Jet Fuel Testing What’s the significance? Laurence Hayden North East Regional Manager North East Regional Manager.

Jet Fuel Testing

What’s the significance?

Laurence HaydenLaurence Hayden North East Regional ManagerNorth East Regional Manager

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THOUGHTS ON JET FUEL SAFETY

► In terms of true safety risk, jet fuel quality testing is perhaps the most critical of any testing done in an inspection laboratory

► Every responsible party in the chain of jet fuel manufacturing, sampling and testing should ask the following question:

“What if I am boarding the very plane utilizing this fuel?”

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JET FUEL PRODUCTION

Paraffinic Naphtha

Aromatic / Naphthenic

Kerosene

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CHEMICAL PROPERTIES AND COMPOSITION

► Predominant Components

Straight-run kerosene

• Traditionally raw or cracked components create out of specification fuel

• Hydro-cracking processing in recent years introducing higher quality fuels

Straight run kerosene/naphtha blends

Often kerosene from refinery process requires further treatment

Aromatics Limited

• Aromatics do not burn as clean as other hydrocarbons and can cause smoke and carbon deposits, as well as increase the luminosity of the combustion flame

• ASTM D1319 “Standard Test Method for Hydrocarbon Types in Liquid Petroleum Products by Fluorescent Indicator Adsorption”

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SPECIFICATIONS

► ASTM D1655 “Standard Specification for Aviation Turbine Fuels”

► MIL-DTL-83133F “Detail Specification: Turbine Fuel, Aviation, Kerosene Type, JP-8, NATO F-35, and JP-8+100”

► Ministry of Defense Standard 91-91 (DEF STAN): Turbine Fuel, Aviation Kerosene Type, Jet A-1

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SPECIFICATIONS

► ASTM D1655 “Standard Specification for Aviation Turbine Fuels”

► MIL-DTL-83133H “Detail Specification: Turbine Fuel, Aviation, Kerosene Type, JP-8 (NATO F-34), NATO F-35, and JP-8+100”

► Ministry of Defense Standard 91-91 (DEF STAN): Turbine Fuel, Aviation Kerosene Type, Jet A-1

AppearanceCompositionVolatilityFluidityCombustionCorrosionThermal StabilityContaminantsWater Separation Conductivity & Lubricity

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SAMPLING

Sampling procedures are followed as per API Chapter 8

ASTM D4306-07 “Standard Practice for Aviation Fuel Sample Containers for Tests Affected by Trace Contamination”

• ASTM Practice D4057 addresses general sampling of petroleum products

• Testing affected by polar or other compounds

• Properties of concern include water separation, copper corrosion, conductivity, thermal stability, lubricity and trace metals

• Particulate contamination and free water content likely affected by any sampling container

• Table 1 provides a summary of container recommendations

• Section 6 provides approval for containers

• Clean and/or dedicated sampling equipment is critical

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ASTM D4306-12 SAMPLE CONTAINER RECOMMENDATIONS

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Appearance

► Visual Appearance

► Color – Saybolt Color ASTM D156

► Particulate Contamination - ASTM D5452

• Filter membrane delta weight

• Referee method by MIL-DTL-83133 and method specified by DEF STAN 91-91

► Particle Count – IP 564 / IP 565 / IP 577

• Works by laser obscuration to detect particulate down to 4 microns

• Field units now being introduced

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COMPOSITION

► Total Acidity

ASTM D3242 “Standard Test for Acidity in Aviation Turbine Fuel”

Acidity can effect water separation ability of fuel

Acidity can cause corrosion

► Sulfur

May adversely effect carbon-forming tendency in combustion chamber

Sulfur oxides may cause corrosion

Corrosion tests to be discussed later

Several possible methods are specified

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CHEMICAL PROPERTIES AND COMPOSITION, continued

► Sulfur Mercaptan

Causes odor issues

Adverse effect on some elastomers causing leaks

May cause issues with corrosion

ASTM D3227 “Standard Test method for (Thiol Mercaptan) Sulfur in Gasoline, Kerosene, Aviation Turbine and Distillate Fuels”

► Doctor Test- ASTM D4952 or IP30

Alternative method per MIL-DTL-83133H and DEF STAN 91-91

Sample is shaken with sodium plumbite solution, a small quantity of powdered sulfur added, and the mixture shaken again. The presence of mercaptans or hydrogen sulfide or both is indicated by discoloration of the sulfur floating at the oil-water interface or by discoloration of either of the phases.

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VOLATILITY

► Overall seek to balance efficiency of combustion, safety and availability

► ASTM D86 “Standard Test Method for Distillation of Petroleum Products at Atmospheric Pressure” Specifications for 10%, 50%, 90% to ensure spread of distillation ranges as

opposed to only light and heavy components

Final boiling point specification to ensure absence of heavy materials with poor combustion

Distillation residue specification to ensure fuel is consumed without excessive residue

► ASTM D2887 “Standard Test Method for Boiling Range Distribution of Petroleum Fractions by Gas Chromatography” Alternate distillation method for ASTM D1655 and Mil spec: ASTM D86 is referee

May be used per DEF STAN 91-91 for Cetane Index Calculation

Decreases analysis time

Values differ from D-86 but differences are quantified

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VOLATILITY, continued

► Flash Point

Results determine flammability of the product

ASTM D1655 specifies ASTM D56 “Standard Test Method for Flash by Closed Cup Tester” (Tag)

ASTM D3828 “Standard Test Methods for Flash Point by Small Closed Cup Tester” is specified as the alternate method

• Decreases sample size

• Lower cost

• Results generally up to 2ºC lower than ASTM D56, and in the case of dispute, D56 is the preferred method

DEF STAN 91-91 specifies IP170 “Determination of Flash Point- Abel Closed Cup Method”

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LOW TEMPERATURE PROPERTIES

► Must ensure that fuel is delivered to the combustion chamber, including long flights at high altitude

► Freeze Point- solids formation

ASTM D2386 “Standard Method for Freeze Point of Aviation Fuels” most accepted method

Other alternative methods in specifications

► Viscosity, -20ºC- “pumpability”

ASTM D445/ IP470 “Standard Method for Kinematic Viscosity”

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COMBUSTION QUALITY

► Critical for fuel to have good combustion characteristics- burn efficiently

► Net Heat of Combustion: quantity of heat liberated by the combustion of a quantity of fuel with oxygen Energy produced per unit weight used in flight design

Energy used per unit volume used in capacity versus refuel needs

ASTM D4809 “Standard Test Method for Heat of Combustion of Liquid Hydrocarbon Fuels By Bomb Calorimeter”

ASTM D3338 “Standard Test Method for Estimation of Net Heat of Combustion of Aviation Fuels)

Other available methods as well

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COMBUSTION QUALITY, continued

► Testing values must meet specification for Smoke Point or Smoke Point and Naphthalenes

► ASTM D1322 “Standard Test Method for Smoke Point of Kerosene and Aviation Turbine Fuel” Provides an indication of the relative smoke producing properties of kerosenes and aviation

turbine fuels in a diffusion flame. The smoke point is related to the hydrocarbon type composition of such fuels. Generally the more aromatic the fuel the smokier the flame. A high smoke point indicates a fuel of low smoke producing tendency.

The smoke point (and Luminometer number with which it can be correlated) is quantitatively related to the potential radiant heat transfer from the combustion products of the fuel. Because radiant heat transfer exerts a strong influence on the metal temperature of combustor liners and other hot section parts of gas turbines, the smoke point provides a basis for correlation of fuel characteristics with the life of these components

► ASTM D1840 “Standard Test Method for Naphthalene Hydrocarbons in Aviation Turbine Fuel by Ultraviolet Spectrophotometry

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THERMAL STABILITY

► It is critical to maintain high performance of fuel at conditions of operation

► ASTM D3241 “Standard Test Method for Thermal Oxidation Stability of Aviation Fuels (JFTOT Procedure”

Measures level of deposits with heated surface

Utilizes both pressure change and visual inspection

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CORROSION

► Corrosion of engine and related equipment poses a safety hazard as well as large expense

ASTM D130 “Standard Test Method for Corrosiveness to Copper from Petroleum Products by Copper Test Strip”

• Assesses relative degree of corrosivity of a petroleum product

• Corrosive properties often due to sulfur but not directly related to sulfur content

• Test emulates high temperature and pressure conditions and provides a standard for visual comparison

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CONTAMINANTS AND OTHER IMPURITIES

► Water and Water Separation

Small traces of free water can adversely affect jet engine operation via ice formation or other inefficiency

Presence of surfactants or certain compounds in the crude can adversely affect water separation

ASTM D3948 “Standard Test Method for Determining Water Separation Characteristics in Aviation Turbine Fuels by Portable Separometer” the specified method per ASTM D1655 and DEFSTAN 91-91

• Water-fuel sample emulsion created using a high speed mixer

• Expelled through filter

• Measured on transmittance scale 50-100

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CONTAMINANTS AND OTHER IMPURITIES, continued

► Water and Water Separation, continued

ASTM D7224”Standard Test Method for Determining Water Separation Characteristics of Kerosene-Type Aviation Turbine Fuels Containing Additives by Portable Separometer” specified by MIL-DTL-83133H

• Published in July 2007 by ASTM to address ASTM D3948 Limitations

• Provides results similar to ASTM D3948 when strong surfactants are present, and ensure erroneously low results are not reported in the presence of weak surfactants that do not affect current commercial filter separator elements

• Filter media in coalescer test developed to perform similar to current commercial filter separator elements

• Better method precision

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CONTAMINANTS AND OTHER IMPURITIES, continued

► Existent Gum

Large quantities of gum are indicative of contamination of fuel by higher boiling oils or particulate matter and generally reflect poor handling practices in distribution downstream of the refinery

ASTM D381 “Standard Test Method for Gum Content in Fuels by Jet Evaporation”

• Uses steam for evaporation during analysis

• Referee method per ASTM D1655

IP 540 “Determination of the Existent Gum Content of Aviation Turbine Fuel – Jet Evaporation Method”

• Uses steam or air for evaporation during analysis

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CONTAMINANTS AND OTHER IMPURITIES, continued

► Biodiesel has become a major concern due to high quantity of usage in the diesel supply chain

Concerns due to biodiesel performance issues and the behavior of biodiesel at very low temperatures

IP 585 established to determine FAME in aviation turbine fuel- utilizes GC-MS with selective ion monitoring with a range of 0.5 to 50 parts per million

It is possible the test method is not capable of detecting all biodiesel contamination in jet fuel because the biodiesel pool can contain other components that were not included in the development of this test.

Known interference in presence of high concentrations of petroleum diesel. If fuel is contaminated with petroleum diesel at approximately 1.0 mass% or greater, then the test may report a false positive for FAME due to interferences.

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► FAME is a surface-active material.

Can adhere to pipe and tank walls as the biodiesel passes through, and then release from the walls into the following product, which may be jet fuel.

Small amounts of diesel containing FAME remaining within distribution manifolds, tanks, vehicles, and pipes can result in traces of FAME getting into jet fuel transported through the same components.

FAME contamination can impact the freezing point of jet fuel resulting in gelling of the fuel. These conditions can result in engine operability problems, and possible engine flameout

BIODIESEL SURFACE ADHERENCE

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BIODIESEL OXIDATION

► Biodiesel blends are subject to oxidation

• Oxygen will break these chains into shorter chain aldehydes and fatty acids, giving the fuel a rancid odor and increasing acidic properties.

• Oxidation of oils and fats by atmospheric oxygen is known as rancidity.

• Heat, light, presence of some metals, and pressure facilitate this process

• Oil becomes rancid within a short period of time

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► Consequences of oxidation-increased acidity

• Acidity can effect water separation ability of fuel and corrosion

• Test emulates high temperature and pressure conditions and provides a standard for visual comparison

• Small traces of free water can adversely affect jet engine operation via ice formation or other inefficiency

• Presence of surfactants or certain compounds in the crude can adversely affect water separation

BIODIESEL OXIDATION, continued

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► Increased acidity, continued

• Insoluble polymers (gums) are formed

• Large quantities of gum are indicative of contamination of fuel by higher boiling oils or particulate matter ASTM

• Possibly due to oxidative polymerization of smaller compounds

• May cause plugging of fuel delivery system

• Negative effect on thermal stability as more gums formed at higher temperature over time

BIODIESEL OXIDATION, continued

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SUMMARY

► Presentation is simply an overview of critical points of aviation fuel quality

► Other tests and properties, as well as alternative tests, are specified

► Lubricity, Conductivity, Silver Corrosion, Color and Microbial contamination are properties to consider

► Sampling and proper testing using adequate quality control tools are key to risk minimization of jet fuel production, transportation and end use

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QUESTIONS?