Richard L. Chapman

23rd National Tanks Conference

St. Louis, MO

March 21, 2012

ULSD Corrosion Issue-- Preventable, Treatable?

Agenda

ULSD Corrosion Assessment

Likely Causes

Recent Observations

Biological Testing

Low MW Species Results

Water Bottoms Testing

Housekeeping!

Summary

Assessment -- ULSD Corrosion Issue

Innospec involved in and studying problem for several years:

Member of CDFA Task Force

Internal company testing of key fuel/water properties:

Working with several refining and/or marketer customers;

Mostly affects retail/commercial UST & dispensing systems

Sporadic, inconsistent occurrence geographically;

Most OEM’s say not an issue.

ULSD Corrosion – Assessment

Samples from Innospec customers

across the US:

Majority of samples non-passing

for NACE corrosion

Mixture of tank and dispenser

samples

“Good housekeeping” customers

seem to have less problems?

Submersible Pump & Riser(L/H side is Al; R/H side is steel)

Submersible Pump Head(in vapor space -- never contacts fuel)

Recent photos from fiberglass UST

– Newer site tested positive for microbial activity

ULSD Corrosion – Assessment

Inside of steel tank caps (spare openings, highest point in UST, no fuel contact)

Bulbous globules thought to be of a microbial nature

ULSD Corrosion – Assessment

After 3 monthsNew steel corrosion coupon

ULSD Corrosion – UST Detail

No one cause, but rather a mixture……….

Microbial influence getting a lot of attention:

Low MW acids as microbial by-products valid;

Explains both fuel and vapor space corrosion;

Not uncommon to be positive for microbial activity

and/or higher low MW acids, yet have passing NACE;

Salt and other contaminants also a contributing factor?

ULSD Corrosion Update – Likely Causes

Corrosion inhibitor depletion (aka “soap”) theory – acidic additives

form soaps if contacted with excessive tank water cations from

salts or caustic:

Tank water from manufacturing processes (caustic/salt

upsets, biodiesel) provides Na, Ca, source etc.;

Corrosion protection lessened;

Effect similar to soaps formed from acidic lubricity improvers

(mono acids, etc.) and sodium/calcium – lubricity lessened

Poor housekeeping, no biological monitoring, improper application

of biocides exacerbates problem;

ULSD Corrosion Update – Likely Causes

Innospec Fuel Specialties testing ULSD terminal and retail tank

samples:

Bug testing, low MW acids, pH since early 2011

NACE corrosion testing (TM-0172) – ongoing, many years.

Majority of more recent samples positive for biological activity:

HY-LiTE (ASTM D 7463) and/or aerobic/anaerobic cultures;

Majority of samples (tank and dispenser) from nationwide survey

of varied suppliers show non-passing NACE results

ULSD Corrosion Problem – Recent Observations

Low MW acids present in most samples – acetic acid (as

acetate) predominates:

Acid/acetate determination by Ion Chromatography (IC);

pH results very variable, but usually low (4-6):

Addition of a specific biocide produces:

Excellent kill -- no culture growth, reduction in ATP

counts over time;

Raises pH to > 7.00

ULSD Corrosion Problem – Recent Observations

Biological activity established using ATP analyzer and culture tests:

Merck-Millipore HY-LiTE® ATP Analyzer (ASTM D7463) – 5 minute

result, reported as RLUs (relative light units):

<1000 RLU – negative;

1000-5000 RLU – positive – action level, possibly treat

>5000 RLU – positive, heavy – definitely treat with biocide

Culture Tests:

Anaerobic Organisms -- Easicult® S;

Aerobic Organisms (bacteria, fungi, molds)

– Easicult®

– Microbe Monitor 2 ( MM2)

Microbial testing in general agreement – positive HY-LiTE® results

typically showed positive bacteria, fungi, molds presence and vice-versa

ULSD Corrosion– Biological Testing

No single method appears to give accurate representation of what’s happening in the storage tank:

Example -- Detection of Viable Microbes:

HY-LiTE® detects ATP for a short period after using biocide and achieving a kill:

Cultures of the same samples show no growth*;

Trend can continue until ATP level is negligible;

Example -- Low MW Acid Species:

Anions still detected after neutralization (pH change from 4.61 to 8.04 still had significant levels of acetate, etc.)

Some culture media may need a neutralizer prior to using certain types of media.

ULSD Corrosion – Biological Testing

*MICROBIOLOGICAL MONITORING ON-SITE, E.C.Hill, D.J.Collins and

G.C.Hill, ECHA Microbiology Ltd

Biological Testing -- ULSD Retail Tank Example

0

2000

4000

6000

8000

10000

12000

0

1000

2000

3000

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8000

9000

Posi ve Culture - pH 4.61 Nega ve Culture - 8.04 RLU

mg/L

anio

n

Acetate

Formate

Lactate

HyLite RLU

Before Biocide After Biocide

Low MW acid species still

present after biocide - pH

4.61 => 8.04

Samples tested for low MW acids also revealed very high sodium levels:

Average of set was 4401 ppm Na (high = 7626 ppm);

Average of much larger data set from across the US was lower at 2492 ppm Na – still considered high…

Highest level observed ~23,138 ppm or roughly 2.3%!

Na levels roughly 20X average Ca levels (next highest cation concentration);

Suggests that some ULSD corrosion problems might be due to salt (in addition to bugs/low MW acid)?

ULSD Corrosion – Water Bottoms Testing

ULSD Corrosion – Water Bottoms Testing

0

5000

10000

15000

20000

25000

CO

9

CT

1

DE

1

FL

2

IA 5

LA

1

MA

1

ME

3

MI 3

MN

2

MO

2

MT

2

NE

1

NJ 1

NY

7

OH

2

OR

18

PA

40

SD

1

TN

1

TX

1

UT

2

VA

3

WA

1

WI 4

WY

3

pp

m

State

Sodium Levels by State in Water Phase

Housekeeping & Potential Fuel Quality Issues

– What’s Not in the Specs

Fuel specs don’t address water/contaminants that can lead to fuel

storage, dispensing, and vehicle engine problems:

No real water spec – BS&W spec (500 ppm) meaningless;

NACE corrosion – typically measured at refinery – tends to

degrade as fuel moves downstream – usually unknown at end

user;

Particulate/sediment – no gravimetric or particle size distribution

requirement (other than BS&W). OEM’s prefer PSD;

Manufacturing/blending contaminants – caustic, sulfates, salts,

surfactants -- usually well controlled but upsets do occur and can

lead to end user problems.

Housekeeping Concerns – Water!

Change from LSD to ULSD altered diesel fuel composition:

Holds half as much water �more tank water bottoms;

Increased environmental concerns/cost-cutting efforts

� harder to dispose of water bottoms;

End result � more water staying in tanks longer

Housekeeping – Changes in ULSD,-- Impact on biological problems

Changes in ULSD Impact on Microbial Growth

↓ Sulfur reduction 500 to <15 ppm ↑Sulfur antagonistic to microbial

growth

↓Aromatic and/or Olefin Content (includes phenolic compounds)

↑Aromatic and Phenolic

compounds are good growth inhibitors

↑ Saturates ↑Saturates preferred food source

compared to aromatics

↑ Water (free, non-dissolved) ↑ Free water availability increases

More Water Means…..

More potential bug problems – need water to grow;

Contaminates collect in water bottoms – salts, soaps, are

usually water soluble -- carried through distribution system;

Increased storage tank corrosion – more water leads to

premature corrosion -- especially if the water is caustic or

salt-laden.

Housekeeping Concerns – What Can Be Done?

Minimize upstream contaminants to fuel distribution system;

Manage water -- drain tank bottoms routinely;

Routine Testing:

Bug testing – prevents biological growth, helps control

downstream problems;

Proper biocide addition kills bugs and prevents corrosive

acids from forming;

Fuel corrosion -- protection diminishes as fuel travels downstream;

Cation testing -- high metals level can lead to problematic fuel.

Role of Fuel Additives

Quality fuel additives essential to good fuel quality:

Stability additives -- prolongs fuel life, limits oxidation and metal reactions;

Corrosion inhibitors -- protects metal in fuel systems;

Conductivity improvers – lessens static electricity, prevents fires/explosions;

Lubricity improvers – provides needed lubrication in diesel injection systems;

Biocides – preventive use minimizes bugs which may lead to corrosion;

Anti-foulant additives – counteracts fuel degradation & contaminant inter-

actions that lead to filter/injector plugging;

Refinery process streams and finished blends should be routinely tested/optimized

with proper additives & treat rates. Most refiners/suppliers already do this.

Summary-Conclusions

Fuel specs may not identify contaminants that can lead to poor fuel quality

and vehicle problems – corrosion just one of these;

Storage tanks susceptible to water build-up and related problems;

Water is fuel’s enemy – carries contaminants, leads to bugs, causes

corrosion;

Routine bug testing essential in preventing problems – fuel-soluble biocide;

Corrosion more problematic w ULSD & biofuels – end use NACE testing?

Quality fuel additives essential to good fuel storage, handling and

performance:

Fuel must be regularly tested -- correct additive type, optimum treat

rate;

Corrosion protection ensured all the way to final customer;

NACE spec within ASTM D975? - CDFA results may dictate this;

Terminal addition of corrosion inhibitor needed?

Good Housekeeping ensures fuel cleanliness - every fuel handler does their

part;

No water – no bug growth, no solvent to carry weak acids, Na

salts/contaminants;

Water/sediments routinely drawn off storage tanks;

Biological and cation monitoring of tank bottoms important – gives early

warning;

Additives important part in controlling bug growth, corrosion, fuel stabilization

ULSD Corrosion – Future Needs?

Contact Information

Rick Chapman

Industry Liaison Manager

Innospec Fuel Specialties

(630) 386-3406

rick.chapman@innospecinc.com