and very large fireGas processing company had insurance coverage for mechanical failures but not for fire and explosionMechanical failure of head pins caused by gasket failure and subsequent uneven gas pressure against headThe gasket failure before the head failure caused a small gas leak. Did that leak ignite? Although the fire (if it did occur) from this small leak could not cause the blow out, could it trigger the fire exclusion for the property insurer?Does the blow-out of the head qualify as an explosion? Should the damage that occurred due to the fire after the blow-out be excluded from coverage?

Coverage disputes: First case study

Case study 1: Overview of gas processing facilityCase study 1: Clamp push-out initiated by gasket failureVessel filters dust and water droplets from gas as it is pumped out of the ground. 1.07 m diameter, 5 m length, 140 bars internal pressureRemovable closures at each endTwo gasket leaks before accident: one 3 days earlier, the other on day before accidentReplacement O-rings may have been too large in cross-section. O-ring ruptured under clamp (pushed out during accident)Draw-bolt retaining pin broke and nut stripped from safety boltHead ejected 500 m, extensive mechanical damage and fire to facility

Gasket rupture

Pressure failureCase study 1: Details of head-cover failureClamping mechanism

Normal forces on clamp

Subject vessel, failed head at top

567 kg steel head launched at high speed

Case study 1: Ejected head

Case study 1: Post incident damageThe head cover for a hydroelectric turbine separated from the main turbine body, permitting a substantial amount of water and oil to escape from the confined chamber. Significant property loss damageProperty insurance covered certain listed perils, including loss caused by explosion. However, mechanical breakdowns were excludedInvestigation concluded that studs securing the head cover failed because they had not been properly heat treatedHydroelectric company employees reported a loud initial blast followed by a series of resonating thunder-like explosionsLawsuit between hydroelectric company and insurer after insurer denied coverageDid an explosion occur after the mechanical breakdown?

Coverage disputes: Second case study

Case study 2: Typical turbine arrangement

Institute of Engineering and Technology (UK, 2011)2009 Hydroelectric turbine failure SayanoShushenskaya Power plant (Siberia) Case study 2: Damage from similar incidentTurbine approximately 142 vertical feet below water level (penstock head)Hydraulic pressure of 62 psigInvestigation revealed head cover assembly had been violently lifted away from main turbine bodyAll retaining studs had failedSignificant momentum transfer from the escaping waterFlooding and mechanical damage caused loss of 452 MW generating capacity for several monthsNo gas involved in incidentCase study 2: Violent incident. Large lossMechanical problem caused misalignment of the output shaft of large chiller, such that it rubbed against the cast iron housing. Subsequent sustained exothermic reaction between the aluminum and the decomposition products of the refrigerant. Failure of rupture disk and elbow caused extensive damageDispute between Property insurer and Boiler and Machinery reinsurer on who should cover this lossProperty insurance covered fire and explosion but excluded mechanical breakdownBoiler and Machinery insurance covered mechanical breakdown Did a fire or explosion occur in this incident?

Coverage disputes: Third case studyFrictional heat from the spinning impeller (8,000-10,000 rpm) rubbing against the cast iron housing sufficient to melt the impeller (650C). R-11 refrigerant decomposition occurs at 1100 F (593.3 C), releasing chlorine.Chlorine is an aggressive oxidizer similar to oxygenThe molten aluminum reacted with the chlorine, creating aluminum chloride The heat released sustained the reaction, further melting layers of aluminum and decomposing additional amounts of R-11The gases pressurized the system and ruptured an elbow and a stainless steel hoseThe reaction also produced copious amounts of Carbon (soot)

Case study 3: A vigorous chemical reaction

Heated distorted turning vanes

Damage around ruptured hose

Ruptured hose

Suction vanesCase study 3: Heat damage was obviousThe terms fire or explosion was not clarified or defined in any of the disputed policiesSome but not all policies clarified fire (but not explosion) coverage after mechanical breakdown:Loss or damage caused by or resulting from any of the following causes of loss:(1) Fire (including fire resulting from an Equipment Breakdown Loss); or water or other means used to extinguish a fire.(2) Explosion of gas or unconsumed fuel within the furnace of any boiler or fired vessel or within the passages from that furnace to the atmosphere.(3) Any explosion (except for explosion of steam boilers, steam piping, steam engines or steam turbines.Which brings us back to our questions: What is an explosion? What is a fire?Each matter had policy language challengesFrom a colloquial perspective (Webster, McGraw Hill) explosions share distinct characteristicsSuddennessNoiseRelease of internal energyBursting or fragmentationExpansion of gases?Combustion and fire science require elements of fireFast chemical reaction that convert potential (chemical or nuclear) energy to thermal energyRapid pressure riseExplosion investigators highlight the effects but not the causesRupturing, fragmentation, burstingWhat is an explosion? -1Safety standards concerned with both effect (bursting, rupture) and cause (deflagration, combustion, overpressure)Required element is the rapid expansion of gasesNFPA 921- 2004 : The sudden conversion of potential energy (chemical or mechanical) into kinetic energy with the production or release of gases under pressure, or the release of gas under pressure. These high pressure gases then do mechanical work such as moving , changing, or shattering nearby materialsNFPA 68 -2007/NFPA69-2008: The bursting or rupturing of an enclosure or a container due to the development of internal pressure from a deflagration FM Global Data Sheet FMDS0700 (September, 2006): An explosion is a rapid transformation of potential physical or chemical energy into mechanical energy and involves the violent expansion of gases

What is an explosion? -2Six broad definitions now accepted. All involve gas expansionPhysical (Overpressure, BLEVE)Chemical (Reaction, Thermal, Deflagration, Detonation)Four well characterized phenomena serve as benchmarksDetonation of a high explosive (e.g. TNT or ANFO)Deflagration or rapid, subsonic combustion (e.g. fuel air mixture)Rupture of a gas pressurized vessel (e.g. steam boiler)All three produce gas expansion, rapid release of energy. Significant pV workHydrostatic forced displacement (e.g. fatigue failure of a blind flange)Incompressible fluid. No pV work

What is an explosion? -3From a colloquial perspective (Webster), Fire is the phenomenon of combustion manifested in light, flame and heatIn scientific literature, combustion is defined asAny chemical reaction accompanied by liberation of heat and emission of light (Demidov, 1965)A self-sustained, high-temperature oxidation reaction (Babrauskas, 2003) In Industry, combustion is defined as An exothermic chemical reaction usually (emphasis added) involving oxidation of a fuel by atmospheric oxygen. Glowing combustion involves direct oxidation of a solid or liquid fuel, such as charcoal or magnesium. Flaming combustion involves a gas phase or volatile matter driven off by heat (FM Global, 2006)What is a fire?The fire tetrahedron requires a supply of fuel, a supply of an oxidizer, an ignition source, and a sustained chain reaction

What does the NFPA state?There can be an implicit perception that fires only involve air or oxygenFor most fire protection purposes, fire is: the combination of fuel and oxygen in blazing combustion Fire begins when an ignition source connects with a combustible material in the presence of oxygen. Rapid oxidation, usually with the evolution of heat and light; heat fuel, oxygen and interaction of the three Coverage disputes can occur if insurer contends that only fires involving atmospheric oxygen are covered

What is a fire? -2Gas storage vesselCoverage for mechanical failures/breakdowns but not explosionsDoes the blow-out of the head after the mechanical failure qualify as an explosion? Should the subsequent fire damage be excluded from coverage?Hydroelectric turbineCoverage for explosion but not mechanical failures/breakdownsSignificant damage but did an explosion occur?Exothermic reaction in compressorCoverage for explosions and fires but not mechanical breakdowns/failuresSignificant heat but no oxygen. Did a fire occur?Did an explosion occur?

Case studies: A recapMechanical failure caused the head to be violently ejectedWas this an explosion? Sudden release of high-pressure gas, but there was no increase in pressure inside the vessel and no combustion or chemical reaction prior to the incidentHowever, there was significant pV work due to the depressurization of the vesselQualifies as an explosion based on definitions we just discussed: Rupture of a gas pressurized vesselFire damage due to ignition of natural gas after explosionCase settled by insurance companyNo explicit language in policy stating that fire or explosion exclusion applied after a mechanical failure

Case study 1: Should this be a covered loss?Mechanical failure of bolts holding head to turbine bodyNo combustion or chemical reaction. No expansion of gases. No rapid pressure rise Water is essentially incompressible. No pV workDoes not qualify as explosion: Hydrostatic forced displacementBulk of observed mechanical damage due to the momentum of the water jet imparted by the 144-foot headAnalogous to a high pressure fire house knocking down a screen doorCase settled after expert reports because policy language did not define explosionCase study 2: Should this be a covered loss?As defined by the NFPA, the fire tetrahedron requires Fuel, oxidizer, ignition source and a sustained chain reaction Investigation confirmed all four components were present The oxidizer was not oxygen, rather chlorine from the decomposition products of the R-11Some insurance companies call this event a Freon FireThe heat build-up from the fire and the decomposition of the refrigerant was accompanied by an increase in pressure. This is a requirement of the equation of state pV=nRT The overpressure ultimately caused the rupture of an explosion relief disc, failed a connected stainless vent hose and a cast iron elbowCombustion products vented into room causing electrical damageSplit verdict during arbitration because definition of fire and explosion not included in policyCase study 3: Should this be a covered loss?We have always understood that the everyday definition of explosion and fire should apply An explosion is a large scale, rapid and spectacular expansion, outbreak, or other upheavalThe definition for fire is one that's commonly accepted, one that is understood by the insurance underwriting and buying public, and one that requires that fuel [be] ignited and combined with oxygen to produce heat, light and flame

Precise definitions of fires and explosions and the sequence of mechanical failures vis--vis a fire or explosion should be included in policy language

Some common refrains during coverage disputes